A Is A. l\ Y L A IN I) Geological Survey PRESENTED BY MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY BALTIMORE THE JOHNS HOPKINS PRESS 1929 WAVER LY PRESS, IXC. BALTIMORE. U. S. A. \ Z~7 (o(p\ Sac OF I2Z 33A5 ADVISORY COUNCIL Raymond A. Pearson Executive Officer PRESIDENT OF THE UNIVERSITY OF MARYLAND Joseph S. Ames Ex-Officio Member PRESIDENT OF THE JOHNS HOPKINS UNIVERSITY Robert W. Williams Baltimore John B. Ferguson Hagerstown « SCIENTIFIC STAFF Edward Bexxett Mathews State Geologist SUPERINTENDENT OP THE SURVEY Edward W. Berry Assistant State Geologist Joseph T. Sixgewald, Jr Geologist Eleaxora B. Knopf Geologist Anna I. Joxas Geologist Edward H. Watsox Assistaxt Geologist Also with the cooperation of several members of the bureaus of the National Government and Carnegie Institution. LETTER OF TRANSMITTAL To Raymond A. Pearson, President of the University of Maryland, Sir: — I have the honor to present herewith a report on The Physical Features of Baltimore County. This volume is the eleventh of a series of reports on the county resources, and is accompanied by large scale topographical, geological, and agricultural soil maps. The information contained in this volume will prove of both economic and educational value to the residents of Baltimore County as well as to those who may desire information regarding this section of the State. I am, Very respectfully, Edward Bennett Mathews, State Geologist. Johns Hopkins University, Baltimore, September, 1929. CONTENTS Page Preface 17 Development of Knowledge Concerning the Physical Features of Baltimore County. By Edward W. Berry 21 Introductory 21 Historical Review 21 History of Geographic Research 22 History of Geologic Research 34 Bibliography 38 The Physiography of Baltimore County. By Eleanora Bliss Knopf .... 58 Introductory 58 Geographic Location of Baltimore County 58 Physiographic Provinces of Maryland 59 Topographic Features of the Coastal Plain in Baltimore County. . . 61 Topographic Features of the Piedmont Province in Baltimore County 62 Meadow lowlands 62 Summit uplands 63 Stream gorges 63 Cause of the Topographic Differences 63 Progress of Normal Erosion Cycle 64 Characteristic Topography at Various Stages of the Erosion Cycle. 66 Topographic anomaly in Baltimore County 67 Renuvenation and successive peneplanations 68 Geologic age of uplifted and dissected peneplains 68 , Correlation of residuals of erosion 69 Study of Dissected Surfaces 69 Projected profiles 70 Maps 72 Divide profiles 72 Correlation of Buried Peneplains and Subaerial Surfaces 73 Coastal Plain Terraces of Pleistocene Age 74 Talbot Terrace 74 Wicomico Terrace 75 Upper and Lower Sunderland Terraces 76 Age of the Coastal Plain Terraces 76 Origin of the Coastal Plain Terraces 78 Piedmont Terraces and their Associated Gravel Deposits 79 Hamilton Terrace 81 Howard Park Terrace 82 Catonsville Terrace 82 Sweetair Terrace 84 s Contexts Page Reisterstown Terrace 85 Arcadia Terrace 86 Hampstead Terrace 86 Correlation of Piedmont Terraces 87 Origin of Piedmont Terraces 90 Stream adjustment 93 The Geology of the Crystalline Rocks of Baltimore County. By Eleanora Bliss Knopf and Anna I. Jonas 97 Relation of Geology to Landscape and to Economic Interest 97 Origin of Crystalline Schists 99 Outline of General Geology 102 Igneous Rocks 106 Gabbro 107 Hypersthene gabbr o 109 Hornblende gabbro 110 Meta-gabbro (hornblende gneiss) Ill Pyroxenite, peridotite, and serpentine 114 Granite 123 Pre-Glenarm granites 124 Post-Glenarm granites 125 Epi-Carboniferous granites 131 Alaskite porphyry 136 Pegmatite 136 Diabase 138 Crystalline Rocks of Sedimentary Origin 140 Pre-Cambrian 140 Baltimore gneiss 140 Glenarm Series 152 Setters formation 152 Cockeysville marble 162 Wissahickon formation 166 Peters Creek formation * 176 Age of the Glenarm Series 180 Structure 184 Folding 186 Faulting 190 Age of the structures 191 Geological History 192 The Geology of the Coastal Plain of Baltimore County. By Edward W. Berry 200 Introductory 200 The Lower Cretaceous Formations 200 The Potomac Group 201 The Patuxent Formation 201 The Arundel Formation 203 The Patapsco Formation 205 Contents 9 Page The Upper Cretaceous 207 The Raritan Formation 207 The Pleistocene Formations 209 The Brandywine Formation 210 The Sunderland Formation 211 The Wicomico Formation 212 The Talbot Formation 215 The Recent Deposits 216 The Mineral Resources of Baltimore County. By Edward B. Mathews and Edward H. Watson 219 Introductory 219 The Iron Ores 221 Iron Works in Baltimore County 222 The Ore Banks 225 The Carbonate Ores 225 The Building Stones 228 Granite 232 Marble 233 Gabbro and Serpentine 236 Gneiss 236 Flagstone 237 Fieldstone 238 Road Materials 238 Operations in Building Stone and Road Materials 240 Quarries in Granite 240 Quarries in Crystalline Limestone 243 Quarries in Trap 249 Quarries in Gneiss 254 Quarries in Flagstone 258 Sand and Gravel 263 Operations for Sand and Gravel 265 Clay and Clay Products 270 Operations for Clay 273 Feldspar 276 Quartz 280 Workings for Quartz 283 Chrome 284 Copper 287 The Water Resources 288 Surface Waters 288 Springs 289 Dug Wells 290 Artesian Wells 291 The Coastal Plain area 291 The Piedmont area 300 10 Contexts Page The Soils of Baltimore County. By Wm. T. Carter, Jr., J. M. Snyder, and 0. C. Bruce 305 Introductory 305 Soil Types 311 Summary 344 The Climate of Baltimore County. By Edward B. Mathews and Roscoe Nunn 347 Introductory 347 Atmospheric Pressure 348 Temperature of the Atmosphere 350 Frequency of days with frost 366 Frequency of cold waves 367 Killing frosts and the growing season 367 Warm days and the growing season 367 Warm days in summer 368 Humidity 369 Variations in humidity 371 Absolute humidity 373 Precipitation 374 Influences affecting rainfall 375 Variations in precipitation 375 Monthly, seasonal, and annual averages 377 Excessive rainfall 379 Dry spells 380 Wet spells 381 Snowfall 381 Sunshine and Cloudiness 382 Wind 382 The Magnetic Declination in Baltimore County. By L. A. Bauer 385 Introductory- 385 Meridian Line 385 Descriptions of Stations 387 Corrections for Secular and Diurnal Variations 391 The Forests of Baltimore County. By F. W. Besley 393 Introductory- 393 Distribution of the Forests 393 Description of the Forests 395 Native Trees 396 Important Timber Trees and their chief uses 398 The Lumber and Timber Cut 401 Forest Protection 403 Forest Management 405 Forest Planting 408 Summary 411 Index 413 ILLUSTRATIONS Facing page Plate I. Fig. 1. Profile of the divide between Patapsco and Gunpowder rivers. (Solid line shows Gwynns Falls-Gunpowder divide; broken line shows Gwynns Falls-Patapsco divide) 64 Fig. 2. Projected profile of the area between Parrs Ridge and the Coastal Plain 64 II. Block diagram of an area in northeastern Maryland and southern Pennsylvania showing Piedmont terraces and their stream continuation in fluvial benches 72 III. Map of Baltimore County showing the approximate outline of the Piedmont terraces 80 IV. Fig. 1. a. Water-worn gravels from 600-foot interstream upland at Randallstown ; b. From 540-foot interstream upland at Fishtown; c. From 320-foot terrace on Gunpowder Falls near Monkton 84 Fig. 2. a. Angular residual fragment of ven quartz, 480-foot level on Little Falls near Walker; b-d. High-level gravels from same locality; e-h. Gravels from present flood plain at same elevation and locality as b-d 84 Fig. 3. Water-worn gravels from near Reisterstown: a. Local- ity B of Barrell; b. Locality C of Barrell 84 V. Map showing the course of Little Falls near Walker. Cross indicates position of high-level gravels. Parkton Quadrangle 96 VI. Fig. 1. View showing injection of granite and pegmatite into Setters near the railroad bridge crossing Gunpowder Falls about 2 miles north of the Harford Road 112 Fig. 2. View showing injection of granite and pegmatite into the Wissahickon (?) at the bridge crossing Gunpowder Falls on the Harford Road 112 VII. Fig. 1. View of the earliest settlement on the site of Baltimore . . 120 Fig. 2. View of the present skyline from the Basin 120 VIII. Fig. 1. View of Charles Street and Washington monument, looking north, as it was in the 1840's 128 Fig. 2. A recent view of the Washington monument and Mount Vernon Square 128 IX. Fig. 1. View of the central part of Baltimore from the air 136 Fig. 2. View of Homewood from the air 136 Illustrations Faeint pop* X Fig. 1. View showing basal conglomerate of the Patuxent over- lying the Piedmont crystallines at Roland Park, Baltimore City • 184 Fig. 2. View showing coarse, highly inclined and cross-bedded Patuxent sands near Homestead, Baltimore City 184 XI Fig 1 View showing erosion of old iron mine in the Arundel formation, Schoolhouse Hill, Baltimore County 192 Fig. 2. View showing Patuxent-Arundel contact, south shore of Spring Gardens, the probable locality where Tyson collected the historic Johns Hopkins cycad stump, 1 0O Baltimore County •• XII Fig. 1. View showing the Patuxent-Arundel contact in belt- line cut near the eastern boundary of Baltimore City. 200 Fig 2. View showing Patapsco sands and clays overlain by Pleistocene sands, Baltimore and Ohio Railroad cut, Rosedale Hill, Baltimore County 200 XIII Fig 1 View showing eroded upper surface of the Patuxent overlain by Sunderland deposits, belt-line cut near Charles Street, Baltimore City • • • 208 Fig. 2. View showing Pleistocene gravels at Catonsville, Balti- more County XIV. Fig. 1. View of clay bank at the Monument Street plant of the Baltimore Brick Company • 22 Fig. 2. View of pit of the United Clay Mining Corporation of New Jersey, Poplar 2~ XV Fig I. View of Butler quarry in Setters quartz ite • • AM Fig. 2. View showing operations of the Woodstock Granite Quarrv Company, near Granite • 232 XVI Fig 1. View of part of the flagstone quarry at Wrights Mill, showing the pronounced cleavage of the rock and the smooth joint surfaces Fig. 2. View of tower of the Baltimore City College built of Setters quartzite from Butler • 2 XVII Fig 1 View of dwelling on Falls Road near Butler part of which was built in 1S00 of Setters quartzite from the Butler quarry L"A1"J* Fig. 2. View of Calvary Baptist Church, Towson, built of gneiss from the Setters formation *» XVIII Fig 1 Viewofquairyoftl»elW«dC«dteC«inW»™M.WI ' Fig. 2. View of new quarry of the Beaver Dam Marble Com- ^ panv, Cockeysville • XIX Fig 1. View showing Bluemount Trap Quarry, east end A* Fig 2 View showing Bluemount Trap Quarry, west end JW XX. Map of Baltimore County showing location of quarries and ^ other workings XXI. Chart showing daily march of temperature and pressure M XXII. Chart showing daily march of temperature • Illustrations 13 Facing page XXIII. Fig. 1. View of Gunpowder River near Loch Raven showing the hardwood forest on the Baltimore City water- shed 380 Fig. 2. View of Gunpowder River near Loch Raven showing the mixed hardwood forest on the Baltimore City water- shed 380 XXIV. Fig. 1. View of Patapsco River near Orange Grove showing the characteristic willow growth along the stream banks 388 Fig. 2. View of River Road near Avalon in the Patapsco State Forest showing the young forest returning under management 388 XXV. Fig. 1. View showing plantation of white pine on the Baltimore City watershed along Gunpowder River. Trees 10 years old 396 Fig. 2. View of mixed oak forest of mature trees near Ten Hills 396 XXVI. Fig. 1. View of a portable saw-mill near Ilchester 400 Fig. 2. The product of a portable saw-mill, an operation in a 30-acre timber tract 400 XXVII. Fig. 1. An original forest of mixed oak, hickory, tulip poplar, of which little is left, but showing what can be grown again if properly protected and managed 408 Fig. 2. View showing Pine poles at White Marsh, Baltimore County 408 XXVIII. Fig. 1. View showing the havoc caused by unrestricted lumbering 412 Fig. 2. View showing the result of a timber operation where the trees for cutting were marked by the State Board of Forestry, the small trees and young growth being fully protected for a second crop 412 Figure Page 1. Capt. John Smith's map of 1608 23 2. The Lord Baltimore map of 1635 25 3. The Farrer map of 1651 27 4. The Alsop map of 1666 29 5. Portion of Herman's map of 1670 31 6. Map showing the physiographic provinces of Maryland and their subdivisions 60 7. Diagram showing successive stages in the reduction of a youthful to- pography to a peneplain 65 8. Cross profile through the interstream area between Little Falls and Piney Run (generalized) 67 9. Cross profile through the valley of Little Falls near Walker 83 10. Generalized diagram showing seaward slopes of erosion surfaces in the eastern Appalachian Highland 92 Illustrations Figure Page 11. Cross profile of the Wind Gap at Gap, Pennsylvania showing two- story valley 95 12. Columnar Section of Rocks of Baltimore Count}' 103 13. Diagram of upright folds and overturned folds 184 14. Mean Hourly Temperature 354 15. Total Seasonal and Annual Frequency of Stated Diurnal changes of Temperature 355 16. Greatest Daily Range of Temperature 366 17. Mean Hourly Relative Humidity 371 18. The Mean Monthly Relative Humidity 372 19. Variations in the Mean Annual Relative Humidity 372 20. Average Hourly Frequency of Precipitation 376 PREFACE The present volume on Baltimore County is the eleventh of the series of reports dealing with the physical features of the several counties of Maryland. In it are considerations not only of the geology and mineral resources but also the physiography, soils, climate, magnetic declination, and forests. The Introduction, by Edward W. Berry, consists of an historical review of the development of knowledge concerning the physical features of Baltimore County and a bibliography of the more important maps and reports dealing with the area. It shows that the growth of knowledge has covered a long period of preliminary exploration, begin- ning with the work of Captain John Smith and culminating in the refined investigations of the complicated problems of the crystalline rocks of the Piedmont. The earlier work by Tyson and others without modern technique shows an intuitive understanding of the region of high char- acter. The later modern investigations have been by a great many workers, beginning with the classic studies of the late Professor Williams and numerous studies by students at the Johns Hopkins University. The account of The Physiography of Baltimore County by Eleanora Bhss Knopf represents an exhaustive mature investigation of the surface features of the county in connection with the topographic development of the whole terrane bordering the central Atlantic coast. This report is based upon new methods of research and is not only a clear, consistent explanation of the present surface features of Baltimore County but a distinct contribution to the scientific interpretation of the origin of the various terraces and gorges of the Piedmont area extending from New Jersey southward. The Geology of the Crystalline Rocks of Baltimore County by Eleanora Bhss Knopf and Anna I. Jonas represents the results of years of study. The authors undertook this work with a knowledge of the detailed studies and general interpretation of the region by Williams, Mathews, 16 Preface and their students, but also with a wide experience in similar conditions to the north and south of the Maryland area. The region is particularly intricate and has required close investigation of the highest sort and unusual competency on the part of the authors to unravel the various interlocking threads of the geological history. The Geology of the Coastal Plain, by Edward W. Berry, is a clear description of the various unconsolidated formations which cover the southern border of Baltimore County along the shores of the Chesa- peake. The formations exposed, ranging in age from Lower Cretaceous to Recent deposits, are but a portion of a broad terrane from New England southward in the interpretation of which the author is already a well-recognized authority. The Mineral Resources of Baltimore County, by Edward B. Mathews and Edward H. Watson, is an account of the various sources of mineral wealth which have been the bases of many industries in Baltimore City and County. Most of the deposits had a relatively greater importance in the mineral development of the country before the richer and more profitable deposits of the West were known. The historical account of the iron ore, building stones, copper, and chrome shows how the occur- rence of low-grade sources of mineral wealth had a marked influence on the development of many of the present industries in Baltimore which now secure their raw materials more cheaply from the western states, South Africa, and the islands of the Pacific. The Soils of Baltimore County, by William T. Carter, Jr., J. M. Snyder, and O. C. Bruce, is a report representing the cooperative work between the Maryland Geological Survey, the U. S. Bureau of Soils, and the Maryland Agricultural Experiment Station. The field work for this report was done in 1917 and the report was published by the U. S. Department of Agriculture in 1919. The results of the work on the various types then found is of equal value today and should continue to prove of service in the development of the agricultural interests of the county which are so favorably situated close to the markets of Baltimore City. The Climate of Baltimore County, by Edward B. Mathews and Roscoe Preface 17 Nunn, is a summary of the climatic conditions of the area, based prin- cipally upon the exhaustive work of Dr. Oliver L. Fassig, published years ago as Volume II of the Maryland State Weather Service. The present summary has been brought up to date by the Director and Meteorologist of the State Weather Service. The compilation of statistics and the recording of observations is the cooperative work of the Maryland State Weather Service with the U. S. Weather Bureau. The Magnetic Declination of Baltimore County, by L. A. Bauer, represents one of a series of reports on this subject for definite areas of the State. It contains much important information for the local surveyors of the county and represents in part the results of long continued work by Dr. Bauer in his magnetic surveys of Maryland commenced under the auspices of the State Geological Survey in 1897. The Forests of Baltimore County, by F; W. Besley, is a comprehensive report of the study of the forest conditions of the county which was conducted as part of the work of the State Department of Forestry. This report by Mr. Besley contains mam* helpful suggestions for improving the forest resources, particularly of the woodland lots of the farms of Baltimore County. The volume as a whole is an addition to the recorded results of the investigation of the physical features of Maryland which has been conducted in cooperation with several national bureaus, notably the U. S. Geological Survey, the U. S. Bureau of Mines, the U. S. Coast and Geodetic Survey, the U. S. Weather Bureau, and the U. S. Bureau of Soils and Agriculture which have given many facilities in the conduct of the general investigation and have thereby increased the value of the several reports contained in the volume. For their liberal assistance and cordial cooperation the State Geological Survey desires to express its thanks. THE PHYSICAL FEATURES OF BALTIMORE COUNTY DEVELOPMENT OF KNOWLEDGE CONCERNING THE PHYSICAL FEATURES OF BALTIMORE COUNTY BY EDWARD W. BERRY IXTRODUCTIOX The observations of early explorers in what is now Baltimore County were few and superficial and even as late as the 18th century they related to subjects which have since become separate fields of investiga- tion. The account of the geographic exploration begins with the voyage of Captain John Smith in 1608 and continues down to the cur- rent work of the Maryland Geological Survey and other contemporary investigations. The history of geologic research in the region com- mences with Wm. Maclure's studies of 1809 and is brought down to the present diversified geologic studies of the State Geological Survey and other agencies. Historical Review Baltimore County, lying as it does toward the western head of Chesa- peake Bay and containing as it does so much of the population of the State, is of especial historic interest since in the earlier days of the colony it was subordinate in importance to southern Maryland, and before the daj's of land communications and ocean traffic offered no more favorable site for settlement than the rest of the Chesapeake estuary country. As in all newly colonized regions the earlier maps were no better than the incomplete explorations upon which they were based. The early history of exploration in Baltimore Count}' is therefore a record of the gradual accumulation of information of the general region of which Baltimore County is a part, and this only becomes specific as the county takes shape and the population of the area increases. 21 22 Physical Features of Baltimore County The History of Geographic Research1 The first geographical exploration which was made into the region which is now known as Baltimore County was carried on in the summer of 1608 by Captain John Smith and a few companions, although the results were not published until 1612-14.2 His description of the country lacks precise details and is much generalized and his map would seem to indicate that he simply sailed past the coast of Baltimore County, although the Patapsco is fairly well shown and is named (Bolus) and noted as being navigable for a ship; and "Powels lies" is probably an inaccurate representation of Pool's Island off the mouth of the Gunpowder. Smith spent scarcely a month in his exploration of Chesapeake Bay, but nevertheless was able to present a remarkably well proportioned map of the Chesapeake Bay region as a whole, con- sidering the difficulties which he encountered and the rough methods of work he employed. This map was used for some time afterwards as a basis of exploration and settlement. The Lord Baltimore map of 1635 is more distorted and generalized than the Smith map, especially the upper part of the Bay, although the lower Bay region and the Potomac show some improvements. The unnonned Patapsco is represented as a large bay with mountain peaks both to the north and south of it. The Farrer map of 1651, drawn by Virginia Farrar, a niece of Nicholas Farrer, who was at one time connected with the London Virginia Company, was drawn in London and is a mixture of fact, imagination, and misrepresentation, and might be considered as propaganda for the London Virginia Company, since it attempted to show that in a ten- days march from the head of James River one might arrive in New Albion (California) on the shore of the Sea of China and the Indies. The range of mountains shown, as many previous commentators have pointed out, is a fair representation of the Appalachians as well as in about the position of the Sierra Nevadas as known to explorers of the lThe motive which prompted Smith to this enterprise was the exploration of Chesapeake Bay and the adjacent country, so that the examination of Baltimore County was only a portion of the work accomplished. 'Mathews, E. B. Maps and Map Makers of Maryland, Md. Geol. Surv. II, 1898, pp. 337-488. The First Geological Excursion along the Chesapeake. J. H. U. Circ, 1898, pp. 14-15. Maryland Geological Survey 23 24 Physical Features of Baltimore County Pacific coast. The depiction of the Baltimore County region is espe- cially distorted and inaccurate, the country north of the Bolus (Pa- tapsco) is called "Anandale C"; the latitude given is wrong; and the Hudson, Delaware, Susquehanna, and a large stream just north of the Bolus, called "Willobies River," probably representing a vague combination of the Bush, Gunpowder, and Back rivers, are all parallel in their courses and the last is bigger than the Susquehanna. The Hudson is shown connecting with the St. Lawrence and thence with the Pacific, showing the strange survival from the fifteenth century of the idea that India and China were just beyond the Atlantic border. Fifteen years after the Farrer map George Alsop, apparently an exile from England because of his anti-Cromwellian opinions, got out a small pamphlet in 1666 with a map. He lived in this part of the State so that the upper western shore of the Bay is less distorted than on earlier maps and the name Patapsco, as well as several other places, appear for the first time. The map as a whole is, however, just the sort of a map that a rover or untrained hunter might make, after a few years' acquaintance with the country and some knowledge of the earlier maps. There is marked distortion and many generalizations. The rivers are broad and without individuality while the coast line is represented by a series of sinuous lines bearing no relation to the natural indentations of the Bay. The small mountains of the map are not judiciously placed but, as in the Lord Baltimore map, are scattered indiscriminately over the Coastal Plain wherever the width between the rivers seemed to call for addi- tional illustration. Both maps represent high land on the right bank of the Patapsco. Although quaint with figures, after the manner of the times, the value of the map lies in the use of the place names which have come down to us. In 1670 Augustine Herman brought out a map covering the region, from southern New Jersey to southern Virginia. Herman's history is an interesting one. He first appears in Maryland as an ambassador from Peter Stuj-vesant, the governor of New Amsterdam, in an effort to settle the friction between the two colonies over the Dutch settle- Maryland Geological Survey 25 26 Physical Features of Baltimore County mcnts on the Delaware. Before leaving St. Mary's he wrote to Stuy- vesant suggesting the desirability of making an accurate map of the upper Chesapeake as a basis for the settlement of the dispute between the two colonies, and not meeting with any response, Herman offered to make a map of Lord Baltimore's territory in return for a manor along the Bohemia River. This offer was accepted by Lord Baltimore in 1660, and as soon as the letter of denization was granted to Herman and his family he moved his whole establishment down to the site of the present Bohemia Manor. During the following decade Herman was busy with the preparation of his map and the clearing of the lands about his new home. His own native ability and the wide acquaintance gained in his business as a surveyor soon brought him into considerable promi- nence, and we find him a Justice of Baltimore County, a Commissioner with Jacob Young to treat with the Indians, and empowered to grant passes to traders in the area. He was also on exceptional!}' good terms with the authorities of Delaware, for we find that a road was built at the latter's expense from Newcastle halfway to his manor, while Maryland built the other half. His home was a favorite resort for the higher officials of Maryland, and Charles, Lord Baltimore, is said to have spent much time at Bohemia Manor. The map which he produced in 1670 indicates considerable talent, both as a surveyor and draughtsman. The configuration of the shores about the upper baj* are fairly well represented. The name Baltimore County appears on the map, as well as Back and Gunpowder rivers, and the original Baltemore Towne on Bush River. Baltimore County had been erected about 1659. The original records have never been found among the archives of the State, and no evidence exists indicating whether its erection was due to a proclamation of the Lord Proprietary or his representative, or to some action on the part of the General Assembly. At that time there were St. Mary's, Calvert, Anne Arundel, and Charles counties on the Western Shore, and Kent County on the Eastern. The scattered inhabitants on either side of the Bay from the Patapsco and Sassafras rivers had no nearby county seat in which to transact their business. 28 Physical Features of Baltimore County The earliest settlements within the territory of the original Baltimore County were probably those on Palmer's Island at the mouth of the Susquehanna River where Claiborne and his followers had established trading settlements as early as 1627-28. Settlements subsequent to that of Claiborne were few and scattered until in the decades between 1660 and 1680 the development of the territory around the shores of the head of the Bay was rapid, much of it taking place under the leader- ship of Augustine Herman, who became the leading man of the region. Settlements were formed at this time along the shores of Northeast Creek and the estuaries of what is now Harford County. The center of population for the new county of Baltimore lay about the head of the Bay outside the territory now included within the County. As early as 1661 the court of Baltimore County was held near Howell's Point, below the mouth of the Sassafras River. A few years later, in 1664, Baltimore County court met at Carpenter's Point on the North- east River, and from 1674 to 1768 the county seat of Baltimore was within the present confines of Harford County. It was not until after the election of 1768 that the county seat was established within the territory of the present Baltimore County. Such widely scattered sites for the holding of the county court naturally leads to the question as to what were the original limits of Baltimore County. No terms are given in the records prior to the proclamation of 1674 erecting Cecil County. It is necessary therefore to examine the casual references and early records of land grants, etc., to determine the original limits. From these it appears now well established that Baltimore County was at first intended to include all the northern portion of Maryland, situated on either side of Chesa- peake Bay from the Patapsco on the west to the Chester River on the east, and northward as far as the northward bounds of the Province. This broad region was at the time almost entirely covered with forests and the few settlements, limited almost exclusively to the waterways, were not as widely separated as they would now appear to be. The unexplored forests at their backs and the easily traversed waterways in their midst tended to give a feeling of compactness and relative security to these otherwise isolated settlements. 30 Physical Features of Baltimore County During the decade and a half from the establishment of Baltimore County to the separation of Cecil County in 1674 there gradually arose a feeling of distinction between the territory on the eastern and western sides of the Bay, the former being called East Baltimore County from time to time. After the separation of Cecil County the count}' seat of Baltimore County was established on Bush River at old Baltimore Town, where it remained until 1712, when it was removed to Joppa, whence it was again removed in 1768 to the present Baltimore City. The gradual change to the westward of the county seat was the result of the increasing population along the Patapsco River, and northward from the Bay shore until at the last date given the populations of the upper and lower portions of Baltimore Count}- were approximately equal. The removal of the county seat occasioned considerable feeling between the two portions of the county. The inhabitants of the upper or eastern portion soon expressed a desire for a separation from their successful rivals on the west. Accordingly in 1773 the General As- sembly passed an Act decreeing the erection of Harford County. The western limits of Baltimore County were probably determined at the time of its erection with respect to the older Anne Arundel County ^ from which it was separated, but the first statement on record is con- tained in the proclamation of 1674 which states that the boundary should be "the south side of Patapsco River, and from the highest plantations on that side of the river, due south two miles into the woods." Somewhat later the settlements of Baltimore County are known to be as far up the Patapsco River as Hollofields, and it was probably intended that the county should include the inhabitants on both sides of the river to its mouth. In 1674 there was a practically unsettled region between the Magothy and the Patapsco. We are not here concerned with the later changes in the boundaries of Baltimore. The southern boundary with Anne Arundel was specifi- cally defined in 1698 and altered in 1726. Frederick County was erected in 1748, and Carroll County, after a lively political controversy, was erected in 1837. The present City of Baltimore was authorized by the General Assembly in 1730 and made the county seat in 176S. 32 Physical Features of Baltimore County At the outbreak of the Revolution Baltimore contained about 6,000 inhabitants and the Continental Congress met here during the winter of 1776-1777. Baltimore was incorporated in 1796, the Act becom- ing effective in 1797, and made a separate political unit in 1850. The later modifications of the political boundaries of the City and County have been additions to the area of the city at the expense of the adja- cent suburbs. The history of this and other count}' boundaries in Man-land is given in detail by Mathews3 in his account published in 1906. The account of the development of the geography of Baltimore County would not be complete without a notice of the excellent work done by Charles Mason and Jeremiah Dixon in running the historic Mason and Dixon Line. Their commission was dated the 9th of De- cember, 1763, and their work was completed a little less than five years later, on the 9th of November, 1768. No map appears to have been published as a result of their work, though one was prepared in manu- script, and many notes of interest were recorded in their field books. At about the time of the outbreak of the Revolutionary War, Anthony Smith published a chart of Chesapeake Bay on a scale of 3^ miles to the inch. This chart was intended for a guide to navigators, and such information as shoals, channels, islands, and the various depths of water were represented. No large map of the Chesapeake shores was published as the result of additional surveys after the appearance of Herman's map until 1735. At that time Walter Hoxton, who seems to have been a captain in the merchant service between London and Virginia, issued his draft entitled "To the Merchants of London Trading to Virginia and Mary- land This Mapp of the Bay of Chesepeack, with the Rivers Potomack, Potapsco North East and part of Chester, Is humbly Dedicated & Presented, by Walter Hoxton, 1735." In 179-4 Dennis Griffith compiled a map of the entire State which is much the best that had appeared up to that time. The principal streams and towns of Baltimore County are shown in considerable detail. 'Mathews, Edward B. The Counties of Maryland, their origin, boundaries, and election districts. Md. Geol. Survey, vol. vi, pt. 5, 1906. Maryland Geological Survey 33 A marked advance in the mapping of the region occurred from 1834 to 1840 through the co-operation of Professor J. T. Ducatel, then State Geologist of Maryland (1833-1842) and John H. Alexander, State Surveyor. One map, published with the report for 1835, representing the triangulation of the western shore of the Bay is of interest in showing the location points for what was "almost the only survey and, it is believed, the first in the United States, based upon the proper principles and conducted by a skilled and scientific observer." The degree of accuracy sought was within the limit of error of one-fortieth of a foot. More than 60 stations are represented, and the work here indicated was probably the basis of all the maps constructed prior to the careful work of the Coast and Geodetic Survey, and even later beyond the limits of the latter's work. There are indications that a line of tertiary triangulation was conducted along certain of the waterways, especially in the vicinity of Baltimore. The second sheet in the report for 1839 embraces all of the territory between the Susquehanna and Westminster, i.e., Harford and Baltimore counties with parts of Carroll county, so that there were prepared by Alexander a continuous sketch of the territory from the Susquehanna to the Hagerstown Valley, on the scale of 1 : 200,000. This sheet differs from the preceding ones by having indicated upon it the locations of the more important triangulation stations. There is also some indica- tion of the ore pits of the region which have been of some economic importance. The U. S. Coast and Geodetic Survey began their surveys in the Bay about 1845 and their work represents a great advance in workmanship. The details for these for the Baltimore area are given in Vol. I of the reports of the present State Geological Survey. As the port of Balti- more increased in importance numerous resurveys of the harbor, the Patapsco River entrance, and the Bay were made and published. This activity has continued down to the present time, since 1876 usually in co-operation with the City of Baltimore through the Harbor Board. The U. S. States Geological Survey, which was organized in 1879, initiated work in Maryland in 1883, the Baltimore sheet on a scale 34 Physical Features of Baltimore County of 1 inch to the mile having been published in preliminary form in 1892 to accompany the Guide to Baltimore, prepared by the local committee of the American Institute of Mining Engineers. The present State Geological Survey was organized in 1896 and energetically prosecuted the completion of a topographic map of the State in co-operation with U. S. Geological Survey. Baltimore County has been published on the scale of 1 mile to the inch and the City has been mapped on a much larger scale in co-operation with the Baltimore Topographical Survey, which for many years has done such high-grade work for the municipality. The State Survey has also issued many small maps covering parts or all of the County in connection with its studies of the igneous rocks, building stones, chrome, iron, flint, feldspar, and other mineral occurrences. There have been several atlases of Baltimore County and Baltimore City published by private enterprise. These have not been based upon original surveys and will be found listed in the accompanying bibliography. The History of Geologic Research From a very early date, those who have examined the geology of Baltimore County have distinguished between the crystalline rocks of the Piedmont Plateau and the unconsolidated sediments of the Coastal Plain. These two provinces have always been considered as distinct, and as separated from each other by a great time interval. In the early days of geologic research, when those who pretended to study the science at all were either amateurs or were busy with other occupations during the greater part of the time, the intrinsic problem of the Pied- mont rocks presented difficulties too great to be overcome. The first paper of importance was published by William Maclure in 1809. Although this contribution dealt in a broad way with the geology of the United States, yet it shed considerable fight on Baltimore County. Maclure separated the formations of that region into two great prov- inces, the Primitive and the Alluvial. These two divisions correspond to what we now know as the rocks of the Piedmont Plateau and the deposits of the Coastal Plain, and the fine which separated the two Maryland Geological Survey 35 groups was drawn by Maclure approximately as it is known today. This paper, which was accompanied by a geological map, was repub- lished many times in subsequent years; the last one appearing in 1826. The unity of the Coastal Plain deposits as promulgated by Maclure seems to have been quite generally accepted at the time, for Hayden, in 1820, in a series of essays which attracted considerable attention, referred to these Alluvial deposits and advanced the theory that they were deposited not by rivers but were swept in by a great flood which crossed North America from northeast to southwest. Two years later, Parker Cleaveland endorsed Maclure's map by reproducing it in his treatise on mineralogy. No serious exception seems to have been made to Maclure's inter- pretation until 1824, when Professor John Finch, an Englishman who was making a tour of the United States, called attention to the complex character of the Alluvium. He divided it into Ferruginous and Plastic clay, and correlated these with the Newer Secondary and Tertiary of Europe. John Finch's suggestions seemed to have had a stimulating effect on American geologists, for a number of papers followed in rapid succession in which the attempt was repeatedly made to divide the Alluvium into its natural formations and to correlate them with established horizons in Europe. These early investigators, although keen men in certain instances, did not, however, have the necessary training to cope suc- cessfully with the problems which they sought to solve. None of them seemed to have realized the peculiar difficulties of Coastal Plain stratig- raphy. All of them did their work rapidly and unsystematically, and most of them reached their conclusions prematurely. Seldom was a paper accompanied by a geological map, few localities were given and descriptions were usually ambiguous and unsatisfactory. The result was that the formations described by one investigator were almost sure to be included in those described by another, and out of the endless confusion which arose from this sort of work, little of value has survived. It was not until geologists in connection with the Johns Hopkins Uni- versity, the United States and Maryland Geological Surveys made a 36 Physical Features of Baltimore County systematic study of Maryland and the adjacent region that a sub- division and a natural classification was finally worked out for the Coastal Plain. The crystalline rocks of the Piedmont were much later in being systematically studied and it is only in recent years that their correct relations have been thoroughly understood. The first report of Philip T. Tyson as State Agricultural Chemist of Maryland appeared in Januarj-, 1860. In this paper he published an able summary of the geology of Maryland, and indicated the position and extent of the various formations on a geological map. The crystal- line rocks of Baltimore County are represented on this map in three colors, and are divided into Gneiss, Mica Slate, Hornblende Slate, Trap, and Serpentine; thus representing the most complex series of rocks which had up to that time been distinguished. The organization of the Johns Hopkins University in 1876 inaugurated a period of scientific activity in Maryland, which has meant a great deal in the material advancement of the State. In the winter of 1876-77 Professor J. E. Hilgard, the Superintendent of U. S. Coast and Geodetic Survey lectured on the Methods and Results of Surveys and discussed the features of the Chesapeake basin in 20 lectures. A model of the Druid Hill Park region was subsequently presented to the City. The Biological Department and the Baltimore Naturalists' Field Club) organized by Professor H. Newell Martin, were active in studies of the flora, fauna, and physiography of the Baltimore region, as was also the Maryland Academy of Sciences under the able direction of Professor P. R. Uhler. The Geological Department was started in 1883 when Dr. George Huntington Williams, fresh from petrographic studies in German}-, was appointed instructor in mineralogy. His appointment marked the beginning of a period of investigation of the geology and mineral resources of the State that has been carried on by his associates and successors continuously to the present time. This period is by far the most important in the study of the physical features of the State. The earliest work of Dr. Williams was in the region of crystalline rocks of Baltimore and vicinity, the first studies being concerned with Maryland Geological Survey 37 the gabbros and associated hornblende rocks in 1884, followed in rapid succession by studies of the so-called quartz porphyries, granites, pegmatites, amphiboles, etc. By the year 1887 Professor Williams had extended his studies of the crystalline rocks outside the Baltimore region northeastward into Harford and Cecil counties. In 1887 Wm. Bullock Clark became associated with Professor Wil- liams and actively inaugurated a study of the Coastal Plain of the State. A large scale relief map of Baltimore and vicinity was prepared in 1892. The preparation of a book upon Maryland which should properly set forth its resources, industries, and institutions was intrusted by the Board of World's Fair Commissioners to the faculty of the Johns Hopkins University in 1892; those portions dealing with the physical features having been prepared by Professors Williams and Clark. Following the untimely death of Professor Williams in 1894 Dr. E. B. Mathews was appointed instructor in mineralogy and petrography, and took up the work of Professor Williams on the crystalline rocks of the Piedmont region. A bill organizing the State Geological and Economic Survey was passed by the General Assembly in 1896 and Wm. Bullock Clark was appointed State Geologist. The history of geologic studies in Maryland from that time is largely a history of the activity of the State Survey in co-operation with various Federal bureaus. It may be fairly said that no single individual has exerted more influence in advancing the material interests of the State than did Professor Clark during the 21 years that he administered the office of State Geologist. In so far as these activities relate to Baltimore County they were prosecuted by Dr. E. B. Mathews, who became State Geologist upon the death of Dr. Clark in the summer of 1917. The later publications dealing with the progress of geological studies in Baltimore County are listed in the following bibliography and their discussion in detail would unwarrantedly extend the limits of this chapter. 28 Physical Features of Baltimore County BIBLIOGRAPHY 1608 Smith, John. Chart of Virginia. Published in 1612 (?) Quoted in 1613 by Purchas. 1612 Smith, John. A Map of Virginia With a Description of the Covntrey, the Commodities, People, Government and Relegeon. Written by Captaine Smith, sometime Governour of the Covntrey. Oxford, printed by Joseph Barnes, 1612. 4to. 174 pp. 1624 Smith, John. A Generall Historie of Virginia, New England, and the Summer Isles, etc. London, 1624. [Several editions]. (Repub.) The True Travels, Adventures and Observations of Captaine Iohn Smith in Europe, Asia, Afrika, and America, etc. Richmond, 1819, 2 vols. — from London edition of 1629. Pinkerton's Voyages and Travels, vol. 13, 4to, London, 1812, pp. 1-253 — from London edition of 1624. Eng. Scholars Library Xo. 16. (For bibliography of Smith's works and their republication, see pp. cxxx-cxxxii). 1635 Anon. Xoua Terrae Marie tabula. A Relation of Maryland; Together with a Map of the Country. The Condi- tions of Plantations, etc. London, 1635. 1651 Farrer, Virginia. A mapp of Virginia discouered to ye Hills, and in it's Latt: From 35 deg: & 1/2 neer Florida, to 41 deg: bounds of Xew Englands. John Goddard sculp. Domina Virginia Farrer Collegit. Are sold by I. Stephen- son at ye Sunn below Ludgate: 1651. 1666 Alsop, George. A Land-skip of the Province of Mary-land or the Lord Baltmors Plantation neere Virginia, By Geo: Alsop Gent: Alsop, George. A Character of the Province of Maryland. (Repub.). Gowan's Bibliotheca Americana, Xew York, 1S69, Xo. 5. 1669 Shrigley, Xathaniel. A True Relation of Virginia and Mary-Land; with the commodities therein, [etc.]. London, 1669. (Repub.) Forces's Collection of Historical Tracts, vol. iii, Xo. 7, Washington, 1S44, 51 pp. Herman, Acgcstin. this present Year 1670. 1673 Virginia and Maryland As it is Planted and Inhabited Maryland Geological Survey 39 1676 Speed, John. A map of Virginia and Maryland. The Theatre of the Empire of Great Britain, presenting an exact geography of the Kingdom of England (etc., etc.) together with a Prospect of the most famous Parts of the World, viz., Asia, Africa, Europe, America. London: printed for Thos. Bassett, 1676. Fol. 1708 Moll, H. A new map of Virginia and Maryland. Oldmixon, (John). The british empire in America, 12°, London for J. Nichol- son, 1708, p. 209. 1717 Moll, H. A new map of Virginia and Maryland. Atlas Geographers; or a compleat System of Geography, 4°, in the Savoy — E. Nutt for J. Nicholson, 1717, vol. v, p. 700. 1719 Sexix, J. A new map of Virginia (and) Maryland and Improved parts of Pennsylvania & New Jersey, revised by I. Senix 1719 most humbly Inscribed to the Right Honble the Earl of Orkney &ct. 1730 Moll, H. Virginia and Maryland. 1733 Haxtox, Walter. A Merchants chart of the Chesapeake. "To the merchants of London trading to Virginia and Maryland this mapp of the Chesapeake with the rivers Potomoch, Patapsco and part of Chester is dedicated." 1735 Haxtox, Walter. To the Merchants of London Trading to Virginia and Maryland This mapp of the Bay of Chesapeack with the Rivers Potomack, Pa- tapsco North East and part of Chester, Is humbly dedicated & Presented by Walter Haxton 1735. Senix, Johx. Maryland according to the bounds mentioned in the charter and also of the adjacent country, anno 1630, London, 1735. 1736 Moll, H. Virginia and Maryland. Atlas minor obi. fol. London for T. Bowles and J. Bowles, 1737, No. 50. 1740 Axon. A map of Parts of the Provinces of Pennsylvania and Maryland, with the counties of New Castle, Kent, and Sussex in Delaware according to the most exact surveys yet made, drawn in the year 1740. London. (Chancery Proc.) 40 Physical Features of Baltimore County 1747 Bowes, Eman. A new and accurate map of Virginia & Maryland. Laid down from surveys and regulated by astron'l Observat'ns. A complete system of geography, fol. London, for W. Inns, 1747, vol. ii, p. 647 (Phillips). 1750 Garvin. A map of Virginia and Maryland. London, 1750 (Phillips). 1751 Fry, Joshua, and Jefferson, Peter. A map of the most inhabited part of Virginia containing the whole province of Maryland with parts of Pensil- vania, New Jersey and North Carolina. Drawn by Joshua Fry and Peter Jefferson in 1751. Numerous subsequent editions. 1755 Baldwin, R. A map of Virginia, north and south Carolina, Georgia, Mary- land, with a part of New Jersey (etc.). London, 1755. Dalrymple, J. A map of Northern Virginia, Delaware, New Jersey, Southern Pennsylvania and Maryland. London, Jan. 1, 1755. "From information collected on the spot and entered in his journal." Evans, Lewis. A general map of the middle british colonies in America, viz: Virginia, Mariland, Delaware, Pensilvania (etc.) Evans' geographical, historical, political, philosophical and mechanical essays. 4°. Phila. : B. Franklin & D. Hall, 1755. 1756 Anon. An exact Piatt of Baltimore Town in Baltimore County, Md. 1758 Anon. Carte de la Louisiane, Maryland, Virginia, Caroline, Georgie, avec Partie de la Floride a Amsterdam chez C6vens & Mortier 175S (C. Lepp scult.) Anon. Carte de la Louisana, Maryland, Virginie, Caroline, Jarsey. Sold by William Mount & Thos. Page. Tower Hill. The English Pilot, fourth book fol. London, 1758, facing p. 23. Anon. Karte von der bay Chesapeack und den benach barten landen. Allgemeine historie der reisen zu wasser und lande. 4°. Leipsig: Arkstie & Merkus, 1758, vol. xvi, p. 538. Evans, Lewis (and I. Gibson). A general map of the middle british colonies in America, viz Virginia, Maryland, Delaware (etc.). Carefully copied from the original at Philadelphia by Mr. Lewis Evans 1755 with some improvements by I. Gibson. (London 1758.) Evans, Lewis (and Thos. Jeffrys). A general map of the middle british colonies in America viz. Virginia, Maryland, Delaware (etc.). By Lewis Evans. Corrected and improved by Thos. Jeffreys. London. R. Sayer & T. Jeffreys 1758. A general topography of North America and the West Indies, 1768, No. 32. Maryland Geological Survey 41 1759 Homann, Ioh. Bapt. Virginia, Marylandia et Carolina in America Septen- trionali Britannorum industria excultae repraesentatae a Ioh. Bapt. Homann S. CM. Georg. Xorumbergae. Atlas grographicus maior fol. Xorumbergae curantibus Homanniania heredi- bus, 1759. 1760 Anon. A new map of the Province of Maryland in North America. 1762 Anon. Carte de la Virginia, Maryland, etc., tiree des meilleures cartes ang- loises (Bellin, Paris 1672). 1767 (Hermann, A.) Virginia, Maryland, Pennsylvania East and West Xew Jersey. Dublin. Sold by Geo. Grierson at the Two Bibles in Essex Street. The English Pilot. The fourth book fol. Dublin: B. Grierson, 1767, after p. 24. 1768 Fry, Joshua & Jefferson, Peter. A map of the most inhabited part of Virginia containing the whole province of Maryland etc. A general topography of Xorth America and the West Indies, fol. London, for R. Sayer and T. Jeffery, 1768, Xos. 54r-57. 1775 Fry, Joshua & Jefferson, Peter. A Map of the most Inhabited part of Virginia containing the whole province of Maryland with parts of Pensilvania, Xew Jersey and Xorth Carolina. Drawn by Joshua Fry & Peter Jefferson in 1775. Dedicated to the Earl of Halifax, (et al.). The American Atlas. London, 1778, Sayer & Bennett. Evans, Lewis (and Jeffrys, Thos.) A general Map of the Middle British Colonies in America, viz., Virginia, Maryland, Delaware, Pensilvania, Xew Jersey, Xew York, Connecticut and Rhode Island (etc.). Published by Lewis Evans, Phila., corrected and improved with additions by Thos. Jefferys. In American Atlas, by Thos. Jefferys, Xo. 18, London, 1755. Sold by R. Sayer in Fleet Street and T. Jefferys, Charing Cross. 1776 Pownall, L. General map of Middle British Colonies in America containing Virginia, Maryland, the Delaware counties, Pennsylvania and Xew Jersey, (etc.) corrected from Gov. Pownall's late map 1776. London for R. Sayer & J. Bennett 15 Oct. 1776. The American military pocket atlas. 8°. Smith, Anthony. A Xew and Accurate Chart of the Bay of Chesapeake with all the Shoals, Channels, Islands, Entrances, Soundings and Sailor marks, as far as the Xavogable Part of the Rivers Potowmack, Patapsco, and Xorth East. Drawn from several Draughts made by the most experienced navigators, chiefly from those of Anthony Smith, Pilot of St. Mary's. 42 Physical Features of Baltimore County 1778 Smith, A. Carte de la baie de Chesapeake et de la partie navigable des rivieres James, York, Patowmack, Patuxent, Patapsco, Xorth-East, Choptant et Poko- mack. Redigee pour le service des vaissance du roi, par ordre de M. deSartain d'apres des plans anglois et particulierement ceux d' Antoine Smith, 1778. 1780 Presbcry, C. G. Plan of Baltimore (MS). 1792 Folie, A. P. Plan of the Town of Baltimore and Environs. Dedicated to the Citizens of Baltimore. Taken upon the spot by their most humble Servant A. P. Folie, French Geographer. James Poapard sculpsit, Phila. 1795 Griffith, Dennis. Map of the State of Maryland, laid down from an actual survey of all the principal waters, public roads and divisions of the Counties therein; etc. by Dennis Griffith June 20, 1794 — Phila. pub. June 6, 1795 by J Vallance, Engraver. Map of the state of Maryland and of the Federal Territory as also of the State of Delaware. Philadelphia (J. Vallance) 3 large sheets (Williams). Lewis, Samuel. Maryland. Carey's General Atlas improved and enlarged Xo. 16. Phila., 1795. 1799 Anon. Plan of Baltimore. (Md. Hist. Soc.) 1801 Warner ft Hanna's Plan of the City and Environs of Baltimore, Respectfully dedicated to the Mayor, City Council & Citizens thereof by the Proprietors. Re- published by Lucas Bros. 1870. 1809 Gordan, Silvain. Observations to serve for the Mineralogical Map of the State of Maryland. (Read Nov. 6, 1809). Trans. Amer. Phil. Soc, o. s., vol. vi, 1809, pp. 319-323. Maclure, Wm. Observations on the Geology of the United States, explana- tory of a Geological Map. (Read Jan. 20, 1809.) Trans. Amer. Phil. Soc, o. s. vol. vi, 1809, pp. 411-128. 1810 Hayden, H. H. ["Mineralogical and Geological Description of the Country surrounding Baltimore to the extent of about nine miles.") Bait. Med. Phil. Lye, vol. i, 1810, pp. 255-271. 1813 Griffith, Dennis. Map of the state of Maryland and of the Federal Territory as also of the state of Delaware. 2nd Edition J. Melish. Phila. 1813. Maryland Geological Survey 43 1814 Gilmor, Robt., Jr. A Descriptive Catalogue of Minerals occurring id the vicinity of Baltimore, arranged according to the distribution methodique of Hauy. Bruce Min. Jour., vol. i, 1814, pp. 221-232. 1817 Maclure, Wm. Observations on the Geology of the United States of America, with some remarks on the effect produced on the nature and fertility of soils by the decomposition of the different classes of rocks. With two plates. 12 mo. Phila., 1817. 1818 [Caret, M.] Maryland. Carey's General Atlas, improved and enlarged, 3rd edit. Phila., 1818. [lat edit. 1814] 1820 Hatden, H. H. Geological Essays; or an Inquiry into some of the Geological Phenomena to be found in various parts of America and elsewhere. 8vo. pp. 412. Baltimore, 1820. 1823 Axox. Report by the Maryland Commission on a Proposed Canal from Balti- more to Conowago, with maps and profiles. Baltimore, 1823. (Rev.) X. A. Rev., vol. xviii, 1824, 217. Small, W. F. A map shewing the extent of the Susquehanna Country and its Practical Canal routes as designated by the Susquehanna Commissioners 1823. Report by the Maryland Commissioners on a Proposed Canal from Baltimore to Conowago. Baltimore, 1823. Lucas, F., Jr. A topographical Map of the route of a Proposed Canal and the country between Conowago and Baltimore. Report by the Maryland Commission on a Proposed Canal from Baltimore to Conowago. Baltimore, 1823. Maryland (with plan of Baltimore). Copyrighted Nov. 1, 1819. A General Atlas containing distinct Maps of all the known countries in the world. Baltimore, by Fielding Lucas, Jr., 1823. 1824 Harper, Gexeral [R. S.] Speech to the Citizens of Baltimore on the expedi- ency of promoting a connexion Between the Ohio, at Pittsburg and the waters of the Chesapeake at Baltimore by a Canal through the District of Columbia, with his reply to some of the objections of Mr. Winchester. Delivered at a meeting held at the Exchange on the 20th day of December, 1823. Baltimore, 1824, 78 pp., map. (Rev.) X. A. Rev., vol. xviii, 1824, p. 217. 1825 Sparks, Jared. Baltimore. X. A. Review, vol. xx, 1825, pp. 99-138. 4-4 Physical Features of Baltimore County 1827 Disbrow, Levi. Notice of some recent experiments in boring for fresh Water, and of a pamphlet on that subject. Amer. Jour. Sci., vol. xii, 1827, pp. 136-143. 1828 Anon. First Annual Report of the Board of Engineers to the Board of Direc- tors of the B. & O. R. R. 43 pp. Map of route from Baltimore to Ellicott's Mills. Reviewed by Peter H. Cruse in X. A. Rev., vol. xxviii, 1829, pp. 166-186. 1S29 Anon. Third Annual Report of the President and Directors to the Stock- holders of the B. & 0. R. R. 8vo. 105 pp. 1830 Tyson, Philip T. Notice of some Localities of Minerals in the counties of Baltimore and Harford, Md., with an Appendix by C. U. Shepard (on Deweylite). Amer. Jour. Sci., col. xviii, 1830, pp. 78-84. 1833 Berthier, P. Analysis of Fer Titane of Baltimore. Amer. Jour. Sci., vol. xxiv, 1833, pp. 375-376. Extracted from Annales des Mines, tome iii, p. 39. Analyse de divers Mineraux Metalliques. Fer Titane de Baltimore en Maryland. Ann. des Mines, 3me serie, tome iii, 1833, pp. 41-43. Finch, J. Travels in the United States of America and Canada. London, 1833 . 8vo. 455 pp. Hayden, H. H. Description of the Bare Hills near Baltimore. Amer. Jour. Sci., vol. xxiv, 1833, pp. 349-360, map. Latrobe, B. H. Map o J2 a 3 Be E 03 w -a -a h E II o w Maryland Geological Survey 183 than the Vintage dolomite, and since the Wissahickon formation is conformable upon the Cockeysville marble the whole Glenarm series must underlie the lower Cambrian calcareous sequence. It remains to decide whether this 8000 to 10,000 feet of Glenarm deposit is Cambrian, i.e., the equivalent of the 2200 feet of lower Cambrian arenaceous sedimentation in Pennsylvania or whether it is pre-Cambrian. South of the Peach Bottom syncline the lower formations of the Glenarm series are cut by large intrusions of highly deformed plutonic rocks that contrast strongly with certain other slightly deformed igneous rocks of presumably younger age. Although the lower Paleo- zoic rocks of southeastern Pennsylvania show the influence of igneous action in the presence of tourmaline, pegmatite, and vein quartz, they are conspicuously free from intrusions of deformed igneous rocks, indeed from igneous rocks of any sort. It seems likely that the igneous effect visible in Paleozoic sediments was caused by the proximity of younger plutonics, perhaps genetically associated with the Woodstock granite. Amphibolite schists that are derived from basic intrusions and volcanic flows, are associated with the Wissahickon albite-chlorite schist in south- ern Pennsylvania and Maryland. If these amphibolites, which are lithologically similar to greenstone schists in Catoctin Mountain, repre- sent metamorphosed basaltic flows that are the equivalent in age of the pre-Cambrian volcanics of Catoctin Mountain the pre-Cambrian age of the Glenarm series is established. In view therefore of the facts that the Glenarm series does not cor- respond in lithology or thickness to the lower Paleozoic section as now determined in Pennsylvania and that it is cut by igneous material of presumably pre-Cambrian age it seems fair to conclude that the Glenarm series is pre-Cambrian in age. Correlation. — It is probable that the Glenarm series may be correlated with the Inwood-Manhattan formations of New York state which overlie the Fordham gneiss (correlated with the Grenville gneiss). 184 Crystalline Rocks of Baltimore County Berkey has recently described the pre-Cambrian section in the vicinity of New York City as follows:30 Manhattan schist In wood limestone Lowerre quartzite Fordham gneiss Structure Streams, during their erosion of an upland area, carry in their chan- nels a large quantity of detrital material that eventually finds a resting Fig. 13. — Diagram of Upright Folds (above) and Overturned Folds (below) place either upon land or in the sea. Sediments thus deposited from running water have a nearly horizontal position, a fact which can be readily verified by any observer who studies the silt deposited by a small tributary where it enters a large stream. When these fiat-lying sedi- ments are buried under a load of deposits they are indurated and consolidated into rocks. These rocks may be brought to the surface- by an uplift of certain portions of the earth's crust. If such an uplift is 10 Berkey, C. P., Geology of the West Point quadrangle, New York State Mus Bull. Xos. 225, 226, p. 40, 1919. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE X Fig. 2. — View showing coarse, highly inclined and cross-bedded Patuxent sands near Homestead, Baltimore City Maryland Geological Survey 185 accompanied by strong lateral compressive force the rocks are bent and thrown into a series of parallel arches and troughs known as anticlines and synclines. Such folds may be either upright open folds, Fig. 13 (above), or, if the compressive force be more severe the fold may be pushed over until it is inclined at a steep angle. Fig. 13 (below). The former type of folding is characteristic of the Great Appalachian Valley province in the western part of Maryland, while the latter type of over- turned folding is prevalent in the eastern part of the Appalachian belt within which Baltimore County lies. That compressive force acting as a tangential thrust may produce a crumpling and shortening of the earth's crust as described above has been shown experimentally to be probable.31 Areas of compression are localized in certain orogenic belts that in many parts of the world have been the locus of repeated folding during various geologic periods. The origin of the compressive force that acts to produce folding is still unestablished. It has been suggested that the most probable cause for compressive force is to be found in sub-crustal and intra-crustal changes in heat content. Baltimore County lies in the most easterly part of the Appalachian belt of folding as exposed in Maryland. This belt borders eastern North America and has been affected by several periods of mountain making from the pre-Cambrian to the Permian. Movement through- out that time was from the southeast, that is, from the direction of the Atlantic Ocean and the rocks of the Appalachian belt are folded, over- folded and thrust to the northwest along trends that are in general northeast and southwest, that is, at right angles to the direction of the pressure. Throughout the belt there are curves in the direction of the folds where they swing westward in salients or bend eastward in recesses. These curves are located along axes of transverse folds. Baltimore County lies in the Maryland salient whose cross axis extends from Balti- more northwest through Maryland and Pennsylvania, passing near Harrisburg. 31 Willis, Bailey, 13th Ann. Rept., U. S. Geol. Survey, pt. ii, pp. 217-274, 1893. Mead, W. J., Jour. Geol., vol. XXVIII, No. 6, p. 322, 1920. 186 Crystalline Rocks of Baltimore County Folding. — Baltimore county contains a series of short anticlinal domes that are in sharp contrast with the long folds characteristic of the Appalachian region. Mathews32 has discussed these domes and their significance at the axis of the Maryland salient. These 8 anti- clines lie parallel to each other in four belts which strike in general southwest. They strike S. 70° W. to the cross axis and they curve steeply southwest again. These anticlines comprise from northwest to southeast the Phoenix, the Texas, and in the third belt the Glenarm- Towson, the Chattolanee and the Woodstock. The Ben Run and Albert on anticlines are small uplifts just east of the Woodstock anti- cline. Baltimore City anticline, the most southeasterly of them all, is covered in large part by Coastal Plain sediments. These anticlines expose a core of Baltimore gneiss overlain by Set- ters formation and Cockeysville marble, which dips under the synclines of the Wissahickon formation that separate the anticlines. All of the anticlines are short, domical folds, the longest being the Phoenix which is 17 miles long and the shortest the Alberton, only one mile long. Northwest of Phoenix anticline, the Peters Creek formation occupies a syncline in the Wissahickon formation. This syncline extends north- east across Maryland and into Pennsylvania, where it contains Peach Bottom slates. Northwest of the syncline of Peters Creek formation the Wissahickon albite schist is folded into the Tucquan anticline whose axis passes through Shamburg and Bentley and extends northeast into Pennsylvania, where it was named. The Peach Bottom syncline and Tucquan anticline have trends parallel to the anticlines and synclines southeast of them but are long folds in contrast to the short ones of southeastern Baltimore County. The Phoenix anticline extends from three miles northeast of the Baltimore-Harford County line southwest to Worthington Valley near Glyndon. It is oval in shape and has minor folds on its flanks, especially on the northwestern side. There is a syncline also within the anticline from southwest of Glencoe to St. Johns Church. « Mathews, E. B., Anticlinal Domes, [etc.], J. H. U. Circ. X. S. 1907, No. 7, pp. 27-34. Maryland Geological Survey 187 The core of the Phoenix anticline like the others in the county is made up of Baltimore gneiss and is bordered by overlying members of the Glenarm series that are separated from the Baltimore gneiss by an unconformity. The contortion in the Baltimore gneiss is so great that in some cases minor folds have a vertical pitch. This close folding may have been acquired during the intrusion under pressure of pre-Glenarm granite. The structure of the Baltimore gneiss is discordant to the overlying Glenarm rocks that dip away from the anticline on all sides and for the most part do not show overturned folding. The Setters formation which overlies the Baltimore gneiss in a large part of the anticline dips under the Cockeysville marble at an angle of 40-70°. In the Buffalo syncline southwest of Glencoe and along Worthington Valley, Cockeysville marble directly overlies Baltimore gneiss. Its absence and that of the Cockeysville marble on the northeastern flank of the anticline, where the Wissahickon formation is in con- tact with the Baltimore gneiss, may be due to lack of deposition or to faulting. The Texas anticline lies less than 2 miles south of the Phoenix anti- cline and in a north-south cross axis of the Chestnut Ridge syncline. It is a small dome bounded on the west side by the Ruxton33 thrust fault that has carried it northwestward over part of the syncline of Wissa- hickon gneiss east of Cockeysville. The pre-Setters core is largely composed of igneous granite gneisses. The Setters formation, best exposed on the north side of the anticline, dips north 10° to 20° under the Cockeysville marble which in turn dips 40°-4o° northeast under the Wissahickon formation. The strike of the Setters and Cockeysville marble follows the curve of the anticline from Warren to the south side of the anticline. The Setters is absent on the south side because of the invasion of the Gunpowder granite. The Glenarm-Towson anticline extends from northeast of Long Green Creek to Lake Roland where its western side is broken by the Ruxton fault which extends south from the west side of the Texas anticline through Ruxton and Mount Washington. Its northeast end m Mathews, E. B., Bull. Geol. Soc. Amer. Vol. XVI, 1905. 188 Crystalline Rocks of Baltimore County is a compressed fold striking N. 45° E. and overturned to the northwest. Southwest of Gunpowder Falls the anticline is not overturned and the dip of the Setters quartzite changes from 60° S.E. in the northwest side of the fold to 40° N.W. in the vicinity of Oakleigh and westward. The direction of the axis of the anticline changes near Oakleigh to east and west which is the trend of the Chattolanee anticline west of the Bare Hills syncline. The Setters formation and Cockeysville marble are exposed for a short distance on the southeastern flank of the Glenarm- Towson anticline near the northeast and the southwest end. In the intervening area the Glenarm rocks have been cut out by the Gun- powder granite which probably was intruded during the folding of the Glenarm-Towson anticline. The Chattolanee anticline extends for 8 miles along an east and west axis lying south of Green Spring Valley and west of Bare Hills syncline. The Baltimore gneiss core is flanked by Setters quartzite, which dips steeply under the Cockeysville marble of the surrounding valleys. The northern side of the anticline is bordered by Cockeysville marble and the southern side of the anticline is closely folded and Cockeysville marble occupies compressed folds in the Setters formation. For a distance of a few miles along the south side of the anticline the marble has been cut by a northward overthrust of Wissahickon formation. The northern part of the Woodstock anticline lies two miles southwest of the Chattolanee anticline. The strike of the folding changes to N. 30° E. in the Woodstock anticline and continues in that direction in Howard County where the southwestern part of the anticline is exposed. In Baltimore County Glenarm rocks dip away from off the Baltimore gneiss basement on the north and northeast sides of the round plunging anticline; on the south side thrust faulting has compressed a syncline south of Davis and an anticlinal fold south of it. Less than a mile east of the Woodstock anticline there is a remnant of an anticline 1 mile long and not a quarter of a mile wide. This fragment consists of a narrow core of Baltimore gneiss overlain by quartzite and a small remnant of Cockeysville marble. This anticline has been thrust west over Wissahickon formation. Maryland Geological Survey 189 The Alberton is a small closely folded anticline only one square mile in exposure. It has a core of Baltimore gneiss from which Setters forma- tion and Cockeysville marble dip away in all directions. The folding is closely fluted on the northwest side of the uplift. In the city of Baltimore is exposed the most southerly of the anti- clines of Baltimore County. The Baltimore gneiss of this anticline dips gently northwest with minor waves in the folding and is overlain on the northwest side from Gwynns Falls to Jones Falls by interbedded mica and quartz schist that may represent the Setters formation. The southeast side of the anticline has been invaded by gabbro and is covered by Coastal Plain sediments on its south and southwest end. The Chestnut Hill-Sweetair syncline lies between the Phoenix anti- cline and the Glenarm-Towson and Chattolanee anticlines. It is occupied by Wissahickon formation, except in the cross anticline that extends north and south through Cockeysville and Texas, and exposes Cockeysville marble gently folded and dipping under the Wissahickon formation. The Wissahickon is folded into three synclines east of the cross valley. The Cockeysville limestone valleys at Hyde and "the Caves" are anticlinal folds in the synclinal axis. The synclines south of the Glenarm-Towson and Chattolanee anti- clines are also occupied by the Wissahickon formation exposed in remnants; one northwest of Gunpowder Falls; a second west of Mount Washington; and another north of Bare Hills and Randallstown. These small areas are what remains of the formation in the syncline after intrusion of gabbro and Gunpowder and Port Deposit granite gneiss. The cross axis of the Cockeysville marble exposed south of the Phoenix anticline is covered south of Ruxton by the westward thrust of the Towson anticline. The Peach Bottom syncline is a narrow fold about 2 miles wide oc- cupied by the Peters Creek formation in this area and bordered on either side by Wissahickon formation. It crosses the county in a south- westerly direction from the Harford County line near Gemmills and passes through Whitehall, Pleasant Grove, and Glen Falls. The syn- cline takes its name from the Peach Bottom slates that are infolded in 190 Crystalline Rocks of Baltimore County the Peters Creek formation for a distance of 18 miles, in both Penn- sylvania and Maryland. The Sykesville granite intrudes the Peters Creek formation in Carroll County and injects the formation in Balti- more County near North Branch of Patapsco River. The Peters Creek formation of the syncline is closely folded into minor anticlines and synclines and the south side, as has been mentioned, may be the edge of an overthrust fault which has thrust the Wissahickon formation northwestward over the syncline. The Tucquan anticline is a fold in the Wissahickon albite-chlorite schist lying northwest of the Peach Bottom syncline. The axis of the fold passes through Bentley and Shamburg and the Wissahickon schist dips about 45° in either direction at the axis. The minor folding is much steeper and the rock is closely crumpled. The Tucquan anticline is the southwestward continuation of that fold named in Pennsylvania where its axis crosses the Susquehanna River near Tucquan. Faulting. — The Ruxton thrust fault lies west of the Texas and Towson anticlines along a direction about S. 10° W. The thrust has carried the Texas anticline over the northern fold of the Sweetair syncline and has moved the Towson anticline westward over the Bare Hills syncline. The southward continuation of the fault is lost in the igneous rocks south of Mount Washington. Its northeastern extension north of Warren is lost in the Wissahickon formation. Brecciation accompanied the faulting and recemented fault breccia first noted by Mathews and Miller34 outcrops in a small run that parallels the road 2 miles south of Warren. Brecciated quartzite outcrops also in the county Alms House grounds a mile south of the first mentioned occurrence. Farther south a zone of shearing outcrops in the railroad cut near Lake Roland station. The thrusting along this fault was from the southeast and the displace- ment not more than a few miles. Faulting has occurred on the southeast side of the Woodstock anti- cline south of a narrow minor anticline in Baltimore gneiss. From relations seen in Howard County it seems probable thrusting has been m Mathews, E. B. and Miller, W. J., Geol. Soc. Amer. Bull., vol. XVI, p. 365, 1905. Maryland Geological Survey 191 to the southeast and such a possibility has been discussed by Mathews35 in his article on the anticlinal domes of Maryland. The Ben Run anticline which is fully 1 mile east of this thrust fault from the northwest has been thrust westward. The most important thrust fault of southeastern Maryland, the Martic overthrust lies northwest of Baltimore County in Carroll and Frederick counties. It was first worked out in the McCalls Ferry- Quarryville36 area of Pennsylvania. It is a low angle overthrust with a southeast dipping fault plain called the Martic overthrust and has carried the rocks of the Glenarm series northwest over Paleozoic rocks. The albite-chlorite Wissahickon schist forms the northwestern part of the fault block from Schuylkill River to Carroll County, Md. It is considered probable that the crystalline rocks of Baltimore County have been carried northwest on this fault. The thrust suggested along the diaphthoritic zone already described on the south side of the Peters Creek syncline may have been the result of piling up of the blocks during the period of the thrusting which produced the Martic overthrust. AGE OF THE STRUCTURES OF BALTIMORE COUNTY 1. Pre-Cambrian folding. — The Baltimore gneiss was injected and intruded by igneous material and closely folded before the deposition of the rocks of the Glenarm series which were laid down on the bevelled edges of the old folds. This period of folding must have been in the early pre-Cambrian. The Glenarm series was folded before Cambrian times and intruded by granites and gabbros probably during that folding. At that time the region lay to the southeast of its present position nearer the border of the continental area as we know it to-day. It is possible that the short anticlinal domes of Baltimore County were formed in this early period. It is obvious that their direction parallels younger Appalachian folding of the area to the west, so it is possible that the direction of "Mathews E. B., Anticlinal domes in the Piedmont of Maryland: Johns Hopkins University Circ, new ser., No. 7, pp. 27-34, 1907. « Knopf, E. B., and Jonas, A. L, U. S. Geol. Survey Bull. 799, 1929. 192 Crystalline Rocks of Baltimore County Paleozoic folding is posthumous and followed and was controlled by pre-Cambrian lines. It is known that in Frederick County, Maryland, lower Cambrian rocks lie unconformably on eroded surfaces of the folded Glenarm recks and this evidence strengthens the theory that much of the folding of the Glenarm rocks of Baltimore County was pre-Cambrian. 2. Paleozoic folding. — The date of the Martic overthrust maybe as far back as late Ordovician time but not after the Permian because no rocks younger than Chazyan are involved in the thrusting, and Triassic sediments are not affected by it. The Martic overthrust parallels other faults farther west in the Appalachian folded belt. These faults west of the Blue Ridge anticlinorium affect Carboniferous rocks and hence occurred during Appalachian deformation. The Martic thrust may have occurred earlier than these post-Carboniferous faults because it lies in an eastern, hence older belt of folding and because it was folded after thrusting took place. Evidence of such folding is seen along the eroded edge of the thrust in the vicinity of Mine Ridge Hill anticline which is part of the autochthonous block and which was folded with the overlying Wissahickon albite schist after the thrusting. The Mine Ridge Hill axis of uplift continues southwest in the Wissahickon albite schist as the Tucquan anticline. The open folding of this anticline is older also than the schistosity which cuts across it. Thus second schis- tosity may have been produced in this eastern area in the latter part of pre-Permian folding when thrusting was going on farther west in the Appalachian belt. The compressive stresses which had been operating since pre-Cam- brian times were satisfied in this area at the close of Appalachian de- formation for subsequent deformation from the Triassic period to the present has manifested itself in vertical uplift and normal faulting. Geological History In pre-Cambrian time Baltimore County was covered by water in which detritus was accumulating from some neighboring land mass. The exact location of this land is a matter of conjecture. The character of the sediments in the Baltimore gneiss indicates that the formation MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XI Fig. 2. — View showing Patuxent-Arundel contact, south shore of Spring Gardens, the probable locality where Tyson collected the historic Johns Hopkins cycad stump, Baltimore County. Maryland Geological Survey 193 was derived from the disintegration of granitic rocks, granodiorites, and quartz monzonites. The ancient highlands that furnished the material for the Baltimore gneiss was very probably somewhat similar in composition to the Sierra Nevada range of the present day. After a period of considerable duration sufficient to allow for a thick accumulation of arkosic material these sediments were consolidated into the rocks that later were transformed into the Baltimore gneiss. If, as appears probable, the Baltimore gneiss is the equivalent of the Grenville series, then the orogenic movement that accompanied the early Laurentian igneous activity must have intensely deformed the Baltimore gneiss and may also have established the main structural lines of the region. The intrusion of some granite magma possibly that of the Hartley granite, furnished an abundance of advance emana- tions in the form of alkalic vapors and highly fluid solutions that penetrated by lit-par-lit injection along the bedding planes of schistos- ity in the upper layers of the formation thereby producing a banded injection gneiss. A subordinate amount of basic igneous rock was probably intruded at the same time since we find stringers of horn- blendic gneiss within the biotite Baltimore gneiss. A considerable period of erosion followed and later there was laid down the Glenarm series. The oldest member of this series consisted of arkosic, siliceous, and argillaceous sediments that now compose the Setters formation. Whatever fossil remains these sediments may have contained were destroyed by the metamorphism that converted them into gneiss, quartzite, and schist. Local oscillation of the sea brought about a change in the character of deposition and calcareous and magnesian deposits accumulated in a transgressing sea. This impure calcareous magnesian material has formed the Cockeysville marble. A recurrence of the conditions that prevailed at the beginning of Glenarm sedimentation resulted in a thick accumulation of interbedded siliceous and argillaceous sediments with abundant arkosic beds. The arkosic beds were products of near- shore sedimentation derived from decay of adjacent igneous feldspathic rocks. The siliceous sediments were better sorted and were accu- 194 Crystalline Rocks of Baltimore County mulated farther out in the sea, while the argillaceous sediments were deposited in quieter waters. Subsequent metamorphism of this recur- rent series of sand, clay, and arkose has produced the southern type of Wissahickon mica gneiss and schist with a lithology almost identical to that of the Setters formation. In the northwestern part of Baltimore County the albite-chlorite schist represents a thick bed of feldspathic clay which has been sub- sequently metamorphosed into an albite-chlorite schist. Studies by the writers37 along the Susquehanna River south of Columbia, Penn- sylvania, have suggested the possibility that the albite-chlorite schist represents a northern facies of what is called the Wissahickon formation to the southeast. Sedimentation toward the end of Glenarm time gradually became less feldspathic and more siliceous, forming the series of arenaceous deposits interbedded with argillaceous beds of unknown thickness that has given rise to the Peters Creek formation. These Peters Creek deposits together with the northern albite-chlorite schist facies of the Wissahickon formation show a much milder type of anamorphism than the thoroughly recrystallized oligoclase-mica schist of the Wissahickon formation with its abundant development of the heavy minerals char- acteristic of zones of intense metamorphism. After the deposition of the Glenarm series the country was once more thrown into a series of folds that probably coincided with the major axes of the previous folding. Extensive invasions of gabbro took place followed by intrusions of granite and granodiorite. It is probable that the gabbro was intruded at the close of the period of folding. Since the granite cuts across the Glenarm anticline and intrudes the gabbro it is obvious that it is of later age than the deposition of the Glenarm series. It is itself deformed and may represent a later intrusion in a definite sequence of plutonic intrusions inaugurated by the gabbro, ,T Knopf, E. B., and Jonas, A. I., McCalls Ferry -Quarryville district: TJ. S. Geol. Survey Bulletin 799, 1929. Maryland Geological Survey 195 and resembles in texture the Columbia granite of Virginia which is pre-Ordovician3S and probably pre-Cambrian. No Paleozoic sediments occur in Baltimore County and its history for that time must be inferred from adjoining regions. Lower Cambrian deposition is known to have occurred in Frederick County where argil- laceous and arenaceous sediments were laid down on the beveled edges of rocks of the Glenarm series. It is possible that this early Paleozoic sea extended east of the present extent of the Lower Cambrian rocks and that erosion has since removed them in Baltimore County. A further clue to Paleozoic history may be gained from Virginia in a belt south of the Potomac to south of James River. In that area erosion had removed all but pre-Cambrian sediments by Chazyan time during which fine argillaceous sediments were deposited upon the surface of pre-Cambrian rocks. This trough in Virginia lies southwest of Balti- more County in the trend of the Peach Bottom syncline but the existence of a contemporaneous deposition in Baltimore County is a matter of conjecture. Post-Chazyan history of the rocks of the Glenarm series of Baltimore County must be sought along the western edge of these rocks in south- eastern Pennsylvania and western Maryland. In that area it is seen39 that the Glenarm rocks and overlying Cambrian sediments were thrust northwest along a low angle thrust called Martic overthrust. This thrusting was post-Chazyan and was followed by folding which affected overthrust and autochthonous rocks alike. The thrusting and folding may have taken place in a period of de- formation which closed the Paleozoic or it may have been begun earlier in late Ordovician or Devonian folding. After the last period of thrusting and folding which affected the area a granite intrusion occurred now represented by the Woodstock and Ellicott City granites and associated pegmatites. These granites 38 Taber, Stephen: Geol. of Gold Belt in the James River basin. Virginia Geol. Survey Bull., Vol. VII, 1913, pp. 39-52. Jonas A. I.: Geologie Reconnaissance in the Piedmont of Virginia Bull. Geol. Soc. Amer., Vol. XXXVIII, 1927, p. 841. 39 Loc. cit., U. S. Geol. Survey Bull. 799, 1929. 195 Crystalline Rocks of Baltimore County show by their slightly deformed granitic texture that they are post- tectonic granites hence probably post-Paleozoic in age. After the Appalachian revolution Baltimore County was eroded until Triassic times, when it is possible that sandstones and shales of the Newark group were deposited in this area although none of these deposits now exist there. The western part of Baltimore county lies 20 miles southeast of the western belt of Triassic sediments and only a little northwest of the central axis that separates the western and eastern belts of Triassic rocks. The igneous activity that accom- panied Newark sedimentation left its mark in the diabase dike that crosses the county. Normal faulting which characterized Triassic deformation has not been observed in Baltimore County. The crystalline rocks of Baltimore County have originated in two ways: some as igneous rocks that have consolidated from a molten condition beneath the earth's crust, and subsequently revealed to view by removal of the overlying material; others as sedimentary rocks that are the disintegrated materials of former land surfaces, washed down from the highlands, deposited under water, and then consolidated. Both types of rocks have been altered from their original form under the influence of intense pressure, high temperature, and chemical reaction. Owing to this alteration the rocks now appear under new forms with changed mineral components. New characteristics are superimposed upon the old so that when the alteration is complete the old form is totally obliterated. In the case of such profound alteration the derivation of the rocks must perforce remain a matter of speculation. The altered rocks are known as crystalline schists and their char- acteristic feature is their schistosity, or tendency to split readily along a given direction. This property of schistosity in a rock is caused by a definite arrangement of the mineral components. Certain tabular or platy minerals such as mica, hornblende, or feldspar possess an inherent tendency to split along a given direction, which property is known as cleavage. Such minerals, if originally scattered at random in the rock, may be rearranged, under pressure, so that they lie with their cleavage planes parallel; or such minerals may be newly formed, Maryland Geological Survey 197 with parallel cleavage directions, by recrystallization of chemical com- pounds that were originally present in some other mineral combination. This parallel arrangement of the cleavage planes in the mineral compo- nents produces schistosity in the rock. These schistose rocks, which are largely made up of tabular crystals of such minerals as mica and hornblende, have a characteristic banded and sparkling crystalline look, in which they differ greatly both from the loose unconsolidated sands and gravels of the Coastal Plain and from the indurated and compara- tively lustreless sandstones and shales of the Triassic Valley. The oldest crystalline schist of sedimentary origin is the Baltimore gneiss, a light colored rock of granitic aspect that is well exposed in numerous quarries within the city of Baltimore. The upper part of the formation has been thoroughly penetrated by the emanations from an underlying molten mass of granitic composition. The resultant banded rock, which is an injection gneiss, forms a large part of the arched uplift, near Phoenix. The sediments of the Baltimore gneiss were deposited during pre-Cambrian time, in the oldest era of the earth's geological history. They are separated from the overlying Glenarm series by an erosional unconformity, an interval during which the Baltimore gneiss sediments were folded, uplifted above sea level, and wasted away under the processes of land erosion. Subsequently the worn and dissected land mass was covered by Glenarm sediments. The lowest formation of the Glenarm series is the Setters, which was laid down as an irregular shore deposit of variable thickness in a sea that doubtless lapped upon an embayed coast line fringed with numer- ous islets. The materials of the Setters were sandy with occasional layers of mud. They are now recrystallized to mica-gneiss, quartzite, and mica-schist. The Cockeysville marble was formed over the Setters formation, or over the Baltimore gneiss where the Setters formation is entirely absent. It is a calcareous deposit alternating with magnesian layers. The whole formation was later converted into marble and certain beds furnish an excellent building stone which has been utilized in many public buildings, notably in the Washington Monument. 198 Crystalline Rocks of Baltimore County The thickest part of the Glenarm series is comprised in the Wissa- hickon formation and the overlying Peters Creek formation. The Wissahickon is separated into two mineralogical facies on the basis of difference in conditions of recrystallization (metamorphism). The southern facies (oligoclase mica-schist) was recrystallized under deep seated conditions from a series of sands and shales essentially similar to the sediments of the Setters. The northern facies (albite-chlorite schist) was crystallized from the same type of sediments as the oligo- clase-mica schist but alteration took place in the uppermost zone of metamorphism. The Peters Creek formation is a highly arenaceous series, comprising quartzite, quartzose schists, and mica-schists. It occupies the trough of a synclinal fold and overlies in conformable sequence the Wissahickon oligoclase-mica schist on the south side of the syncline and the Wissahickon albite-chlorite schist on the north side. There is no evidence of any break in deposition during the sedimenta- tion of the Glenarm series and the occasional absence of the lower formations of the series probably means that the sea advanced over the land, thereby carrying the upper deposits further inland, where they rest upon the Baltimore gneiss, rather than that the lower beds have been originally present and removed by erosion before the upper beds were laid down. The whole series is believed to be pre-Cambrian because there are greenstone schists infolded with Wissahickon formation of northern Maryland and southern Pennsylvania and these greenstones are derived from basaltic lavas similar to the lavas that were poured out during pre- Cambrian time from volcanoes in Catoctin Mountain, Maryland, and South Mountain, Pennsylvania. Basal Cambrian conglomerate un- conformably overlies the greenstones and albite chlorite facies of the Wissahickon schist of the Piedmont so that it seems evident that the whole Glenarm series was laid down before the opening of the Paleozoic era. The absence of fossils in these crystalline schists is probably due to absence in the sediments of forms of life that would be preserved in a manner capable of surviving the subsequent deformation that the rocks have undergone. Maryland Geological Survey 199 The igneous rocks of Baltimore County comprise both light colored, prevailingly grayish rocks of granitic character, and dark colored, usually green rocks known as gabbro, serpentine or diabase. Several granitic rocks have been described, belonging to at least three different periods of granitic intrusion ranging in age from the pre-Cambrian to a much later epi-Carboniferous period of igneous activity that broke out long after the Coal measures had been laid down in western Maryland . The gabbro and serpentine doubtless represent different parts of the same molten magma. They have been formed more recently than the Glenarm series and are intruded into Glenarm rocks. The diabase is the only unaltered rock in the region and is very similar to other diabases that belong in the Triassic period of igneous intrusion later than the epi-Carboniferous igneous activity. Therefore the Baltimore County diabase is believed to be Triassic. The region of Baltimore County corresponds in its lithology, geologic structure and age to the crystalline rock in the district of New York City. The relations between the crystalline rocks of New York City and of Baltimore that are suggested by the present work may be defi- nitely established by further study in New York, Connecticut, and Massachusetts. THE COASTAL PLAIN DEPOSITS BT EDWARD W. BERRY Introductory The Coastal Plain deposits of Baltimore County occupy approxi- mately the southeastern fourth of the county and present no local features which differ from the adjacent areas to the northeast and south- west. During the immeasurably long interval following the formation of the rocks of the Piedmont three-fourths of the county, this region was above the sea and accumulated no permanent sediments. This interval, during which Baltimore County was a land area, embraces more than half of the Mesozoic era and comprises what are known as the Triassic and Jurassic periods. There seems to have been a depression of this old land surface at the close of Jurassic time, which permitted the accumulation of the non- marine, continental deposits of the Lower Cretaceous which are known as the Potomac group of formations. This depression was in the surface of the weathered crystalline rocks similar in character to those now outcropping in the Piedmont part of the county, and these rocks form the present irregular sloping floor upon which the Coastal Plain sediments rest. This accumulation of Lower Cretaceous continental deposits followed the southeastward warping of the old surface and occurred chiefly in the present drainage basins of Whitemarsh, Stemmer, and Herring runs. The Lower Cretaceous Formations The Lower Cretaceous deposits of Baltimore County outcrop in inconsiderable areas in the southern part of the county. They con- stitute a part of the belt of deposits along the inner margin of the Atlantic Coastal Plain from Pennsylvania to southern Virginia. They are more extensively developed in Maryland than elsewhere throughout 200 MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XII Fig. 2. — View showing Patapsco sands and clays overlain by Pleistocene sands, B. & O. R. R. Cut, Rosedale Hill, Baltimore County Maryland Geological Survey 201 their extent and have been much studied, especially in the region be- tween Baltimore and Richmond, where they are more fossiliferous than in Baltimore County. The deposits are largely sands and clays of varying stratigraphic and lithologic characteristics and are, for the most part, unconsolidated, although in places sandstones are developed by local consolidation, often through the agency of iron oxide. The deposits in general dip gently toward the southeast, the dip usually becoming flatter in passing seaward or upwards in the series. THE POTOMAC GROUP The Potomac group, originally named the Potomac formation by McGee, consists of highly colored gravels, sands, and clays, crossing the county in a belt from northeast to southwest from Gunpowder to Elkridge, underlying much of Baltimore City and the Coastal Plain, and furnishing artesian water to the Aberdeen Proving Grounds and the great industrial development on both banks of the Patapsco south- east of the City of Baltimore. The Potomac group is now recognized as made up of the Patuxent; Arundel, and Patapsco formation, all three being recognized in Baltimore County. The Patuxent Formation The Patuxent formation was named from Patuxent River in the basin of which these deposits were first recognized as an independent formation. Areal distribution. — The Patuxent has the largest areal extent of any of the Potomac formations in Baltimore County although considerable areas have been removed by the active erosion of the region. Its area of outcrop extends from the Gunpowder near Loreley westward past Germantown on Belair Road, where there is an area of several square miles, nearly to Towson where its inner boundary turns to the south, there being considerable areas south of Towson and around Govans, separated from the large area underlying the central part of Baltimore City by Setters, Baltimore gneiss, gabbro and Cockeysville. South of the area of Baltimore gneiss in west Baltimore there are 202 Coastal Plaix Deposits of Baltimore County j extensive exposures of the Patuxent in the region between the Frederick Road and the southern boundary of the county at Patapsco River around Westport, Yioletville, Halethorpe, Lansdowne, St. Denis, and Relay. All the mapped Patuxent lies within the area outlined except for a considerable outlier around Catonsville. There are considerable areas of gravel in the Green Spring Valley, the Dulaney Valley, and in the valley of Goodwin Run, as well as around Baldwin near the Harford line, that after considerable hesitation have been mapped as Brandywine, and which may be of Patuxent age. Character of materials. — The materials comprising the Patuxent formation are extremely variable, although prevailingly coarse in Balti- more County. Buff and light colored sands, sometimes more highly colored by ferric oxide, predominate. These sandy materials are often highly arkosic, that is, they contain considerable amounts of kaolinized feldspar. They are in many places cross-bedded and in this region frequently merge into gravels with pebbles of considerable size. Inter- bedded with the sands and gravel bands are small and large lenses of clay, which are commonly light colored, very rarely containing enough carbonaceous matter to give them dark tones, and locally highly colored by ferruginous oxides. Organic remains. — The organic remains, or fossils, of the Patuxent formation are neither plentiful nor varied. In Baltimore County they are restricted to fragments of petrified wood, occasional cones of a sequoia, and fragments of silicified stumps of cycads. The first cycad stumps found in America were collected by Tyson, former State Geologist, from near Spring Gardens at the extreme southern part of the county, now a part of Baltimore City. A considerable flora made up of ferns, cycads, and conifers, has been described from the Patuxent. These were obtained for the most part from outcrops of the formation in northern Virginia. Strike, dip, and thickness. — The strike of the Patuxent formation in Maryland is in a general northeast-southwest direction, becoming more nearly north and south as the valley of the Potomac is reached, to the south of which, in Virginia, the strike is north and south. Maryland Geological Survey 203 The dip of the beds is to the southeast but is variable in amount, especially in proximity to the "fall-line," where in places it largely exceeds the dip of the main body of the deposits farther eastward. The dip to the southeast varies from 50 to over 100 feet to the mile, averag- ing about 60 feet, but showing considerable variation along the immediate border of the Piedmont. It is 90 feet at Bay View, 66 feet at Perry Hall, 66 feet at Towson, and 1 14 feet at Catonsville. The maximum thickness of the Patuxent formation in this area has been estimated from well data as between 350 and 500 feet. There is considerable variation due to the uneven floor of crystalline rocks upon which it was deposited and to the removal of considerable thicknesses by erosion in some areas. The surface outcrops in Baltimore County are usually inconsiderable in thickness. Stratigraphic relations. — Throughout its extent in Baltimore County the Patuxent formation rests, with marked unconformity, on the ancient crystalline rocks of the Piedmont. It is in general overlain unconform- ably by the Arundel formation. Where erosion has been marked it may form the surface as is the case in many outcrops between Govans and Perry Hall, or it may be overlain unconformably by Pleistocene surficial deposits. The A rundel Formation The Arundel formation was named from its typical development in Anne Arundel County, Maryland. Areal distribution. — The outcrops of the Arundel formation are confined to the region adjacent to the "fall-line" in the southeastern part of the county. These are extensive in the vicinity of Halethorpe, Lansdowne, and eastward to Westport on the neck between Middle Branch and Patapsco River. They may also be seen in the uplands both north and south of Herring Run and in the cuts of the Baltimore and Ohio and Pennsylvania railroads in the vicinity of Stemmer Run. Lithologic character. — The Arundel formation consists typically of drab, more or less lignitic clays; in places carrying nodules, flakes and ledges of earthy iron carbonate or siderite, which is often oxidized to form limonite. These ores were formerly mined, particularly in the 204 Coastal Plaix Deposits of Baltimore County region between Baltimore and Washington, the furnace at Muirkirk having gone out of operation only a few years ago. Strike, dip and thickness. — The strike of the Arundel formation is essentially parallel to that of the Patuxent formation, being northeast to southwest across Baltimore County. The dip of the beds is to the southeast, and is in general about 50 feet to the mile. The observed thickness of the Arundel formation varies from a few feet to about 100 feet. Organic remains. — Both animal and plant fossils have been found in the deposits of the Arundel formation, although only the latter class of remains are known from Baltimore County. A considerable fauna of great interest and including a variety of dinosaurs, crocodiles, and turtles has been described from outcrops of the Arundel formation in Prince George's County, and a few poorly preserved fresh-water mollusks are occasionally encountered. The only notable Arundel plant locality in Baltimore County is in a low cut along the Baltimore and Ohio Railroad near Bay View, from which 8 different species of ferns, cycads, and conifers have been described. The Arundel flora is of the same general type as that of the Patuxent formation and a large number of species of the latter survived into the Arundel. Stratigraphic relations. — The Arundel formation rests unconformably on the Patuxent, occupying depressions, believed to be old drainage lines in the surface of the late Patuxent and is thought to represent deposits formed in favorable situations in swamps toward the close of Patuxent time. It can not be recognized northeast of Baltimore County and disappears south of the Potomac River in Virginia. Its large con- tent of iron is due to the areas of crystalline rocks high in iron such as the gabbro, whose weathered products made up its materials. In the presence of the carbonaceous materials accumulating in the Arundel swamps the iron was deposited as the carbonate. In the sediments of the earlier Patuxent and later Patapsco formations there was not enough carbonaceous material to reduce these iron salts, consequently they are responsible for the highly colored nature of so much of their sedi- ments which are in striking contrast to the less highly colored and often drab and dark colors of the Arundel deposits. Maryland Geological Survey 205 Except where the later sediments have been removed by erosion the Arundel is overlain unconformably by the deposits of the Patapsco formation or in the absence of the latter by the Raritan or Pleistocene. The Patapsco Formation The Patapsco formation was named from Patapsco River in the lower valley of which its deposits are well exposed and were first studied and recognized as an independent formation. Areal distribution. — The Patapsco formation outcrops in Maryland in a belt of varying width extending from the Delaware line southwest- ward to the District of Columbia, generally immediately to the south- east of the Patuxent or Arundel formations. In Baltimore County most of the higher elevations along the inner margin of the Coastal Plain on both sides of the "fall-line," from Harford County on the east to Anne Arundel County on the south, are capped with the deposits of the Patapsco formation. Other areas mapped as Patapsco, notably a large area in Election District No. 12 between Gunpowder and Back rivers, are mostly concealed by surficial deposits. Character of muterials. — The Patapsco formation consists chiefly of highly colored and variegated clays, interbedded with sandy clays, sands, and gravels, the materials of different kinds grading into one another both horizontally and vertically. In many places the sandy beds in the vicinity of the clays are indurated to form layers or pipe-like, or irregular pseudoconglomeratic layers of ironstone. The variegated clays exhibit a great variety of rich and delicate tints in blotched pat- terns. The sands are commonly cross-bedded and may carry pellet of clay or decomposed feldspar. A red ochre, known locally as "paint rock" or "paint stone," is not uncommon, especially in the district immediately south of Baltimore City. In general the materials that constitute the Patapsco formation are readily distinguished from those of the Arundel formation by their color. At certain localities where the Patapsco clays contain much carbonace- ous material they may be drab and are then likely to contain recognizable plant remains, as at Federal Hill. The Patapsco differs from the Patux- 206 Coastal Plain Deposits of Baltimore County ent in the predominance of clayey over sandy materials and in their, in general, more brilliant colors. Organic remains. — The Patapsco deposits have yielded a few speci- mens of poorly preserved unios and an extensive flora, including repre- sentatives of ferns, cycads, conifers, and flowering plants. The ferns, cycads, and conifers represent for the most part the dwindling remnants of the Patuxent-Arundel flora, some species being common to all three formations and the genera being largely identical. The fern genera Scleropteris, Schizseopsis, and Tsmiopteris have disappeared, but Ruffor- dia, Cladophlebis and Onychiopsis are still common. Petrified remains of a species of the fern known as Tempskya and impressions of fronds of a peculiar new genus of ferns, Knowltonella, are highly characteristic of this formation. Among the cycads Podozamiies and Zamites are repre- sented, but the genera Nilsonia, Dioonites, Cienis, Ctenopteris, and Ctenopsis of the older Potomac have disappeared. Silicified trunks of Cycadeoidea have been found in the Patapsco, but it is questionable if they have not been reworked from the older formations. Among the conifers Laricopsis, Baiera, Cephalotaxopsis, and Arthro- taxopsis are no longer represented. Species of Widdringioniies and Pinus are new and characteristic, while the genera Sequoia, Sphenolepis, Brachyphyllum, and Nageiopsis are still present. The marked distinctness and more modern aspect of the Patapsco flora is due, however, to the abundance of Dicotyledonae, which fore- shadow and were undoubtedly for the most part ancestral to the Dicoty- ledonae of the Upper Cretaceous Raritan formation. The more characteristic of these are the various species of Araliaephyl- lum, Sterculia, Cissites, Celastrophyllum, Populophyllum, etc. The compound leaves of Sapindopsis are one of the most striking dicotyle- donous elements present. Three species are known and all are strictly confined to this horizon in eastern North America. In Baltimore County the only prolific fossiliferous locality is that of Federal Hill. Most of this area is now built over, but during the grading and opening of streets many large collections of fossil plants were made. These contained 10 different species of ferns, a very common Equisetum, 9 Maryland Geological Survey 207 different conifers, and 9 different species of flowering plants, or Angio- sperms as they are called. Strike, dip, and thickness. — The strike of the Patapsco formation is essentially identical with that of the older formations of the Potomac group. The normal dip varies from 35 to 40 feet to the mile toward the southeast. The thickness is variable, the maximum being in well sections where a thickness of 260 feet has been found. Surface outcrops both in the county and elsewhere are usually much less than this, the maximum observed being at Red Hill in Cecil County where a thickness of 130 feet was measured. Stratigraphic and structural relations. — The Patapsco formation in Baltimore County is everywhere underlain by the Arundel formation, but the latter is conspicuously absent in Cecil County, and also in the Potomac Valley and southward in Virginia. In places, as at Relay, the Patapsco transgresses the older Potomac formations and rests on the crystallline rocks of the Piedmont, thus affording clear evidence of the unconformity at the base of the Patapsco, which is corroborated by the striking contrast between its flora and that of the Patuxent and Arundel. The Patapsco formation was much eroded prior to the deposition of the overlying Raritan formation. Southwest of Baltimore County where the Raritan becomes thinner and finally disappears altogether, the Patapsco is overlain by later Cretaceous or Tertiary deposits, and, in the absence of these, by Pleistocene materials. The Upper Cretaceous Several Upper Cretaceous formations have been differentiated in Maryland, chiefly on the Eastern Shore and in Southern Maryland, the only Upper Cretaceous formation represented in Baltimore County being the earliest of these, known as the Raritan formation. The Raritan Formation The Raritan formation receives its name from the typical development of beds of this age around Raritan Bay in New Jersey, where they were long known as the Amboy Clays and afford the basis of an extensive 208 Coastal Plain Deposits of Baltimore County industrial development. There is considerable question among geolo- gists as to the propriety of correlating the southwestward extending belt of sands and clays with the very extensive development of these in the Amboy district of New Jersey, and it is possible that the latter represent a long interval of essentially estuarine deposition not represented else- where in the Atlantic Coastal Plain. Area! distribution. — In its wider distribution the Raritan formation has been recognized from the type locality in the Amboy district of New Jersey around Raritan Bay eastward on Staten Island and on west- ern Long Island, New York, and southwestward across New Jersey, Delaware, and Maryland to the valley of the Potomac, although, as stated in a preceding paragraph, there is some doubt as to the validity of this correlation. In Baltimore County, what has been mapped as Raritan is exposed in limited areas immediately overlying the Patapsco on Back River neck between Middle and Back rivers, and on Patapsco River neck between Back and Patapsco rivers, and in a low exposure near Rocky Point at the mouth of Back River where erosion has brought it to light from beneath the Pleistocene cover. The Raritan is encountered in wells, lying on top of the Patapsco formation and beneath the Pleistocene in all of the peninsulas between the Gunpowder and Patapsco rivers in the southeastern part of the county. Character of materials. — The Raritan consists of materials similar to those of the underlying Patapsco, that is clays, sands, and subordinate amounts of gravel. The clays, although frequently variegated, are generally less highly colored than those of the Patapsco. Often they are more or less drab in color due to their content of carbonaceous matter, and thin lignitic and more or less pyritiferous laj'ers may then be intercalated. The sands are frequently white or buff in color and these may be locally indurated into hard ledges by either silica or iron oxide. In the latter case they will be brownish or reddish in color. Paleontologic character. — In the region southwest of New Jersey only plant fossils have been found in the Raritan. In Maryland these have been found chiefly on Elk Neck in Cecil County and at Congress MARYLAND GEOLOGICAL SURVEY BALTI MORE COUNTY. PLATE XIII Fig. 2.— View showing Pleistocene gravels at Catonsville, Baltimore County Maryland Geological Survey 209 Heights, across the Anacostia River from Washington. The only locality in Baltimore County where identifiable plant fossils have been found is at the mouth of Back River near Rocky Point where a few leaves of Dicotyledons have been collected. Strike, dip, and thickness. — The strike and dip of the Raritan forma- tion correspond closely with those of the underlying Patapsco formation. The normal dip varies from 30 to 50 feet to the mile, reaching a maximum to the northwest and flattening toward the southeast. None of the few exposures in the county show any considerable thickness. In the artesian well at Bay Shore the supposed Raritan is 165 feet thick. The formation thickens toward the northeast beyond the limits of the county. Siratigraphic relations. — The Raritan is considered to overlie the Patapsco formation unconformably, although there is no evidence of such an unconformity within the limits of Baltimore County, in fact there are few outcrops in this area that expose the contact with the Patapsco. It is considered to be unconformably overlain by the Magothy formation in other parts of the Coastal Plain of Maryland, but in Baltimore County it is almost entirely concealed by the surficial deposits of the Talbot formation of the Pleistocene. The Pleistocene Formations The Pleistocene formations of Maryland and the Coastal Plain to the southward are usually considered to constitute the Columbia group, so named by McGee. They are of similar origin and have many characteristics in common, consisting mostly of surficial gravels, sand, and loam, with occasional cobbles and buried swamp deposits, with the same physiographic expression. Within the area of Baltimore County four formations have been mapped, although others have been recognized, the difficulties of determining their exact age or of correlating circumscribed exposures, particularly of the older, has prevented positive conclusions until the comparable deposits of the whole province of which Baltimore County is a small part, shall have been studied in detail. The formations recognized, from oldest to youngest, are the Brandy- 210 Coastal Plain' Deposits of Baltimore County wine, Sunderland, Wicomico, and Talbot. It is impossible to differen- tiate these by either lithologic or paleontologic criteria as the materials of which they are composed are largely derived from the older formations which occur in the region, and all except the youngest are not at all or sparingly fossiliferous. The lithology varies both horizontally and vertically and is apt to change with the underlying formations so that the deposits belonging to the same formation may, in different areas, differ more than the deposits of two different formations in proximity to one another and to the common source of their sediments. Sometimes a formation will appear as a lithologic unit in a single exposure. At other times there are local breaks denoting rapid changes in sedimentation. Their differentiation and mapping has therefore depended almost entirely upon their physiographic expression (see chapter on Physiography). The Brandywine formation The term Brandywine was proposed by W. B. Clark1 in 1915 to replace what had previously been called "Lafayette" in Marj'land after it was shown that the type section of the Lafayette in Mississippi was of earlj' Eocene age. It was named from the exposures near the town of Brandywine in Prince George's County. As defined by Clark, it comprised what had been called Lafayette and still earlier Appomattox, and included supposed high-level restricted outliers in the District of Columbia, Baltimore and Cecil counties (470 to 508 feet) as well as the extensive more or less dissected but continuous plain extending from 200 to 300 feet above sea level that forms the peninsula of Southern Mary- land southeastward to the scarp near Charlotte Hall which separates it from the Wicomico formation. It was subsequently shown by Bascom and Miller2 that the high-level gravels just alluded to differed in age from the lower-level more con- tinuous plain of Southern Maryland, and the name Bryn Mawr was applied to the former which has not been recognized in the Coastal 1 Clark, W. B., Amer. Jour. Sci., vol. XL, pp. 499-506, 1915. Bascom, F. and Miller, B. L., Elkton-Wilmington Folio, U. S. Geol. Survey, 211, p. 12. 1920. Maryland Geological Survey 211 Plain. These latter are discussed in the chapter on the Physiography of Baltimore County. What is believed to represent the thus modified Brandywine is present in limited areas in Baltimore County, but no where in a surely recognizable condition, since it is readily confused with high-level Sunderland and with residual gravels of the Cretaceous. The Sunderland formation The Sunderland formation was named by G. B. Shattuck3 in 1901 from Sunderland, Calvert County, where its deposits are typically developed. Areal distribution. — The Sunderland formation is developed as a terrace or plain topping the secondary stream divides along the inner margin of the Coastal Plain. In Baltimore County it occurs as a fairly continuous but much dissected border along the "fall-line," 2 to 3 miles in width and at altitudes of 160 to 200 feet, entirely across the county. In its wider extent it extends in a similar situation along the Atlantic border into the South Atlantic States. Character of materials. — The materials of the Sunderland consist of variable proportions of gravel, sand, and clay, showing large amounts of vertical and horizontal variation within short distances. Occasional cobbles of considerable size are believed to have been brought into the area of sedimentation by river ice, just as the Susquehanna River at the present time distributes such cobbles around the head of Chesapeake Bay. The pebbles of the Sunderland as a rule show less weathering than those of the high-level gravels of the Piedmont region of the county, as at Catonsville, Reisterstown, etc. Physiographic expression. — The Sunderland deposits constitute the Sunderland plain, and were laid down during the depression of early Pleistocene time, when the waters of the Atlantic extended up the river valleys and over the lower interstream areas. These waters tended to remove and spread out the existing irregularities of surface and to cut a cliff or escarpment where their waves broke on higher parts of the shore. In places this scarp bounding the landward margin of the Sunderland is preserved, particularly in parts of the Coastal Plain south of Baltimore 3 Shattuck, G. B., Johns Hopkins Univ. Circ. Xo. 152, 1901. 212 Coastal Plain" Deposits of Baltimore County County. The surface of this Sunderland plain ranges in altitude from 160 to 200 feet and slopes gently toward the southeast and toward the larger estuaries at a rate of 8 to 10 inches to the mile, a slope so gentle as to be practically indistinguishable in the narrow belt of deposits that have been preserved in Baltimore Count}'. Paleontologic character. — No recognizable fossils have been discovered in the deposits of Sunderland age in Baltimore County, although a considerable flora has been described from beds of this age in Calvert County. Thickness. — The thickness of the Sunderland in any region depends upon the nature of the surface upon which its deposits were spread and to some extent upon the variations in the amount of clastic material and according to the character and degree of weathering of the rocks over which the Sunderland sea transgressed. Stratigraphic relatio?is. — The Sunderland deposits overlie unconforma- bly whatever older formations constitute its base. The Wicomico formation The Wicomico formation was named by Shattuck4 from the typical development of its beds in Wicomico County on the Eastern Shore of Maryland. After an interval of emergence, a change of level permitted another invasion of the sea over the area but this was a lesser submer- gence than that of the Sunderland and consequently extended over a smaller area. Areal distribution. — The Wicomico deposits form a plain lying at a lower level than the Sunderland and consequently form a seaward border to the latter from which they are normally separated by a wave-cut scarp representing the shoreline of the Wicomico sea. Wicomico de- posits extend entirely across the county in a belt lying immediately to the southeast of the Sunderland belt. In their wider extent they can be traced from New Jersey into the South Atlantic States and are beauti- fully developed on the Eastern Shore of Maryland. The terrace plain formed by the upper surface of the Wicomico deposits is slightly over 3 4 Shattuck, G. B., Johns Hopkins Univ. Circ. Xo. 152, 1901. Maryland Geological Survey 213 miles wide southeast of Whitemarsh in the eastern part of the county and over 4 miles wide on Patapsco River neck. It is well developed in Baltimore City south of North Avenue, although now entirely obscured by grading and buildings. It is also well developed in the City of Washington, Capitol Hill consisting of deposits of this age. Character of materials. — The materials which constitute the Wicomico formation are similar to those of the Sunderland and in fact they were largely formed by degredation and redeposition of the unconsolidated sediments of the latter. As in all the Pleistocene deposits of the county, the materials comprise varying amounts of gravel, sand, clay, and loam, with occasional cobbles brought in by ice. South of Baltimore County peat beds, sometimes with huge cypress stumps, are buried in the base of the formation, but no occurrences of this sort have been discovered in the county. Physiographic expression. — The Wicomico is developed as a terrace bordering the outer edge of the Sunderland and extending as reentrants up the larger stream valleys. Its surface forms the Wicomico plain so extensively developed in regions to the south of Baltimore County. The surface of this plain lies at altitudes of from 80 to 100 feet and slopes gently toward the sea and the larger estuaries. Paleontologic character. — No recognizable fossils have been found in the Wicomico deposits within the limits of Baltimore County. Outside this area occasional molar teeth of elephants have been found, as well as numerous fossil plants. In excavating at the site of the Walker (now Mayflower) Hotel on Connecticut Avenue in Washington, a few years ago, a 6 to 9-foot bed of peat containing huge stumps of the bald cypress was encountered at the base of the Wicomico. This peat has yielded 78 species of diatoms5 and 28 species of terrestrial plants, as well as various insect galls.6 Thickness. — The thickness of the Wicomico formation is not at all uniform, owing to the uneven surface upon which it was deposited. This thickness may range from a few feet to 50 feet or more. The forma- * Mann, Albert, Jour. Wash. Acad. Sci., vol. 14, pp. 26-32, pi. 4, 1924. « Berry, Edward W., Idem, pp. 12-25, pi. 1-3. 214 Coastal Plain Deposits of Baltimore County tion thickens in the old valleys and thins on the divides and is seldom as great as might be supposed from the fact that the base in places may be as low as 40 feet above tide while the surface may rise to 100 feet. Notwithstanding these irregularities the formation as a whole occupies an approximately horizontal position, with a slight southeasterly dip. The average thickness in Baltimore County is probably from 20 to 25 feet. Stratigraphic relations. — In this area the Wicomico overlies uncon- formably the crystalline rocks of the Piedmont or the sands and clays of the Cretaceous. It may locally rest on remnants of the Sunderland but if so the relations would probably not be recognized because of the identity of the materials in each. Age. — It has been accepted by most geologists that the Sunderland) Wicomico, and Talbot formations were of Pleistocene age and that the topographically highest was oldest and the lowest youngest. No direct confirmation of this assumption has been possible since the fossil content is insufficient and the species determined are too similar if not identical with still surviving forms. It has also been assumed that despite the presence of cobbles and even boulders that were obviously carried by floating ice, that in general these formations corresponded with interglacial instead of glacial periods, on the assumption that the locking up of water in the ice sheets would have caused a general lowering of sea level and as the times of deposition of these formations were times of submergence, these must have alter- nated with the times of glaciation. Recent work by Leverett in the Susquehanna watershed in Pennsylvania has furnished presumptive evidence that the Wicomico is of the same age as the valley train from the terminal moraine of the Illinoian ice sheet preserved at the junction of North and West Branch of the Susquehanna River. The plant and animal remains found in the Wicomico indicate climatic conditions as warm or even warmer than prevail at the present time at the localities where they have been found, and it would therefore seem that the defi- nite reference of these Pleistocene terrace formations exclusively to glacial or interglacial stages is not warranted. Maryland Geological Survey 215 The Talbot formation The Talbot formation was named by Shattuck7 from its typical development in Talbot County on the Eastern Shore. It is the young- est and least modified of the Pleistocene terrace plains. Areal distribution. — The Talbot formation is well developed and the least altered of the Pleistocene terraces in Baltimore County. It occu- pies practically all of the southeastern part of the county between the seaward edge of the Wicomico formation and the present Bay shore. Its surface is a nearly level, gravelly and nearly undissected plain bordering the lower river estuaries and intervening necks of the County and ranging in altitude from 20 to 40 feet. In its wider extent the Talbot has been traced from New Jersey to the Carolinas and probably to the Gulf of Mexico, although its deposits have received different names in the different States. In Virginia and North Carolina, what corresponds to the Talbot in Maryland has been divided into 2 or 3 separate stages. It seems very likely that more detailed field work in Maryland will show that what is here called the Talbot is capable of subdivision into stages corresponding to the Chowan and Pamlico formations of North Carolina, and the Mathews formation of Virginia. This is particularly true of the development of the Talbot on the Eastern Shore and in Southern Maryland. Character of materials. — The materials of the Talbot formation are essentially similar to those of the other Pleistocene formations of the county, namely, loam, clay, sand, gravel, occasional cobbles; and variable in their distribution. They differ from the earlier terrace formations in their more frequent inclusion of impure peats representing buried swamp deposits, and most of these swamp deposits, which are abundant around the Bay shore, appear to have been bald cypress bays or ponds such as are found today from southern Maryland to eastern Texas. Physiographic expression. — The Talbot formation is developed as a terrace whose surface forms a plain lying around the margin of the T Shattuck, G. B., Johns Hopkins Univ. Circ. No. 152, 1901. 216 Coastal Plain* Deposits of Baltimore County higher and older Wicomico plain from which it is separated in many places by a wave-cut scarp. Its seaward boundary is the present shore usually marked by a low wave-cut scarp. Its surface is so young, geologically, that erosion has not had time to destroy its nearly level surface, nor are its constituent materials as weathered as those of the older terraces. Its surface may be as high as 40 feet above tide , as between Bush River and Havre de Grace, but around 20 feet is the usual height, and where its extent is great, as in the lower peninsula of South- ern Maryland, the surface may decline to the neighborhood of 10 feet. Paleontologic character. — The Talbot formation is the most abundantly fossiliferous of our Pleistocene formations and contains the remains of both marine and terresterial life. As previously mentioned, buried swamp deposits are not uncommon, as southeast of Chase on the Gun- powder River, near Bowley Run, and at the mouth of Back River. An abundant flora of leaves and seeds as well as various insect, chiefly beetle remains, have been collected from Talbot swamp deposits. Elephant and mastodon teeth and turtle bones are also widely scattered in these deposits. At many places the Talbot contains the remains of an abundant marine fauna, chiefly shells of about 40 species of mollusca, as well as crabs, barnacles, sponges, and foraminifera. Thickness. — The thickness of the Talbot formation is very variable and for the same reasons as cited in the case of the Wicomico, and ranges from a few feet to a maximum of 40 feet, but is usually about half the latter figure. Stratigraphic relations. — The Talbot formation rests unconformably upon whatever older formation lies beneath it. In Baltimore County this is probably everywhere Cretaceous. There may be some indistin- guishable remnants of Wicomico sediments beneath it along its land- ward border. The Recent deposits In addition to the Coastal Plain terrace deposits described in the pre- ceding section, a fifth is now in process of formation by the waters of the present rivers and estuaries. This terrace is everywhere present along Maryland Geological Survey 217 the shores, extending as a gently sloping surface from high-tide level to a few feet below low-water mark. It is the youngest and topographi- cally the lowest of the series. Its inner edge coincides with the scarp which forms the seaward face of the Talbot formation or whatever else constitutes the present shore. The deposits of this Recent terrace are similar to those of the Pleistocene terraces and comprise muds, sand, gravel, and peat, deposited in deltas, beaches, bogs, dunes, bars, and spits. THE MINERAL RESOURCES OF BALTIMORE COUNTY BY EDWARD B. MATHEWS and EDWARD H. WATSON Introductory The industries based upon the local mineral resources in Baltimore City and County have been developed primarily for the meeting of the local needs of a growing community rather than because of the occur- rence of any unique deposits which could meet the demands of larger areas more successfully than deposits from elsewhere. Little of the production during the last century has been shipped beyond the Hmits of the State except in the case of a few small unusual deposits such as chrome. At the same time the occurrence of small bodies of unusual minerals and the skill with which they were exploited in the early days have had a profound influence on the localization in Baltimore of such industries as the refining of copper by the Baltimore Copper Works, now the Baltimore Copper Smelting and Refining Company; and the Baltimore Chrome Works, now the Mutual Chemical Company of America. The occurrence of small deposits of magnesite in the Bare Hills ser- pentine is also the occasion of the local development of pharmaceutical and chemical works which have added materially to the business ac- tivity of the community. All of these industries now secure their raw materials more advantageously from sources outside the State where the deposits are richer and the cost of production is lower. It should, however, be recognized that the localization of these and kindred indus- tries in Baltimore and vicinity is the result of the former operation of small local deposits when the knowledge of the mineral resources of the world was slight, and to the farsighted development of the pioneers who first introduced in America professional chemists into industrial plants. Fortunately the situation of Baltimore on the seaboard with good railroad connections to the rich deposits of steam coal has enabled 219 220 Mineral Resources of Baltimore County the existing plants to utilize advantageously raw materials from all over the world and thus to maintain in Baltimore a leadership which originally was due to relatively insignificant deposits of raw materials. The geological situation of Baltimore on the boundary line between the unconsolidated clays and sands of the Coastal Plain and the crystal- line rocks — granites, marbles, etc. — of the Piedmont Plateau has like- wise had a marked influence on the development of the city, and in the establishment of local quarrying and clay-working plants. It is this combination of raw materials which explains the peculiar architecture of Baltimore, with its long lines of brick dwellings made from the Creta- ceous clay of the Coastal Plain and trimmed with white marble and approached by marble steps from the marble quarries around Cockeysville. The similarity of geological environment with that of Philadelphia is shown by the similarity in architecture. In general the brickyards and the quarries for foundation stone have been just outside the residential portion of the city. As the city has grown the increased value of the land and the juxtaposition of dwellings has caused an outward move from the city, the brickyards and quarries leaving, for a time, scars which disfigure the appearance of the city until their area is covered by construction. With the change in type of architecture from small brick and stone edifices to the huge steel and concrete buildings there has been a distinct change in the character of raw materials demanded for construction. Cement, with sand and gravel necessary for concrete construction, is produced only in particularly favorable localities, and the local industries formerly supplying the building materials of the city have dwindled in competition with the new materials which in large measure are secured outside of the limits of Baltimore County. This change in the character of the materials demanded has been particularly noticeable in the construction of our homes. Prior to the beginning of the present century our streets were paved with irregular cobblestones or cut Belgian blocks in large measure from the nearby crystalline rocks; the curbing and stepping stones of granite or gneiss came from the old quarries along Jones Falls and Gwynns Falls or from Ellicott City, but now almost all curbs are built of cement with a metal flashing. Maryland Geological Survey 221 The Iron Ores The iron industry is a survival of the earlier activities in Colonial times, based upon iron found at various points in the State. The first reference to the iron ore in Baltimore County was in 1648. Twenty years later the General Assembly of Maryland passed an act encourag- ing the manufacture of iron within the Province but most of the activity at this time was probably in Cecil County where the first iron furnace was built at Principio. The second furnace in the State was erected in 1723 at the mouth of Gwynns Falls where John Moale had a small deposit of iron ore which he thought was more valuable than the loca- tion of a town site at this point. The mining of iron ore in Maryland probably started on the banks of the Patapsco, as we find that the Principio Company acquired rights of ore on Gorsuch Point in 1724 and on Whetstone Point in 1727, and for the next 30 or 40 years the iron industry was probably based entirely on the nodules of iron carbonate found in the Arundel formation of the Coastal Plain. Somewhat later this deposit came into competition with the limonite ores of the western Piedmont in Carroll, Frederick, and Washington counties; and still later in competition with the ores from the western counties of the State. With the change in demands from charcoal iron to steel and the discovery of larger deposits of rich ore in the Lake Superior region and in Alabama, the mining of ore in Maryland diminished until practicalby none has been produced recently. The last of the charcoal furnaces — that at Muirkirk — closed down in 1906. These old workings have left a record in the ruins of old furnaces and ugly abandoned ore pits, offset by hugh modern steel plants local- ized about Baltimore which utilize the already developed lines of trade in iron located in Baltimore at the very advantageous site on deep water, near readily accessible coals and limestones of western Mary- land and the adjacent states. The ore used in these modern plants is a low-phosphorus magnetite ore from Cuba and not the carbonate ores found in nodules in the Coastal Plain formations. Dr. Joseph T. Singe wald, Jr. in his report on the Iron Ores of Mary- land1 has given an interesting account of the old iron works of the State Maryland Geological Survey, vol. ix, pt. 3, 1911. 222 Mineral Resources of Baltimore County from which may be summarized the following description of the iron industry of Baltimore County and City. IRON WORKS IN BALTIMORE COUNTY Gwynns Falls Furnace. — This furnace, which was the second built in Maryland, was erected in 1723 at the mouth of Gwynns Falls by the Baltimore Company on land owned by John Moale for the utilization of carbonate ores found in the vicinity. How long this furnace operated could not be ascertained. About the same time the forge known as the Mount Royal forge was erected on Jones Falls, probably in the neighbor- hood of the present Monument Street. Onion Furnaces and Forges. — These were erected prior to 1743 at the head of the Gunpowder, about 1 mile from old Joppa. These works were erected by Stephen Onion, one of the Principio Company, who died in 1754. No further mention of these works is found beyond the fact that they were offered for sale in 1769. They were probably situated on the north side of the bridge of the Baltimore and Ohio Rail- road over the Gunpowder River on the site subsequently occupied by the Joppa Iron Works, erected in 1820 and rebuilt in 1851. This latter plant was in successful operation until about 1860 and the ruins are still standing on both sides of the stream. Kingsbury Furnace. — The Kingsbury furnace was built in 1744 by the Principio Company on the east side of Herring Run just below the Philadelphia Road, on the site of the present power house, and went into blast in April the succeeding year. This furnace produced, for a time at least, an average of 75 tons per month and more than 3000 tons of iron which was produced were shipped to England. It probably ceased operation after its confiscation by the Maryland General As- sembly in 1780. Nottingham Works. — These are first referred to in the Maryland Gazette of January 4, 1749. They were located on Honeygo Run, a branch of Whitemarsh Run, some 300 yards from Cowenton station on the Baltimore and Ohio Railroad. A few remnants of the stone work are still standing which suggest that it was a forge and not a furnace. Maryland Geological Survey 223 Lancashire Furnace. — This plant was apparently erected about 1744 by Dr. Charles Carroll, of Annapolis, who sold it to the Principio Com- pany in 1751, the deed being signed by Lawrence Washington, a cousin of George Washington who was also interested in the company. This plant was subject to confiscation in 1780 and probably was not operated after that date. Northampton or Hampton Furnace— This was originally built about 1760, 2\ miles from Towson, and the site is still marked by ruins. It continued in operation for many years but was discontinued or aban- doned before 1829. Whittaker's Furnace. — This furnace was built on the Gunpowder, just below Frankhnville, in 1810 and abandoned before the Civil War. Patapsco Furnace. — This was erected on Locust Point, in Baltimore City, in 1835. The ore was at first secured from the nearby ore pits but Alexander, writing in 1840, states that the iron was then coming from Spring Gardens. Operations were continued until 1849 and the plant was burned down in 1853. It was in this furnace that the first cast steel was made in Maryland. The product was used by the Avalon Works for bar iron as well as hoops, nails, etc., and in the manufacture of rails for the Baltimore and Ohio Railroad. The Avalon Works were destroyed by a cloudburst in 1868 and were never rebuilt. Ashland Furnace. — This was erected at Ashland, just north of Cockeysville, in 1837. It used ore from the Oregon ore bank and the many ore pits in the vicinity of Timonium and scattered pits from the Green Spring Valley, and other points in northern Baltimore County. It was found that pig iron could be made more cheaply here than at Oregon and the two works were consolidated during the fifties under the management of Richard Green. These works were ultimately abandoned about 1880. Maryland Furnace. — This furnace was located at Jackson and West streets on the south side of the Basin in Baltimore City, was built in 1840, and continued to operate until just before 1890. Most of their product was used locally. Cedar Point Furnaces. — These furnaces were built at Boston and 224 Mineral Resources of Baltimore County Potomac streets between 1843 and 1845 and were known for a time as the Numsen Iron Works. They discontinued operation about 1880, when the property was sold to the Philadelphia, Wilmington and Balti- more Railroad. Locust Grove Furnace. — The Locust Grove furnace, frequently re- ferred to as the Stemmer Run furnace, was built in 1844 about a quarter of a mile north of Stemmer Run station. It was in active operation for 40 years, using carbonate ores of the neighborhood until it was aban- doned in 1885. Chesapeake Furnaces. — These furnaces were erected on Clinton Street, near Seventh Avenue, Canton, in 1845 and 1853 and continued in active operation until about 1882, with an annual output of more than 2000 tons of forged metal which was largely exported to other states. Laurel Furnaces. — These furnaces, frequently referred to as the South Baltimore furnaces, were erected on the south side of the Basin in 1846 and 1856. They had about the same capacity as the Chesapeake fur- naces and were abandoned about the same time. Gunpowder Furnaces. — These furnaces were erected in 1846 on the site of the old Long Cam forge (erected 1760) on the south side of the Gunpowder Falls, about 100 yards above the Philadelphia Road. This location had been the site of iron enterprises for over a century. It was operated by Robert Howard, the owner of the Locust Grove furnace, until 1860. Ruins of the stack and probably the walls of the old forge building are still standing. Oregon Furnace. — The Oregon furnace was erected for the utilization of the ore from the Oregon ore banks in 1849. Subsequently it was consolidated with the Ashland Iron Company until it was abandoned in favor of the furnace at Ashland. In 1855 the output was 4,419 tons of pig iron. Stickneij Furnaces. — Iron furnaces were erected on the sites of the present Baugh Fertilizer Company at the foot of Clinton Street, as earl}- as 1854. The first one was known as the Cecilia furnace, later as the Lazaretto furnace, and after 1876 as the Stickney furnaces, operated by the Stickney Iron Company. The annual output of these furnaces MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY, PLATE XIV Fig. 1. — View of clay bank at the Monument Street Plant of the Baltimore Brick Company Fig. 2. — View of pit of the United Clay Mining Corporation of New Jersey at Poplar Maryland Geological Survey 225 was about 10,000 tons of pig iron. They were closed down in 1893. One of the furnaces was converted into a tin-plate plant in 1895; the other continued operation until 1896 and was the last of the old charcoal furnaces operated around Baltimore. Subsequently the plant was sold to the American Tin Plate Company and in 1901 the property passed into the hands of the Baugh Fertilizer Company. The Ore Banks Scattered widely over Baltimore County are abandoned openings made for the recovery of iron ore, which were the scenes of active opera- tions for nearly a century. The success of these operations depended upon a ready market for the ore at nearby furnaces and ceased to be operated whenever the furnaces were abandoned at the dates indicated in the foregoing discussion. These ore banks may be classified accord- ing to the character of the deposit and situated by areas where opera- tions were most active. The most important of these are the carbonate ores of the Arundel formation, which served as the basis for the Colonial industry and the operation of the charcoal furnaces in vogue prior to the introduction of the modern methods of steel manufacture. Next in importance are the hmonite ores found associated with the marble deposits of the Piedmont, either at the contact between the calcareous rocks and the underlying quartzites and overlying schists, or at the contact between the marble and the surficial covering of Creta- ceous clays rich in iron which cause a concentration of iron when the percolating waters encountered the underlying calcareous rocks. The third class of ore deposits, which have never been of any importance in Baltimore County, are the local segregations of magnetite in the ser- pentine. The accompanying map, plate XX, and the text will give a summary of these abandoned ore openings which are of local interest historically. THE CARBONATE ORES The ore banks in which carbonate ores in Baltimore County occur is a belt extending in a southwest direction across the southeastern portion 226 Mineral Resources of Baltimore County of Baltimore County from the Gunpowder Falls of the Patapsco River, passing through the eastern and southern portions of Baltimore City. Although the ores have been worked throughout the whole of this re- gion, the most important area has been that to the southwest of the city. "The Arundel ores2 occur scattered throughout the clays of the formation in the form of lumps and nodules of various sizes and shapes. The distribution is quite irregular; in some places the clays containing large quantities of ore, in others the ore occurring sparingly. In general, the nodules are of concretionary structure, and often consist of a number of nuclei which have coalesced to form one larger lump. Such lumps have been found weighing several tons, when it is necessary to break them by driving wedges into them before they can be removed. Ex- cept in the case of these unusually large lumps, the nodules can easily be shattered with a blow from a sledge hammer. Though tending to irregular spheroidal shapes, large flat nodules also occur with a concen- tric structure. A less frequent occurrence is in the form of a bed of limited extent in which the concentric structure is seemingly lacking. Such beds do not contain the purest ores, and it may be that they repre- sent a large flattened nodule in which, on account of its size and the large amount of foreign material included in the form of sand and clay, the concretionary structure is obscured. The concretions usually have a septarian character, and the walls of the septae are lined with crystals of which minute crystals of siderite and crystals of gypsum are the most common. "Two types of ore occur, the iron carbonates and the limonites. The former are the original ores, while the latter are formed by the subse- quent alteration of the carbonates brought about by the processes of weathering. "The carbonate ores are called by the miners 'white ore' or 'hone ore.' The name 'white ore' has been applied on account of the very light gray color of the pure carbonate ore, and the name 'hone ore' because the smooth pieces of high-grade ore make excellent whetstones. The color * Singewald. Joseph T. Jr., Iron Ores of Maryland. Md. Geol. Survey, vol. ix, pt. 3, 1911, pp. 255-256. Maryland Geological Survey 227 of the ores when perfectly fresh varies from a very light gray to a dark slate color. The slightest trace of weathering gives to them a rusty tinge, and from this they grade over into the brown, red, and yellow hydrated oxide ores. The ores free from impurities break with a per- fectly smooth conchoidal fracture. Less pure specimens show a rougher surface, and with increasing quantities of sandy material the fracture becomes irregular and the surface may feel as rough as a sandstone. The miners are able to recognize the slightest difference in quality by running their fingers over a fracture surface "The limonites are collectively designated by the miners as 'brown ore,' irrespective of the actual color which varies through all shades from brown to red or yellow. Since they are derived from the carbonates, they exactly resemble the carbonates in shape and form, except that the conchoidal fracture is likely to give way to a 'shelly' structure. Lumps are very abundant which have an exterior consisting of con- centric shells of limonite and an interior of 'white ore' breaking with a perfectly smooth conchoidal fracture, showing that the concretionary structure is inherent in the nodule and is brought out sharply in weathering "The kind of ore obtained is merely a question of position with refer- ence to the agencies of weathering. Some banks have yielded only 'brown ore' down to the lowest levels. Others have yielded 'white ore' almost to the surface. In most cases in working downward, 'brown ore' is first encountered, and this passes over gradually into 'white ore' as the depth of the bank increases. The depth to which the al- teration has taken place depends on various factors, such as the charac- ter of the drainage overlying the ore, and the porosity of the clay. The amount of carbonaceous material present in the clays must also be of influence in this respect. As the process of alteration involves oxidation of ferrous to ferric iron, the presence of carbonaceous matter would tend to hinder that oxidation, and thus preserve the carbonate." Though the clays has been worked for a period of nearly 200 years only a small percentage of the total area has been touched and there is still an enormous quantity of this ore available. The failure of the prod- 228 Mineral Resources of Baltimore County uct has boon due to lack of a largo market and a sufficiently remunera- tive price. At the present time, since the abandonment of the Muirkirk furnace in 1906, there is no market for this material. Probably the most flourishing period in the history of the mining of these ores was during the Civil War, w hen the}' brought as high as S8.00, or even more, per ton. After the war they brought from So .00 to S6.00 for some time and then gradually decreased in price until a sudden drop in the early nineties brought them down to S2.00. This practically destroyed the industry, as the subsequent rise in price has not been sufficient to bring about more than the desultory operations of today alrcad}' mentioned. The Building Stones introduction The Building stones of Baltimore County are confined to the Pied- mont Province of hard crystalline rocks lying to the north and north- west of Baltimore City. They are largely quarried for local consump- tion, though considerable quantities of marble and some granite and gneiss are shipped beyond the confines of the State. The earliest refer- ence of scientific value to the quarrying of Maryland stone is found in a paper by H. H. Hayden published in 1810. In this little-known pub- lication3 we learn that at the time of writing the stone \\ miles from Baltimore (the quarries on Jones Falls above Xorth Avenue bridge) was recognized as "highly valuable and useful in various branches of masonry" and that it was "quarried on both sides of Jones' Falls, to considerable advantage to the proprietors." When the Baltimore Cathedral was constructed during the years 1806 to 1812 and subsequently from 1815 to 1821, the material was hauled from Ellicott City to Baltimore along the old Frederick Road in huge wagons drawn by nine yoke of oxen. Those two statements indicate the primitive conditions of the industry a hundred years ago. 3 Mineralogical and Geological Description of the County surrounding Balti- more to the extent of about nine miles." Balto. Med. Phil. Lye, vol. i, 1810, pp. 255-271. Maryland Geological Survey 229 Merrill in his History of the Building Stone Industry states that the greater part, if not all, of the stone for construction was secured from boulders prior to 1825 when one Jonathan Mathews was successful in working granite from ledges for a bridge across the Kennebec River, Maine. The early stone in Maryland was probably blocks loosened by frost at the tops of exposures which were broken off by wedges, much in the way that some of the larger blocks are still secured in the Wood- stock quarry. The earliest quarries in Baltimore were probably located in the valleys of Jones Falls and Gwynns Falls in the gneiss exposed on either side. At first they were secured a long distance from Baltimore City and far removed from any residential sections. The first quarries were probably situated on the west bank above the North Avenue bridge on the spot later occupied by the Mount Vernon shops. Operations were carried on at this point until about 1830 when the Northern Central Railroad was constructed. The quarries on the east bank which are now so much more evident were opened about this time and have been worked more or less continuously until very recently when the extension of the residences almost to the upper edges of the quarry occasioned complaint against the blasting. In spite of the fact that these quarries were excel- lently situated, with the rock in sheets ranging in thickness from 4 or 5 inches to 5 or 6 feet and the sheets broken by joints nearly at right angles to each other, they are now nearly abandoned. At about the same time that the granite quarries at Ellicott City and Woodstock and the gneiss quarries at Jones Falls commenced pro- duction the marble quarries around Cockeysville and Texas were started. They have been in intermittent operation since, both for the production of building stone and the burning of lime. The flagstone of Green Spring Valley was employed in a small way for local uses during the last century and may be seen in old buildings and bridge abutments in the region. With the increasing cost of land in the vicinity of Baltimore, the proximity of houses, and the growing practice of long distance trucking the quarrying industry has tended to spread to the outlying portions of 230 Mineral Resources of Baltimore County the county, much of the material now in use coming from a number of small quarries scattered over a wide area. As may be seen on the map (Plate XX) a few of the old quarries are still working well within the city, though they will probably not be long lived, and several have been abandoned within the past few years because of injunctions against the blasting, leaving large unsightly holes in the midst of real estate de- velopments. The majority of the other quarries shown on the map are within a radius of 10 to 15 miles from the center of the city, concentrated here and there in clusters due to the occurrence of good material. Nearly one-half of these openings have been developed within the last 10 or 15 years, no doubt due to the outward migration mentioned above. The greater number of these newer quarries are small and are only worked when a contract for stone is obtained. The types of building stone being quarried in Baltimore County at present may be classified as follows: granite, marble, gneiss, flagstone, gabbro, serpentine, and field stone. All these rocks are quarried in place except the field stone and are restricted in area, according to the underground geology, to a belt 20 miles wide running northeast-south- west across the county north of Baltimore City. North of this belt the rocks exposed are the schists of the Wissahicken and Peters Creek formations, which are mostly unsuited for structural purposes. The uses to which these various stones are put depend on the charac- ter of the rock. Only the granite and the marble arc made into finished stone, that is, polished material with exact dimensions. For this reason it is only these two types which are quarried by the expensive methods of channeling and broaching, and then sawed or smoothed off by finish- ing machines. The gneiss, flagstone, and some of the marble are quarried into rough blocks and are placed in structures in that con- dition. In some operations rough slabs and blocks which approximate to certain definite dimensions are produced, the stone from the Jones Falls quarries and some of the flagstone localities being especially adaptable to this purpose. Besides its use as natural stone, the building stone of Baltimore County is. employed in many other ways, both as an aggregate in Maryland Geological Survey 231 artificial structural materials and in many special products. The mak- ing of artificial stone in the past two decades has increased greatly, and today there are nearly a dozen small plants operating around the city. At these plants a mixture of cement and sand or crushed rock is tamped into a die of appropriate design and allowed to harden. Most of this material is used in industrial buildings or cheaper dwellings, though the trimmings and foundations of the Forest Park High School are made of a plain concrete block which can not be distinguished at a distance from a fine-grained limestone. There is considerable objec- tion on artistic grounds to the use of artificial stone in the better grades of buildings, and, though this is generally well founded, much better effects may be obtained if plain blocks were employed and better ar- chitectural designs followed. The materials for these artificial products are chiefly derived from two sources: ground limestone and sand, the latter from the Coastal Plain deposits. These materials are quite satisfactory as aggregates but further interesting results might be obtained, both in color and tex- ture, by the use of other r.ocks as fine and coarse aggregates, similar to those seen in terrazzo flooring and decorative stones. The quarrying methods employed in Baltimore County are the same as those common everywhere and will not be described. In all but a few cases they are simple and on a small scale. About a dozen opera- tions are large and continuous and use fairly extensive equipment; 6 of them produce 300 tons or more a day. The remainder are worked intermittently or are abandoned after a few years, due to a variety of causes. The economic conditions which determine the success or failure of a quarry are often difficult to determine, but the principal factor appears to be the size of the operation. The most profitable workings are those which produce a large daily output shipped to a wide market. This is especially true if several quarries are worked by the same organization. Other factors are important, such as the amount of overburden, the volume of water flowing into the workings, the proximity to markets and railroads, the position of the working face, the character of the 232 Mineral Resources of Baltimore County rock in reference to its use, and many others. The amount of rock available is usually of lesser significance than those enumerated above, since the geologic occurrence of building materials is widespread, but is of little moment if the working conditions are unfavorable. Examples are numerous in Baltimore County where one or more of these factors were unfavorable and caused the cessation of the operation. The most favorable combination of conditions is when a rock of good quality and widespread use exists in a bold exposure with little overburden so that it may be worked back on a level from the place of handling and shipping the product, thus eliminating deep workings and the at- tendant trouble from water. There should be a siding from a nearby railroad, and the market should be reasonably close. The conditions of the quarrying industry are precarious at best and competition forces the selling price to its lowest possible amount, especially for common products. Therefore, in the case of a small single operation a slight decrease in demand, or decrease in selling price, or the existence of any of the unfavorable conditions mentioned above will bring about its failure. With a large organization, however, par- ticularly those that work several quarries, the profit per unit of output is small but is compensated for by mass production, and periods of de- pression may be tided over until better times. In recent years there has been a marked increase in the use of various non-metallic products for building materials and with its diversity of mineral resources Baltimore County should be able to supply a large demand. The actual amounts of the various types given above are for all practical purposes inexhaustible and there is no reason why as healthy an industry as has existed in the past should not be maintained. GRANITE The granites of Baltimore County which are used for building pur- poses are limited to the region around Woodstock, although other deposits of granite are found east of Cockeysville and in the vicinity of Franklintown on the Gunpowder. The latter has never been worked except in a small way for local use. The utilization of the granite from MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XV Maryland Geological Survey 233 Woodstock on the main branch of the Baltimore and Ohio Railroad commenced about 1832 and has continued to the present. This stone occurs in a small body a mile or so across in the center of which is the small hamlet of Granite. This rock is free from schistosity found in most of the other granites of the State, and is evidently a later intrusion into the gneisses, although no dikes or apophyses into the surrounding rock have been noted. One of the striking features of the quarries is the sharpness of the ver- tical and horizontal joints and the conchoidal weathering of the stone into huge ovoids. Many of these are strong enough to be used for dimension stone. This method of weathering gives to the quarry ledge something of the appearance of a great wall of cyclopean masonry with the blocks from 15 to 20 feet in length and from 2 to 8 feet in height. Individual blocks are somewhat rounded and separated from each other by incoherent granitic sands and rubble. This mode of occurrence facilitated the easy working of the quarries and so brought the rock into early notice but there is necessarily a good deal of waste and increased expense in reducing these ovoidal boulders to rectangular form. The Woodstock granite is bright gray with a bright luster and occa- sionally a faint pink tone. The mica occurs in evenly disseminated fine black flakes which improve the appearance of the stone without detracting from its light color or strength. MARBLE The marbles of Baltimore County are secured from a series of valleys in the central part of the county, the most active operations centering about the town of Cockeysville on the Harrisburg Division of the Pennsylvania System about 20 miles to the north of Baltimore City. The high quality of the stone was recognized soon after the Revolution- ary War, but the actual development received its first major impetus in the erection of the Washington monument in Baltimore between 1815 and 1829. The material for this monument, the first erected by a municipality to George Washington, came from what was then known as the Taylor and Scott quarries; the former yielding the monolith 234 Mineral Resources of Baltimore County originally quarried as a single piece and subsequently cut into three blocks which forms the well-known statue at the summit of the monu- ment. When Dr. David Day Owen made his report in 1847 there were 13 quarries in the district of which the Baker and Connelly quarry became the largest during its operation by the Beaver Dam Marble Company. The character of the stone quarried varies very widely in composition, texture, and quality. The dominant stone is a dolomite, but many of the beds are nearly pure calcite. Some times these beds are thick and sharply defined; at other times the interbedding shows as many as 50 alterations to the foot. The texture varies from the coarsely crystal- line marble or alum stone used in the lower courses of the Washington monument in Washington forming a cohesive mass of individual grains one-half to three-quarter inch in diameter, to the fine-grained dolomites in which are inclosed particles closely interlocked, seldom exceeding one-sixteenth inch in diameter. It is this fine-grained rock, usually dolomitic in composition, that has been most successfully used in the quarrying of structural stone. Throughout the history of the region there has been a constant competition in the use of the material for structural purposes and as a source of agricultural lime. As early as the second decade of the last century there was an annual output of fully 200,000 bushels and this output has at times reached considerably more than this, the demand for lime varying with the practices of the nearby farmers in the use of agricultural lime for manure or artificial fertilizers. At times a small amount of material has been ground and applied directly as a soil ameliorative. The color of the stone in the best grade is a clear white with now and then a few streaks of faint-gray color. The poorer grades often show brownish bands due to a local development of brown mica. The exact areal distribution of the various good and bad portions of this marble deposit has never been determined because of lack of exposures and the fact that much of the territory is under a high state of cultivation. The entire region has been highly metamorphosed but the more general structure of the area suggests that the district in the vicinity of Cockeys- Maryland Geological Survey 235 ville is very nearly horizontal and that there is a greater variation verti- cally than parallel to the surface. This interpretation, if established, would have an important bearing on the development of the quarrying industry in this region which in the last few years has entered into a new period of increased activity. During the last 20 or 30 years the burning of lime has steadily de- clined in the region and today Lindsay's kiln at Texas is the only one still operating. A few others work intermittently in the area east of Hern wood but they are of little moment: Proportionate with this decline, however, there has been a considerable increase in the use of ground, unburned limestone as a fertilizer and much of it has come from the local quarries. Aside from its use as a building stone, as a road material, and for agricultural purposes, limestone of late years has been increasingly employed in a variety of minor ways, among which may be enumerated: pebble dash for stucco; poultry grit ; filler in paint, linoleum, and rubber; whiting putty; dusting powders; and as an aggregate in cast stone, cement, and concrete. The quarries of Baltimore County have sup- plied varying quantities of material for these purposes, and with the expansion which will likely occur in the future, should form the basis of a valuable industry. The variations within the limestone mentioned above are advantageous to the production of a variety of products, but they are nearly impossible to predict before development and recourse should be made to core drilling. At certain places where the coarse-grained variety occurs and the topography is favorable the Cockeysville marble is overlain by a greater or less .amount of disintegrated rock which breaks down to a calcite sand. In this condition it is very easily worked and adaptable to several of the uses given above, especially in plaster, mortar, and concrete. A small amount of very pure material is marketed for children's play boxes. The depth to which this disintegrated material occurs varies greatly and can only be determined by digging, though the more favor- able localities are usually in small depressions. Concomitant with the general increase in the use of natural stone 236 Mineral Resources of Baltimore County the marble around Cockeysville and Texas has been more actively worked in the last ten years than at any time since the beginning of the present century. The new Beaver Dam quarry is now supplying stone for a 50 million dollar building in Detroit. Several other quarries have been opened recently in response to local demand for the material. gabbro and serpentine The area bounded by the Green Spring Valley on the north, the Patapsco River on the west, and Baltimore City on the southeast is largely underlain by a great mass of gabbro and peridotite with its serpentinous alterations. Similar material occurs in a belt along the Belair Road northeast of Baltimore, at Soldiers Delight south of Reisterstown, and at several scattered localities in the northern part of the county. The greater part of this material is used as road stone but occasionally it has been used for foundations and backing. The material is too sombre for general use in structural work, though some of the colonial houses were made of it — no doubt because it was available close by. More recently the green serpentine of Bare Hills has been used in the construction of small buildings with pleasing effect, though its durabil- ity is questionable. GNEISS As already stated, gneiss was first quarried in Baltimore City at about the close of the eighteenth century. The gneiss valuable for building purposes is geologically restricted to five elliptical areas within the county and city (see geological map). Immense quantities have been obtained and it is still probably the most valuable stone for rough struc- tural purposes. Recently it has come into considerable vogue for the construction of suburban houses — the so-called "rust rock" of the trade. This in Maryland has consisted of random blocks of gneiss and highly siliceous quartzite and schist which have been broken up into blocks along their jointing planes by weathering. The beauty of these blocks in construction lies in the fact that thin films of varying colors have been Maryland Geological Survey 237 deposited along the surface of the block which, when used, adds diver- sity and interest to a building which might otherwise appear somewhat more commonplace. In the use of rock of this character which has undergone the incipient stages of weathering only such blocks can be used as are sound in the interior. The brittleness of the Baltimore gneiss, Peters Creek quartzite, and Setters Ridge quartzite caused the fracture of the formation into more or less rectangular blocks and the hard character of the material leaves the interior sound and suitable for construction. FLAGSTONE The type of rock designated as flagstone is restricted to the Setters formation which outcrops as a narrow band a few hundred feet wide surrounding the elliptical areas of Baltimore gneiss (see geological map). It is more resistant to erosion than the surrounding formations and forms long narrow ridges, usually with a limestone valley on one side. Only part of the formation is suitable for structural purposes, the re- mainder is schistose or composed of massive quartzite. The flag- stone is a thin-bedded arkosic quartzite which cleaves into neat, parallel- sided slabs 1 to 6 inches thick. The cleavage surfaces are usually covered with small scales of white mica (sericite) and often have black prismatic crystals of tourmaline on them. The color of the slabs varies from a light-buff to a dark-brown, giving a pleasing mottled effect when used in walls and footways. The occurrence of flagstone in narrow ridges considerably facilitates quarrying, especially as a well-defined limestone valley usually borders it. Also it is overlain by little or no decayed material, and its cleavage and abundant jointing are all aids to exploitation. This stone has attained considerable prominence of late as a building and flagging material, especially in the better class of suburban develop- ments. The very thin-bedded types are best adapted to flagging, and the thicker types to general building construction. Many very at- tractive houses in the Guilford-Homeland area north of Baltimore have been built of this stone, and the new Baltimore City College 238 Mineral Resources of Baltimore County (Plate XVI, fig. 2) shows that it is suited to the construction of larger buildings. The quarries working the flagstone are small and are only operated when a contract is obtained. They are widely scattered throughout an area within 15 or 20 miles of Baltimore and delivery is made directly by truck to the building operation. FIELD STONE The term field stone is used to cover all those loose rocks and boulders which occur on the surface of the ground in the fields and woods and are employed for rough building purposes in lieu of more suitable materials of greater expense or from a greater distance. Farmers, in the con- struction of rough bridges or the foundations of their barns and houses, often employ the rock immediately at hand. These take the form of gneiss, granite, quartzite, schist, or trap rock, depending upon the local geology. In the Coastal Plain area of Baltimore County one not in- frequently sees small bridge abutments and building foundations made of the very rough and often friable iron-stone conglomerate which occurs locally in the soft deposits. These are lenses of sand or gravel which have been cemented by iron-bearing solutions into a relatively hard conglomeratic mass. On the North Point Road near Todd Point on Back River a large dwelling is entirely made of this material, and a few others exist throughout the region. Generally the use of field stones is unsatisfactory for any but the roughest of structures and they are seldom employed at the present time. Road Materials The tremendous development of the automobile industry in the last 25 years has sent repercussions throughout the economic organization of the nation, not the least of which is in highway construction. The former dirt and crushed-stone roads of a generation ago have given way to broad bands of hard surfaced highways which accommodate an ever increasing traffic. Maryland Geological Survey 239 The materials for these roads are cement, sand, crushed stone, bitumi- nous material, and rock dust. In the earlier years of this highway de- velopment macadam was the dominant type built, whereas in the last 10 years concrete has been most commonly used. Macadam roads are cheaper to build but concrete gives a much evener surface, requires much less maintenance, and is more durable. In the earlier years of the history of Maryland the improved roads were made from the crushed stone and sand and gravel secured locally. The amounts used were at no time very great and represented but a small fraction of that used today. In those days the greatest demand for road materials was in the construction of city streets. The old cobblestones of Baltimore, a few of which still remain, came from the gabbro ("niggerhead rock") around the city. Also great quantities of granite were used in making the Belgian block pavements of the nine- teenth century, and additional amounts were used in constructing the curbs. Today streets are almost universally paved with asphalt — a bituminous sheet on a concrete base. Macadam roads are built of crushed stone arranged in courses — the largest sizes at the base, grading to dust and grit at the top, the surface rolled and bound together with a binder. Tar is now almost universally used as a binder, though water has been used somewhat in the past (the so-called "water-bound" macadam). In the construction of these roads trap rock (gabbro and serpentine, sometimes called "basalt") is the predominant stone used. In its ability to resist wear, as well as its cementing quality and strength, it is superior to other rocks. Some of the harder and more compact gneisses are nearly as good and have been employed for this purpose. In the construction of concrete roads the materials are cement, fine and coarse aggregate. The cement comes from outside of the county, but the majority of the aggregates are secured locally. The sand for the fine aggregate is now largely gotten from the deposits of the Arundel Corporation in Baltimore harbor and at Northeast in Cecil County. The coarse aggregate is supplied from a variety of sources and from several types of rock. Limestone, trap, gneiss, and gravel are all used and for the most part come from the operations within the county. 240 Mineral Resources of Baltimore County At the present time sand and gravel roads are not being built to any extent within the limits of Baltimore County, though they were built to some extent in the past, and are still built, in southern Maryland and on the Eastern Shore. The deposits of these materials are discussed further under Sand and Gravel. Many of the quarries which produce building stone also crush the rock for road materials. The general remarks made above concerning the methods of development and economic conditions of the building- stone quarries apply to those for road stone. At the present time the coarse aggregate used in building the state roads in Maryland is 85 per cent limestone. However, large quantities of rock are used on county and city roads, as railroad ballast, and in general construction, and since these come from the same sources this proportion would not apply throughout. Gravel is largely used in both building and road construction in Baltimore City, trap is the predominant material for both railroad ballast and macadam roads, and other enterprises use a variety of materials. As an estimate the coarse aggregate used in concrete construction in and around Baltimore which is supplied locally is valued at over a million and a half dollars a year. This represents a considerable industry, and with the continued expansion of the city and its suburbs in Baltimore County the present sources of supply will still be exploited. The volume and variety of material which exists for these purposes in Baltimore County are enor- mous and, with the proper precautions should prove of considerable profit to its developers. Operations in Building Stone and Road Materials quarries in granite Woodstock Granite Quarry (1) The workings of the Woodstock Granite Quarry Company, commonly known as "The Fox Rock Quarry,'' are situated one-half mile southwest of Granite and three-eighths of a mile northeast of the Old Court Road. This quarry is nearly a hundred years old and the old stone ties used on MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XVI Maryland Geological Survey 241 the Baltimore and Ohio Railroad at the beginning of its history are reported to have come from here.4 The opening consists of a deep, circular pit 300 feet in diameter and 75 to 100 feet deep. There is little soil overburden but the decayed rock extends to a depth of 25 feet. A 2-inch pump operating two hours a day keeps the quarry free of water. The rock is a medium-grained, compact, epidote biotite granite of light-grey to pink color. It is very uniform in composition and texture. The jointing is very irregular ; the most pronounced plane is N.45° E.65°W. In addition there is some horizontal jointing. Blocks are lifted from the pit by a 20-ton derrick operated by a 40- horsepower electric hoist. Most of the rock is finished by surfacing machines in sheds at the edge of the quarry; a small amount is crushed. The stone from this quarry has been extensively employed for a long time both in and out of the State. Among the buildings made from it in Baltimore may be mentioned: the Fidelity Trust Company, the Court House, Woodstock College, St. Ambrose Church, the Jenkins Memorial, and the Holy Rosary Church. Old Guilford and Waltersville Quarries, Granite (2) Two other large openings in this area which also originated about the time of the "Fox Rock Quarry" are those of the Old Guilford and Waltersville Company, situated just north of the town of Granite, and 400 yards north of the Old Court Road. They were closed four years ago due to disputes in management and are now the property of Bradley J. Blunt. The quarry to the northeast is the larger, 400 feet in diameter with the rock exposed in walls 40 feet above the water. The smaller quarry immediately adjacent to the southwest is 200 feet long and 100 feet wide. The water level in the smaller quarry is 15 feet higher than in the larger and is said to be 75 feet deep in places. The rock is an epidote biotite granite — much the same as that at the 4 See Merrill, G. P., and Mathews, E. B., "The Building and Decorative Stones of Man-land," Maryland Geological Survey 1898, p. 150. 242 Mineral Resources of Baltimore County "Fox Rock Quarry." It occurs in large monolithic, horizontal layers, often with thinner decayed layers between, especially towards the top. This passes upwards into the decayed overburden where remarkable examples of the spheroidal weathering of granite may be seen — elliptical lenses of fresh granite contained in soft weathered material. These monolithic layers varjr from 1 to 12 feet in thickness and show no ob- servable jointing nor cleavage. What equipment and buildings that remain are now in a very dilapi- dated condition but they indicate the former existence of a very large operation. A railroad spur from the Baltimore and Ohio 2 miles away formerly existed and the grade still remains but the rails are gone and the right-of-way has been lost. EUicott City Granite Quarries (3) Extensive operations for building stone formerly existed in granite on both sides of the Patapsco River below Ellicott City. These quarries were probably opened some time in the latter part of the eighteenth century and during the early part of the nineteenth century supplied the stone for the construction of the Baltimore Cathedral.5 They continued to be worked intermittently throughout the nineteenth cen- tury and into the beginning of the present century. The rock is very variable, though its dominant phase is a porphyritic granite with a gneissic texture. It was formerly used extensively in curbing around Baltimore in which the characteristic phenocrysts of feldspar may be seen. The largest opening of this group is 500 yards east of the town on the Frederick Road. It exposes a face 200 feet long and 30 feet high. There is no overburden nor water and the quarrying conditions are excellent, but the value of the land probably prohibits further operation. Morgan College Quarry, Herring Run (4) T. A. Gatch, formerly operated a quarry on the Morgan College property at Herring Run and Arlington Avenue. The rock is a massive, 6 Op. cit. p. 147. Maryland Geological Survey 243 biotitic, granite gneiss (Gunpowder granite). It is extensively in- jected with pegmatite, and contains basic lenses as well. The main jointing is coincident with the gneissic banding — N.60° W.18°S. The opening consists of a deep elliptical hole, 200 feet long (N.-S.), 100 feet wide, and 50-60 feet to the water level. There is little overburden. The rock is suitable for both crushing and rough structural purposes. The depth of the opening, the excessive water, and its location close to urban development will probably prevent any further exploitation at this locality. OPERATIONS IN CRYSTALLINE LIMESTONE Beaver Dam Marble Quarry, Cockeysville (5) The old Beaver Dam quarry, famous for its stone for over a hundred years, is now idle and full of water. Many large structures have been built of this stone, among them the National Capital, where 108 large columns, each 26 feet in length were furnished; the old U. S. Post Office and Washington Monument in Washington ; the Peabody Insti- tute and Maryland Club in Baltimore; the Drexel and Penn Mutual Insurance Buildings in Philadelphia; and the spires of St. Patricks Cathedral in New York. Thirty years ago the output of this quarry was 27,000 tons of cut stone a year.6 In 1918 the Beaver Dam Marble Company opened a new pit several hundred yards east of the old opening, one-half mile west of Cockeys- ville. The quarry is now 200 feet long, 100 feet wide, and 30 feet deep. Only cut stone is obtained. A clay overburden of 10 feet occurs, though the rock is fresh to that point. An excessive amount of water runs into the quarry, between 100,000 and 150,000 gallons a day. The rock is a white, dense, and compact dolomitic marble of fine grain and high compressive strength, essentially similar to that in the old opening. It works well and is largely free from cracks and fractures. Phlogopite (brown mica) is an accessory and occurs in wavy bands, showing the rock has been subject to much compression. The stone is gotten out in large rectangular blocks 5 feet by 9 feet by • Op. cit. p. 172. 244 Mineral Resources of Baltimore County 16 feet. About 30 per cent of the volume of rock moved is lost in the quarrying operations. Two methods are employed in obtaining the blocks — by broaching, and by channeling. In broaching a series of drill holes are sunk a short distance and the block is then wedged and broken out. This is about three times faster than channeling but is more wasteful of the rock and pieces with uneven fractures are often obtained. It is the best method to employ in the poorer grades of rock, especially where it is uneven. In channeling a machine operating on a short track drives a chisel which cuts a smooth, even surface. It is considerably slower than broaching but neater pieces are gotten and it is more economical of material. These blocks are lifted by derrick from the quarry and carried to the sawing plant, immediately to the south. The plant is a large building, 50 years old, in which much of the stone from the old quarry was sawed. Gang saws of soft steel are operated with shot and sand as abrasives which cut the blocks into slabs of various sizes. Twelve to 18 hours is required to saw through a block with the dimensions given above. The blades are generally replaced after three sawings. The following machinery is employed: 2 rapid sawing machines (Patch) ; 4 air compressors (each 2400 cubic feet a minute) ; 5 channeling machines (4 steam, 1 electric); Osgood traveling crane; 3 30-ton boom derricks; 1 50-ton boom derrick; 7 broaching machines; 20 Ingersol jack hammers. There is a blacksmith shop with automatic tool machines, and a railroad siding from the Pennsylvania Railroad. The larger part of the output from this quarry has gone into the con- struction of the new Fischer building in Detroit, which is to cost 50 million dollars, for which 240,000 cubic feet of stone have been obtained. The new buildings of Loyola College are also of this stone. The same operators are working a quarry for crushed stone 300 yards to the east of the main plant . The opening is 200 feet long, 100 feet wide and 25 feet deep, and the rock is largely decomposed into a car- bonate sand for 20 feet below the surface. It is used for pebble dash; chicken grit; cast stone, concrete, and cement aggregate; and agricul- tural ground lime. The product is crushed, screened and bagged. The spur track to the main quarry runs by the bins. Maryland Geological Survey 245 H. T. Campbell Quarry, Texas (6) H. T. Campbell of Towson is operating a large quarry for crushed stone in dolomite 400 yards west of Texas station on the Harrisburg Division of the Pennsylvania Railroad. The pit has largely been de- veloped in the last few years, though it is an extension of an earlier opening. It is 600 feet long (northwest to southeast), 400 feet wide, and 100 feet deep. The rock is a white, fine-grained, dense, dolomitic marble. The amount of brown mica (phlogopite) is subordinate, and there is a little accessory quartz, pyrite, tourmaline, and wollastonite. The banding of the rock is generally horizontal, though it varies con- siderably by contortion. There is no very uniform jointing and the rock breaks into large, irregular blocks. The best plane of jointing is N. 60° W. 75°S. The overburden consists of 8-10 feet of red clay soil which passes at places into a carbonate sand. Considerable water flows into the quarry. The rock is broken on the quarry floor and loaded directly to trucks which take it to the crusher. A concrete roadway has been built down into the pit, and the trucks are equipped with pneumatic tires. This has been found more economical than solid tires on a rough roadway, in saving wear on the trucks. The crusher is housed in a large concrete elevator. It is of the gyratory type, and has a diameter of 7 feet. The quarry produces 600 tons of crushed stone a day, which is largely employed in concrete road construction. The carbonate sand which occurs with the overburden is 5 to 10 feet thick at places, and is used for plastering, brickwork, concrete, and un- burnt agricultural lime. Mr. Campbell also operates a small quarry 300 yards northwest of the large pit for marble building stone. It is 100 feet in diameter and is equipped with a wooden derrick. The Rosewood School at Reisters- town recently was built of this stone. These workings are equipped with a railroad siding. 246 Mineral Resources of Baltimore County McMahon Brothers Quarries, Mount Washington (7) The McMahon Brothers operate two quarries on the west side of Green Spring Avenue one-half mile north of Smith Avenue, and 2 miles northwest of Mount Washington. Captain Boyle, a retired sea cap- tain, first opened the main quarry, and the present operators obtained it in 1910. The former operations were only for carbonate sand, and the greater part of the development has been in the last 15 jrears. The main pit near the road is a large circular opening 300 feet in diameter and 100 feet deep. The overburden is thin and little water occurs in the quarry. The rock is a medium-grained, impure dolomite, which is strongly banded, and looks much like a common gneiss at a distance. It carries considerable brown mica (phlogopite), which, with the variations in coarseness of the carbonate grains, are arranged in bands one-quarter inch to 2 feet thick. The banding and main jointing is N. 70° E. 50° S., which causes the rock to break into thick slabs, 1 to 3 feet across. The smaller quarry is 1,000 feet west of the main pit along the same ridge and is 200 feet long, 100 feet wide, and 60 feet deep. The over- burden is 10 feet thick. Only a little water comes into the pit. The rock is similar to that in the larger opening, though its fracture is somewhat more uniform and most of the building stone produced is gotten here. The equipment consists of 1 gasoline shovel, 2 cranes, 2 boom der- ricks, a 450-foot cable way, 2 air compressors, 2 jaw crushers, and a 400-ton bin. The machinery is operated by 10 electric motors. The stone from these openings is usually crushed, though con- siderable building stone is gotten out at times. Formerly small pits to the south of the main opening were worked for carbonate sand, though this is now largely obtained from the dust of the crusher. The follow- ing sizes are produced: dust (concrete sand and macadam) : five-eighths inch (with dust and stone in septic tanks and wash tubs): 1-inch (con- crete and tarring roads): lA-inch, 2-inch, 2|-inch, 3-inch, and 3j-inch (for concrete). About 300 tons are produced in a day. Most of this goes for county, state and private roads. Maryland Geological Survey 247 Gunpowder Quarry, Cockeysville (8) A large quarry in dolomite, on the east side of York Road, one-half mile south of Cockeysville, has recently been acquired by Dr. E. F. Kelly and new equipment installed. The quarry was formerly operated by H. T. Campbell. The opening is a large circular pit 500 feet in diameter and 75 to 100 feet deep with vertical walls. The overburden is thin (2 to 8 feet), and only a moderate amount of water must be pumped. The rock is horizontally bedded dolomite. The beds are massive, 2 to 5 feet thick, and the bedding is the most pronounced plane of jointing. The rock is hard and compact, and carries considerable philogopite mica. A new electric wooden stiff-legged derrick with a 50-horsepower motor loads the stone directly to trucks. It is employed in rough building construction. Maryland Calcite Company Quarry, Texas (9) The Maryland Calcite Company, Inc. operates a quarry in crystal- line limestone and dolomite 300 yeards southwest of Texas station. The opening is circular — 400 feet in diameter, with a working face 30 to 40 feet high on the south and southeast sides. A new opening has recently been sunk into the quarry floor. There is a thick overburden of 10 to 15 feet of red soil, which is removed by tractors. About 12,000 gallons of water are pumped from the hole in a day. Two main types of rock occur — the "alum-stone," or pure, coarsely crystalline calcite rock; and the "blue-stone," or finer-grained, impure dolomite. The former is the most desirable for the operations of this company. It occurs in a bed 30 feet thick which strikes east-west across the quarry floor, with a steep dip to the south. The new opening in the quarry floor is into this rock. The south face is made of the "blue-stone." The "alum-stone" is remarkably pure and white, with the individual grains of calcite averaging one-quarter of an inch across. The follow- ing are analyses made by Penniman and Browne of Baltimore : 248 Mineral Resources of Baltimore County SiO, 3.17 4.43 1.23 AljOj 0.03 0.06 0.02 Iron Oxide 0.12 0.32 0.15 CaO 53.19 53.02 54.47 MgO 0.10 0.15 0.43 Ignition 42 57 42 07 43.43 CaCOj 96.07 94.67 97.26 MgC03 0 21 0.32 0.90 The "blue-stone" is finer-grained, darker in color, and is highly dolo- mitic, with abundant brown phlogopite mica, and accessory tremolite, pyrite, quartz, and tourmaline. The rock is loaded to cars on the quarry floor and hauled up an in- clined railway to the crusher and screens at the north edge of the open- ing. The majority of the products marketed by this company are made from the "alum-stone." Sixty per cent of the output is used as aggregate in the making of cast stone. The remainder is variously distributed among the follow- ing products: stucco dash; chicken grit; concrete aggregate (for side- walks, swimming-pools, etc); cast stone facings; "white flow" (calcite and lime as a finish) ; whiting putty ; filler in paint, linoleum, and rubber ; dusting coal mines; foundry flux; and road stone. In addition to these sufficient stone for the continuous operation of Lindsey's kiln is used. The present pit of the Maryland Calcite Company was opened in 1840 by a Mr. Shipley for lime. The Company has made extensive core drillings on its property in the neighborhood, and has a large reserve of the "alum-stone." T. E. Thompson, Texas (10) T. E. Thompson has opened a pit for calcite sand on the Beaver Dam Road three-eighths of a mile northwest of Texas Station. The opening is 100 feet long, and 20 feet deep. The depth of the disintegrated dolomite (carbonate sand) is variable, and hard rock has been en- countered at two places. The sand is sold to local builders for con- creting and plastering. A little building stone is being moved. The pit is worked intermittent!}' by two or three men. Fig. 2. — View of Calvary Baptist Church, Towson, built of gneiss from the Setters Formation Maryland Geological Survey 249 L. H. Burton, Texas (11) A pit for carbonate sand is occasionally worked on the property of L. H. Burton, one-half mile northwest of Texas Station on the Beaver Dam Road. The opening is 200 feet long (north to south), 125 feet wide and 20 feet deep, and all the rock exposed is completely disinte- grated. The rock is horizontally bedded. The sand is sold to builders for mortar and plaster, to farmers for unburnt lime, and a small amount of pure material to Baltimore department stores for children's play boxes. Ankowiac's Kiln, Hernwood (12) Martin Ankowiac burns the limestone on his property on the Mar- riottsville road just north of the North Branch of the Patapsco River. Only small amounts are burned and are marketed locally. The rock employed is a highly micaceous, banded, dolomite and is not as suitable for burning as that around Texas. Robinson's Kiln, Hernwood (13) Lemuel Robinson is burning limestone just west of the Marriottsville road l|-miles southwest of Hernwood. The kiln has been spasmodi- cally worked since before the Civil War. Only small amounts are produced and are sold locally. Some of the stone employed is high in magnesia. The fuel is coal. Lindsay's Kiln, Texas (14) Only one kiln is now operating in the Texas-Cockeysville area — that of Mr. Lindsay, which burns the "alum-stone" produced at the Mary- land Calcite Company's quarry just west of Texas station. It produces lime for both building and agricultural purposes. Wood is used as fuel. QUARRIES IN TRAP ROCK Gatch Quarry, Raspeburg (15) This quarry is on the west side of the Belair Road just north of Glenarm Avenue. It is operated by T. A. Gatch. The opening is 250 Mineral Resources of Baltimore County large— 400 feet long (N. 40° E.), 250 feet wide, and 100 feet deep. The rock is meta-gabbro, with a pronounced gneissic banding (north, 25° W.). The most pronounced jointing is coincident with the foliation of the rock; other planes are very irregular. The overburden is 10 to 15 feet thick. About 100,000 gallons of water are pumped from the quarry in a day. A cable-way brings the rock to the crusher, whence it is screened into bins. The quarry also operates a machine shop, a blacksmith shop, and three air compressors. All the rock is used for macadam roads and concrete aggregate. Longley Quarry, Gardenville (16) Wm. W. Longley operated a large quarry in trap rock just east of the Belair Road at Biddison Lane until January 1, 1929. The opening is a deep circular pit, open at one end, about 250 feet long and 100 feet deep at the north face. The rock is gabbro and metagabbro (hornblende gneiss) and is very hard and compact. t It is very irregularly jointed — often into roughly polygonal blocks. The major jointing is N. 25° W. 70°E. The soil and decayed rock overburden is 10 to 15 feet, and there is but a small amount of water in the pit. The material was crushed and largely used for macadam roads. Though unlimited quantities of rock remain dwellings have encroached to the very edge of the quarry, and the city obtained an injunction against further operations. Woodberry Trap Rock Quarry (17) This quarry is in gabbro 500 yards north of Woodberry on the west bank of Jones Falls, just at the Pennsylvania Railroad trestle. It is operated by T. C. Davis. All the rock is crushed and used in local road and concrete construction. The rock is worked from the level of the Falls into a face 100 feet high and 400 feet long, and is loaded di- rectly into trucks and hauled to the crusher. Most of the rock is fine- grained, dark, granular gabbro, with a little metagabbro (hornblende gneiss). A 4-foot sill of quartz-diorite (Relay) occurs in the upper Maryland Geological Survey 251 part of the gabbro face. The quarry is equipped with bins (330 tons capacity), and a railroad siding. Thomas R. Martin Quarry, Cooks Lane (18) Thomas R. Martin operates a quarry directly on the city line 500 yards west of Cooks Lane and one-half mile south of Franklintown. It is a large elliptical depression 300 feet in diameter and 50 feet deep. The overburden is thin and the pit is dry. The rock is largely gabbro, with some metagabbro. The massive rock varies in color from dark- purple to light-green. The rock is much more jointed than the other trap quarries in the neighborhood, though in a very irregular manner. The material is hauled by an overhead cable-way to the bins and crusher at the east edge of the pit. Three Blake jaw crushers are used, and the bins hold 200 tons. The rock is crushed for county macadam roads. Bolton Quarry, Franklintown (19) Joseph Bolton owns a quarry in gabbro 300 yards south of the Frank- lin Road and about 1 mile east of Franklintown. At present it is leased by F. D. Carozza. There has been no operation for some months. The quarry is an elliptical pit 150 feet long, 100 feet wide, and showing a 50 feet face of rock about the water level. The water is reported to be 25 feet deep. Both gabbro and metagabbro are present, the latter banded in a plane N. 60° E. 50°N. The equipment consists of a No. 2\ climax jaw crusher and derrick. Hillsdale Quarry, Weather edville (20) This quarry, operated by the United Railways, is on the east bank of Gwynns Falls, one-half mile southeast of Dickeyville on the Hillsdale Road. The rock is gabbro and metagabbro. The gabbro is an excep- tionally hard and compact rock of dark purplish color. The gneissic banding of the metagabbro is N. 80°E. 70°N. The rock is worked in on a level with the road against a large face 450 feet long and 100 feet high. It has been worked back about 100 feet. The overburden of 5-10 feet of decayed rock is not separately removed. Two crushers are 252 Mineral Resources of Baltimore County used and four grades of stone produced. The bins hold 400 tons. The machinery is all electrically driven. All the rock is used as ballast for the electrical railways around the city. Milford Trap Quarry (21) J. E. and H. T. Mallonee formerly operated a quarry north of Milford Avenue and seven-tenths of a mile north of Liberty Road. The quarry is a horseshoe-shaped exposure 100 feet across with a face 40-45 feet high. The rock is in a good position for quarrying and there is no water but a thick clay overburden of 15 feet made it too expensive to operate. The rock is a hard compact gabbro and meta-gabbro of purplish-black color and is an excellent road stone. It weathers into spheroidal "nigger-heads" at the top. The structure is generally mas- sive, though some jointing in the direction N. 25° W. vertical occurs. It was employed largely for macadam roads. Hollofield Trap Quarry (22) A quarry for trap rock was started in the spring of 1929 by J. E. and H. T. Mallonee on the Patapsco River 200 feet south of the bridge at Hollofield Station. The material is a basic igneous rock which has been somewhat serpentinized. It is exposed in a steep slope 200 feet high with little overburden, and is in an excellent position for quarrying and shipping. The opening is now 75 feet long and 25 feet high. There are two jaw crushers, screens, and a bin, and dust, 1-inch, and 2-inch sizes are produced. It is all used for macadam roads. Blue Mount Quarry (23) The J. E. Baker Company of York, Pennsylvania, operates what is probably the largest quarry in Baltimore County. It is on the Gun- powder Falls along Big Falls Road 1 mile southwest of 'Whitehall. The opening is an exposure 450 feet long, 140 feet high on the north and 70 feet high on the south; it has been worked back from the Falls about 150 feet. The overburden of 3 feet of soil and decayed rock is stripped by hand. No water is encountered in the workings. .Maryland Geological Survey 253 The stone is a slightly serpentinized basic igneous rock (trap). A few veins and irregular masses of green serpentine with chromite grains occur, and some of the surfaces have thin films of magnesite and dewey- lite. As a whole, however, it is dark, purplish-black, with a hackly fracture, and is an excellent grade of trap. The main jointing is N. 75° W. 75° X. The rock is first loosened by primary blasting; done by a 6-inch cy- clone drill with 60 per cent dynamite. The resulting blocks are broken by secondary blasting, and then mauled by sledge, loaded to cars drawn by horses, and hauled to the crusher. The cars are worked by contract and a man is paid 37J cents for one load. Thirty cars, made of steel, are operated. The rock is first put into a 30-inch by 24-inch Superior jaw crusher, and then through a Xo. 6 Gates gyratory crusher, from which it is elevated 135 feet b}r a 20-inch bucket conveyor-belt to a Xo. 8 Xiagara vibratory roller-bearing screen of 3-inch mesh. This 3-inch size is largely used for railroad ballast. The undersize is lifted up a 115- foot elevator belt to a Xo. 4 Xiagara vibratory screen which separates the lf-inch size. From this it goes to a Xo. 3 Xiagara screen which produces the three-quarter-inch, one-half-inch, and one-quarter-inch sizes. The undersize is used as dust. All the oversizes from these screens are returned to the gyratory crusher. The sizes under 3 inches are largely used in macadam and concrete. Seven electric motors drive this machinery, with an aggregate of 380 horsepower. Each of the above sizes is stored in a 75-ton bin. The plant is connected by a rail- road spur lj miles long up the Gunpowder River from the Pennsylvania Railroad. The output of the quarry is used for railroad ballast, and county and state concrete and macadam roads, largely in Maryland and Pennsyl- vania. The York Road, Middletown Road, and Monkton Road were built of this stone, and all the ballast of the Baltimore Division of the Pennsylvania Railroad comes from this quarry. Production amounts to 825 tons a day. About 60 men are employed. 254 Mineral Resources of Baltimore County Bare Hills Quarries (24) Two small quarries are being worked in the Bare Hills serpentine at the junction of Falls Road and the Old Pimlico Road by Lewis 0. Stern. The pit to the east is the larger with a face 200 feet long and 40 feet high. The opening on the west is 75 feet long and 30 feet high. The rock varies in color from a light straw yellow to a dark purple-green. It is extensively veined by thin stringers of magnesite, chalcedony, calcite, deweylite, chrysotile (asbestus), and opal. The rock is in- tricately fractured and the jointing is very irregular, producing hackly and uneven blocks. There is no water nor overburden in the quarries. Both crushed stone for roads and concrete, and building stone are produced. The school house at the top of the hill south of the quarry, and the two small buildings nearby along Falls Road were built of the stone; also the new Howard Park Methodist Church About 5,000 tons are gotten out in a year. Dyer Quarry, Delight (25) A quarry is being worked in serpentine south of the Nicodemus Road \\ miles west of the Reisterstown Road by A. A. Dyer of Reisterstown. It is near the site of the old Calhoun chrome mine, which has not been operated since 1880. Veins of deweylite and chalcedony are common on the quarry face, and at some places large rhombs of calcite bounded by picrolite are seen. The rock is used for road work. QUARRIES IX GNEISS Falls Road Quarry, Jones Falls (26) T. A. Gatch operates the only remaining quarry of what was once an extensive series of openings in this area. The first mention of these quarries is in 1811, when it was reported that [the gneiss] ". . . .is here quarried on both sides of Jones' Falls to considerable advantages to the proprietors/'7 which indicates that they were worked considerably prior to that date. The first excavation was probably on the west side 7 For a full account see Merrill, G. P and Mathews, E. B., "The Building and Decorative Stones of Maryland," Maryland Geological Survey, 1898, p. 161. Maryland Geological Survey 255 of the valley, and the old opening may still be seen just above the Pennsylvania Railroad car shops north of North Avenue. The most extensive working, however, was on the east side, and several quarries, now concealed by dumping, existed from the Maryland and Pennsyl- vania Railroad freight station north to the Electric Railway trestle in the Ston3" Run Valley. These were worked continuously through the last century, and in 1900 three companies were moving a large amount of stone. These were the Peddicord, Curley-Schwind, and Atkinson quarries. Much of this stone has been used in construction around Baltimore, as, for example, in the older buildings at Goucher College, and in the old City Jail and old Court House. It has been most extensively employed, however, in foundation work, and other places where rough unfinished stone may be used. The present Falls Road Quarry Company is operating two adjacent pits on the east side of the valley just below the junction of Stony Run with Jones Falls, between Twenty-sixth and Twenty-eighth Streets. Both pits are about 150 feet long, and 50 feet wide, and are working into a face 50 feet high. In the last few jrears the presence of buildings above the openings has forced the working downwards rather than far- ther into the quarry face. At the north pit they are now 40 feet deep, and 30 feet deep at the south pit. Due to this restriction the life of the quarry is estimated at 6 or 7 years. There is an overburden of 15 feet of Pleistocene gravel and decayed rock. The rock is a massive feldspar biotite gneiss of light-gray color. There is a pronounced jointing which is coincident with the gneissic texture, and probably with the original bedding (N. 30° E. 40° N. W.). Two other joint planes occur: N. 60° W. 70° S. W. and N. 30° E. 65° S. E., which cause the rock to conveniently break into rectangular slabs. These slabs are commonly 3 to 18 inches thick, 2 to 5 feet wide, and 6 to 24 feet long. They are easily worked, and are broken into rough di- mensional pieces by the "plug and feather" method. None of the stone is crushed, but all goes for rough construction — foundations and small buildings. Of the stone used for these purposes 256 Mineral Resources of Baltimore County around Baltimore that from this locality is probably more easily worked than any. Gwynns Falls Stone Corporation Quarry (27) The quarries in the Gwynns Falls area of Baltimore City have not been worked as long as those in Jones Falls, though they have been in continuous operation since 1850. 8 An immense amount of rock has been moved from them, and the largest quarry in Baltimore City at the end of the last century was that of John G. Schwind at this locality. Today two quarries are operating here. The largest is the Gwynns Falls Stone Corporation; owned by T. C. Campbell, who acquired the property in 1927. At the present time it is probabljr the best equipped quarry within the area of Baltimore City. It is situated on the west bank of Gwynns Falls about 500 yards north of the Pennsylvania Railroad bridge. The exposure is 400 feet long in an east-west direction against a face of rock 70 feet high. The work- ings have gone 20-30 feet below the level of the railroad tracks. The overburden of 10 to 15 feet of decayed rock is removed by steam shovel. About 4000 gallons of water a day are pumped from the pit. Both the character of the rock and its structure are very similar to that at Jones Falls. It is a gray, thick bedded, "salt and pepper" gneiss, composed of biotite, feldspar and quartz. The gneissic texture and main jointing are coincident in a plane N. 30° E. 35° W. At the east end of the quarry the dip of the rock changes to form a gentle anticline. Other planes of jointing are irregular, and rough dimensional slabs are not as easily won as at Jones Falls. The rock is extensively veined with pegmatite. The rock is lifted from the pit by a 20-ton, traveling crane on a stand- ard gauge track, and by a stiff-legged steel derrick, both operated by steam. One jaw crusher and two gyrator}' crushers reduce the stone to various sizes, from whence it is fed through a large rotary screen and four shaker screens (Hum-mer). The crushers, bucket belts, and •Merrill, G. P. and Mathews, E. B., op. cit., p. 166. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XVIII Fig. 2. — View of new quarry of the Beaver Dam Marble Company, Cockeysville Maryland Geological Survey 257 screens are operated by electricity. The bins have a capacity of 500 tons. About 50 per cent of the rock is crushed and 50 per cent is used for rough building stone. No dimension stone is produced. About 400 tons are produced a day. The crushed material goes into macadam roads and concrete, and the building stone into various structures, chiefly around Baltimore. Among recent buildings, the First English Lutheran Church at Charles and 39th Streets (with stone from the But- ler Quarry), the Church of the Holy Nativity at Forest Park, and the Landsdowne Methodist Church were built of this stone. Hilton Quarries, Gwynns Falls (28) Just south of Campbell's quarry on the west bank of Gwynns Falls, and about 1200 feet north of the Pennsylvania Railroad bridge is a quarry recently opened by Wm. H. Guntrum and T. U. Donohue. They are now working a small part of a 400-foot face, the site of an old quarry now partly filled with water. The rock is the same as that to the north. None of the rock is crushed; the majority is used for rough building construction, chiefly small houses. Some has been marketed for breakwater riprap: at Seven Foot Knoll and Havre de Grace in Maryland, and even beyond the State. Considerable pegmatite has been encountered and is sold at $4.00 a ton without cobbing. Loch Raven Quarry (29) The quarry of Thomas P. Murray is situated along the Maryland and Pennsylvania Railroad a quarter of a mile northeast of Loch Raven station. The opening is in the Setters formation, though it is not the typical flagstone rock seen along the Green Spring Valley. Here it is a highly quartzose, feldspar biotite gneiss. A few quartz and pegmatite veins occur. The upper part of the quarry is more schistose and carries tourmaline. The rock is worked into a cliff above the railroad 200 feet long, 100 feet high, and has been quarried back from the tracks for 75 feet. The bedding plane and main jointing of the rock is parallel to the railroad 258 Mineral Resources of Baltimore County and dips steeply down towards the quarry floor, N. 50° E. 60° X. This is the only persistent plane and causes the rock to break into rough two-sided pieces. There is no water and little overburden in the quarry. There is a small crusher with a rotary screen and a bin connected to the railroad by a siding. About one-half of the output is crushed stone and one-half building stone. The former is used in county and private roads and the latter for small houses. quarries in flagstone "Rustic Quarry," Loch Raven (30) Harry T. Campbell of Towson is operating a quarry for building stone on the Maryland and Pennsylvania Railroad and Cromwell Bridge Road one-half mile east of Oakleigh station. The rock is being worked along the strike into a face 70 feet high, 100 feet wide, and has advanced 100 feet from the stream into the hill. A smaller pit is being worked on the west side of the little valley. The main type of rock is a fine grained, banded, quartz, feldspar biotite gneiss, part of the Setters formation. A little of the more typical quartzitic phase occurs to the south up the hill. The rock breaks into rough slabs — 3-4 feet by 1 foot by 6 inches. The banding and main jointing of the rock is N. 45° E. 35° N. Other good planes of jointing occur. All of the rock is used for rough building construction and flagging. The quarry floor is above the water table, and there is little overburden. The stone is easily handled and is hauled directly out by trucks to various building operations about Baltimore. The quarry operates a small derrick and employs 10 to 15 men. Several private homes in the Guilford-Homeland area, and the Presbj - terian and Baptist churches at Towson are built of this stone. The Calvary Baptist Church at Towson is shown on Plate XVII, Fig. 2. Butler Quarry (31) H. T. Campbell is working a quarry on the property of Oscar Gray 200 feet north of Butler on the east side of Falls Road along Blackrock Maryland Geological Survey 259 Run. It is reported that the quarry was first operated in 1800 and the old mill building, now used as an engine and tool house for the quarry, is said to have been built of the stone at that time. Also, the house of Mr. Gray along Falls Road at this point was partly built at the same time from the old workings (see Plate XVII, Fig. 1). Mr. Campbell began the recent development in 1923. The opening has been worked back from the stream about 100 feet along the strike of the rock and is 100 feet wide and 75 feet high at the back. (Plate XV, Fig. 1). Recently a new opening has been made just to the south which is 75 feet across and 30 feet high. No water occurs in the workings and there is very little overburden. The rock in the main pit is the typical flagstone of the Setters forma- tion, an arkosic quartzite which cleaves readily into slabs 1 to 8 inches thick. Some of the rock is more of a gneiss, and that in the south pit is a narrow-banded "ribbon" gneiss, of quartz, feldspar, and biotite. The flagstone rock has only one good plane of cleavage — the bedding plane ; whereas the gneiss of the south pit is claimed to work nearly as a freestone. The banding and main jointing is vertical and strikes paral- lel to the crest of the hill in the direction N. 65° E. The old mill which was formerly used for grinding flour has been con- verted to supply the power needed in quarrying. Two overshot water- wheels 16 feet in diameter and 6 feet wide develop 90 horsepower and work the air compressor. A derrick is used in the south pit. In recent years many buildings, churches, and small houses in and around Baltimore have been built of the stone from Butler. The new City College in Baltimore obtained 86 per cent of its stone from here. Some other buildings are: the First English Lutheran Church at Charles and Thirty-ninth Streets, the Lutheran Church at Thirty-third Street and Alameda Boulevard, and the Masonic Temple at Reisterstown. Water's Quarry, Pikesville {82) Two hundred yards south of the Old Court Road and one-quarter of a mile east of Seven Mile Lane there is a quarry for building stone on the Waters property worked by the Mallonee Brothers of Pikesville. The 260 Mineral Resources of Baltimore County exposure has been made north into the ridge and is 300 feet long and 50 feet high. There is no water and very little overburden. The rock is in the Setters formation and is predominantly a biotite gneiss; some of the quartzitic flagstone type occurs in the center of the workings. Tourmaline in dendritic growths is common on the cleavage surfaces, and a few quartz and pegmatite dikes cut the gneiss. The rock cleaves easily and is well suited for flagging and rough building purposes. The bedding and cleavage of the rock is N. 70° E. 48° S. — that is, parallel to the ridge and dipping under the limestone which occurs in the valley to the south. Wright's Mill Quarry (33) At old Wright's Mill ("Jew Bottom"), three-quarters of a mile north- west of Alberton, Mr. Feeney of Granite is working the Setters forma- tion for flagstone. The opening was started in 1928, and has only exposed the rock at the nose of the hill, 125 feet long and 30 feet high. There is no water nor overburden. The rock is the quartzitic flag- stone type which cleaves easily into slabs 1 to 3 inches thick. The sur- faces of the flags are covered with scaly white mica and a few crystals of black tourmaline, thougli the latter are not as abundant as usual. The rock is very easily worked, which is not only facilitated by the cleavage but by the presence of many good planes of jointing (Plate XVI. Fig. 1). The jointing is E.-W. 35° N. The rock is excellent for flagging, it is in a good position for quarrying, and large quantities exist, but a long truck haul over bad roads will probabhy interfere with rapid development. Blunt Quarries, Hernwood (34) Openings for flagstone in the Setters formation are being operated by Otis W. Blunt on the north side of Powell's Run Road 300 yards north of the Marriottsville Road. One quarry is immediately along the road and the other is 100 feet to the east. They are small workings about 30 feet across and 25 feet high. The rock, which is the typical quartzite, cleaves in a remarkable manner, most commonly into pieces 1 inch thick, and gives the impression of a giant layer-cake. The cleavage is Maryland Geological Survey 261 in the direction E.-W. 50° N., which with numerous other planes of jointing make the rock easily worked. The cleavage surfaces have less mica than at the Wright's Mill quarry, but considerably more black tourmaline. The stone is hauled by truck to various suburban developments north of Baltimore, and some has been sent to Gibson Island in Anne Arundel County. The new Catholic Church at Chevy Chase Circle near Wash- ington, D. C, was built from these quarries. An interesting feature of these openings, as well as that of Knopf to the south along this ridge, is the presence in them of cavities of consider- able size. In his eastern pit Mr. Blunt reports an opening "large enough for a horse to fall into," and one may be seen in the Knopf quarry which is 1 foot wide, 8 feet high perpendicular to the strike and dip of the rock, and extends down the dip out of sight for at least 15 feet. The walls of these cavities are smooth and are parallel to one of the sets of numerous joint planes which characterize the quartzite of this region. A slight current of cold air blows from them. These openings could not have been formed by solution, as in limestone, and their relation to the fracture planes in the rock points to recent faulting or crustal movements of small magnitude, probably sometime in the Tertiary. Knopf Quarry, Hernwood (So) A small quarry was opened in 1928 by Albert Knopf on his property south-about three-eighths of a mile along the ridge from Blunt's quarries. The rock is similar, although somewhat thicker slabs occur, and the small jointing is present. The main cleavage is N. 80° E. 25° N. Two exposures occur, each 20 feet across and 10 feet high. All the rock has been shipped to Homeland, north of Baltimore, for flagging. About S6.00 a ton is gotten for the rock. It is estimated that the haulage costs $4.00 a ton. Jones Quarry, Hernwood (36) Joseph C. Jones is operating another quarry for flagstone south of Knopf and Blunt on the east side of the Marriottsville Road about 1 262 Mineral Resources of Baltimore County mile north of the north Branch of the Patapsco River. It is a small opening about 30 feet across and of the same rock as the other nearby quarries expose. Three men are employed and the stone is shipped to Homeland in Baltimore. Wittingham Quarry, Pine Hill (37) Dr. E. F. Kelly of Cockeysville has been working a small opening for building stone on the Wittingham property, one-half mile west of York Road on the Gold Bottom Road. The quany is small, a face 15 feet by 10 feet about 25 feet back from the road. The rock is in the Setters formation, but is not the typical flagstone. It is a heavy, thick-bedded mica quartzite. The grain is coarse and irregular, really pegmatite, and probably has been injected by quartz solutions. A little tourmaline and magnetite occur. The bedding is vertical and strikes N. 50° E. The slabs are 2 to 10 inches thick. Stevenson Quarry (38) Three-eighths of a mile west of Stevenson station along Setters Ridge south of the Green Spring Valley is a quarry in flagstone on the Baetjer property. The rock at this place is probably the most desirable of its kind around Baltimore, and may be taken as the type locality for the Setters formation. The exposure is in a bold cliff 60 feet high and 50 feet across with no overburden. The stone cleaves readily into neat, clean slabs 1 to 5 inches thick which are covered with abundant crystals of black tourmaline. On the south wall of the quarry the schistose phase of the Setters formation occurs, impregnated with abundant tourmaline. The rock here is admirably situated for quanying and shipping and was worked for a time by Waters, but it occurs in an area of high-class residences and the owners object to the noise and unsightli- ness of the operation. Shoemaker Quarry, Chaitolanee (39) Along the same ridge, three-eighths of a mile west of Chattolanee on the Garrison Road is the old Shoemaker quarry, which was intermit- tently worked throughout the nineteenth century for flagstone, and Maryland Geological Survey 263 supplied much of the material for the old buildings of the region. The rock is similar to that at the Stevenson quarry, though it is not as fresh and clean nor so well exposed. An interesting example of "creep" in the layers near the surface may be seen,, where the freezing action of frost has pushed them out of line down the slope. This opening has not been worked for a long time. Rogers Quarry (40) South of Setters Ridge from the Hillside Road, Green Spring Valley, and one-half mile east of Rogers station is a quarry in flagstone owned by the Cathedral of the Incarnation (Protestant Episcopal). The rock is similar to that at the Stevenson quarry farther west, though it contains fewer tourmaline. The property is held in order to insure a permanent supply of stone for completion of the Cathedral of the Diocese of Mary- land on Charles Street and University Parkway. Some has already been quarried to build the "Pro-Cathedral." Just across the little stream from this opening Weber started to work the rock and opened a series of trenches parallel to the stream and across the strike of the formation. The venture was unsuccessful, but it exposes a good section of the Setters formation with the schistose phase to the south, and flagstone phase on the north with intercalations of thick-bedded massive quartzite. Sand and Gravel Sand has always been indispensable in building operations — for ce- ment, plaster, and mortar, and increasingly of late years as a fine aggre- gate in concrete. Its geologic distribution is widespread and varied and it has been worked around Baltimore since colonial times. Gravel, except in the making of sand and gravel roads, was not so extensively employed until more recently, when it has been used as a course aggre- gate in concrete construction of all kinds. Geologically, sand and gravel in commercial quantities are largely restricted to three formations around Baltimore, all in the Coastal Plain deposits: the Patuxent, the Columbia group, and the recent river 264 Mineral Resources of Baltimore County and estuarine deposits. The Patuxent formation, the basal member of the Lower Cretaceous, is predominantly a white, cross-bedded sand, though locally it contains both gravel and clay lenses. It outcrops across southern Baltimore County in a northeast-southwest direction, underlying much of the downtown sections of Baltimore City and oc- curring farther to the northwest as isolated outliers ontheolder crystalline rocks. The Columbia group, of Pleistocene age, is composed of a series of terrace deposits at various levels throughout the southern end of the county. They are largely of sand and gravel, though locally they con- tain layers of clay. They are most commonly encountered either as isolated masses capping the hills of the region (the higher terraces — Brandywine and Sunderland), or as low-lying deposits bordering the streams and estuaries (the lower terraces — Wicomico and Talbot). The recent streams and drowned river valleys along the Chesapeake Bay are continually depositing and redepositing masses of clay, sand, and gravel in the form of bars and spits. Where the current is gentle clay is deposited, and where more rapid sand and gravel; the location of these deposits depending on the configuration of the valley, the velocity of the water, and the relation to the tides. When it is recalled that 200 years ago ocean-going sloops ascended the Patapsco River as far as Elkridge Landing (Relay) and that today that channel has been nearly completely filled to Brooklyn, the rapidity of this process of deposition will be realized. All of these deposits have served as sources for sand and gravel around Baltimore. In the past probably the Patuxent sand was most avail- able as bank 'deposits, and later the terrace deposits were utilized for roads and building purposes. In later years since the dredging of the harbor, large'deposits of gravel and sand in bars were encountered under water, and these now supply the greatest amount consumed in the city and its environs. The methods of working the bank deposits of the Patuxent and Columbia group are usually very simple. The material is soft and easily excavated and if sufficient quantity is present with little over- burden and no water it may prove profitable to work for local markets. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XIX Fig 2. — View showing Bluemount Trap Quarry, west end Maryland Geological Survey 265 Most of these operations are short-lived, however, as the numerous small abandoned pits throughout the region testify. Occasionally a bank sand is worked on a larger scale, with more extensive equipment, such as the Arundel Corporation's pit at Patapsco, Howard Count}', and the Caton Sand Company at Landsdowne. Local deposits of sand and gravel are frequently worked for material on a neighboring road, after which they are abandoned. More recentfy a number of pits have been opened to supply sand to the manufacturers of concrete block and other artificial building materials. There are two areas where bank deposits are now being actively worked: northeast of Baltimore in the region along Whitemarsh Run, and southeast of Baltimore around Landsdowne. These producers for the most part supply a local demand, where the competition is not too keen, with the large bar deposits in Baltimore harbor. About 70 per cent of the sand and gravel used in and around Balti- more is supplied by the Arundel Corporation from their bar deposit in Baltimore harbor at Spring Gardens, and from their bank deposit at Northeast, in Cecil County. The successful operation of this Corpora- tion on such a large scale, with extensive equipment, in comparison with the short-lived operations of the smaller pits illustrates the greater econ- omy of large scale production and its greater usefulness to the community. The available supplies of sand and gravel which remain around Balti- more are large. The quantities which still may be gotten from the Patuxent and Columbia formations are enormous. The Arundel Cor- poration is constantly exploring the harbor and Patapsco River, as well as the Bay itself for future reserves, and though considerable amounts exist, they become more expensive to work the farther they are from the city markets. OPERATIONS FOR SAND AND GRAVEL Arundel Corporation, Baltimore {41, 42, 43) By far the largest producer of sand and gravel around Baltimore is the Arundel Corporation. It probably supplies over 70 per cent of the 266 Mineral Resources of Baltimore County sand and gravel used in the city and its environs. The material marketed in Baltimore comes from two sources — a bank deposit at Northeast, Cecil County, and a bar deposit in the Baltimore harbor south of Spring Gardens. Besides these operations the corporation is engaged in extensive dredging for the State and Federal governments, and for private interests. The materials moved in these latter opera- tions are not marketed, but are disposed of on the government dump at Kent Island. The bar deposit in Baltimore harbor is worked by large dredges, from which buckets are suspended by derricks, or a series of conveyor buckets are used (ladder dredges). The material is washed on the dredges and then taken to one of the shipping points, where it is separated into the various grades of sand and gravel. If any further washing is necessary it is sent to the Brooklyn re washing plant. That intended for concrete is also sent here. There are four points for the separation, storage, and shipment of the material around Baltimore: Brooklyn, Bush Street, Clinton Street, and Pier 2 Pratt Street. The largest amount of material passes through the Pratt Street plant where 4,450 tons are handled daily. The largest equipment is at the Brooklyn plant, where extensive machinery is installed for mechanically handling large volumes of material in the operations of washing, screening, and shipping. The largest amount of the product is made up of two types each of sand and gravel; building sand, rewashed sand, 2y-inch gravel, and 1 j-inch gravel. About equal volumes of sand and gravel are consumed. About 20 per cent of the total sand is building sand, used for plaster and mortar; the other 80 per cent is the rewashed sand, used as a fine aggregate in concrete. The gravel is used as a coarse aggregate in con- crete— 60 per cent is the lj-inch size, and 40 per cent, the 2£-inch size. Besides these, 3 intermediate grades are produced at Brooklyn — three sixteenth-inch for pebble dash, three-eighths-inch for roofing grit, and three-quarter-inch for small concrete forms. Occasionally very large boulders and cobbles are encountered in dredging; these are crushed and sold as coarse aggregate. Maryland Geological Survey 267 The selling price at the present time is 70 cents a ton for sand, $1.40 a ton for the larger gravel, and SI. 60 for the three-quarter-inch gravel. Forty per cent of the total output is used for building construction and 60 per cent for road construction. The total volume marketed is 2 million tons a year. Twenty years ago only about 500,000 tons were produced in a year. On the map (Plate XX) 41 is the Brooklyn plant, 42 is Pratt Street, and 43 is Bush Street. Colon Sand and Gravel Company, Landsdowne (44) This is the largest operation in bank sand in Baltimore County and is situated southwest of the junction of Washington Boulevard and Sul- phur Spring Road. The opening is 500 feet long, 300 feet wide, and the working face at the west end is 80 feet high. The section at this face shows a 5-foot overburden of iron-stained sand, gravel, and clay below. This is a compact white clay lens, 18 feet at the thickest point and pinch- ing out 50 feet in either direction; the remainder of the exposure to the base is of white, pure, cross-bedded sand. The material is worked by a gasoline shovel, loaded to cars, and hauled to the screens. The screens are of the vibratory type, of one-quarter inch mesh. The sand is not washed, and is lifted by conveyor belts to the bin. The bins load di- rectly by gravity into trucks. About 35 truck-loads, at 5 or 6 tons a load, are produced a day. The sand is all employed in mortar and plaster around Baltimore. A large amount of material has been removed from this opening, but considerable quantities still remain. The occurrence of the clay and sand is very variable, however, and presence of much clay may cause difficulty. S. Link Sand Company, Landsdowne (45) The workings of S. Link are immediately adjacent to those of the Caton Company along the Washington Boulevard, and are similar though on a smaller scale. The opening is against a working face 200 feet long and 45 feet high. An irregular bed of clay and gravel occurs 268 Mineral Resources of Baltimore County at the top of the section, 3 to 8 feet thick ; the remainder is white, cross- bedded sand, with the exception of a three-foot bed of clay and gravel mid-way on the face. The material is worked by steam shovel and passed through a rotary screen. It is used for building sand around Baltimore. Sadler Bank, Landsdowne (Ifi) Mrs. M. S. Sadler owns a sand and gravel pit at the northwest comer of the Washington Boulevard and Sulphur Spring Road. The opening has only been sporadically worked, though considerable material is present and in a very accessible position. It is in the upper part of the Patuxent formation, and consists largely of white cross-bedded sands, with a little gravel and two white clay lenses. The exposure is 300 feet long and 30 feet high, and is worked back 100 feet on a level with the road. Oterlea Sand a?id Gravel Company, Belair Road (^7) T. A. Gatch operates a large pit for sand and gravel 200 yards north- west of the Belair Road, at a point 400 yards northeast of Whitemarsh Run. The opening is 300 feet long (north and south), 250 feet wide, and varies from 10 (south) to 30 feet (north) in depth. The property is largely worked out as a cemetery adjoins it to the northeast and a power-transmission line to the west. The working face at the north shows a heavily cross-bedded gravel which contains two lenses (1 foot and 4.5 feet) of compact white clay. The clay is not utilized and must be separated. The excavation is done by a gasoline crane, and is hauled to the screens and bins by cars on a track. Considerable water is pres- ent in the workings. The sand and gravel are used in local concrete construction. Schleagel Property, Belair Road (4.8) Two pits for sand and gravel are worked on the Schleagel property 200 yards northwest of the Belair Road at a point j mile southwest of Silver Spring Road. The smaller pit to the east is 100 feet in diameter and is operated by the Polesne Brothers; that to the west is 200 feet in Maryland Geological Survey 269 diameter and is worked by Henry Diegert. The material is cross- bedded sand and gravel. No clay lenses nor overburden are present, and there is no water in the workings. Considerable material remains and no real estate developments are close. Sommers Pit, Necker Ave. (4-9) Five hundred feet east of Belair Road, and 150 feet north of Necker Avenue there is an opening for sand and gravel 100 feet long, 50 feet wide with a face 15 feet high. There is no overburden, but a thick growth of pine and oak requires much grubbing. The exposure is all sand and gravel, but considerable iron-stone conglomerate and iron staining are present. Schwartz Pit, Rosedale (50) George Schwartz is operating a pit for sand and gravel on the property of the Champion Brick Company, one-quarter of a mile southwest of Hamilton Avenue on the Philadelphia Road. The opening was made 7 years ago, and is now 350 feet long and 100 feet wide. The present working face is 25 feet high and consists of white cross-bedded sand and gravel, with a 3 to 5 foot white clay lense near the top. The material is worked by a gasoline bucket shovel and is loaded directly on trucks. Part of the sand and gravel goes to local builders, and some is used in the manufacture of concrete blocks. Hesse Pit, Rosedale (51) R. D. Hesse operates a pit for sand on the Old Philadelphia Road one mile northwest of Hamilton Avenue. The pit is 300 feet long, 200 feet wide, and 10 feet deep. The material is rather pure, fine- grained sand, and is neither screened nor washed. It is used by local builders. Gasoline loaders and tractors are used. Kahl Pit, Whitemarsh (52) U. P. Kahl operates a small pit for sand along the Philadelphia Road 200 yards northeast of Silver Spring Road. It is a small opening 100 feet in diameter and 30 feet deep, exposing cross-bedded Patuxent sand, 270 Mineral Resources of Baltimore County with considerable iron-stone and some gravel. The sand is shipped to the Cast Block Company, at Bengies, for concrete block. Richardson Pit, Whitemarsh (53) Three hundred yards northeast of Whitemarsh Run along the Balti- more and Ohio Railroad, J. F. Richardson is operating a pit for sand and gravel. The pit is 200 feet long, 100 feet wide, and 20 feet deep, and has 10 feet of water in it. The material is worked by a centrifugal pump on a barge. The stream from the pump is passed through a 4- foot washing screen, which separates the sand and gravel and washes away any clay that is present. Conveyor belts and loaders bring the sand and gravel to trucks. There is a railroad siding. Clay and Clay Products The making of brick around Baltimore is probably as old as the period of colonization. The first settlers in Southern Maryland used the local clay banks to fashion brick, and when they later founded Baltimore the abundant supplies around the new town were no doubt utilized also. It is often claimed that the bricks in very old structures were shipped in from England, and although this was doubtless true in some cases, prob- ably the greater number of colonial houses were made directly from Maryland brick. Baltimore City has been noted throughout its history for its long rows of red brick dwellings with white marble steps and lintels, and this once rather prosaic building material has now assumed a certain amount of dignity with age. The greater amount of this brick has been obtained and manufactured locally, and still forms the basis of a considerable industry. By far the larger amount of clay used in the manufacture of brick around Baltimore has come from the Coastal Plain deposits kying to the east and southwest of the city. A small amount has in the past been derived from the residual clays of the crystalline rocks, but the quantity has been small and the quality inferior. Of the four unconsolidated formations which outcrop around Balti- Maryland Geological Survey 271 more, the Patuxent, Arundel, Patapsco, and Columbia group, the Arun- del has been the most productive as a source of brick material. The dominant phase of the Arundel formation is a compact, drab-colored clay, which contains considerable iron, both in the form of carbonate nodules, and as a cementing matrix in thin gravel lenses (the so-called iron-stone conglomerate). This clay possesses good plasticity and is locally somewhat siliceous, and has been found very suitable in the manufacture of common brick as well as more specialized products. All the other formations enumerated above have been employed in the ceramic industries of the Baltimore region, though not so extensively as the Arundel. At the present time only one operation is working in these other formations — the Burns and Russell Company in Columbia clay on the Patapsco River Neck. The Patuxent formation is dominantly of sand, and has been employed as an ingredient in the manufacture of refactory ware. The Patapsco formation consists of both sands and clays and has been used to some extent in brick making. Its variability necessitates considerable caution in working, however. The Rossville Plant of the Baltimore Brick Company is working a bank at the junc- tion of the Arundel and Patapsco formations, and is combining these materials in proportions which give a desirable mix. The Columbia clays around Baltimore are low-lying deposits, generally within 30 feet of tide, and have been rather extensively employed in the past in the fashioning of clay products. They are generally sandy, but nevertheless quite plastic and burn to a bright-red color, though not as red as much of the Arundel and Patapsco materials. Among the types of clay products made from the clay around Balti- more brick-making has assumed a predominant position. In the past other ceramic products were of some importance, but today only one operation other than for brick exists. These other products were: terra cotta, sewer pipe, fire clay, and pottery clay. The materials for these special products still exist and they will doubtless be utilized again in the future. The one operation mentioned above is that of the United Clay Mining Corporation of New Jersey, north of Middle River, which is shipping material to the potteries at East Liverpool, Ohio, and Tren- ton, New Jersey. 272 Mineral Resources of Baltimore County Among the brick manufacturers in Baltimore City and Baltimore County five plants produce common brick and one produces paving brick with some sewer brick. The latter is the Westport Paving Brick Company of Baltimore. Of the common brick manufacturers two of the plants designate part of their product as face brick. The methods employed in working the clay deposits are simple. The material is quarried where there is little overburden and water, and where there is sufficient for a considerable operation. Banks of 20 to 30 feet in height are dug by a power shovel and loaded to cars on tracks and hauled to the plant. Generally the composition of the clay is amenable to immediate fabrication, though in some cases various types from a single working are combined in proportions which are more desirable. At the plant of the Westport Paving Brick Company a mixture of ground shale and clay is used; the shale coming from Freder- ick County, the clay from the bank at the plant. It is generally found unprofitable to work a deposit which contains an overburden greater than 6 to 8 feet, or a lens of deleterious material greater than this within the deposit. Also the presence of ground water within a clay bank renders the workings unprofitable. The making and burning of brick around Baltimore is accomplished by the methods common to that industry even-where. The clay is mixed with water in a pug-mill and forced through the die of a brick-making machine. At four of the plants the cross-section of the die is that of the smallest dimension of the brick, and "end-cutting" machines are used; at two of the plants the bricks are "side-cut." They are then loaded on small cars and placed in drying tunnels for about 36 hours. In the common brick plants up-draught kilns are used of the normal rectangular shape, with a capacity of 300,000 to 500,000 bricks. In these they are burned for 5 to 7 days, and allowed to cool for 3 to 4 days. No accurate thermal control is employed. At the Westport Paving Brick Company smaller, circular, down-draught kilns (60,000 bricks each) are used, the firing lasts 8 or 9 days, and they are allowed to cool nearly as long. Here recording pyrometers are used in both the drying tunnels and kilns. MARYLAND GEOLOGICAL SOEVEY BALTIMORE COUNTY, PLATE XX Maryland Geological Survey 273 About 140 million bricks are produced in Baltimore City and County in a year, which represents about $2,000,000. This is at a price of about $14.00 a thousand, which has been the standard price for several years, though recently some have been marketed for as low as $11.00 a thousand. The output of brick from the Baltimore region increased immediately after the war, but since 1921 it has declined slightly. In 1919 the out- put was $819,622, and in 1921 it was $2,713,240. This recent decrease is proportionately even greater since the consumption of building mate- rials has increased in that time. The substitution of natural stone, and especially of concrete block and other artificial products for brick is largely responsible for this decline. As in the past so at the present time the large proportion of the bricks produced around Baltimore is used locally. Some is shipped, however, and several of the operators are filling orders for brick from various points along the Atlantic Seaboard. Since brick and other clay products should continue to hold an im- portant place as structural materials the utilization of the claj's near Baltimore will probably be maintained as a healthy industry. The amount of available clay, both for brick and more specialized products, is enormous. Large areas of Columbia clay exist on the Patapsco River and Back River necks, and much of the Arundel formation is available to the northeast and southwest of Baltimore in the general belt tranversed by the Pennsylvania Railroad. For a more extended description of the clays and clay-working indus- tries in Maryland see Heinrich Reis, "Report on the Clays of Maryland,"' Maryland Geological Survey, vol. IV, 1902, pp. 203-503. OPERATIONS FOR CLAY Westport Paving Brick Company (54) The plant of the Westport Paving Brick Company is on Waterview Avenue, Westport, Baltimore City. About 40,000 paving brick and 20,000 manhole and sewer brick are produced daily. These brick are made from a mixture of ground shale and clay. The shale is obtained 274 Mineral Resources of Baltimore County from Ijamsville, Frederick County, and is ground at the Westport plant. The clay comes from the bank at the plant. The mix used is one-quarter ground shale to three-quarters clay. The clay is quarried from the hill immediately behind the plant. The opening is 400 to 500 feet long and |30 feet high, and exposes red clay above and dark-bluish clay below with white sand at the base. The blue clay is the most desirable for paving brick, though some red clay is also used. The clay and shale are fed to a dry pan and then mixed with water in a pug mill; the brick-machine die has the dimensions of the side of the brick. There are 21 drying tunnels and 23 circular, down-draught kilns. Each kiln will hold 60,000 brick, and they are fired for 8 or 9 days, with an additional length of time for cooling. Including loading, firing, cooling, and unloading one charge takes about one month. The heating of both the tunnels and kilns is controlled by recording pyrometers. The plant is equipped with both a railroad siding and a wharf. Baltimore Brick Company, Rossville Plant (55) The Rossville Plant of the Baltimore Brick Company operates a 70- acre tract of land on the south side of the Philadelphia Road 1\ miles northeast of the Golden Ring Road, Baltimore County. The material has been worked out over an area of 12 acres, with banks 20 to 30 feet high surrounding it. The upper levels of the workings show a variegated sandy clay with some sand lenses; the lower levels are of reddish clay with much iron-stone conglomerate. They probably represent the Arundel-Patapsco contact. These materials are mixed in certain pro- portions in preparing the bricks. The plant has 6 kilns and 18 drying tunnels, and produces around 75,000 bricks a day. The product is all common brick. Baltimore Brick CompaJiy, Monument Street Plant (56) The Monument Street Plant of the Baltimore Brick Company occu- pies a large tract of land in East Baltimore, bounded on the south by Maryland Geological Survey 275 Monument Street and the Philadelphia Road and on the north by the Pennsylvania Railroad. It contains about 500 acres and is surrounded on all sides by urban development. The present workings lie west of Loneys Land, and are in variegated Arundel clay. The clay is dug by steam shovel in banks about 30 feet high, loaded on cars, and hauled to the plant. No sand lenses of any size occur, though there is some iron-stone conglomerate which is hand-cobbed at the bank. The plant operates 8 up-draught kilns of the normal type, and pro- duces both common and face brick. The output is from 2 to 6 million bricks a month. The bricks burn a bright red. The location of this plant in the midst of industrial development pre- vents any further expansion, though it is estimated to have material for 30-years production. Burns and Russell Company, Back River (57) In the spring of 1929 the Burns and Russell Company opened a pit and built a plant for brick just north of the North Point Road on Back River, at Rosebank Lane. The opening was into the flat land along the river and is now 100 feet long, 30 feet wide, and 20 feet deep at the north end. It is in uniform, compact, drab-colored clay, which contains con- siderably less iron than the other banks being worked around Balti- more. There are four up-draughts kilns and the plant has a capacity of 100,000 bricks a day — largely common brick, with a little face brick. The bricks are brighter in color and require a slightly higher firing tem- perature than most of the other plants near Baltimore. About 80 men are employed. Champion Brick Company, Rosedale (58) The Champion Brick Company controls a tract of about 90 acres lying on the southeast side of the Philadelphia Road at Rosedale, Balti- more County. The entrance is about 500 yards southwest of Hamilton Avenue. The material worked is a buff to gray-blue clay — very com- pact and uniform; probably the Arundel formation. Considerable reserve exists, and the surrounding region is not highly developed as 276 Mineral Resources of Baltimore County yet. The plant consists of 6 up-draught kilns, with 15 drying tunnels. Two hundred and seventy-five cars are operated (600 bricks a car), and the plant produces 75,000 bricks a day. Only common brick is produced. Recently the company has received an order for 26 million bricks from the Western Electric Company. New Jersey United Clay Mining Corporation, Poplar {59) This opening for clay is on the Baltimore and Ohio Railroad 200 yards southwest of the Middle River Road. The pit was opened in August, 1925, by the New Jersey United Clay Mining Corporation, and the greater part of the clay is shipped to the Trenton, N. J. and East Liverpool, Ohio, potteries. Some is shipped to the Locke Insulator Company in Baltimore. The workings expose the following section: 5 ft sand, iron-stone, red clay — (overburden). 5 " sandy clay. This is the Arundel formation. The pit is 250 feet long (North and South), 100 feet wide, and 25 feet deep. The material is handled by a gasoline derrick, loaded on trucks and taken to a Crosby shredder, and then placed on the cars. About 150 carloads, at 50 tons a car, are produced in a year. Feldspar is a mineral compound composed essentially of silica, alumina, and one or more of the bases-potash, soda, or lime. As a constituent of the crystalline rocks it is the most abundant mineral in the earth's crust. Because of its intimate association with other min- erals it is only in certain geological bodies that its commercial exploita- tion is possible. These bodies are known as pegmatites, or popularly, "giant granites," and it is in them, along with quartz and more or less mica, that feldspar occurs in workable quantities. The pegmatites 10 English "ball clay" (dark). Feldspar Maryland Geological Survey 277 occur as lens-shaped dikes intrusive into other rocks and are believed to represent the residual liquids from which the other larger bodies of molten rock solidified. In the Baltimore area the pegmatites and their contained feldspar are confined to the hard, crystalline rocks which outcrop to the north and west of the city. They are most abundant in the areas of schist and gneiss which occur between the large masses of granite and gabbro. Two kinds of feldspar are produced commercially — the potash-rich variety known as microcline, and the soda-rich variety known as al- bite. In Baltimore County the great bulk of the feldspar is the potash type, though it generally carries an appreciable percentage of soda. This type of spar is commonly pink in color. The use of feldspar is largely in the ceramic industries. With clay and quartz as the other ingredients, feldspar is used in the manufacture of white pottery ware, both in the body and glaze of the product. It is also used in vitrified sanitary ware, and in the manufacture of glass and enameled wares. There are also a variety of other uses among which may be mentioned: scouring soaps, poultry grit, opalescent glass, roofing and stucco grit. Among potential uses of feldspar are the extraction of potash and alumina, and its use as a constituent of cement. For a few years Maryland ranked third among the feldspar producers of the United States (1916-1917) though in 1926 it had faUen to eighth place, notwithstanding an increase in production of 50 per cent for the country as a whole during that period. Some of this production came from Baltimore County, but at the present no deposits are being worked in this area. The output during the last few years has been: — FELDSPAR PRODUCTION FOR BALTIMORE COUNTY 1928 None 1927 None 1926 None 1925 None 1924 $679 1923 625 1922 None 1921 2,729 1920 4i f 425 1919 14,206 278 Mineral Resources of Baltimore County Former workings for feldspar are grouped into two districts in Balti- more County: the area bordering the Patapsco River from Woodstock to Ellicott City, and a smaller district north of the Gunpowder River from Loch Raven to beyond Glenarm (see plates III and IV, vol XII, Maryland Geological Survey, 1928). The numerous small pits found scattered throughout these areas attest to the sporadic nature of the industry and to the small size of most of the deposits. The manner of working is simple, though many factors enter into what determines the optimum conditions for devel- opment. Probably the three most important factors are: (1) a deposit of sufficient size to warrant continuous exploitation, (2) at least one- half of the rock moved to be of marketable spar free from excessive deleterious minerals, and (3) proximity to a shipping point. By far the greater number of pits in Baltimore County were worked for only a short time, chiefly by local farmers. A few, however, were larger operations. The series of openings one-half mile south of Hollo. field station on the Patapsco River must have seen considerable activ- ity, though they have not been worked for some time. Singewald reports:9 "These deposits were last actively worked by E. E. Fagan about 19 years ago. The Product Sales Company again took out a carload in the winter of 1917. The two larger openings at this locality have the dimensions 100 feet long by 30 feet wide by 20 feet deep and ' 60 feet long by 30 feet wide by 20 feet deep." Much of the feldspar and quartz are segregated into masses distinct from one another, which facilitated the operation. An unusual amount of white mica occurs with the quartz. The feldspar is the common pink potash variety. Another series of rather large openings was worked by the Guilford and Waltersville Granite Company just east of the Old Granite Rail- road near the Patapsco River. They have been idle for about 12 years. The largest of these openings is 200 feet long (northeast) 40 feet wide and 30 feet deep. Singewald says:10 "The quarry was opened in 1906 • Singewald, J. T., Jr. "The Feldspar Industry in Maryland," Md. Geological Survey, vol. XII, 1928, p. 112. 10 Op. cit., p. 115. Maryland Geological Survey 279 and for several years was an active producer, ten men being employed and air drills used. The rock was loaded by means of a chute directly into the railroad cars from the quarry." Parallel to the larger opening are two others, farther toward the river to the southeast. A large operation which employed 25 men in 1917 was that of the Feeney and Atherton Feldspar Company, occurring on the hill running south of the Baltimore and Ohio Railroad tunnel one mile west of Al- berton. The daily output of 30 tons was hauled to the railroad siding three-eighths of a mile away. There is a large opening on the Gilmor farm one-quarter of a mile southwest of Summerfield Station on the Maryland and Pennsylvania Railroad. The dike contains potash feldspar but is rather too fine- grained and has too much mica to produce a high grade of pottery spar. There is a railroad siding. Should there be an increase in the demand for any of the products mentioned above the Baltimore County deposits of feldspar could supply a large demand. If processes for obtaining the potash or alumina from feldspar should be perfected those deposits would have considerable value. As the conditions are at present no known body contains a sufficient amount of high-grade pottery spar to warrant development though it would seem possible that some of the deposits might be worked if the waste material were marketed as second-grade feldspar, and poultry, stucco, and roofing grit. If, as has been contemplated, a high-grade cement, which would com- mand a higher price than the present product, were to be made from ground limestone and feldspar, the deposits northeast of Loch Raven could be utilized. Here the pegmatites containing the feldspar occur in dolomitic limestone and in many of the existing quarries both types of material are adjacent to one another. The value of such an operation would be further enhanced if potash could be extracted from the dust of the feldspar grinding. One mill for grinding feldspar and allied products operates in Balti- more City, the Product Sales Company, situated at Claremont on the Baltimore and Ohio Railroad. Both Virginia and Maryland feldspars 280 Mineral Resources of Baltimore County are being ground at present. The mill has a capacity of 65 tons a day. It is driven entirely by electricity. The apparatus for grinding feld- spar consists of 2 jaw crushers, a Hardinge mill, 2 Schmidt continuous- feed and discharge finishing mills, and an air separator which takes the grindings under 200 mesh. For further details concerning the feldspar industry, and for a com- plete description of the openings in Baltimore County see J. T. Singe- wald, Jr., "The Feldspar Industry in Maryland." Maryland Geological Survey, vol. XII, 1928, p. 93. Quartz (Flint) Quartz is one of the commonest minerals in nature and occurs under a wide range of geologic conditions. The quartz with which this section deals occurs as lens-shaped veins and dikes intercalated in the crystal- line rocks of the eastern Piedmont Province, in much the same manner as the pegmatites. In fact, the quartz veins and pegmatites are proba- bly genetically related to one another and in some cases are gradational. The trade name for this quartz is flint, though from a mineralogic stand- point the latter is a crypto-crystalline form of silica of entirely different appearance and geologic occurrence. Quartz is silicon dioxide; it is harder than steel or glass and has a hackly fracture which causes it to break into sharp-edged fragments. As it occurs in dikes and veins it is a massive, crystalline material of vitreous luster. The occurrence of vein quartz in Baltimore County is in an area roughly coincident with that of the feldspar deposits, though that of the quartz is somewhat more extended. This is in a belt about 15 miles wide running northeast and southwest across southern Baltimore County, including the northern part of Baltimore City. The quartz deposits are most abundant in the gneisses and schists of the area and rarely exceed 30 or 40 feet in width and a few hundred feet in length. The most important occurrences are in southwestern Balti- more County, in an area bounded on the west by the Patapsco River, on the east by Reisterstown Road, and extending from Ellicott City north to about Reisterstown. There has been no production outside of this area. Maryland Geological Survey 281 Quartz is principally used in the manufacture of pottery, as an abra- sive, and as a filler. It is also used in the packing of acid towers, in metallurgical work as an alloy, in the making of fused glassware for laboratory utensils, for roofing, stucco, and minor quantities for poultry grit . Only the purest grades can be employed for pottery as small quan- tities of iron will discolor the ware on burning. Its use in the manufac- ture of wood filler and for paints, and as an abrasive in sand belts, sand- paper, sand blasts, scouring soaps, etc., does not demand quite so pure a product. For a number of years Maryland was the most important flint-pro- ducing state. The production, however, is subject to great variation, and, whereas there were 5 active flint-grinding mills in the State 10 years ago, today there is only one. Also, the activity within the State is sub- ject to great variation. Thus in 1923 Maryland produced flint aggre- gating $42,125, nearly all of which came from Baltimore County, while in 1926 Maryland produced §47,507, very little of which came from Baltimore County. This fluctuation is due to the small scale of the workings, and also to the fortunes of the local mills which afford the only market to the quarrymen. The spasmodic production in Baltimore County may be directly traced to the history of the two mills now operating in the region. The mill of the Product Sales Company at Claremont, Baltimore City, formerly ground a small amount of quartz along with feldspar, and used the same apparatus. This practice has now been largely discontinued. The mill of the Maryland Quartz Company at Glen Morris has been running intermittently for a long time. In 1910 it was entirely rebuilt, and in 1926 the mill was acquired from the Pitcher estate by M. M. Goodman of Baltimore. Since the latter date it has seen continuous activity. A few operators have for a time shipped their flint out of the State, but the great majority of them have worked the deposits only when a nearby mill was in operation. At the present time all of the quartz quarried in Baltimore County is sent to the mill at Glen Morris, and most of the operators are within 10 miles of the mill. An opening is usually worked for only a short time, 282 Mineral Resources of Baltimore County for when it becomes necessary to move much waste rock, or the workings reach any depth, a new body is found. Much of the quartz brought to the mill is from loose, residual boulders found scattered over the fields. The more continuous producers have been operations from veins or dikes in situ. Many of the operators are farmers who quarry a few loads of quartz during slack seasons in the farm work. At the present time there are three rather continuous producers, these are : the Baer quarry, worked by Walter O'Dell, 2 miles northeast of Marriottsville ; the L. L Green quarry near Oakland; and the William Yox quarry at Berryman Lane and Deer Park Road. These quarries are all worked by simple methods and the quartz is hauled by truck to the mill at Glen Morris. The producers receive S4.00 a long ton for the best grade of flint at the mill. The mill at Glen Morris is well-equipped and efficiently operated. It is described as follows by Singewald:11 "The rock is fed by hand to a jaw crusher and elevated to a bin from which it is fed automatically to a set of rolls. At this point three coarse sizes, 2|-2 inches, 2-1 inch and l-§ inch, for use in filters may be screened out. The under ^-inch size or the entire roll product is reelevated to a screen with 3/16-inch circ- ular holes. The oversize passes through a second set of rolls and 3/16-inch screen, the oversize of which goes to a third set of rolls. The undersize of the two screens and of the third rolls passes through three screens, the first of which has 3 sections and the next two 2 sections, the oversizes of which make 7 finished products of the following sizes respec- tively: over 3/16-inch, 3/16-1/8-inch, 8-10 mesh, 10-12 mesh, 12-16 mesh, 16-20 mesh, 20-2-4 mesh. These sizes are used for filters and pottery. The 20-24-mesh size is also used in lithographing. The undersize of these screens, the under 24-mesh, goes to a bolting machine that makes 9 oversizes of the following screens: 30-mesh, 34-mesh, 40-mesh, 54-mesh, and 72-mesh grit gauze screens, and No. 9, No. 10, No. 11, and No. 17 bolting silk; and a tenth product which is the under- 11 Singewald, J. T., Jr., "The Quartz (Flint) Industry in Maryland," Maryland Geological Survey, vol. XII, 1928, p. 156. Marylaxd Geological Survey 283 size of the last bolting cloth. These products are used in lithographing, as abrasives, and for polishing. A fourth set of rolls is used to regrind sizes that are produced in excess of the demand. All of the apparatus is connected with air suction and the elevators and chutes tightly boxed so as to reduce the dust to a minimum. The power for the plant is steam." The mill of the Product Sales Company atClaremont, Baltimore City, is described in detail under the discussion of feldspar. The future of the flint industry in Baltimore County is a matter of considerable speculation. The quantities of flint which exist are very large, but at the present prices, and under the existing conditions of development no very great expansion can be expected. Also, many of the products listed above as produced from the vein quartz of Baltimore County are in competition with the more easily worked deposits of sandstone, and no expansion may be expected at the present in that direction. These sandstone deposits, of which the workings in the Oriskany formation of West Virginia and the St. Peters sandstone of Illinois are examples, are quarried on a huge scale, with power shovels in open cuts and the attendant grinding and crushing is much less than in the massive vein deposits. However, there are apparently certain differences in the grade of products produced to permit of competition; thus it is claimed that for certain sizes the abrasives made from vein quartz are superior to those from sandstone. Also, due to the increase in the price of metal products and other structural materials the glass industry is experiencing a considerable expansion, and it may be quite possible that new uses will be found for ground flint products made from vein quartz. WORKINGS FOR QUARTZ Yox Quarry, Soldier's Delight (60) William Yox is operating a quarry for flint about one-half mile east of the junction of Deer Park Road and Berryman Lane. The deposit is vein quartz which forms a body 20 feet wide and extends in a direction N. 65 °E. It is vertical and has been followed for about 180 feet. The wall- 284 Mineral Resources of Baltimore County rock is mica schist which is sharply cut by the vein. The quartz is white and glassy, and the texture varies from massive to coarse-granular. There is a little accessory black tourmaline. The material is shipped by truck 5 miles to the mill at Glen Morris. Baer Quarry (61 ) Flint is being worked on the form of Gottlieb Baer west of Ward's Chapel Road at a point 1\ miles south of North Branch. The deposit is a large mass of quartz intercalated in a wall-rock of schist. There are two openings: one 100 feet long, 40 feet wide and 30 feet deep which is worked out; and another adjacent to it which is now being operated. This locality has been worked spasmodically for a long time and much of it was formerly shipped to sandpaper manufacturers. It is now being sent to the Maryland Quartz Company's mill at Glen Morris. Chrome The commercial source of the element chromium is exclusively in the mineral chromite, which when pure, is an iron chromate of the formula FeO.Cr203. It is a heavy, opaque, iron- to brown-black mineral, with a pitchy luster, uneven fracture and hardness nearly that of steel. Geologically it is almost entirely restricted in occurrence to the dark ultrabasic rocks and their serpentinous derivatives. In Maryland chromite is found only in serpentine — a rock which is readily recognized by the barren country it produces. These "barrens," as they are locally called, are stretches of uncultivated country which support only a sparse growth of grass, scrub oak, and pine. It is believed that this condition is due to the chemical composition of serpentine (a hydrous magnesium silicate), which prevents a vigorous growth of vegetation, thus allowing the soil to be rapidly eroded, leaving the dull, fractured, greenish-yellow serpentine rock exposed at the surface. The principal use of chromium is in the manufacture of ferrochrome, which, in turn, is used in making high-grade steel. The second most important use is as a refractory substance — chiefly as a lining in the basic open-hearth steel process, which produces three-quarters of the Maryland Geological Survey 285 steel of the United States. Considerable amounts are used in the chemical industries — in tanning, dyeing cloth, and for pigments. The history of chrome mining in Baltimore County is of particular interest, in that it was due to the activities of Isaac Tyson, Jr., of Balti- more, that Maryland came to be the chrome producing center of the world for a considerable time.12 It was on Tyson's farm at Bare Hills, just north of Baltimore, that chromite was first discovered and mined. This date is variously placed between 1808 and 1827, but from the fact that most of the workings at Bare Hills had been abandoned some time previous to 1833 a time nearer to 1808 is probably correct. The occur- rences at Soldiers Delight, the barren stretch of country 12 miles north- west of Baltimore, were discovered in 1827, and the discovery of other regions in Maryland followed soon after. These were all the result of the superior acumen of Tyson, who recognized that the chromite always occurs in the serpentine and was able to follow this rock by the barren areas to which it gives rise. All the ore mined in Maryland and the adjacent region in southeast- ern Pennsylvania was shipped to Baltimore, and nearly all of the chrome produced in the world between 1828 and 1850 came here. Isaac Tyson, Jr., established a chrome plant in Baltimore in 1845, and thereby gained a monopoly in the chemical use of chrome as well as in its mining. Mary- land continued to be the principle producer of chrome until the middle of the last century, when the deposits in Asia Minor assumed importance, and the exports from Baltimore ceased in 1860. The Baltimore Chrome Works maintained its monopoly until 1885, and continued to do a thriving business until 1908, when the Tyson family sold out to the Mutual Chemical Company of America. The mining of chromite again became active in Maryland during the seventies of the last century, but since 1880 there has been but a small and irregular production of sand chrome, and, except a small amount between 1917 and 1925, none of rock chrome. 12 For fuller accounts see Glenn, Wm., Trans. Amer. Inst. Min. Engineers, vol. XXII, 1895, pp. 487-492; and Singewald, J. T., Jr., Maryland Geological Survey vol. XII, 1928, pp. 158-160. 286 Mineral Resources of Baltimore County The mineral chromite is widely disseminated in small quantities in the serpentine of Bare Hills and Soldiers Delight, but is is only at a few places that it occurred in payable quantities. These bodies of richer material are very irregular in size and shape, and it is very difficult to determine their value or extent. At several places at Bare Hills adits run into the hill below the outcrops above failed to find ore at the lower levels. The dimensions of the ore bodies vary from a few inches to several hundred feet in extent. Since serpentine weathers more readily than chromite the disintegration of the rock leaves the chromite intact, and surfaces waters collect it at favorable localities. This "sand chrome," as it is called, is recovered by washing, and has been the main source of the more recent workings at Soldiers Delight. Because of the comparative small size of the Maryland chromite deposits, the mining and milling of the ore has been on a small scale and by simple methods. Many of the workings at Bare Hills and Soldiers Delight were in small open pits, and these may still be seen from the roads which traverse the areas. At both localities, however, shafts with drifts were dug and at some places large volumes of rock removed. The Weir mine, Soldiers Delight, on the Ward's Chapel Road, 1§ mi. N. of Holbrook, was the largest in the county, and the workings, which con- sist of two vertical shafts 60 feet apart, are said to have reached a depth of 200 feet. The Choate mine, on Deer Park Road, Soldiers Delight, was another large operation, and considerable work was done during 1917 and 191S in clearing debris about the mine, but no ore was produced at that time. The economic outlook for the future mining of rock-chrome in Balti- more County is not very good. At best the deposits at Soldiers Delight are very small compared to those now worked in Rhodesia, New Cale- donia, and Asia Minor, and it was only under the forced stimulus of the World War that they assumed any interest at all. Though it is probable that other deposits similar to those already found exist, their discovery is purely fortuitous and uncertain. It is only through the methods of geophysical prospecting that any assurance could be had. The produc- tion of sand chrome seems more feasible, in that until recently there Maryland Geological Survey 287 has been a demand for a small amount of this ore for shipment to Europe, where it is used in the setting of colors on fine procelain ware. It is claimed that the Maryland ore is particularly adapted to this purpose. The amount of sand chrome which exists would be sufficient and rich enough for this purpose. For a fuller discussion of the "Chrome Industry in Maryland" see J. T. Singe wald, Jr., Maryland Geological Survey, vol. XII, pp. 158-191. Copper Though copper mining in Baltimore County will probably never attain to economic importance again, it has considerable interest historically, and, with the deposits elsewhere in Maryland, was largely responsible for the establishing of the copper refining industry in Baltimore City. Copper was mined in Maryland before the Revolution, and the Liberty mine, Dolly Hyde mine, and New London Mine, all in Frederick County, were worked until as late as 1914. Most of these operations were short- lived, and many of the larger mines have been worked by several com- panies at different times. At present there is no activity, and the large deposits being worked elsewhere in the world give little prospect that any of the Maryland occurrences will again be of value. One of the largest mines in the State was the Bare Hills copper mine. This is not directly within the serpentine of Bare Hills but occurs one- half mile to the south along Smith Avenue, and about a mile northwest of Mount Washington station on the Pennsylvania Railroad. At the present time only the mine dumps and the foundations of one or two outbuildings are visible. The deposit was opened in 1845, but little work was done until 1860, and in 1864 the Bare Hills Mining Company was formed. At this latter date the workings consisted of a 600-foot shaft, with levels "at various points." It was claimed the material occurred in a vein 5 feet thick, with a content of 11 \ per cent of copper. Work was continued intermittently between 1864 and 1880 when the mine finally closed. During this time it is reported that 32,500 tons of 18 per cent copper were produced at a value of SI, 755,000. In 1900 a stock company was formed and plans made for reworking the mine but 288 Mineral Resources of Baltimore County nothing came of the project. This occurred again in 1905, and the mine was unwatered, but little ore was actually mined. The ore at this locality occurs in hornblende gneiss, which has been extensively injected by pegmatite and epidote. The ore minerals are chalcopyrite, bornite, and magnetite. A large suite of other minerals occur as a gangue to the ore, and the locality has been a mecca to stu- dents and mineral-collectors for a long time; so much so, in fact, that little material of interest remains on the dump. As early as 1815 a copper rolling mill, the direct ancestor of the present Baltimore Copper Smelting and Rolling Company, was started by Levi Hollingsworth on the Gunpowder River, to work the output of the Mary- land mines. In 1845 a copper smelting works was started at Canton, and a little later another at Locust Point. In 1886 the present Balti- more Copper Smelting and Rolling Company was founded under an amended charter of the old Gunpowder Copper Company. Many prominent citizens of Baltimore have been interested in these works, among them the Browns, McKims, Garret ts, Keysers, and Johns Hopkins. The interests of these people were not confined to the local industry, but extensive holdings were obtained in the copper deposits of Arizona and Montana, and it is because of this expansion that Baltimore today has the largest refineries in the country. The Water Resources The water resources comprise springs, streams, dug wells and artesian wells. Since the County is the most populous county in the State springs and dug wells have gradually gone out of use because of their liability to contamination and none are now permitted in the City. SURFACE WATERS The region is well supplied with streams. Those of the Coastal Plain portion, as previously mentioned, are tidal estuaries, with brackish water and with much mineral and vegetable matter in suspension, and are entirely unsuitable for domestic or municipal use. The streams of the Piedmont Plateau portion of the county are rapidly flowing, fluctuating Maryland Geological Survey 289 streams which when not contaminated by man are available as sources of municipal water supply. All are a part of the Chesapeake Bay drainage system and reach the Bay through the broad estuaries of the Gun- powder, Middle, Back, and Patapsco rivers. The principal Piedmont streams which are rapid and more fluctuating are the Gunpowder and its branches, Stemmers Run, Herring Run, Jones Falls, Gwynns Falls, and Patapsco River. The upper courses of these streams are variously utilized, but the lower courses are all rather thickly settled and unsani- tary. Baltimore City obtains its supply from the Gunpowder at Loch Raven, where an impounding reservoir with a capacity of 23 billion gallons has recently been completed. The water is treated chemically and filtered and its use has resulted in the elimination of typhoid and similar diseases. The Piedmont streams develop considerable water power which is utilized locally for small milling and manufacturing purposes. SPRINGS There are numerous springs in Baltimore and vicinity, the majority of which are located near the "fall line" in the Coastal Plain section and throughout the deeply dissected Piedmont section. Many of these within the city limits were formerly used, but all have now been aban- doned on account of the danger of contamination. In the Piedmont area around Baltimore there are many springs, both large and small, some of which, like the Chattolanee Spring in the Green Spring Valley, have long been celebrated. These spring waters are utilized in the manufacture of soft drinks and in supplying table water. More than a million gallons of table water are sold annually in Baltimore and vicinity. The principal con- cerns engaged in this business are the Chattolanee Spring Water Com- pany, Powhatan Spring Water Company, Rognel Heights Water Com- pany, Royal Spring Water Company, Caton Spring Water Company, and Brooklandwood Farms and Spring Company. The Chattolanee and Brooklandwood springs are situated in the Green Spring Valley north of the city. The Royal Springs are at Rux- 290 Mineral Resources of Baltimore County ton Heights. Caton, Powhatan and Rock Crystal springs are west of the city at Catonsville, Woodlawn, and Rognel Heights respectively. Good springs are numerous at Bengies, Chase, and Westport, and throughout the central and northern parts of the county and are much utilized locally. In some localities springs are scarce, for example, in the region of Middle River there are only a few, and at Walters only one was noticed. These springs occur at the base of the hills or in small depressions in the surface of the terraces. Most of them have a good yield of clear, cold water, but the supplies are little used except in places where the springs are near dwellings. The amount of inorganic matter carried in solution is seldom large, though at Chase there is a noticeable quantity of iron, and there is also some sulphur. DUG WELLS Although no longer used in the City shallow dug wells are still largeh- utilized throughout the rural parts of the County. Their depths and the amount of water which they yield are variable. They generally reach the water table in loose materials overlying the crystalline rocks. The depth of these wells varies considerably, the shallowest being only 14 or 15 feet and the deepest about 80 feet. The source of the water is usually a white sand or gravel, but locally, as at Chase, the water bed is reported to be a red, clayey sand. There are clay beds above the water horizons at Westport, Walters, and Bengies. These clay beds are important because they exclude impure surface waters, but locally their value is impaired by their lack of continuity. The amount of water in the dug wells differs from place to place and in some localities it varies with the rainfall. The following list gives a good idea of the variation in depth. Feet Westport 30-40 Walters 25-50 Middle River 14-30 Bengies 15-40 Chase 12-80 The quantity of water could not be determined at all these places. At Westport the wells contain 8 to 10 feet of water, at Middle River 3 to 6 Maryland Geological Survey 291 feet, and at Bengies and Chase 3 to 4 feet. The quantity of water at most of these localities is not greatly affected by normal droughts, but during continued dry weather some of the wells may become dry. The quality of water obtained from the dug wells is variable though in most places it is hard. Soft water is reported from some wells at Walters, and others near the Chesapeake and its estuaries yield brackish water. In general, the amount of mineral matter in solution is not great enough to be objectionable. At Bengies and Chase some wells supply water containing large quantities of iron, and at the latter place a few of them yield sulphur water. In general it may be said that the use of shallow wells becomes more dangerous each year as the country becomes more thickly settled. Unless the wells are situated so that they cannot be contaminated by surface drainage and the seepage of sewage their use should be discontinued. artesian wells The artesian waters of the Baltimore district are considered under two heads, one treating of the artesian waters of the Coastal Plain area and the other the deep-well waters of the Piedmont area. The former is the more important of the two, since it so intimately connected with the great industrial development in the Coastal Plain area south and south- east of the city. The Coastal Plain Area This region includes the southern and eastern parts of Baltimore City and the country bordering Patapsco River to Bay Shore and Bodkin Point. A large number of successful wells have been drilled though but few of them flow. The flowing wells have only been obtained on low ground, but the principles governing the occurrence of the water are the same for both the flowing and the non-flowing wells, and hence they are all classed as artesian. From the present industrial development in this section there is reason to believe that a large number of new wells will be drilled in the future. The most important water horizons occur in the Patuxent formation, which consists of beds of sand, gravel, and clay resting on the sloping 292 Mineral Resources of Baltimore County surface of the crystalline rocks of the Piedmont region which extends beneath the Coastal Plain. In Canton and vicinity the wells show the presence of at least three, and possibly four, water-bearing horizons. The lower of these horizons is a bed of gravel lying on the floor of the crystalline rocks. This bed, which will be indicated as Patuxent horizon No. 1, furnishes a very large amount of water and supplies a large number of wells in South Baltimore, Canton, Highlandtown, and the region to the southeast. Patuxent horixon No. 2 lies about 35 or 40 feet above No. 1 and is also a very large producer of good water in num- erous wells in this district. Another horizon, No. 3, lying about 30 feet above No. 2, yields a little water, but its maximum capacity is not known because it has not been extensively exploited. There appears to be a still higher horizon, No. 4, but it only shows in a few places. These horizons were recognized and discussed by Darton13 in an earlier report on this region, but since Darton's bulletin was published the lower or No. 1 horizon has been more extensively developed in the vicinity of Canton and Highlandtown, and is now regarded as of equal importance to the No. 2 horizon. The wells in the Canton and Highlandtown districts are situated mostly along Clinton Street on the water front and along the line of the Philadelphia, Baltimore & Washington Railroad from the grain elevators north to Fayette Street. The No. 2 horizon, like the No. 1 horizon, supplies a large number of wells, including those at the Lazaretto lighthouse; several wells at the No. 1 elevator, Northern Central Rail- road; most of the wells at the Standard Oil Company's Refinery on Toome Street; etc. The No. 3 horizon lying approximately 100 feet above the crystalline rocks supplies several wells. The wells between Canton and the basin are mostly situated along the river front on Boston Street. While most of them obtain water from the No. 2 horizon of the Canton and Highlandtown region, there are several that are supplied by the No. 1 horizon. At the J. S. Young Company, 2731 Boston Street, there is one well 147 feet deep yielding 60 gallons per minute. This well probably obtains its water from No. 2 horizon. At 13 Darton, N. H. U. S. Geological Survey, Bull. No. 138, pp. 142-148. Maryland Geological Survey 293 this locality a well which was drilled to a depth of 1000 feet encountered crystalline rock at about 190 feet. About 55 gallons per minute was secured in this well, and while the exact depth to the supply is not known, the driller reports traces of water at 400 feet, and a large quantity at 640 to 660 feet. According to the statement of the superintendent of the plant the water was unfit for use because it was muddy. The well was cased to the crystalline rock but was later drawn back 40 feet and thus increased the supply to about 100 gallons per minute. This well doubtless obtains water from both the No. 1 and No. 2 horizons. Another well at this locality yields 40 gallons from a depth of 96 feet; probably from the No. 3 horizon. The well at the Canton Box Com- pany, 2515 Boston Street, obtained slightly salty water at a depth of 96 to 100 feet, probably from the No. 2 horizon. This well was drilled over 20 years ago and possibly the salt water enters from the harbor through a corroded casing. The 176-foot well of H. J. McGrath, Atlantic Wharf, and the wells at the foot of Wolfe Street belonging to the American Ice Company, appear to draw from the No. 1 horizon. The Ice Company wells tap the No. 2 horizon and possible the No. 3 horizon. The No. 3 horizon supplies the 106-foot well at Louis Grebb's, 2357 Boston Street; the 98-foot well of Miller Bros. & Company, 901-913 S. Wolfe Street; the 94-foot well of the Booth Packing Company, Wolfe and Lancaster Streets; and the 90-foot well of J. Langrell, 2115 Aliceanna Street. For various reasons manj^ of the wells in this region have been abandoned. In some places the wells have become clogged, while in other places the ground is so saturated with acids that the pipes are corroded and the water contaminated. On the water front between Wolfe Street and the head of the basin there is a small number of wells and many of the older wells of this locality have been abandoned. All of those belonging to the city were closed by the Health Department, and others were abandoned on account of changes in the burned district. At the plant of Louis Eckels Ice Manufacturing Company, Gough Street near Broadway, three wells were reported as having depths of 125, 135, and 165 feet respectively. 294 Mineral Resources of Baltimore County They obtained water from a horizon which has been correlated with the No. 1 horizon of the Canton district, and the crystalline rock was en- countered at about 95 feet. The yield, in the order mentioned, 32, 20, and 45 gallons per minute. There are several wells situated on Central Avenue which probably draw from the No. 3 horizon.14 The wells at the plant of Louis Elmer & Sons, Central Avenue and Bank Street, obtain water from the same horizon at depths of 60 to 70 feet. They only yield 15 to 20 gallons each. At the Bennett Potteries there is one well 50 feet deep which furnishes a large supply of water from a horizon that has not been definitely correlated with those at Canton. At the plant of the Cooperative Ice Company, S. Frederick Street near Baltimore Street, a 125-foot well did not obtain water, though it passed through the No. 1 horizon and entered the crystalline rock at 60 feet. The Hammond Ice Company drilled about 30 wells to a depth of 100 feet at the foot of Block Street. Water was encountered in all of these wells and some of it contained sulphur. This horizon has been corre- lated with the No. 2 horizon at Canton.15 The ice factor was never completed and hence these wells were never used. Sharp & Dohme, Pratt and Howard Streets, have four wells, 77, 85, 90, and 94 feet deep, respectively. Rock is reported at 77, 85, and 88 feet. The 90-foot well has a yield of 4 gallons of water, but the depth to the water horizon is not known. The 94-foot well obtained 20 gallons of water from a bed of clean, yellow sand at a depth of 62 feet. This sand extends down to the crystalline rocks and the water is from horizon No. 1 . At the plant of the Baltimore Refrigerating & Heating Company, 426 S. Eutaw Street, 20 wells were drilled to a depth of 100 feet. Crystalline rock was encountered at 70 feet and the water occurs in a bed of gravel at 45 to 55 feet deep. The aggregate yield of the 20 wells is 60 gallons per minute and the same amount can be obtained by pumping 10 of them. Another well at this place was drilled to a depth of 304 feet. Solid rock was encountered at 70 feet and 45 gallons of water per minute " Darton, N. H. U. S. Geological Survey, Bull. No. 138, p. 144. 15 Op. cit., p. 144. Maryland Geological Survey 295 was obtained at 304 feet, but the yield subsequently diminished to 25 gallons. The cause for this reduction could not be ascertained. The Knickerbocker Ice Company, York and William Streets, reports eight wells which were originally 150 feet deep. These wells filled up to a depth of 90 feet with sand. An aggregate yield of 250 gallons per min- ute was obtained from the eight wells and all appear to be supplied by the Xo. 1 horizon. The water has a brackish taste and contains consider- able iron. The American Ice Company, Hughes and Henry Streets, have eight wells ranging in depth from 110 to 136 feet. The water occurs in the No. 2 horizon, which is here a coarse, yellow sand. The aggregate yield of the eight wells in 615 gallons per minute. Wm. Xumsen & Sons, Jackson Street and Fifth Lane, have reported one well which obtained 26 gallons per minute from a bed of sand at 100 feet. The supply is somewhat hard and contains some sulphur. A 65- foot well at this locality yields about the same amount of water as the deeper one. There are several wells located close to the water front between Fort McHenry and the intersection of Jackson Street and Fifth Lane. They range in depth from 109 to 138 feet and obtain water from the No. 1 and No. 2 horizons. The well at Piatt & Company, Clement and Boyle Streets, obtained 30 to 40 gallons per minute in a bed of white sand and gravel representing the No. 2 horizon. Torsch & Company's well, Lawrence and Clement Streets, obtained 50 gallons per minute at 138 feet in a fine gravel with a pinkish cast, which is probably the No. 1 horizon. At the Piedmont & Mt. Airy Guano Company's plant, foot of Woodall Street, there is a well 109 feet deep. Water occurs in the No. 2 horizon which, at this locality, is a bed of coarse gravel overlain by a white, sandy clay. The well had a large yield but it was abandoned be- cause the water formed a hard glass-like scale in the boilers. G. Ober & Sons Company, foot of Hull Street, near the ferry landings, has had several wells drilled. One well which was sunk in 1891 has a yield of about 20 gallons per minute from the No. 2 horizon at a depth of 90 feet. In 1897 a second well was sunk to a depth of 110 feet and gave 296 Mineral Resources of Baltimore County about 30 gallons per minute. The present well, 130 feet deep, was drilled in 1901 and has a yield of 30 gallons per minute, probably from horizon No. 1. At 125 feet a water horizon was encountered that sup- plied water having a brilliant red color. The ground at this place is thoroughly saturated with sulphuric acid which rapidly destroys the casings and renders the water unfit for use within less than six years from the time the wells are drilled. Louis Ehrman, 1032-34 Haubert Street, has a well 128 feet deep which yields about 40 or 45 gallons of water per minute. This water occurs in a fine white sand belonging to the No. 1 horizon. At the Baltimore Dry Dock Co., close to Fort McHenry, there is a well 118 feet deep which has a fair yield of soft water. Salt}- water was obtained at a depth of 190 feet near the electric plant of the Consolidated Gas & Electric Company, formerly the Maryland Telephone Company, at Gold and Winder Streets. The National Enameling & Stamping Company, Light and Wells Streets, have one well 162 feet deep, which yields 90 gallons of excellent water per minute. In the West port region the underlying crystalline rock is near the sur- face, though in the southeastern part of the district there is a thin veneer of the Patuxent formation and horizon No. 1 is present. The Maryland Glass Corporation procured a small quantity of water in crystalline rock at 238 to 267 feet, and the Western Maryland Railroad obtained a little poor water at 60 feet. The Carr-Lowry Glass Company have one well 205 feet deep. Crystalline rock was encountered at about 80 or 90 feet and the water was probably obtained from horizon No. 1. No water was found in the rock. The supply previously mentioned contained a white sediment. This company sank two or three other wells to the crystalline rock without obtaining water. They also have two or three old wells of unknown depth that have been abandoned because of the small quantity of water. In the region between Canton and Sparrows Point there are numerous successful wells, and while most of them are located at the plant of the Bethlehem Steel Company, there are several at other places. Some of Maryland Geological Survey 297 these are the well 296 feet deep at the No. 3 elevator of the Northern Central Railroad where three water-bearing beds were encountered, the first at 185 feet, the second at 220 feet, and the third at 296 feet. The horizons should probably be correlated with Nos. 1, 2, and 3 of the Can- ton district. The elevator well yields 104 gallons per minute, but it is not known whether it draws from all of the water horizons or from only the lower one. At St. Helena there is one well which yields 75 gallons per minute from a depth of 75 feet, possibly from the No. 4 horizon. At Sollers Station, near Bear Creek, two wells were drilled for the United Electric Railway's powerhouse. A section of one of these wells shows water at 19 to 21 feet, 149 to 159 feet, and 284 to 287 feet. The water encountered in this well at 19 to 21 feet is probably surface water. The other well secured 110 gallons at 200 to 226 feet. It is quite possible that these supplies come from Nos. 2, 3, and 4 horizons. The 160-foot well of the Aluminum Ore Company at Turners Station probably taps the No. 4 horizon. The two wells of the Bartlett Hay- ward Co. at Turners Station clearly show the southeastward continua- tion of the deep channel underlying the Coastal Plain and conspicuously shown by the well records in Highlandtown. These wells each yield 200 gallons of good water for steaming purposes, the water heading within 15 to 20 feet of the surface. Considerable success has been met with in the wells belonging to the Bethelehem Steel Company located at Sparrows Point. A large num- ber of wells have been drilled ranging in depth from 112§ to 611 feet. There seem to be four general horizons here similar to those in the region to the northwest. Each of these horizons furnishes good supplies, the largest yields usually coming from the deepest wells. One well 509 feet deep yields 364 gallons per minute, while another well 301 feet 7 inches deep yields 328 gallons per minute. At Fort Howard there is one well 314 feet deep which yields 110 gallons per minute, probably from the horizon just above the lower one at Sparrows Point. The 743-foot well at Bay Shore Park flows 50 gal- lons per minute at 3 feet above the ground. A section of this well does 298 Mineral Resources of Baltimore County not show any water horizons except that which occurs at 721 to 743 feet. It probably coincides with the lower horizon at Sparrows Point. The water is somewhat hard and contains some iron. The depth of the No. 1 horizon at this locality is about 150 feet lower than it should be if the slope of the underlying crystalline rocks maintained the uni- formity indicated elsewhere in the Coastal Plain. Presumably there is a valley-like depression in these rocks underneath Bay Shore extending northwest along the north shore of Patapsco Neck, as is indicated by the well records at Sparrows Point, Highlandtown and Turners Station. Approximate depths can be calculated from the contours of the map shown in Figure 90 on page 339. At Rosedale, about 1 mile east of the city limits on the Philadelphia Road, several wells have been drilled ranging in depth from 75 to 150 feet. There is a bed of red clay varying from 35 to 100 feet in thickness overlying the water-bearing sand. These wells are all close together and they have an average yield of about 10 gallons per minute each. At Rossville, about 3 miles northeast of Rosedale on the Philadelphia Road, a well was drilled 229£ feet and secured a large supply of water in rock ; the water is hard and contains iron. At Middle River, on the Philadelphia, Baltimore & Washington Rail- road, an attempt was made to obtain a flowing well. Water was found at 20, 70, and 123 feet, but it was so turbid that the well was abandoned. The well drilled on the property of George R. Willis near Bengies j'ields 40 gallons per minute from a light yellow sand with a small quantity of gravel, probably the No. 2 horizon, at a depth of 180 feet. At Prospect Park on Eastern Avenue near Back River 25 to 30 gallons per minute were secured at a depth of 136 feet, and at the disposal plant of the Baltimore City Sewerage Commission, located on Back River near Eastern Avenue, 10 to 15 gallons per minute were secured at 156 feet in a fine yellow sand. Probably the No. 3 horizon is the source of supply in both of these wells. The large number of successful wells in the vicinity of Brooklyn, Seawall, Curtis Bay, and Hawkins Point indicate a wide and general extension of the Patuxent water under the Curtis Bay-Patapsco Penin- Maryland Geological Survey 299 sula. At Brooklyn several wells have been sunk to a depth of 55 to 85 feet, dependent upon the surface elevation, which yield a fair supply of water carrying a small amount of iron. At East Brooklyn and Sea- wall several successful wells have been sunk. The wells at the plant of the Martin Wagner Company show water at the following depths: 95 to 105; 230 to 240; 310 to 375. These wells probably tap horizons Nos. 2, 3, and 4. The section of another well at this locality shows these three horizons at about the same depth. At the pumping station of the Brooklyn & Curtis Bay Light & Water Company, opposite the South Baltimore car shops, there have been a number of wells drilled to depths ranging from 109 to 575 feet. The deeper wells at this locality encounter rock at about 375 feet. Water-bearing strata occur at 70 to 90, 100 to 120, 180, 200, 215, 235, 300, 337^ feet. The Curtis Bay Chemical Company have 10 wells from 200 to 275 feet deep which average 77 gallons each, the water being eminently satisfactory for boiler use and manufacturing purposes. The Standard Guano Company have three 200-foot wells which overflow at the surface and yield about 15 gallons each. The Republic Distilling Company have 19 wells, four 100, three 125, and twelve 300 feet deep. The deeper wells apparently tap the Patuxent water bed No. 3, so conspicuous along the north shore of the Patapsco, and yield satisfactory boiler and distilling water which heads about 30 feet below the surface and each pumps about 300 gallons per minute. The 125-foot wells head within 17 feet of the surface and pump 250 gallons per minute. The 100-foot wells head about 30 feet below the surface and pump 125 gallons per minute. These evidently tap the No. 4 or a still higher Patuxent water bed. Evidently large quantities of soft water can be obtained in this district within 300 feet of the surface. At Flood's Park, Curtis Bay, a large supply of good water was obtained at about 65 feet, which is probably from the No. 4 horizon. At the TJ. S. Revenue Cutter Service Station, Arundel Cove, water was obtained at about 216 feet, probably in the No. 3 horizon. Two wells have been drilled at the Quarantine Station to depths of 136 and 150 feet respectively. The first well obtained 40 gallons per minute at about 132 feet. The water horizon in the second well is at the 300 Mineral Resources of Baltimore County bottom. This water has been condemned by the Health Department of Baltimore. The well was drilled to rock which was encountered at 420 feet, but no water was obtained below 150 feet. Horizons Nos. 1, 2, and 3 are absent here, but it is quite probable that these wells tap the No. 4 horizon. At Hawkins Point there are three wells, two located at the works of the Davison Chemical Company and the third at Fort Armistead. The wells at the chemical works are 148 and 160 feet deep, yielding 40 and 60 gallons per minute, respectively, and are from the No. 4 horizon. At the fort there is a well which is 570 feet deep and yields 50 gallons per minute. It is quite possible that this water occurs in the crystalline rock though the character of the horizon could not be ascer- tained. The Piedmont Area Since the largest percentage of the population of Baltimore County is suburban to Baltimore City and is largely served by water companies, and since in the more rural districts springs and shallow dug wells are largely utilized, the exploitation of the underground resources is less than might be expected. This has been further influenced by the uncertainty attending the drilling of wells in the crystalline rocks which underlie so much of the county, as well as the great cost of such drilling as compared with operations in the unconsolidated sediments of the Coastal Plain. In crystalline rocks the underground waters occur in joint and fault planes and minute cavities in the rocks, and since such rocks are intri- cately folded and faulted it is impossible to predict the prospects with any degree of accuracy. Occasionally a well will fail completely as for example, a 265-foot well at Gwynnbrook which was entirely dry. A number of wells have been put down at Arlington to depths of from 100 to 200 feet and all reach water under a good head and pump from 20 to 100 gallons per minute of satisfactory water rather high in iron. A 125- foot well at Lutherville pumps 70 gallons per minute of hard water which heads 15 feet below the surface and is derived from the Cockeysville Maryland Geological Survey 301 marble. Other and deeper wells at Lutherville yield much smaller quantities of water. Numerous wells have been put down in the towns suburban to Baltimore, especially around Pikesville and Reisterstown. These are for the most part between 100 and 300 feet deep and all yield small amounts of siliceous water with a fair head. Some of the deeper wells in this district, as the 500-foot well at the Suburban Club, give greater yields up to 50 gallons per minute, while other deeper wells have small yields, like the 587-foot well at the Jewish Consumptive Hospital which yields but 17 gallons per minute. The Ruxton Water Company has two wells, 152 and 178 feet deep, which together pump 60 gallons per minute. The Suburban Water Company at Arlington have seven 8-inch wells ranging in depth from 70 to 175 feet and supply a daily consumption of about 300,000 gallons. The Artesian Water Company at Howard Park have five 6-inch wells to depths of from 117 to 200 feet and supply a daily consumption of about 72,000 gallons. The former Roland Park Water Company in addition to utilizing springs had twenty-five 6-inch wells from 95 to 500 feet deep and supplied a daily consumption of about 250,000 gallons. Little can be said of the artesian prospects throughout the county, although small yields are usually obtained at moderate depths. Some of the wells which have been drilled in the Coastal Plain region into the underlying Piedmont rocks have already been mentioned. It may be said of the general artesian prospects of such wells that pre- vious experience is an unreliable indication of what may be expected. Some of these wells have furnished satisfactory amounts of water of good quality and others have not. In general, it may be said that even if they reach water the head is apt to be low. The amount of information available for wells in the crystalline rocks is not large, and the usual uncertainty regarding artesian prospects in crystalline rocks is strikingly illustrated. These rocks are intensely folded and abound in small joint and fault planes so that definite water beds are absent, the main water content circulating through these mi- nute cavities which may be at one level in one well and at a very different 302 Mineral Resources of Baltimore County level in a nearby well. The head is also liable to vary through wide limits, and for the same reasons in adjacent wells. A number of wells have been drilled in the northeastern section of Baltimore City as the 3,000 foot well at Gay and Lanvale Streets which showed small returns although a 600-foot well at this place struck a water zone at a depth of 300 feet which was reported as pumping 200 gallons per minute. Wells at Gay and Federal Streets, 315 and 400 feet deep, each yielded between 25 and 30 gallons per minute. A well on Brehms Lane east of Belair Road, was sunk to a depth of 1500 feet without encountering a satisfactory supply, although about 13 gallons per minute were struck between 700 and 800 feet. A well at Gay Street and Lafayette Avenue, 286 feet deep, furnishes 15 gallons per minute of ferruginous water. At the corner of Gay Street and North Avenue, a 300-foot well was reported as yielding 120 gallons per minute. Several wells in the vicinity of Gay Street and North Avenue yield small amounts of water, and it would appear that the chances of obtain- ing small supplies at depths around 300 feet are fairly good in this immediate vicinity. The Evergreen Lawn Improvement Association on Hamilton Avenue near Harford Road have three 6-inch wells. One 240 feet deep struck 36 gallons per minute at 80 feet and probably tapped a nearby vertical fault plane containing water. Another well was sunk to a depth of 475 feet without encountering any water, and a third 654 feet deep yielded over 100 gallons per minute. The number of wells in the northwestern section of the city is small and the prospects are simi- larly uncertain. The Roland Park Company put down a number of wells and obtained large amounts of water from depths between 148 and 227 feet. One well at Mount Washington was entirely dry and the other wells in the vicinity are all shallow and probably obtain small amounts of water from the loose materials above the crystalline rocks. The West Arling- ton Improvement Association have two 197-foot wells in which the water rises to within 30 feet of the surface and the yield is reported as large. Maryland Geological Survey 303 Successful wells have been drilled at Melvale and along Park Heights Avenue, but no definite water horizon can be predicted. The Garrett well on Charles Street near University Parkway yields 70 gallons per min- ute from a depth of 342 feet, the water heading 50 feet below the surface. A 190-foot well at Electric Park furnishes 75 gallons per minute, and two wells at Denmore Park 106 and 140 feet deep yield 50 and 20 gallons respectively. But few wells have been drilled in the western section of the city and the results are very irregular. The abbatoir well at Calverton furnishes 60 gallons per minute from an unknown depth. The American Ice Company have several wells; one at Schroeder and Baltimore Streets was sunk to a depth of 1017 feet. It furnished 20 gallons per minute. This company has two other wells at Franklin and Pulaski Streets which are 200 and 242 feet deep. At 200 feet water was struck which headed 15 feet below the surface. The yield was 40 gallons per minute from one well and 60 gallons from the other. The Baltimore Refrigerating & Heating Company at 426 S. Eutaw Street have a 304-foot well which produced 25 gallons per minute, but the water is so bad that the well is not used. There are a considerable number of wells at Claremont. All of these yield greater or less amounts of water. The water from the 48-foot well at the Claremont Abbatoir was unsanitary and is not used. An 82^-foot well at this plant yields 70 gallons per minute. The Davison Chemical Company have two wells at Claremont lOlf and 139| feet deep. They are reported as each furnishing 75 gallons per minute. The Greenwald Packing Company have two wells at Claremont each 196 feet deep. One is reported to yield 130 gallons per minute and the other 12 gallons. The Globe Brewing Company at Hanover and Conway Streets drove a 197-foot well which yields 10 gallons per minute, and the Hannis Distilling Company, Ostend and Warner Streets, an 800-foot well that yields 20 gallons per minute from a depth of 200 feet. Wells on the Frederick Road near Mount Olivet Cemetery and at Mount Winans report small yields from between 238 and 360 feet. At Levy's Hat Factory, Pratt and Lombard Streets, a 525-foot well fur- 304 Mineral Resources of Baltimore County nishes 130 gallons per minute, the water heading 37 feet below the surface. It would appear that the chances of striking water within 300 feet of the surface in the western section of the city are good, but that the amount is an entirely uncertain quantity. THE SOILS OF BALTIMORE COUNTY BY WM. T. CARTER, Jr., J. M. SNYDER and 0. C. BRUCE Introductory A considerable proportion of the population of the county is comprised in small villages or represents the suburban homes of people engaged in business in Baltimore City. This proportion has increased rapidly within the last decade. Aside from these the population is classed as rural and the principal industry is agriculture as it has always been since the county was erected in 1659. Tobacco was the principal crop for many years and large shipments were made to Europe from Elkridge and Baltimore during the Colonial period. Considerable wheat was grown as early as the latter part of the eighteenth century and ground into flour at water mills. Early in the nineteenth century corn, wheat, and hay had largely taken the place of tobacco. Beef cattle, horses, and other stock were raised in a small way at an early date. Improvement in farm lands has been most pronounced in the last 50 years. Since the Civil War more attention has been given to building up the soils and in the last 25 or 30 years most of the farms have gradu- ally increased in productiveness through careful crop rotation, the use of lime and commercial fertilizers, the keeping of more cattle and other stock, and the plowing under of organic matter. According to the census, there were 39,433 acres in corn in 1879, producing 1,204,698 bushels. There were 28,629 acres in wheat, producing 393,402 bushels. Oats occupied 16,264 acres and produced 314,060 bushels. Hay was cut from 37,772 acres and produced 41,032 tons. From 4,990 acres of rye a total of 49,821 bushels was obtained. Market-garden products were valued at 8533,197 and orchard products at S101,808. 305 306 The Soils of Baltimore County Slightly smaller acreages of corn and wheat were grown in 1889 than in 1879, but yields per acre were somewhat higher. Hay was cut from 51,126 acres, producing 68,855 tons, and 6,863 acres of rye were grown, producing 75,936 bushels. There were 3,775 acres in potatoes, with a production of 296,960 bushels. The value of market- garden products, including small fruits, sold was $232,231. The census of 1900 shows some increase in the corn acreage, this crop being grown on 38,447 acres and producing 1,530,990 bushels, while wheat was grown on 36,486 acres and produced 536,290 bushels. Rye had been reduced to 3,953 acres and oats to 5,785 acres. Clover was cut from 6,863 acres, with a production of 7,164 tons. Over 41,000 acres of tame grasses were cut for hay, producing nearly 44,000 tons. From 4,549 acres of potatoes 356,256 bushels were gathered. The vegetables reported grown in 1899 were valued at more than 8900,000. A total of 479 acres of strawberries produced over 1,000,000 quarts, and there were over 100 acres of other berries. Orchard prod- ucts were valued at 8142,838. Animals sold or slaughtered brought $311,436, dairy products over 8900,000, and poultry 8161,219. The present varied agriculture has been carried on for many years. It consists in the production of general farm crops for sale and for home use, dauy farming, market gardening, and the feeding of beef cattle, with hog raising and fruit growing as side issues. Combinations of these types of agriculture are often followed. Many farmers engaged in general farming grow some vegetables and fruit, while some market gardeners grow corn for work stock. Some farmers combine general farming and dairy farming, and the feeding of beef cattle is always carried on in combination with general farming. Hay is grown on a larger acreage than any other crop. The census of 1920 reports 49,989 acres in tame hay, producing 70,026 tons, and 246 acres of wild grasses cut. A large part of the hay is used on the farm, but some is sold in Baltimore. Corn is the second crop in acreage and importance and is grown on practically every farm. According to the census, 34,917 acres were grown in 1920, with a production of 1,955,322 bushels. A con- Maryland Geological Survey 307 siderable acreage is cut for ensilage. The greater part of the corn produced is used on the farms for feeding work stock and dairy stock and fattening steers and hogs. The remainder is sold in Baltimore. The third crop in importance is wheat. A total of 31,956 acres were devoted to wheat in 1919, producing 628,924 bushels. Much wheat is used locally, but the greater part is shipped from the county, most of it to Baltimore, from which point it is sent to other markets. Oats and rye are grown to some extent. The oat crop is rather un- certain owing to occasional dry springs or other unfavorable climatic conditions, but fair yields are often obtained. In 1919, 5,733 acres were in oats, producing 121,508 bushels. Rye was grown on 1,195 acres, producing 15,117 bushels. These crops are also valuable for spring pasturage. Dairying is a very important industry. Some farmers specialize in the production of milk, and many general farmers, especially near the railroads, produce some milk for market. The census reports over $1,450,000 worth of dairy products in 1920, including the amount used in the home. Dairy herds ordinarily range from 10 to 20 cows, but some dairies have over 100 cows. Holstein, Guernsey, and Jersey and grades of these breeds predominate. Nearly all of the milk is sold in Baltimore, but a part is taken by small local creameries for the manufacture of butter. Numerous farms are equipped with silos. Many steers are shipped into the county from Virginia and other near-by Southern States and some from as far west as Chicago. These are brought in late in the fall and sold in lots of 5 to 50 to farmers, who feed and graze them several months and ship them when fattened to Baltimore and other cities. Some farmers use ensilage as part of the ration. The steers are grazed in mild weather and heavily fed on corn, fodder, and hay during the winter, with occasionally some cottonseed products. In 1909 there were 8,854 calves and 4,336 other cattle sold or slaughtered in Baltimore County. The census reports 20,573 hogs sold or slaughtered in 1909. Prac- tically every farm has a few hogs, but on none of the farms is the number large. The value of the poultry and eggs produced is given as $919,095 308 The Soils of Baltimore County for 1920. Every farm produces some poultry and eggs, and these are sold largely in Baltimore. Near Baltimore market gardening is by far the most important branch of agriculture, and market gardening either exclusively, or in conjunction with general farming, predominates throughout a con- siderable portion of the southern half of the county. Irish potatoes are an important crop, being grown in all parts of the county in areas up to several acres in connection with either general farming or market gardening. Berries and fruits are grown in a small way on many farms. The census reports the value of vegetables produced in 1920 as S3, 156,780. Irish potatoes were grown on 5,981 acres, producing 568,273 bushels. These are mainly late potatoes of the McCormick variety. Other vegetables were grown on about 14,000 acres. Fruits and nuts produced were valued at $362,267. Strawberries were grown on 224 acres, producing 368,537 quarts, and over 50 acres of other berries were grown. Baltimore affords an excellent market for all these products. The chief canning products are tomatoes, sugar corn, peas, and beans, and the canning industry is very important in and around Baltimore. There are no large commercial orchards, but nearly every farmer and market gardener has a small orchard of apples, pears, peaches, plums, cherries, or quinces, from which fruit is sold in Baltimore. The principal varieties of apples are York Imperial, Stayman Winesap, Grimes Golden, and Ben Davis. The value of all the agricultural products of Baltimore County and City in 1919 was $12,491,337. Cereals produced were valued at $4,959,821, hay and forage at $1,556,660. The farmers of Baltimore County have learned in a fairly definite way the crop adaptations of the various soils. They realize that the heavier soils are best suited to grass and small grain, the loam types to corn and wheat, and the lighter soils to vegetables. They recog- nize that the Montalto clay loam and the Chester, Louisa, Hagerstown, and Mecklenburg loams arc good soils for corn, wheat, and grass; and that the Iredell and Conowingo silt loams are better suited to grass Maryland Geological Survey 309 and wheat or other small grains than to corn or other crops. The Manor loam, while considered best suited for potatoes, vegetables, and fruit, is also known to be a fairly good soil for corn where well fertilized, but is often too light for high yields of wheat and grass. It is well known that the Sassafras sandy loam and gravelly loam are better suited to vegetables then to other crops, and that the Sassafras loam and silt loam are well suited to vegetables and corn and fairly well suited to wheat. The Leonardtown silt loam is best suited to grass and wheat; the Leonardtown loam to grass, wheat, and corn; and the Keyport silt loam to grass and vegetables. The farmers recognize the inherent adaptation of the Congaree silt loam to corn, but they understand that under present conditions of drainage it is better suited to pasturage than to cultivated crops. In the vicinity of Baltimore City, and as far as the county lines on both sides, the soils are used to a great extent for vegetables, though better suited to other crops. The proximity of the good city market is the determining factor and the soils are fertilized and manured heavily to overcome as far as possible the deficiency in adaptation. In growing corn the land is plowed generally in the spring to a depth of 6 or 8 inches and harrowed until a good seed bed is worked up. Corn is cultivated three or four times. Wheat is drilled in on the corn land in the fall without plowing, the land being harrowed to remove the trash. Frequently wheat is grown two years in succession. In this case the stubble land is plowed as soon as possible after harvest, dragged, and then harrowed several times before seeding. Timothy is drilled in with the wheat where wheat is not to follow the next year, and the following spring clover is sowed in the wheat and grass. After the wheat is harvested the timothy and clover are cut for hay the following year and pastured to some extent. The timothy is pastured or cut for hay for another year, when the land is again plowed for corn. The usual rotation is corn one year, wheat two years, and grass two years, but this is sometimes varied in the time devoted to wheat and grass. The farm buildings are generally substantial, and the houses are often of stone. The barns are large, and usually of the "bank-barn" 310 The Soils of Baltimore County type. They have accommodations for a considerable number of stock and a large amount of hay and grain. The work stock is mainly of rather heavy draft type, and the farm machinery is adequate and of improved types. Traveling thrashing outfits serve the farmers. In 1909 nearly 80 per cent of the farmers used fertilizers, at an average expenditure of SI 15.20. Fertilizer is used principally for wheat, corn, and vegetables. As a rule that used for wheat and corn contains 8 or 10 per cent of phosphoric acid and sometimes a very low amount of nitrogen, usually not over 2 per cent. Until the last year or two many of the fertilizers contained a small amount of potash. Recently con- siderable ground phosphate rock containing 14 or 16 per cent of phos- phoric acid has been used. Ordinarily 300 to 500 pounds per acre is used for wheat and somewhat less for corn. Many farmers do not fertilize the land for corn. Large amounts of high-grade mixtures are used by market gardeners. Most of the farmers lime their land and the practice is considered beneficial. Lime is frequently applied to land to be used for wheat and sometimes to corn land. The general impression prevails that quicklime is the best form of lime to buy. The applications range from 20 to 35 bushels per acre every 5 or 6 years. Hydrated lime is more conveniently applied. Used in this form from 600 to 1,000 pounds per acre is applied. Barnyard manure is considered very valuable and is used by all farmers, though often not enough is available except on dairy farms. Manure is applied to grass land and corn land. All the manure in Baltimore is bought and used by market gardeners, and garbage from that city is also used in large quantities. Owing to the demands of the numerous commercial industries farm labor is very scarce in Baltimore County. Much of the farm labor is colored. Wages vary greatly according to the season and the necessity for harvesting. Market gardeners employ considerable labor and have to pay high wages. The farms range from a few acres to 200 or 300 acres. Most of them contain from 80 to 150 acres. Market-garden farms range ordinarily from 10 to 50 acres. The census for 1910 gives the average size of farms as 78.1 acres, only about 10 acres less than in 1880. Maryland Geological Survey 311 About 75 per cent of the farms are operated by owners, 20.6 per cent by tenants, and 4.5 per cent by managers. Tenants usually remain on the same farm for a number of years. A share of the crops, approxi- mately one-half, is usually paid as rental, the land-owner furnishing part of the seed and fertilizer. The census of 1910 reports 4,178 farms in the county. The improved land averages 55.2 acres per farm. In 1910 the value of all property per farm was 89,883, of which the land represented 57.9 per cent, buildings 30.6 per cent, implements 4.1 per cent, and domestic animals 7.5 per cent. The price of land in Baltimore County varies widely. Within a zone of 8 or 10 miles from Baltimore City it varies according to the distance from that city. In the rest of the county the price depends largely on location with respect to railroads and State highways. Soil Types Baltimore County lies principally within the eastern division of the Piedmont Plateau, the physiographic province just east of the Blue Ridge. The southeastern one-fifth, approximately, lies within the Coastal Plain. The boundary between these provinces is fairly well marked, though small isolated areas of each province are included in the other. Thus, near the general boundary some high areas of Pied- mont material are capped by small bodies of Coastal Plain material, while low slopes of Piedmont material have been exposed by erosion within the Coastal Plain section. The general boundary reaches in a general southwesterly direction from the Harford County line near Frankhnville, passing just south of Towson and through the northwest corner of Baltimore City and leaving the county near Relay. A con- siderable body of isolated Coastal Plain material lies around Catonsville. In places the Coastal Plain deposits extend 10 or 12 miles from the coast. There are three general groups of soils: Residual soils, formed in place through the disintegration and weathering of the underlying rocks; soils of the Coastal Plain, formed by the weathering of unconsolidated sedimentary deposits which were laid down on the floor of x former ocean; and alluvial soils, which represent recent water-deposited sedi- ments along streams. 312 The Soils of Baltimore County The Piedmont Plateau in Baltimore County is made up principally of igneous and metamorphic rocks, but small areas are composed of consolidated sedimentary deposits. The igneous and metamorphic rocks are mainly granite, gneiss, schist, gabbro, serpentine, and diabase. They have weathered into a relatively deep accumulation of soil. The consolidated and sedimentary rocks consist of limestone (Cockeysville marble) and quartzite (Setters quartzite). The limestone has weathered deeply in places. It underlies the soils in a number of small valleys in the central part of the county. These valleys are usually more than 100 feet below the tops of the steep Piedmont slopes adjoining. The quart- zite occurs on narrow ridges, frequently as high as those of the igneous and metamorphic rocks and often bordering the limestone valleys. The Coastal Plain material in the southern and southeastern parts of the county consists of interbedded unconsolidated sand, gravel, and clay. This material has been brought down in former ages from the Appalachian, Piedmont, and limestone-valley regions through the agency of rivers. It has been washed and reworked by the sea and deposited over the crystalline rocks. The alluvial soils consist of silt, and sand, and clay washed from the uplands and deposited in narrow strips along streams, forming bottom lands through all parts of the county. The alluvial soils are not extensive. The upland soils represent the long-continued weathering of the bedrock formations and old sedimentary deposits. They show some relationship to the parent materials, and differ according to original differences in the lithologic and chemical character of the rocks. The soils are grouped into series on the basis of difference in color, origin, and structure, and classed in types according to texture. The soils of the Piedmont Plateau derived from the igneous and metamorphic rocks are grouped in the Chester, Manor, Louisa, Montalto, Mecklen- burg, Iredell, and Conowingo series. Those derived from the consoli- dated sedimentary rocks (limestone) are placed in the Hagerstown series. The sedimentary materials of the Coastal Plain have produced the soils of the Sassafras, Leonardtown, Susquehanna, Keyport, and Elkton series. The alluvial soils are mainly of the Congaree series. Maryland Geological Survey 313 The Chester series has brown to yellowish soils and yellow to yellowish- brown subsoils. This series covers the greater part of the northern half of the county. Where it is derived from granite and gneiss the subsoil is heavy on the gently rolling areas and gritty and friable on the slopes, but the lower subsoil is very friable in the areas derived from schist, owing to the admixture of finely divided mica. The Manor series has brown to yellowish surface soils with light-red to reddish-yellow or brown subsoils. The material is characteristically micaceous, especially in the subsoil, and when moist the subsoil has a greasy, slick feel. This series is derived from schist and to some extent from gneiss. The Louisa series has brown to red surface soils, with red to brownish- red subsoils, usually somewhat micaceous. These soils resemble the Chester on the surface, and are somewhat similar to the Manor in the subsoil, though containing less mica. They are derived from schists. The Montalto series includes types with brown to reddish-brown surface soils and red to brownish-red subsoils. The one type mapped, the clay loam, is derived principally from gabbro and to a slight extent from diabase. The soils of the Mecklenburg series are brown and the subsoils yellowish brown to reddish yellow, with a characteristic greenish tinge, especially in the lower subsoil. These soils are derived from the wea- thering of gabbro and occasionally serpentine. The Iredell series comprises light-brown or dark gray surface soils, with yellow, yellowish-brown, or brown subsoils. The lower subsoils are characteristically waxy and plastic and have a greenish tinge. These soils are derived from the weathering of gabbro and diorite. The Conowingo series has gray to pale-yellow surface soils, with yellow or brownish, heavy subsoils. A pronounced greenish tinge is characteristic in the lower subsoil. The Conowingo soils are derived from the weathering of serpentine. The Hagerstown series includes brown to reddish-brown soils, with reddish-yellow to reddish-brown or dull-red subsoils. The one type mapped, the loam, is derived from the Cockeysville marble, a phlogopitic limestone. 314 The Soils of Baltimore Couxty The soils of the Sassafras series are brown to yellowish brown, with yellowish-brown to brownish-yellow or reddish-brown, friable subsoils. This series is derived from highly weather Coastal Plains deposits. The Leonardtown series comprises light-brown to grayish or pale- yellow surface soils, and yellow to mottled yellow and gray subsoils that are characteristically compact in the lower part of the 3-foot section. These soils consist of Coastal Plain deposits that are less weathered and less aerated than those forming the Sassafras series. The Susquehanna series represents soils light brown to yellow in color, underlain by heavy, plastic, mottled red or pink and gray clay subsoils. The Keyport series consist of soils on low, smooth terraces. They are derived from Coastal Plain material, and are probably estuarine sediments. The surface soils are light brown or gray to pale yellow. The upper subsoils are yellow and the lower subsoil mottled yellow and gray. Owing to the comparatively smooth topography, the lower subsoil is imperfectly oxidized. In small areas on this terrace where the topography is such that drainage is good and oxidation has progressed deeply, small areas of the Sassafras soils appear. In the low, wet, basinlike areas of this terrace the Elkton series is developed. The Elkton soils are characteristically gray to whitish and are underlain by gray or mottled gray and yellow subsoils which are more or less impervious. It will be seen that on these low coast terraces there is a close relationship between the Sassafras, Keyport, and Elkton soils, The Sassafras, represent the better drained and more highly oxidized material, while the Elkton are the least advanced in drainage, aeration, and oxidation. The Keyport series represents a transition of the Elkton into the Sassafras and lies between them in age and development. The Congaree soils are brown, with brown to yellowish-brown subsoils. The lower subsoils are sometimes grayish or mottled. The Congaree soils represent stream-bottom lands that have been built up from soil sediments washed from areas of the crystalline rocks of the Piedmont Plateau. The one type mapped in Baltimore County has been formed in places in the central part of the county from sediment washed from Maryland Geological Survey 315 the limestone soils. In the southeastern part of the county it is also derived in places from sediments washed from Coastal Plain material. Tidal marsh has been formed by the deposition of very fine sediments from the waters of the estuaries of the Chesapeake Bay. This material has been laid down along streams emptying into the bay or deposited from backwater due to tidal movements. In the following pages the various soils are described in detail. The following table gives the name and the actual and relative extent of each for the County and outlying portions of Baltimore City. AREAS OF DIFFERENT SOILS Soil Chester loam Manor loam Hagerstown loam Sassafras loam Congaree silt loam Leonardtown silt loam. . . . Montalto clay loam Mecklenburg loam Leonardtown loam Sassafras sandy loam Unclassified city land Keyport silt loam CHESTER STONY LOAM The surface soil of the Chester stony loam is a brown or yellow loam 8 inches deep. In timbered areas the surface 2 or 3 inches is brown, but below this the color is yellow. The subsoil to 36 inches is a yellow Or yellowish-brown loam or clay loam, somewhat micaceous and having a slick greasy feel in the lower part. Numerous fragments of schist ranging up to several inches in diameter are scattered over the surface and through the subsoil. Considerable of the type is underlain by more or less weathered bedrock at less than 3 feet and outcrops of the rock sometimes occur. This is not a very extensive or important soil type. It occurs in Acres 116,672 97,024 26,880 25,856 20,288 17,024 14,016 13,056 12,928 13,952 10,816 10,368 Per cent 26.7 22.5 6.2 6.0 4.7 4.0 3.3 3.0 3.0 3.2 2.5 2.4 Soil Chester stony loam. . . . Sassafras silt loam Iredell silt loam Manor stony loam Conowingo silt loam . . . Shallow phase Sassafras gravelly loam Susquehanna silt loam . Tidal marsh Louisa loam Elkton silt loam Total 433,920 316 The Soils of Baltimore County a number of narrow strips on steep valley slopes in the northern part of the county, along Gunpowder Falls, Little Falls and some of their tributaries. Small areas along these streams near Spook Hill are so rough as to warrant the classification of Rough stony land, but owing to their small size they are included with the Chester stony loam. Several small patches or strips of the type are mapped in the central part of the county, occupying ridges composed of Setters quartzite. One of these lies just north of Butler. The topography of the Chester stony loam is rather steep and occa- sionally rough. The drainage is rapid, and if cleared the soil is likely to erode badly. Probably less than 40 per cent of the type is in cultiva- tion. The forest growth consisted largely of chestnut, white oak, red oak, and hickory. Where cultivated the type is farmed in conjunction with the Chester loam, with which it is closely associated. It is practi- cally the same type as the Chester loam, except for its stoniness and steeper topography. It is, of course, handled with more difficulty than the loam, and is likely to suffer from erosion. It is farmed, fertilized, and managed in the same way as the Chester loam, but lower yields are obtained. The inclusion of this soil in farms tends to lower the selling price. The Chester stony loam is probably best suited to pasturage purposes and forestry. If cleared it should be used for grazing. Grass and clover grow well on the soil. CHESTER LOAM The surface soil of the Chester loam is a grayish-brown, brown, or yellowish-brown friable loam, 6 or 8 inches deep. In timbered areas where the soil remains in its virgin condition the surface soil is yellow or brownish yellow, and takes on the brown color under cultivation through the admixture of organic matter. The surface soil is often relatively high in silt. The subsoil to depths ranging from 18 to 24 inches is a yellow to brownish-yellow or yellowish-brown friable clay loam, frequently containing a small but noticeable admixture of finely divided mica particles, the proportion increasing with depth until at 18 to 24 inches the material is a friable micaceous loam. The lower Maryland Geological Survey 317 part of the subsoil is occasionally a mass of finely divided mica. As a rule the micaceous material is nearest the surface on the slopes, and it may not occur within the 3-foot section on the wider ridges. The Chester loam has weathered to depths of several feet, but throughout the soil and subsoil there are fragments of partially weathered gneiss and schist and many small irregular fragments of quartz. These rocks rarely occur in quantities sufficient to interfere with cultivation. In the northern part of the county the soil is derived from a smooth schist and the subsoil has a rather slick feel, due to finely divided mica. Where derived from gneiss, as in the vicinity of Glencoe, the subsoil is a loose, gritty loam containing little mica. Narrow beds of quartzite are closely associated with the gneiss and schist rocks. The soil derived in part from this rock is very similar in color and texture to that derived entirely from gneiss, and as the areas are small they are included with the Chester loam. In such places there are sometimes considerable fragments of quartzite on the surface and in the soil and subsoil. The stony areas, unless mapped as Chester stony loam, are shown by stone symbols. Small bodies of Louisa loam and Manor loam too small to map also occur throughout the areas of Chester loam. About 2 miles southwest of Shawan in the west-central part of the county an area of more than 1 square mile of Chester silt loam is included with the Chester loam. In the western and central parts of the county there are several good-sized areas in which the underlying parent rocks are Baltimore gneiss and granite. These occur principally 1 mile south of Warren, 1 mile south of Glenarm, between Baltimore and Towson, just north of Pikesville, around Granite, and 3 miles southwest of Catonsville. Here the soil differs materially in structure and texture from that derived from schist. It consists of a friable, brown loam about 8 inches deep, underlain by a yellow or yellowish-brown clay loam to clay. On the steeper slopes much of this part of the type is underlain by a subsoil of yellowish or brownish gritty loam. A number of small areas of Cecil loam occur throughout this part of the type. The Chester loam is the most extensive type mapped. It occurs in 318 The Soils of Baltimore County large areas and many small ones throughout the northern, central, and western parts of the country. The surface is gently rolling to hilly, but practically none of the type is too steep for cultivation. The greater part of it lies from 300 to 800 feet above sea level. Drainage is everywhere thorough. The subsoil is permeable but heavy enough to retain moisture well, and crops are carried over considerable periods of light rainfall with little injury from drought. Care is necessary to prevent erosion on some of the steeper slopes. The Chester loam is one of the most important soils in Baltimore County. Probably 85 to 90 per cent of it is in cultivation or in pasture. Many small areas support a forest of white oak, red oak, hickory, occasional pine, and other trees. The leading crops are corn, wheat, and hay. In certain sections oats, rye, and buckwheat are grown in small acreages. Wheat is the chief money crop, corn and hay largely being used to feed work stock, dairy cattle, beef cattle, and hogs. A surplus is sold in Baltimore. Considerable dairying is carried on. Potatoes, cabbage, and other vegetables are grown for market. There are no large commercial orchards, but every farm has a small orchard of apples, pears, cherries, plums, and sometimes peaches, from which some fruit is sold in the Baltimore markets. Corn yields range from 30 to 80 bushels per acre, wheat 15 to 30 bushels, and hay 1 to 1| tons. These yields are sometimes exceeded in favorable seasons on some of the better farms. Irish potatoes yield 100 to 200 bushels, rye 12 to 20 bushels, oats 30 to 60 bushels, and buckwheat 20 to 40 bushels per acre. The Chester loam is friable and easily tilled where properly culti- vated, and does not clod or bake to a great extent on drying, especially where a fair supply of organic matter is maintained. Most farmers employ good methods of cultivation and fertilization, and the soil is very responsive. Systematic crop rotation is practiced. All the wheat is fertilized, as well as much of the corn. Potatoes are fertilized heavily. In general, the fertilizers contain 8 to 10 per cent phosphoric acid, 1 to 2 per cent nitrogen, and 1 to 2 per cent potash. Maryland Geological Survey 319 Wheat and corn receive 300 to 500 pounds per acre. Most of the farmers on this type use lime. Where quicklime is used the applications range from 1,600 to 3,000 pounds per acre. Where hydrated lime is used the applications are considerably lighter but are made more frequently. Large amounts of stable manure are used on corn land. As a rule the farms are most productive where large quantities of manure are used, and these are usually farms where dairying or steer feeding is carried on. The Chester loam is very productive if cultivated and fertilized properly, but if neglected it soon deteriorates. It should be limed every few years and a good supply of organic matter should always be maintained. Growing leguminous crops, such as clovers, alfalfa, and cowpeas is very beneficial. The organic-matter supply can be main- tained by plowing under weeds and crop residues and green-manure crops, and this together with the use of barnyard manure and the grow- ing of legumes should furnish sufficient nitrogen for most crops. There are a considerable number of fields of alfalfa on this type. Many farmers have grown this crop with profit and the acreage devoted to it is apparently increasing. There seems to be no reason why alfalfa should not become a very important crop if the soil is properly prepared, inoculated, and manured or fertilized. The soil also seems well suited to oats, but climatic conditions are not in every way favorable. The Chester loam is apparently a very good fruit soil. Orchards are thrifty and productive, where cared for, and the growing of fruit on a commer- cial scale would probably be successful. The apples grown are chiefly York Imperial and Stayman Winesap. The type also produces fine grapes, small fruits, and berries. MAX OR STONY LOAM The surface soil of the Manor stony loam is a yellow or yellowish- brown loam about 8 inches deep. In cultivated fields the color has been changed to brown by the incorporation of organic matter. The subsoil to 36 inches or deeper is a reddish-yellow, brown, or brownish- yellow, friable, micaceous loam, having a slick, greasy feel due to fine mica particles. The amount of mica increases with depth. Scattered over the surface and throughout the soil mass is a considerable quantity 320 The Soils of Baltimore County of schist fragments, and the bedrock, more or less weathered, comes near the surface or outcrops in many places. The Manor stony loam is found in a number of small areas in the northern part of the county. It occupies steep slopes along Gun- powder Falls and some of its tributaries. The largest areas lie in the vicinity of Parkton and White Hall. Some areas of rough stony land near Parkton, White Hall, and Cockeysville, too small to map, are included with this type. The surface of the Manor stony loam is rather steep and hilly, though usually smooth. Where unprotected the soil erodes badly. Probably not more than 35 per cent of the type is in cultivation, and this is usually in small areas forming part of fields of Manor loam. The forest growth, consisting of chestnut, white oak, red oak, poplar, and hickory, with a few other trees, is rather heavy. The same crops are grown as on the Manor loam, principally corn, wheat, and grass. The soil is handled and fertilized in the same way as that type. Yields are somewhat lower. The soil is cultivated with difficulty, owing to its steep and stony character, and it can probably be used to better advantage for grazing and forestry than for cultivated crops. The type is very similar to the Manor loam in texture and tilth, and practically the same as the Chester stony loam in topography and stoniness. It decreases the price of farms in which it is included. MAXOR LOAM The surface soil of the Manor loam consists of a brown or grayish- brown, friable loam, about 8 inches deep. The subsoil is a reddish- yellow, friable, micaceous clay loam grading at 12 to 15 inches into a micaceous loam which ranges from reddish yellow to light red or reddish brown. In places a loam texture extends from the surface soil to a depth of 36 inches or more. Finely divided mica is a characteristic of the subsoil, the lower part of which is frequently a mass of this material. The surface soil also frequently contains considerable mica. Quartz and schist or gneiss fragments occur over the surface and throughout the soil in small quantities. On the steepest slopes partially weather Maryland Geological Survey 321 schist or gneiss may lie within a few feet of the surface or outcrop. There are many included areas of Chester loam and Louisa loam too small to indicate on the map. The Manor loam occurs in a number of large areas throughout the Piedmont section of the county. The largest areas occur in the north- eastern part around Baldwin, Jacksonville, and Unionville; in the central part around Sparks, Gentsville, and Hereford; and in the western part around Holbrook and Woodensburg. The topography is characteristically rolling and hilly. There are numerous small valleys, many of them deeply intrenched with steep walls, but as a rule the slopes are smooth enough for cultivation. Drainage is everywhere thorough and erosion is severe in places. Owing to the porous nature of the subsoil and substratum the movement of soil water is rapid, but usually there is sufficient clay in the subsoil to maintain considerable moisture supply. On the steeper slopes where the mica content of the subsoil is greatest the soil mass is more porous and permeable than in the areas of more gentle topography, where as a rule there is more clay in the subsoil. Probably 85 or 90 per cent of the Manor loam is in cultivation. In small uncultivated areas the native growth of white and red oak, hickory, and some poplar still remains. Much of the best timber has been cut. The principal crops on this type are corn, wheat, and hay. Relatively unimportant areas are devoted to oats and rye. Small quantities of orchard fruits, grapes, and berries are produced, principally for home use. A little fruit finds its way to the Baltimore market. Vegetables are grown by some farmers for the same market. Dairying is carried on in conjunction with general farming, the milk being shipped to Baltimore, sold to creameries, or made into butter on the farm. On many farms beef cattle are fattened. Hogs and poultry are raised on all the farms and a few sheep are kept on some. The condition of a few small fields of alfalfa seen during the survey indicated that the better areas of this soil are fairly well adapted to this crop, if well prepared, manured, and inoculated. 322 The Soils of Baltimore County Corn ordinarily yields 25 to 50 bushels per acre. The yield is some- times much higher on the better farms and in especially favorable seasons. The yield of wheat is 12 to 25 bushels, and of hay 1 to 1| tons per acre. The Manor loam does not bake or clod badly on drying and is easily cultivated and kept in good tilth. Practically all the farmers follow a rotation, consisting of corn 1 year, wheat 1 or 2 years, and timothy and clover 2 years. Most farmers apply lime, the applications ranging from 1,000 to 3,000 pounds per acre. Lime is generally applied once in each rotation. All farmers use commercial fertilizers for wheat, at the rate of 300 or 400 pounds per acre. Its use for corn is less general. Usually the mixtures are of low grade, containing about 8 per cent phos- phoric acid, 1 or 2 per cent of nitrogen, and sometimes in addition 1 or 2 per cent of potash. In late years ground phosphate rock, containing about 16 per cent of phosphoric acid, has been substituted on many farms for the treated phosphate. Barnyard manure is used for corn, but the supply is usually inadequate except on the dairy farms. The Manor loam, where neglected, quickly deteriorates, but under proper methods of farming it is productive and can be maintained so. It responds quickly to applications of lime, organic matter, manure, and commercial fertilizers, but the results are not so lasting as on the Chester loam. Lime should be used on this soil once during each rotation, at the rate of 2,000 or 3,000 pounds per acre. In conjunction with liming organic matter should be supj lied, by turning under sod, weeds, crop residues, or, where the supply of such materials is not sufficient, by growing green-manure crops, such as cowpeas and crimson clover. Certain areas, especially those steeply sloping, should be handled carefully to prevent erosion. LOUISA LOAM The surface soil of the Louisa loam is a brown to reddish-brown, friable loam 6 or 8 inches deep. The subsoil is a light-red, reddish-yellow, or reddish-brown clay loam containing some fine mica particles which give it a greasy feel. The mica content increases with depth and in places Maryland Geological Survey 323 at 24 to 36 inches the material becomes a micaceous loam. A few small quartz and schist fragments occur throughout the soil and subsoil. Only a few small areas of this type are mapped. It occurs in the west-central part of the county, a few miles north of the Green Spring Valley and in the vicinity of Cronhardt. A small area of Cecil loam about 1 mile east of Texas is included with this type. The surface of the Louisa loam is gently rolling to rolling. The type usually occupies high, broad ridges in areas of Manor loam and Chester loam, and patches too small to map are frequently included with those soils. Drainage is everywhere good. Probably 80 per cent of the soil is cultivated, the remainder being covered with white oak, red oak, tulip poplar, hickory, and other trees. The principal crops are corn, wheat, and hay (timothy and clover). The type is farmed in the same way as the Chester loam, and yields are about the same. It is quite productive if limed and well manured. Some commercial fertilizers are successfully used for wheat and corn. Vegetables, fruits, and berries do well. MECKLENBURG LOAM The surface soil of the Mecklenburg loam is a brown, friable loam about 8 inches deep. The subsoil to 36 inches in a brownish-yellow or reddish-yellow to yellowish-brown, friable clay loam or loam. The lower subsoil is quite friable owing to the admixture of coarse fragments of disintegrated rock. The subsoil usually has a characteristic greenish tinge. On some steep slopes the parent rock (gabbro or serpentine) may come within 1 or 2 feet of the surface. A few small fragments of the rock sometimes occur throughout the soil mass. Stone symbols are used on a few small areas to represent the Mecklen- burg stony loam. These lie in the extreme southern part of the county along the steep slopes of the Patapsco River, and in places are so steep and stony as to constitute Rough stony land. Only small patches of the Mecklenburg stony loam are included in fields, and it can not be cultivated except with great difficulty and then only after the removal of some of the stones. 324 The Soils of Baltimore County The Mecklenburg loam is not a very extensive type. It occurs in several areas a square mile or more in size in the southwestern part of the county and within a few miles of Baltimore. An important area occurs just north of Mount Washington, and another just south of Powhatan. A small area occurs in the eastern part of the county near Fork. The surface is gently rolling to very rolling, with some rather steep slopes. The type often lies on the steep slopes of areas of gabbro where the higher surfaces consist of Montalto clay loam and Iredell silt loam. On some of the steeper and unprotected slopes erosion may be severe. The type has good underdrainage. The native growth on this soil is tulip poplar, white oak, and red oak, with some beech along the lower slopes. Perhaps 75 per cent of the type is cultivated. The principal crops are corn, wheat, and hay. Some potatoes, tomatoes, and other vegetables are grown for market. There are some small orchards rf apples, Dears, and small fruits and patches of berries. These fruits seem well suited to the type. The same general farming methods are used as on the Chester loam. Where the soil is properly handled and fertilized it gives good returns. Corn yields from 25 to 65 bushels per acre, wheat 15 to 30 bushels, and hay 1 to 1§ tons. This soil requires some liming and is greatly improved by the use of barnyard manure and by plowing under vegetation. Most of this type lies near Baltimore, and its selling price is enhanced by its value for suburban residence. In the table below are given the results of mechanical analyses of samples of the soil and subsoil of the Mecklenburg loam : MECHANICAL ANALYSES OF MECKLENBURG LOAM Nu in her Description Fine gravel Coarse sand Medium sand Fine sand Very fine sand Silt Clay 201242 201243 Soil Subsoil per cent 3 5 .9 per cent 3.8 2 2 per cent 3 5 1.8 per cent 18 0 26 7 per cent 20.7 22 1 per cent 40 0 26 5 per cent 10.2 18.8 Maryland Geological Survey 325 IREDELL SILT LOAM The surface soil of the Iredell silt loam is a light-brown to yellowish- brown, smooth silt loam, 8 or 10 inches deep. The immediate surface dries out to a light-gray color. The upper subsoil begins as a yellow silty clay loam, in many areas slightly mottled with gray. At a depth of 16 or 18 inches it abruptly passes into a heavy, waxy, plastic clay of a yellow to brown color with a slight greenish tinge. Soft, partially weathered diorite, gabbro, or serpentine rock is usually encountered at 24 to 36 inches below the surface. Some dark iron concretions are occasionally found on the surface or mixed with the soils. The Iredell silt loam occurs in several areas in the southern part of the county a few miles west of Baltimore. The largest are around Hebbville, Ralston, Howard Park, and Arlington. The soil is locally called "white land." Most of the area of the Iredell silt loam is undulating to gently rolling, and only in a few places does it occupy moderately steep slopes. Surface drainage is fairly good, but owing to the compactness of the lower subsoil the underdrainage is not thorough. Where the surface is nearly level water stands and the soil becomes "cold" and sour. Probably 80 per cent of the type is in cultivation, the remainder being in the native forest growth of white oak, black oak, red oak, poplar, cedar, and hickory. The principal crops grown are corn, wheat, and hay. As much of the soil lies within a few miles of Baltimore it is used to an important extent for market gardening. Potatoes, cabbage, toma- toes, sugar corn, beans, peas, turnips, beets, and other vegetables are grown. There are some small orchards of apples, pears, and plums, and patches of berries. On the better farms corn ordinarily yields 25 to 40 bushels per acre, wheat 15 to 25 bushels, and hay 1 to 2 tons. The Iredell silt loam bakes rather hard on drying unless cultivated when it contains just the proper amount of moisture. Where general farming is carried on corn, wheat, and timothy and clover are rotated. Commercial fertilizers are used for wheat and sometimes for corn. Vegetables are grown with the aid of heavy fertilization. Consider- able barnyard manure is used, but not enough for best results. The 326 The Soils of Baltimore County Iredell silt loam is deficient in organic matter, and heavy applications of manure and all crop residues should be incorporated with the soil. Probably all the type is in need of lime. The price of farms on this type is influenced largely by proximity to the Baltimore suburbs and nearness to the city markets. This soil seems best suited for growing hay and small grains such as wheat. Some very good yields of timothy hay have been obtained. The following table gives the results of mechanical analyses of sam- ples of the soil, subsoil, and lower subsoil of the Iredell silt loam : MECHANICAL ANALYSES OF IREDELL SILT LOAM Number Description Fine gravel Coarse sand Medium sand Fine sand Very fine sand Silt Clay per cent per cent per cent per cent per cent per cent per cent 201249 Soil 3.2 2.5 0 6 3 2 9.0 68.6 12.5 201250 Subsoil 2.1 1.1 .3 1.7 4.0 69.1 21 6 201251 Lower subsoil 14 10 .3 1.9 4 0 43.0 48 3 CONOWINGO SILT LOAM The surface soil of the Conowingo silt loam, locally called "white land," is a yellowish-brown or light-brown silt loam, 8 or 10 inches deep, which on drying assumes at the immediate surface a light-grayish color. In forested areas the surface 1 or 2 inches is whitish and the rest of the soil pale yellow. The subsoil to 18 or 24 inches is a yellow silty clay loam, frequently slightly mottled with gray. Below this it grades into a slightly waxy, sticky clay of yellow or brown color, tinged with green and frequently mottled with gray. This passes, often above the depth of 36 inches, into soft disintegrated greenish serpentine rock. Fre- quently the material is not waxy and the subsoil, from 18 or 24 inches consists of the disintegrated and only partially decomposed rock. In many places the lower subsoil contains black iron concretions. On some slopes and in other places the parent rock comes near the surface or outcrops. There are only a few small areas of Conowingo silt loam in Baltimore County. These occur in the southern part just west of Baltimore and Maryland Geological Survey 327 between that city and Patapsco River. The largest body of the type occurs around Belmont in a strip more than 1 mile wide and several miles in length. A small strip lies in the eastern part of the county just south of Fork, and a small area just south of Kingsville. The topography of the Conowingo silt loam is undulating to gently rolling. Surface drainage is fairly good, but the underdrainage is rather poor, as the lower subsoil is somewhat compact in many places. About 80 per cent of this type is under cultivation or used for pas- ture. Some of the original timber growth of white oak, blackjack oak, and hickory remains. The large proportion of the type in cul- tivation is doubtless due to its favorable location near the Baltimore markets. Both general farming and market gardening are carried on. In general farming corn, wheat, and hay are grown. Various vegetables are produced, together with some apples, pears, peaches, and cherries. Sometimes the growing of general farm crops is com- bined with vegetable production. On the better farms corn ordinarily yields 25 to 40 bushels, wheat 15 to 25 bushels, and hay 1 to 3 tons per acre. Vegetables yield fairly well. This soil is inclined to bake on drying. Wheat and clover sometimes suffer from the freezing of the soil. Lime is used with good results. Commercial fertilizers are applied to wheat land and sometimes to corn land. Fertilizers are in general use by market gardeners and truckers. Barnyard manure is used, but an insufficient amount is available for best results. This soil seems best suited to the production of hay and wheat. It is deficient in organic matter and much of it is rather cold and probably inclined to be acid. It should be heavily limed and manured, and all vegetation and crop residues plowed under to increase the supply of organic matter. Conowingo silt loam, shallow phase. — The Conowingo silt loam, shallow phase, consists of 6 or 8 inches of grayish-yellow silt loam, underlain to 18 or 20 inches by a subsoil of yellow or yellowish-brown silty clay loam. From this depth downward more or less disintegrated serpentine rock is frequently encountered and most of the phase has the rock within 36 inches of the surface and in many places outcrops 328 The Soils of Baltimore County occur on the steeper slopes. In some places a layer of yellow or reddish- yellow, slick clay loam or clay, having a greenish tinge, occurs just above the rock, at depths of 18 to 36 inches. There are many variations in color, texture, and depth of the subsoil, according to the depth of soil covering above the rock. There is always a prevailing greenish tinge in the lower subsoil. This phase occurs in one body, a few square miles in extent, about 4 miles west of Green Spring Junction, in the extreme western part of the county. Its topography is rolling to gently rolling. Erosion has cut many small valleys and gullies, exposing the underlying rock, making the surface in places very rough and stony. Probably less than 25 per cent of the phase is cultivated, and much of the native timber remains, principalh' a thin forest of blackjack oak with some white oak. Old fields, where the soil mantle is very thin, have a very scant growth of broom sedge. Small areas of this phase are devoted to corn, wheat, and hay, but yields are very poor. Owing to the generally unfavorable soil and surface conditions, the land has very little agricultural value. Included with this phase is an area of "barrens." This lies in the south-central part of the count}', about 3 miles north of Baltimore, and has an extent of somewhat less than 1 square mile. The area is hilly and serpentine rock outcrops frequently, being in nearly all places less than 8 to 18 inches below the surface. There is very little soil accumulation at any place, but occasionally about 6 inches of brown to reddish-brown loam overlies a reddish or yellowish clay loam or clay which has a pronounced greenish tinge. In places the subsoil may extend to 18 inches before the rock is encountered. The subsoil con- tains numerous small particles of soft serpentine, which gives it a soapy feel. The surface is rolling to hilly, with steep, eroded, and gullied slopes. A few blackjack oaks and pines with a sparse growth of broom sedge and some other grasses occupy the land. It was formerly culti- vated, but has no present value, except for the rather indifferent grazing it affords. In the table below are given the results of mechanical analyses of Maryland Geological Survey 329 samples of the soil, subsoil, and lower subsoil of the typical Conowingo silt loam: MECHANICAL ANALYSES OF CONOWINGO SILT LOAM Number Description Fine gravel Coarse sand Medium sand Fine sand Very fine sand silt Clay per cent per cent per cent per cent per cent per cent per cent 201246 Soil 11 2.2 0.8 4.2 6 7 70.7 13 9 201247 Subsoil 16 2 5 .9 6 3 11 6 57.6 19 0 201248 Lower subsoil 5.2 3 0 10 14.8 16 0 33.6 26.0 MONTALTO CLAY LOAM The surface soil of the Montalto clay loam, locally known as "red land," is a brown to reddish-brown clay loam, 4 to 8 inches deep. The subsoil to 36 inches is a dull-red to brownish-red or reddish-brown, rather heavy, smooth clay. In some places erosion has removed the surface soil and the clay subsoil is exposed, but these areas are too small to map accurately and have not been separated. Frequently the surface soil is relatively high in silt and occasional small areas of true silt or loam are included. Much of the surface is strewn with fragments of gabbro, occasionally several feet in diameter, and some small areas could properly be classed as a stony type. Symbols are used to indicate the more stony areas. The Montalto clay loam occurs in a number of good-sized areas in the eastern and southern parts of the county. The largest body lies around Kingsville, near which place several smaller areas also occur. Areas are mapped also a few miles west of Baltimore, and near Rock- dale, Arlington, Sudbrook Park, Franklin, Kingsville, and North Bend. In topography the type ranges from gently rolling to rolling and hilly. It occupies some very steep, high slopes adjacent to the larger streams and is well drained. Some of the slopes where unprotected are subject to erosion. The subsoil is quite retentive of water. About 75 per cent of this type is in cultivation. Where it is uncleared the original forest growth, consisting principally of white oak, and tulip poplar, with some pine, cedar, hickory, and red oak, remains. Some 330 The Soils of Baltimore County of the land is used for growing corn, wheat, and hay, but it is devoted very largely to the production of vegetables, even at a distance of 10 or 12 miles from the city. Potatoes, beans, peas, cabbage, tomatoes, sugar corn, and turnips are important products. Small orchards of apples, pears, and other fruits are successful. Small fruits and berries are grown to some extent. Corn yields 30 to 60 bushels per acre, wheat 15 to 25 bushels, potatoes 120 to 200 bushels, and hay (timothy and clover) 1 to 2 tons. Good yields of vegetables are obtained. This soil is rather heavy and somewhat difficult to cultivate, but if plowed when not too wet or too dry it may be kept in fairly good tilth. It bakes in hard clods if plowed when wet, and these are broken down only with difficulty. Baking is most pronounced where the clay subsoil comes near the surface or is exposed. For the general farm crops the land is limed, fertilized, and handled in about the same way as the Chester loam. The same rotation is followed. Much barnyard manure is used in the production of corn and vegetables. The soil is greatly improved by growing leguminous crops such as clover and by adding organic matter. The Montalto clay loam is a strong soil, seemingly especially well suited to wheat and grass. It is apparently adapted to the production of apples. HAGERSTOWX LOAM The surface soil of the Hagerstown loam is a brown, usually rather silty loam, 5 to 8 inches deep and of a reddish-brown color. The subsoil to 36 inches is a red, reddish-brown, or reddish-yellow clay loam to friable clay. In some places where the parent rock contains considerable mica the subsoil is slightly micaceous. This is also the case along the outer margin of the type where mica has been washed down from the higher slopes occupied by the Manor loam. Just north of Towson there is a thin scattering of quartz gravel over some areas of the type. Many areas of Hagerstown clay loam too small to indicate on the map are included in the Hagerstown loam. They consist of a red to reddish-brown clay loam underlain by red to light-red c\a.y. They Maryland Geological Survey 331 occur on slopes and in swales. The soil is slightly more difficult to cultivate than the loam but is used for the same crops. Several very- small areas of a soil in the Green Spring Valley just west of Lutherville which resembles the Conowingo silt loam are also included. The Hagerstown loam occupies a number of irregular areas in the limestone valleys in the central part of the county. These valleys are from one-fourth mile to 2 or 3 miles across and generally connected. The largest areas of the type comprise the Green Spring Valley about 6 miles north of Baltimore, Dulaney Valley just north of Towson, and Worthington Valley just east of Emory Grove. The towns of Cockeys- ville, Lutherville, and Texas are located on this soil. The Hagerstown loam has a gently rolling to rolling surface, favorable for agriculture. The type occurs in the form of long, narrow valleys bordered by somewhat steep slopes of Manor loam or Chester loam which rise in places to a height of 100 feet or more above the valley floor. Surface drainage and underdrainings are generally good, but in a few small areas streams coming down from the higher lands spread over the undulating areas of the Hagerstown loam and form poorly drained spots. Some of these are ditched. The subsoil of the type is sufficiently heavy to retain moisture for crops throughout considerable periods of dry weather. Practically all of this type is in cultivation. The principal crops are corn, wheat, and hay (timothy and clover). Potatoes are grown on many farms and some farmers produce vegetables for the Baltimore market. Small orchards of apples, pears, peaches, plums, and cherries do well, and bush fruits and berries succeed. Dairying is engaged in on a number of farms, and some of the largest dairies in the county are located on this type in the Green Spring Valley. Some beef cattle are fed. Hogs and poultry are raised on all the farms. A few large fields of alfalfa, some containing as much as 80 acres, are established on the type, and the crop gives good results, especially in connection with dairy farming. On the better farms corn yields as much as 100 bushels per acre, but ordinarily 40 to 60 bushels; wheat 20 to 30 bushels, oats 40 to 60 bushels, and timothy and clover hay 1 to 2 tons. Alfalfa 332 The Soils of Baltimore County yields 3 to 5 tons per acre in 4 cuttings. Large yields of corn ensilage are obtained on some dairy farms. The Hagerstown loam is fairly easy to till, except in the small spots where clay loam occurs at the surface or is turned up by the plow. Where general farming is practiced the regular crop rotation consists of corn 1 year, wheat 1 or 2 years, and grass 2 years. On the farms where no small grain is grown, as in dairy farming, this system is modi- fied. Heavy applications of lime are used on this soil, and commercial fertilizers are used for wheat and oats and sometimes for corn. Approxi- mately the same kinds and amounts are applied as on the Chester loam. Considerable barnyard manure is used for corn and alfalfa, and on dairy farms the heavy manuring gives excellent results and renders unneces- sary the use of commercial fertilizers for these crops. The Hagerstown loam is naturally a strong, productive soil. Farms composed largely or entirely of this type range greatly in price according to location. The use of lime and heavy applications of barnyard manure are neces- sary for best results on this soil, and with liming and heavy manuring it is probable that only small amounts of commercial fertilizers would be needed, except for some phosphoric-acid fertilizers for the small grains. It is said by some growers of alfalfa that applications of wood ashes have improved the stand and yield of that crop. The best results in seeding alfalfa have been obtained by inoculating the soil. SASSAFRAS GRAVELLY LOAM The surface soil of the Sassafras gravelly loam consists of 6 or 8 inches of brown or yellow gravelly loam or gravelly sandy loam. The subsoil to 36 inches is a yellow, yellowish-brown, or brown gravelly loam or gravelly clay loam. The immediate surface material dries out to a grayish color. The gravel in the soil and subsoil consists of smooth, rounded fragments of quartz ranging up to 2 or 3 inches in diameter. The gravel constitutes 25 to 75 per cent of the soil material and in many places is used in road building and other construction. This type occurs in a number of small areas scattered over the southern Maryland Geological Survey 333 part of the county in close association with the Leonardtown and Sassa- fras soils. The largest area is located just west of Necker. The topog- raphy is rolling, and in some places steeply sloping, with some narrow bodies forming gently sloping crests of narrow ridges. Surface drainage is good throughout the type and underdrainage is excessive. Probably not more than 5 per cent of the type is in cultivation, the remainder being covered with forest of oak, and other trees. The cultivated areas are small, generally forming parts of fields of other soils. On the less gravelly areas fair yields of tomatoes are obtained. Other vegetables, small fruits, and berries succeed fairly well where the land is well manured and fertilized. Grapes would probably do well. sassafras sandy loam The Sassafras sandy loam consists of 8 to 12 inches of a brownish-gray to brown, light sandy loam, underlain to a depth of 36 inches by a yellow or yellowish-brown to reddish-yellow sandy loam. In unculti- vated areas or in fields where only a small amount of organic matter has been incorporated in the surface the color is often pale yellow. The immediate surface in dry cultivated fields has a grayish color. Some- times the lower subsoil in depressions is slightly compact and faintly mottled with gray. Frequently there is a small quantity of rounded quartz gravel in the soil, subsoil, and substratum. On the lower terraces near the coast the soil and subsoil are of a richer brown color than on the higher positions farther inland. The Sassafras sandy loam occurs in a large number of small areas throughout the southeastern part of the county. The largest body occurs in the vicinity of Chase and just north and west of Bengies. Smaller areas occur east of Baltimore in the vicinity of Brooks Hill and Stemmer Run. To the east of Fort Armistead there are small bodies of Sassafras sand which are less productive than the typical soil. These sand areas were not separated in the map on account of their small extent. The topography is gently rolling. Frequently the smaller areas occupy the ridgelike or knoll-like positions surrounded by areas of the 334 The Soils of Baltimore County Leonardtown soils and other Sassafras soils. In the vicinity of the coast the surface is nearly level to gently undulating. Surface drainage is good and the underdrainage is rapid, although the subsoil contains sufficient clay to hold a fair amount of moisture. About 80 or 90 per cent of the Sassafras sandy loam is under cultiva- tion. Some smaller bodies of the original forest remain. This consists principally of pine, white oak, red oak, and black oak. Vegetables are the principal crops. Some small fruits and berries are also grown. These crops are produced for the Baltimore market. The soil where properly cultivated and given applications of manure and high-grade fertilizers produces good yields. It dries out rapidly and warms up early in the spring, which makes it valuable for growing early vegetables. It is natural^ deficient in organic matter, which may be applied either in the form of barnyard manure of green-manure crops. The surface soil of the Sassafras loam is a brown, friable loam, about 8 inches deep. The subsoil to a depth of 36 inches is a brown, brownish- yellow, or reddish-brown clay loam or silty clay loam. In a few patches the subsoil is red. Frequently some small, rounded quartz gravel occurs in the soil and subsoil. Occasionally faint gray mottlings occur in the subsoil at 30 to 40 inches below the surface. Some areas of Sassafras sandy loam too small to show on the map are included in this type. SASSAFRAS LOAM The Sassafras loam is not an important type, owing to its small ex- tent, although it occurs in a large number of bodies widely scattered throughout the southern part of the county within a few miles of Balti- more. The largest areas lie around Landsdowne, Grange, and Walters, and within the city limits of Baltimore. The topography is gently rolling to rolling. Surface drainage and underdrainage are good. The native forest growth consists of pine, white oak, red oak, poplar, chestnut, and other trees. Much of the timber has been removed, and perhaps 85 per cent of the land is in cultivation. The Sassafras loam is used principally for the production of vegetables, Maryland Geological Survey 335 largely tomatoes, potatoes, sugar corn, beans, and peas, to be sold in the Baltimore market and to canneries. Small acreages are devoted to wheat, corn, and hay. There are small orchards of apples, pears, and peaches. Small fruits and berries are grown by market gardeners. The ordinary methods of cultivation and fertilization are followed for general farm crops and vegetables. Wheat is produced with commercial fertilizers, and large quantities of fertilizers are used in growing vege- tables. Manure is used in large quantities for vegetables and corn. Lime is also applied. Corn yields 20 to 60 bushels per acre, wheat 15 to 25 bushels, and hay 1 to 1^ tons. Irish potatoes yield 100 to 150 bushels per acre and tomatoes 150 to 200 bushels. Oats may yield 40 bushels per acre in favorable seasons, but the production is small owing to the uncertainty of the crop. Alfalfa does well and is grown in a few small fields. The price of this land is based principally on its value for building sites, as it is located near Baltimore and its suburbs. Thie type is more easily improved and kept in a good state of pro- ductiveness than the Leonardtown soils, and it is somewhat better adapted to the production of vegetables and small fruits, although it is necessary to use manure and organic matter as well as lime and com- mercial fertilizers in order to maintain good yields. SASSAFRAS SILT LOAM The surface soil of the Sassafras silt loam consists of 8 or 10 inches of brown silt loam. The subsoil to 36 inches or more is a yellow, yellowish- brown, or brown silty clay loam, often faintly mottled with gray in the lower part. This type occurs in a number of small, widely separated areas throughout the southern part of the county, where it is closely associated with the Sassafras loam and the Keyport silt loam. Its topography is very gently undulating to gently rolling, and it has good surface drainage and underdrainage. Some of the type lies on the low terraces which form narrow peninsulas projecting into Chesapeake Bay and which are composed largely of the Keyport silt loam. 336 The Soils of Baltimore County Probably 90 per cent of this type is cultivated. The growth in the uncleared areas is largely white oak, red oak, and poplar. The crops grown are principally vegetables for the Baltimore market, with occa- sionally a small acreage in corn, wheat, and hay. The soil is quite productive. It is well suited to vegetables and fruits, but for best results should be fertilized, limed, and manured. It is handled in the same way as the Sassafras loam, and gives practically the same yields. Owing to its higher position and better drainage it Ls better suited to cultivation than the Keyport silt loam in similar situations. LEOXARDTOWX LOAM The Leonardtown loam consists of about 8 inches of pale-yellow or light-brown loam, underlain by yellow or brownish-yellow clay loam or silt}' clay loam to depths of 24 to 36 inches, slightly compact and faintly mottled with gray in the lower part or in the substratum. In uncultivated areas only the immediate surface is brown, the soil in general being brownish-yellow. On drying the surface becomes some- what grayish. A small quantity of small, rounded quartz gravel is sometimes mixed with the soil and subsoil. As mapped the type includes small areas of Leonardtown silt loam, Sassafras gravelly loam, and Sassafras loam. The Leonardtown loam is a type of little importance. Its principal areas occur around Perry Hall, Xecker, Parkville, and Rosedale. Numerous small bodies are mapped throughout the southeastern part of the county. The type occurs in close association with the Leonardtown silt loam and the Sassafras soils. The topography is undulating to gently rolling, with some steep slopes and moderately deep valleys. Surface drainage is good through- out the greater part of the type. The under drainage, while better than that of the Leonardtown silt loam, is not very thorough in many places, owing to the slightly compacted condition of the subsoil and substratum. Probably 85 per cent of the Leonardtown loam is under cultivation. Where uncleared it supports a growth of white oak, red oak, and black oak, with some pine and hickory. Much of the more valuable timber Maryland Geological Survey 337 has been cut. A large part of the type is used for the production of vegetables, as it is located along good roads and easily accessible to the Baltimore markets. Some corn, timothy, and wheat are grown. Most of the type is used for market gardening, the principal crops being Irish potatoes, tomatoes, cabbage, turnips, kale, spinach, and sugar corn. There are on this type several orchards of apples, peaches, cherries; plums, and pears. Berries and small fruits are grown to some extent. Corn ordinarily yields 20 to 50 bushels per acre, wheat 12 to 25 bushels, and hay 1 to \\ tons. The condition of small fields of alfalfa indicates that this crop may be grown successfully in favored sections. Irish potatoes yield 100 to 150 bushels per acre, and tomatoes 150 to 200 bushels. Where general farming is carried on the farming methods are about the same as on the Chester loam. Commercial fertilizers are used for wheat and sometimes for corn, and heavy applications of high-grade fertilizers are made for vegetables. Barnyard manure and garbage also are used in large quantities for vegetables. Many farmers use lime for all crops. The soil is deficient in organic matter and is greatly benefited by plowing under vegetation. The Leonardtown loam is well suited to the production of vegetables, corn, small fruits, and berries where the supply of organic matter is maintained and the soil is limed and fertilized properly. Probably most areas of the type would be improved by tile drainage. LEONARDTOWN" SILT LOAM The surface soil of the Leonardtown silt loam is a light-brown or brownish-yellow silt loam, 2 to 8 inches deep. In cultivated fields the surface soil is brown to about 8 inches, but where the land has never been cultivated the lower part of the surface soil is yellow. When dry the surface in cultivated fields has a grayish appearance. The subsoil to 18 or 30 inches is a yellow silty clay loam, frequently slightly mottled with gray at 30 inches. Below 18 or 30 inches and extending to 36 inches the subsoil is a compact mottled yellow and gray silty clay loam or silty clay. This compact layer or so-called hardpan is a characteristic 338 The Soils of Baltimore County feature of the type. It is very hard in many places and almost imper- vious. Sometimes small rounded quartz gravel is scattered sparingly through soil and subsoil. The Leonardtown silt loam is mapped in a number of small areas in the southeastern part of the county. The largest occur around Upper Falls, just north and east of Whitemarsh, just north of Baltimore, and around Hamilton and Parkville. The topography is nearly level to gently undulating and in places gently rolling. In general, the type has fairly good surface drainage, but there are many small basinlike areas in which water stands after rains. The compact lower subsoil and substratum retard the under- drainage. Probably 70 per cent of this land is in cultivation. The areas farther from Baltimore are cultivated to a less extent than those near the city. Within a few miles of the city nearly all this soil is used for the production of vegetables. The more remote areas are used also for corn, wheat, and hay. The vegetables produced are chiefly cabbage, potatoes, tomatoes, beans, peas, sugar corn, spinach, turnips, onions, and kale. Con- siderable quantities of manure and high-grade fertilizers are used for vegetables, which give moderate yields. Corn yields 20 to 50 bushels per acre, wheat 12 to 25 bushels and hay 1? to 2 tons. For corn, manure and sometimes commercial fertilizers are used, the fertilizer being applied at the rate of 300 or 400 pounds per acre. These fertilizers are of various kinds, but as a rule phosphoric acid is the most important constituent. Potash gives good results, and its use in mixtures up to 6 per cent has been found profitable for wheat. Lime is used with profit on this soil. The Leonardtown silt loam has a tendency to become acid, and lime should be used regularly. The aeration of the soil, which is poor, could be improved to a considerable extent by tile drainage. This soil is naturally deficient in organic matter, which is supplied in the form of barnyard manure and crop residues. The type seems especially adapted to the production of hay. The results of mechanical analyses of samples of the soil, subsoil, Maryland Geological Survey 339 and lower subsoil of the Leonardtown silt loam are given in the following table: MECHANICAL ANALYSES OF LEONARDTOWN SILT LOAM Number Description Fine gravel Coarse sand Medium sand Fine sand • Very fine sand Silt Clay per cent per cent per cent per cent per cent per cent per cent 201232 Soil 14 3.1 1.6 6.1 9.2 64.0 14.4 201233 Subsoil .9 2.0 1.1 4 0 5.7 61.6 24.7 201234 Lower subsoil 1.7 2.8 1.6 56 7.8 55.1 25.3 SUSQUEHANNA SILT LOAM The Susquehanna silt loam is a brown to yellowish silt loam, 8 or 10 inches deep, underlain to 18 or 20 inches by a yellow, brownish-3'ellow, or yellowish-brown silty clay loam, and below that depth by a red or pink, mottled with gray, heavy tough clay or silty clay. This type is not very uniform and in some places it resembles the Leonardtown silt loam, but at a depth of 3 feet the distinguishing reddish, mottled clay is encountered, which is a sufficient basis for differentiation. The Susquehanna silt loam occurs in several small, widely separated areas in the southeastern part of the county. One of the largest lies just north of Rossville, another near ftosedale, another just east of Landsdowne, and one east of Halethorp. The topography is gently rolling to rolling, and the type has fair surface drainage, but the underdrainage is poor, owing to the impervious nature of the subsoil. Probably 75 per cent of this soil is cultivated. Forested areas support a growth of white oak, red oak, and pine. Like the surrounding Coastal Plain soils this type is used principally for market gardening. It is farmed in conjunction with the Leonardtown and Sassafras soils, and has about the same agricultural characteristics as the Leonardtown silt loam. It is naturally somewhat "cold," owing to poor drainage. The application of lime, organic matter, and fertilizer is necessary for the best results. The type is probably best adapted to the production of hay. 340 The Soils of Baltimore County KEYPORT SILT LOAM The surface soil of the Keyport silt loam consists of about 6 inches of yellowish-gray to grayish-brown silt loam. The subsoil to a depth of 12 or 15 inches in typically a yellow silty clay loam or silt, though in depressions it may show mottlings of gray. From 12 or 15 inches to 36 inches the subsoil is a mottled yellow and gray, compact silty clay loam, approaching a silty clay in the lower part in places. In the more rolling areas the gray mottling of the subsoil is less pronounced than in the level or depressed areas. Throughout the type there are patches of Elkton silt loam and occasionally Sassafras silt loam, too inextensive to map. The Keyport silt loam occupies several square miles in the south- eastern part of the county on Patapsco River Xeck, Back River Neck, and Middle River Xeck. The largest areas extend northward for several miles from Sparrows Point. These necks, which are cut into by a number of small bays and creeks, are smooth terraces lying a few feet above the waters of Chesapeake Bay, from which they are separated by a low bluff. The topography is gently undulating to nearly level, with many slight depressions. Most of the type lies less than 40 feet above sea level. Drainage is fairly good in most places, though much of the land would be improved by artificial drains. Probably 75 per cent of the type is cleared and used for crops. Un- cultivated areas support a forest consisting principally of white oak, red oak, water oak, pin oak, sweet gum, and pine. This soil is used principally in growing vegetables for the Baltimore market and for canneries. The more important crops are beans, peas, tomatoes, spinach, cabbage, potatoes, sugar corn, turnips, and kale. Only small acreages of corn, wheat, and hay are grown. There is a small production of apples, peaches, and small fruits and berries. In some of the better drained situations small fields are devoted to alfalfa. Beans yield 200 to 250 bushels per acre, tomatoes 200 to 250 bushels, potatoes 100 to 200 bushels, spinach 700 to 1 000 bushels. Lime is used to some extent on this soil and barnyard manure, garbage, and other refuse is applied in large quantities. Commercial fertilizers Maryland Geological Survey 341 are also used extensively, principally nitrate of soda and phosphoric- acid mixtures. The Keyport silt loam is fairly productive where drainage is good. It needs liming and large applications of barnyard and other organic manure. Tile drainage would prove of great benefit. The type is well suited to the production of hay. Mechanical analyses of samples of the soil, subsoil, and lower subsoil of the Keyport silt loam gave the following results: MECHANIC AL ANALYSES OF KEYPORT SILT LOAM Number Description Fine gravel Coarse sand Medium sand Fine sand Very fine sand Silt Clay per cent per cent per cent per cent per cent per cent per cent 201227 Soil 0 1 1.1 1.2 6.2 10.7 66.0 14.4 201228 Subsoil .0 .7 1.0 4 4 9.3 61.0 23.7 201229 Lower subsoil .0 .5 1.1 6.0 10.8 48.3 33.1 ELKTON SILT LOAM The surface soil of the Elkton silt loam consists of 6 or 8 inches of gray silt loam, nearly white when dry. The subsoil is a gray and yellow mottled silty clay loam to silty clay, which below 24 inches is in places compact and lighter in texture than the upper subsoil. This type occurs in small, scattered areas in the southeastern part of the county. Many areas exist that are too small to map. The type is developed on the low marine terrace which occupies the necks of land projecting into Chesapeake Bay. The surface is flat to very slightly depressed, and surface drainage is very poor. The subsoil is almost impervious, and underdrainage is correspondingly deficient. Probably not more than 5 per cent of the total area of the type is cultivated. The rest is covered with forest growth consisting of pin oak, water oak, water maple, white oak, and a brush undergrowth. The soil without artificial drainage is of low productiveness, grass seeming to do best on it. When drained it is best adapted to the production of hay and wheat, but even with improved drainage the soil requires lime and heavy applications of manure and other forms of organic matter to make the crop yield satisfactory. 342 The Soils of Baltimore County CONGAREE SILT LOAM The surface soil of the Congaree silt loam is a brown or gray silt loam, frequently very micaceous. It has a depth of 8 to 15 inches. The subsoil to 36 inches is typically a brown loam or in places clay loam, but varies in color to yellow or yellowish brown. Frequently the lower subsoil is mottled with gray and rusty brown. There are some textural variations in this type. Xear the banks of the small streams the texture is usually loam, while adjacent to the uplands in very narrow strips of low wet land the soil is a grayish silt loam underlain by a mottled gray or bluish-gray and yellow or rusty brown silty clay loam subsoil. In some of the very narrow valleys or creek bottoms the soil is almost entirely a brown, micaceous loam to a depth of 2 or 3 feet. The Congaree silt loam occurs along streams throughout the county, occupying bottom lands which vary in width from 100 or 200 feet to more than one-fourth mile. In the southeastern or Coastal Plain part of the county the soil is grayer and resembles the Ochlockonee series, but on account of its small extent such areas are not mapped separately. The Congaree silt loam has a nearly level surface. In the wider bottoms certain narrow areas adjacent to the upland are slightly lower than near the stream. Drainage is fairly good except where water stands for some time, producing marshy conditions in places. The type ordinarily lies only 3 to 6 feet above the stream bed and overflows occur occasionally. The danger of crop loss through floods prevents extensive cultivation. Probably much less than 10 per cent of this soil is used for crops. Some corn is grown with fair yields. There are few farms in the county that do not include a small acreage of this type. Much of it is cleared or partly cleared of timber. Such areas make fine pasture. The forest growth consists of white oak, pin oak, shingle oak, some poplar and sycamore, and a small tree locally called ironwood. The type is used almost entirely for the pasturage of all kinds of stock, and is a very valuable soil for this purpose. The Congaree silt loam if properly drained and protected from over- flow is a valuable soil for corn and forage crops. It is naturally quite Maryland Geological Survey 343 productive, and with ditching and straightening and deepening of the streams more of it could be farmed. With better drainage conditions it would be well suited to the growing of vegetables. Just south of the reservoir at Loch Raven, in an area of perhaps 50 acres or more occupying a stream terrace approximately 25 feet above the river bed, the soil is a brown, heavy silt loam, 8 inches deep, underlain to 3 feet by a brown to bluish-gray silty clay loam. The surface is level, but the area lies above overflow and has good drainage. It is farmed and gives good yields of corn, potatoes, and other crops. Owing to the small extent of this soil it is included with the Conagree silt loam on the map. TIDAL MARSH The term Tidal marsh is applied to the narrow strips of wet lands along the lower courses of streams and estuaries of Chesapeake Bay. The soil material is a black to bluish or bluish-gray silt loam with faint mottlings, mixed with a mass of finely divided and more or less decomposed grass roots. The surface is covered with water most of the time. In its present condition the Tidal marsh has no agricultural value, Near Carroll Island, where some of the type lies rather high, the sur- face becomes dry at times and some marsh grass is mowed for hay, which is used for bedding. If thoroughly drained this soil might be well suited to growing onions and celery, but the cost of reclamation would probably be prohibitive under present conditions. UNCLASSIFIED CITY LAND The term Unclassified city land is applied to areas in Baltimore City and Sparrows Point and at the edge of Baltimore City, where the soil has been changed by excavations and fillings for buildings and other purposes. In much of the city the area is covered by buildings and pavings, while at the edge of the city much material has been dumped on the soil and has completely changed it. 344 The Soils of Baltimore County Summary Baltimore County lies in northeastern Maryland, reaching from Pennsylvania to Chesapeake Bay. It surrounds Baltimore City on all sides except where the city touches the waters of the Chesapeake. The area surveyed, including Baltimore City, covers 673 square miles, or 430,720 acres. The topography varies from nearly level or undulating to strongly rolling and hilly, the greater part beiny strongly rolling. Narrow, level bottom lands are developed along the streams. The elevation ranges from sea level along the coast to more than 900 feet in the northern part of the county, the greater part between 200 and 700 feet above sea level. All the drainage flows into Chesapeake Bay. Baltimore County had a population of 74,817 in 1920, all classed as rural. Baltimore City had a population of 733,826. The Official estimate of the population of Baltimore City as of January 15, 1929 is 836,522. The principal towns, all of them small, are Towson, Cockeys- ville, Lutherviile, Texas, Catonsville, and Sparrows Point. Transportation facilities are good throughout the southern half of the county, but the northern part has only one railroad. Excellent high- ways extend throughout the county. All parts of the county are connected by telephone. There are numerous churches and schools. Baltimore is the principal market for all the farm products. Some of these are reshipped to other markets, and a large quantity is used by canneries in and around the city. The climate is mild and healthful. The mean annual temperature as reported at Baltimore is 55.3° F., and the mean annual precipitation 43.3 inches. There is a normal growing season of 214 days. The agriculture of Baltimore County consists in the production of general-farm crops, including corn, wheat, and hay; dairy farming; the feeding of beef cattle; hog raising; and market gardening. The farm buildings are large and substantial, and the farms are well kept and fenced. Good work stock and improved farm machinery are used. Uniform farming methods are followed throughout the county. Farmers practice systematic crop rotation. Lime and commercial Maryland Geological Survey 345 fertilizers are generally applied to the land, especially for wheat and market-garden crops. Manure is used extensively, and market gar- deners use a large amount of garbage and sewage from the city. Farm labor is scarce and high priced. The greater part of Baltimore County lies within the Piedmont Plateau region. Approximately the southeastern fifth lies within the Coastal Plain. The soils of the Piedmont are formed from the weathering of schists, gneiss, granite, gabbro, serpentine, diabase, and to some extent lime- stone. These rocks produce soils of the Chester, Manor, Louisa, Cono- wingo, Montalto, Iredell, Mecklenburg, and Hagerstown series. From the unconsolidated deposits of the Coastal Plain the Sassafras, Susque- hanna, Leonardtown, Keyport, and Elkton soils are derived. The alluvial soils are grouped in the Congaree series and Tidal marsh. The Chester loam and Manor loam are the main soil types of the county. They are farmed and fertilized in much the same manner, and the farming methods generally followed throughout the county are practically the same as on these two leading types. The Chester loam is best suited to corn, wheat, and hay, and the Manor loam to corn, Irish potatoes, vegetables, and fruit. The Montalto clay loam is especially suited to the production of apples and other fruits and of wheat and hay. The Conowingo and Iredell silt loams seem best suited to grass and wheat. The Mecklen- burg loam is a good soil for corn, vegetables, and fruit. The Hagerstown loam is best suited to grass, wheat, alfalfa and corn. The Leonardtown silt loam and loam are good grass soils and under the best management are well adapted to wheat, corn, and vegetables. The Sassafras sandy loam and gravelly loam have a special adaptation for vegetables, berries, and small fruits. The Sassafras loam is a fine vegetable and corn soil and is fairly well adapted to wheat, alfalfa, and grass. The Sassafras silt loam gives good yields of hay, corn, and other general farm crops. This is also used successfully in the production of vegetables. The Keyport silt loam is a fine grass soil, and with good management is well adapted to vegetables and other crops. 346 The Soils of Baltimore County The soils of Baltimore County are on the whole rather strong and suited to a large variety of crops. They may be built up to a high state of productiveness. These factors, with the accessible good market, make the conditions favorable for general farming, dairying, market gardening, fruit growing, and poultry raising. CLIMATE OF BALTIMORE COUNTY BY EDWARD B. MATHEWS and ROSCOE XUNN Introductory Baltimore has had a station of the first order for 56 years with con- tinuous records of the principal elements of the weather, temperature, pressure, rainfall, sunshine, wind velocity, wind direction, and humidity since 1893, while less exact and comprehensive records of temperature and pressure are available for over one hundred years. The immense accumulation of statistical data for the years 1871-1903 has been criti- cally analyzed and reduced to generalized statements in the admirable work of Dr. O. L. Fassig, whose results have been published as Volume II of the Maryland State Weather Service.' Dr. Fassig's work has now been supplemented by the data that have accumulated during the last twenty-three years, 1904-1926, so that this discussion embraces the records for the whole period, 1871-1926, at Baltimore, Fallston, and Woodstock. The conclusions for Baltimore County weather here presented are largely based on these studies of Baltimore climate since "the weather conditions at Baltimore are typical of conditions within a wide area. Situated midway between the rigorous north and the mild south with the equable oceanic conditions on the east and the variable continental conditions on the west the climate of Baltimore County is especially favorable to human activities. Rainfall is abundant but not excessive and quite uniformly distributed throughout the year. Storms of destructive violence are rare and tornadoes almost unknown. The season of plant growth is long and sunshine is abundant without being oppressive." The actual weather conditions from day to day combined into average 1 The Climate and Weather of Baltimore by Oliver L. Fassig, Md. Weather Service, Vol. II, 1907. 515 pp., plates i-xxiv, 170 figs. 347 348 Climate of Baltimore County conditions by statistical studies define the characteristics of the climate. When the period of observations extends over a long term of years, as is the case for Baltimore, the climatic generalizations become of unusual value, since within the records of a century are included all the extremes of variation which are likely to be experienced in a lifetime. The elements comprising weather conditions include atmospheric pressure, temperature, humidity, clouds and rainfall, sunshine, winds, etc., and their quantitative variations day by day and throughout the year. These factors are modified somewhat locally by the configuration of the earth's surface, variations in elevation, presence of large bodies of water, character of the soil and forest cover. All of these are discussed in detail in the chapters on physiography, forests, and soils where it is shown that although Baltimore Count}' has a diversified surface the extremes are not very great. In the southeastern districts below the railroads the lands are flat, rising but slightly above the broad estuaries opening into Chesapeake Bay. Westward of the railroads the land rises rather abruptly, along the "fall-line" into a plateau from 500-800 feet in elevation in which are incised numerous valleys by the principal streams and their tributaries. Above the general level of the plateau rise a few ridges of slightly higher elevation, culminating in the northwestern part of Parrs Ridge along the Carroll County border. These local variations, with the exception perhaps of the Patapsco and Gunpowder valleys, have little influence on the general weather conditions, but the gradual rise of the land to the northwest away from the Bay shows a determining influence in the distribution of temperature and to a lesser degree of the rainfall. Since no adequate understanding of the weather conditions can be gained without some knowledge of the general and specific influences of the various climatic elements, the description of local conditions will be introduced by a brief discussion of the major factors — pressure, tem- perature, precipitation, etc. Atmospheric Pressure Variations in atmospheric pressure are the potent causes in producing movements of the air with the resultant storms and rainfall. The Maryland Geological Survey 349 difference in atmospheric pressure at a single locality, as shown by- changes in the height of the barometer seldom exceeds an inch within a period of several days and in the Middle Atlantic States is usually less than two inches. During the last fifty-six years the highest reading reduced to sea level, observed in Baltimore was 31.02 inches (27, 1, 27) and the lowest 28.73 inches or a difference of only 2.29 inches. This is less than the permanent differences in pressure between different parts of the State. Within these limits are diurnal, annual, and secular periodic changes more or less marked by irregular fluctuations due to the passage of storms or other movements of the atmosphere. Such periodic variations in pressure are seldom revealed by casual readings of the barometer but become manifest by careful analysis of barographic records and statistics. Diurnal wave. — In general the barometer is lowest about four in the afternoon and three in the morning and highest at ten in the morning and ten in the evening, the change due to the diurnal wave being less than 0.04 of an inch. This double diurnal wave is not local but charac- teristic of air pressures over the greater portion of the earth's surface. It is generally more marked in or near the tropics and diminishes in strength with increased distance from the equator. It is apparently due to the sun's rays heating the atmosphere on the rotating earth. Annual wave. — A similar but single wave is evident when the average barometric pressure readings for each day of the year are compared. The maximum occurs in January and the minimum in July. The maximum variation due to this cause deduced by Dr. Fassig from obser- vations recorded at Baltimore for over thirty years is approximately 0.14 inch. Between the diurnal and annual waves are slight irregular waves amounting to 0.08 to 0.19 inch every three or four days. Secular waves. — Besides the diurnal and annual waves of varying atmospheric pressure the records at Baltimore show waves with an average length from crest to crest of something over four years and possible waves whose crests occur at intervals of a quarter of a century or less. All of these changes show that the air is variable in its compres- sion from hour to hour, day to day and year to year, even when there 350 Climate of Baltimore County are no local cyclonic areas increasing the differences in atmospheric pressure. Temperature of the Atmosphere Temperature is perhaps the most influential climatic factor affecting human activities. While it is well known that this is primarily influenced by the latitude, or distance from the equator, and the seasons, other factors such as the distribution of land and water, height above sea level, prevailing winds, cloudiness, and differences in soil have a modifying effect on local values. The apparent or sensible temperature is also greatly modified by the humidity or degree of saturation of the air and by sudden changes in temperature due to shifts in the wind or other causes. Baltimore, situated slightly south of midway between the equator and the poles, and between the equable temperatures of the ocean and the variable temperatures of the land areas to the westward, has annual and summer temperatures 3° to 4° below the average of the entire globe and a winter temperature about 10° below. The changes ex- perienced here are primarily due to the passage of continental storms which move northeasterly across the United States and cause rapid changes in the wind directions. The southerly winds are usually warm and the west and northwest colder. In order to compare conditions it is customary to determine the average temperature for the days, months, and jrears and to discuss the variations from such normal values. Such average temperatures seldom indicate the actual conditions because of the variations in temperature from hour to hour and day to day, and the extremes are more noticeable than intermediate conditions. Thus a few hot days in summer accom- panied by a number of days slightly below normal may represent the average temperature but the impression made is of a monthly tempera- ture much higher than the normal. The same effect is produced for the day, season, or year. Diurnal variation. — The diurnal variation in general is represented by a simple curve which rises steadily from a minimum just before Maryland Geological Survey 351 sunrise to a maximum in the early afternoon hours and then descends gradually to the early morning minimum. In this respect it differs from the diurnal change in atmospheric pressure which has a double period with two maximum and minimum points each day. The thermographic records at Baltimore covering a period of more than ten years show that the high and low points vary slightly in time with the seasons. The lowest temperature of the day occurs usually just before sunrise while the highest temperature varies from 2.30 p.m. in November to 4.00 p.m. in June. The average temperature of the day occurs about 9 a.m. and 8.45 p.m. in the summer months and at 10.30 a.m. and 10 p.m. in the winter months. The average difference between the daily maximum and minimum is greatest in May (17.9°) and least in Decem- ber (13.2°). Considering further the temperature conditions at various hours of the day, under average conditions a temperature of 84° is limited to the afternoon hours from 2 p.m. to 4 p.m. during the month of July; a temperature of 75° between 10 a.m. and 7 p.m. in June, and from 1 p.m. to 5 p.m. in September. In winter the freezing temperature of 32° is limited to the months of January and February from midnight to 10 a.m. The foregoing values are averages from which there are frequent departures. The greatest difference between the lowest and highest temperatures of the day is greatest on clear days, especially in the spring months. Cloudiness reduces the daily range to less than one-half of that on a clear day. On a rainy day the difference between the highest and lowest temperature is usually not over two or three degrees. The clear day is cooler in winter and autumn, about average in the spring, and decidedly warmer in the summer. Cloudy and rainy days are just the opposite — warmer than the average in winter and autumn, cooler in the summer and spring. Snow on the ground makes the temperature about 10° lower. This is due to the more intense radiation from the surface during the night and the absorption of the sun's heat in melting the snow during the day. Such a snow covering prevents the radiation of heat from the earth and the penetration of frost into the ground 352 Climate of Baltimore County thereby protecting the winter wheat and other vegetation. Winds also modify the diurnal range in temperature by mixing the different strata of air which on a windless day differ in warmth, the lower strata next the earth being cooler in winter and hotter in summer. TABLE I. MEAN HOUHLV TEMPERATURE Jan. Feb. Mar. Apr. May June July Aug. Sept Oct. Nov. Dec. 31. 4 29 91,40 1 49 1 59 6 68 0 72 9 71 3 65 2 53 9 44 1 0- n oO U o 31 0 29 4 39 4 48 3 58 8 67 2 72 2 70 7 64 (i 53 3 43 7 0 ,4 - Q 30 6 2S.9|38 8 47 6 58 1 66 471 4 69 9 63 8 52 7 43 2 in ■ £ A 30 2 28.5 38 3 47 1 57 5 65 870 8 69 3 63 1 .52 1 12 . Q ■JO . 0 c CM 1 8 28.1 37 y 4t> 5 57 0 65 2i70 3 68 7 62 5 .51 7 42 3 00 4 6 29 6 27.9 37 6 46 4 57 4 66 170 6 68 8 62 2 51 3 42 0 33 0 7 29 4 27.8 37 s 47 4 59 0 68 2 72 4 70 4 63 1 51 6 41 9 32 9 8 29 7 28.4 38 8 49 5 61 3 70 5 74 7 73 0 65 7 53 6 42 8 33 3 9 30 6 29.7 40 5 51 7 63 4 72 8 77 2 75 4 68 056 0 44 8 34 5 10 32 0 31.3 42 2 53 7 65 2 74 6 79 1 77 7 70 5 58.4 46 7 36 0 11 33 7 33 1 44 0 55 6 67 1 76 3 80 9 79 8 72 6 60 6 4s 6 37 9 3.5 0 34 6 4.", 7 .57 1 68 4 77 5 82 4 si 0 74 2 62 3 50 2 39 4 1 36 0 35 8 47 0 58 2 69 5 7s 7,83 4 s2 1 75 3 63 4 51 4 40.7 2 36 8 36.9 48 2 .Id 0 70 5 79 6 s4 0 82 8 76 1 64.2 52 0 41.6 3 37 2 37.2 4s 7 59 6 70 7 79 9 s4 2 82 9 76 4 64.4 52 2 42 0 4 37 0 37.2 48 8 ,59 6 70 7 70 8 84 1 s2 6 76 3 64 0 51 6 41.5 5 36 .2 36 5 4s 0 59 .0 70 2 7s 9 83 1 si 6 75 1 62.8 50 4 40.5 6 35 4 35 3 47 0 .57 9 69 0 77 6 81 s Ml 5 73 4 61.2 49 2 39.5 7 34 .5 34 4 4.5 6 .56 2 67 0 75 .7 80 1 7s 8 71 6 59 5 48 1 38.6 8 34 0 33 6 44 5 .54 9 65 2 74 1 78 3 77 0 70 2 58.1 47 3 37.9 9 33 0 32.8 43 4 .53 6 63 7 72 6 76 6 7.5 6 68 6 56 9 46 4 37.1 10 32 8 32 2 42 5 52 562 6 71 3 7.5 6 74 4(17 5 55 9 45 .7 36 5 11 32 1 31 6 41 7 51 661 .5 70 2 74 .5 73 2 66 s .5.5 0 44 .9 35 9 Midnight 31 8 31 1 40 1 9 50 560 969 2 73 7|72 2 65 7 .54 2 44 2(35 2 This table shows the mean temperature for each hour of the day, based on the continuous record of a Richard thermograph for the ten- year period ending December 31, 1902. The thermograph record was corrected daily by direct observations of a mercurial thermometer at 8 a.m. and 8 p.m., and by the readings of a maximum and a minimum self-registering thermometer. The annual mean (55.0°) is the average value of over 87,000 hourly observations, and may be regarded as a true normal value for the period covered by the observations. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXI 5 101520 2530 5 10 15 2025 5 10 15 gO 25 30 5 10 15 20 2 530 5 10 1 5 20 25 30 5 ' 1 0 1 5 ^ Q ^ ^ ^ 1 Q 1 ^ ^ Q ^ 5 3 0 ^5 ^ 1 0 15 ^0 ?S 30 5 10 15 2025 30 5 IQ 15 2C 25 30 5 [Q 15 20 2530 51015202530 5 10 15 20 25 30 5 10 15 20 25 5 10 15 2025 30 5 10 15 20 25 30 5 10 15 2025 30 5 10 I5 2O25 30 5 10 15 20 2530 5 10 15 20 25 30 S 10 15 20 25 30 5 10 15 20 25 30 5 10 15 20 2530 5 10 15 20 25 30 Daily march of temperature and pressure. Based upon daily observations for 30 years. A. Average daily maximum temperature. B. Daily mean temperature. C. Average daily minimum tempera- ture. D. Daily mean barometric pressure. (After Fassig.) Maryland Geolo3ical Survey 353 TABLE II. MEAN DAILY TEMPERATURE (Corrected to hourly mean) Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 1 35 1 32 8 38 4 47 5 58 8 68 9 76 0 76 0 73 1 62 1 52 2 42 7 2 35 1 32 4 38 6 49 0 59 6 69 7 76 6 75 9 72 8 61 9 52 2 40 2 3 33 2 33 1 39 1 4s 2 59 4 70 8 77 5 75 7 73 0 62 6 49 8 30 9 4 32 8 33 0 38 8 49 0 60 0 71 1 77 5 76 0 72 7 63 3 40 1 30 2 5 33 1 30 3 37 9 49 8 60 7 70 9 76 S 76 9 72 5 62 7 40 3 39 4 6 33 3 32 4 38 6 50 5 61 7 71 5 77 0 77 2 72 7 62 1 40 5 39 8 7 35 5 34 0 40 6 50 7 61 7 70 4 76 9 77 5 72 9 59 9 49 4 40 0 8 35 0 34 1 40 4 50 2 61 6 70 5 77 3 77 3 72 2 59 5 40 5 39 7 9 33 9 33 8 41 2 49 4 63 1 70 0 77 3 76 9 71 0 59 8 40 5 39 1 10 33 2 33 9 43 1 49 6 63 3 70 9 77 7 77 3 70 5 60 0 49 2 37 5 11 33 4 34 5 42 2 51 0 63 7 71 6 77 6 76 9 69 8 60 4 48 3 38 2 12 33 9 35 1 43 s 52 0 63 4 71 8 77 8 76 3 70 7 58 2 4^ 2 39 0 13 32 2 34 8 43 9 52 0 63 6 71 4 77 7 75 4 70 0 57 3 47 1 39 9 14 33 2 35 8 42 0 53 6 62 6 72 2 77 5 75 3 68 3 57 6 45 5 38 1 15 33 5 35 6 40 8 53 0 63 3 72 6 77 9 75 4 67 8 58 5 45 5 36 1 16 34 5 34 8 41 5 53 0 63 5 72 5 78 9 75 1 69 1 60 1 45 8 35 5 17 34 2 35 2 40 9 53 1 63 7 72 7 78 3 75 2 69 0 59 0 45 5 36 1 18 34 0 35 7 41 4 54 2 64 5 73 0 78 4 74 9 68 3 58 2 46 4 35 8 19 33 6 35 4 43 9 55 7 65 8 73 7 77 2 75 1 68 8 58 7 45 7 35 5 20 34 6 36 0 44 2 55 3 66 2 74 7 77 2 75 2 67 5 56 2 44 2 34 6 21 37 5 36 7 43 5 55 6 66 3 75 4 77 6 75 5 66 s 55 2 44 0 36 7 22 37 3 38 1 44 2 56 5 66 4 74 8 76 8 74 9 66 1 55 1 45 2 37 4 23 36 0 37 4 44 8 57 8 66 4 74 4 77 9 74 4 66 0 55 1 44 6 38 1 24 33 5 35 7 44 5 57 5 65 8 75 7 77 4 75 0 65 9 .33 9 42 5 36 6 25 33 7 36 6 46 2 56 8 66 4 76 0 77 1 73 9 65 6 54 4 42 2 35 2 26 33 0 37 6 47 1 57 9 67 0 76 6 77 5 73 6 65 1 54 3 42 6 33 0 27 34 3 37 0 47 3 58 0 67 2 75 7 77 3 72 4 64 7 54 9 42 7 34 1 28 34 6 37 4 47 3 58 1 68 1 75 7 77 0 71 3 65 2 53 2 41 2 34 1 29 34 ()!36 2 45 8 57 7 67 6 76 2 77 5 72 4 65 2 52 8 40 3 33 9 30 34 2 46 9 60 1 68 5 75 3 77 S 73 1 63 5 52 2 39 3 34 3 31 34 6 47 4 68 7 76 7 73 2 51 (I 34 6 This table shows the mean temperature for each day of the year as derived from the daily maximum and minimum temperatures for 55 years, from 1871 to 1925. To the average daily values derived from these observations, corrections have been applied to reduce them to the true mean based on 24 hourly observations. The altitude of the ther- mometers varied from 40 to 100 feet above the ground. Variation in temperature from day to day is a climatic factor of the highest importance, especially to the weak and sickly. Large, and 354 Climate of Baltimore County especially sudden, changes of temperature within short periods are uncomfortable if not actually harmful. Fortunately such changes are not extreme in Baltimore and its vicinity. The Baltimore figures show that during most of the year the change for the average temperature I I 1 b ! 4 9 K II ■ 2 J ♦ S 6 — i \ - \ / - Sri — — 1 I 1 1 — A V — — • — — ■ jj ' ID Fig. 14. — Mean Hourly Temperature. (After Fassig) from one day to the next is less than 5° and that only 10 times a year is there more than 15 degrees difference. The change of average tempera- ture of two successive days has reached 20° in Baltimore 50 times in thirty years. Such marked changes usually occur in the winter, late Maryland Geological Survey 355 fall, or early spring and never between June and September. This, of course, does not represent the change in temperature from hour to hour or the exceptional changes that sometimes occur. These will be dis- cussed more full}' later. r 2' 3* 4* 5* 6" 7* 8" 9" 10' Year Fig. 15. — Total Seasonal and Annual Frequency of Stated Diurnal Changes of Temperature. (After Fassig.) (a) Total Annual frequency. (d) Total Spring frequency. (6) " Summer " (e) " Winter (c) " Autumn This figure shows the total number of stated changes in the mean daily tem- perature during each season and during the year. The upper horizontal line of figures indicates the degree of change, and the marginal figures to the right of the diagram show the frequency of stated changes. With a long record of over a hundred years of daily observations it is possible to gain a well established value for the normal temperature. 356 Climate of Baltimore County This is 55.7° for Baltimore and somewhat less for the major part of Baltimore County. With this as a starting point it is possible to test the question of periodic changes and the frequently-held impression that in earlier times the winters were colder and the summers hotter or the opposite. The figures show no progressive increase or decrease for the entire period either in the monthly, seasonal, or annual means. Monthly mean temperatures. — The average monthly temperature has been determined for each of the months of the year for periods of over a hundred years at Baltimore and for the last fifty-six years at Woodstock and Fallston, Harford County, as follows: e a >-> J3 i fa u a a Apr. Muy 0 = 3 1-3 73.2 69.5 70 9 j>. "a —> Aug. a o GO o O Nov. © Q •a 3 a a < 55.7 52.4 53 2 Baltimore, 1817-1926 Fallston, 1871-1926 Woodstock. 1871-1926 34.8 31.0 31 9 35.6 31 .7 33.0 43.2 39.8 41.4 54.0 50.8 52.4 64 0 61.3 63.1 77.7 74 0 75.2 75.8 72.0 72.7 68.8 66 0 66.1 57.0 55.1 54 9 46.6 43 4 43.2 37.3 33 8 34 2 How the monthly temperatures vary from the averages for Balti- more from 1860 to 1904 is shown in plate XXI (pi. vi of M. W. S. ii). The variations at Woodstock and Fallston are similar but not exactly the same. In general the departure from the average annual is not over a degree or so. In the summer a departure of more than two degrees is exceptional, and a similar departure of five or six degrees in the winter is unusual. Monthly averages give a good idea of the temperature conditions for crops but seldom compare with our recollec- tions of hot and cold periods. A month with 10 consecutive days of excessively hot weather will be remembered as a hot month but it will not show in the monthly average as such if equal periods of mod- erately cool weather occur. TABLE III. — MEAN TEMPERATURES, BALTIMORE, MARYLAND Year 32.7 39.4 29.2 38 35 7 37 38 .9 30 .8 43 44.0 43 4 41 Monthly and Annual Mean Temperatures 29 6 34.1 34.2 40.8 45 31.6 39.2 32.0 41.6 43 34 4 29 4 37.6 41 31 .8 36 24.6 34 37.5 34 31.3 26 33.6 36 31 .6 36 37.0 35 33.4 28 36 .2 33 39.7 35.9 34 9 37 1 35 1 34 2 33.2 39.1 29.6 28 40.6 37 30.0 39 35.0 40 31 .5 32 42 4 40 36 9 55 2 39.0 51.8 43 4 46 4 4 38 8 48 6 63 6 73 4 39.0 51 0,64 39.4j52.8'62 4149.0 58.2 63 2 43 4 51 6 65 6 42.6'55.0 70 47.6 58.8 65 4 74 0 75 8 2 75 3 81.5 73 5 79 4 75 2 77 3 77 6 X 5 8 80 0 78.4 28 8 35 33 0 42 34.9 29.5 43 31.6 30 4 46 33.6 37.8 49 27 .4 28 .6 41 30.8 27.3 44 40.2 34.2 37 36.5 28.8 47 35.031.2 35 .6 42 .6141 34.0 34 .8 49 .6 51.3 67 2 52 3 59 0 51 .8 .8 52.5 .5 54.6 63 .2 55.6 62 3 51.5 .2 52 6 62 .4 54.6 65 6 54 0 64 38 6 56 S 37 4 51 0 40 3 52 4 48.2 4 0 52.4 40.6 52.8 56 38.1 8 45 .0 53 2 48.6 51 4 41 .7 53 38.6 55 47.1 0 4 74.4 0:69 8 80 8 2 73.2 78.1 9 75.6:78.1 8 73.1 0 62.2 6 63.4 6 61.4 65.3 62.4 69.0 0 62.8 63.9 8 64.5 065.2 71.0 74.2 74.6 .5 73 .3 .5 70.4 .8 72 .2 .8 73 .2 .8 71.5 .0 75 .0 8 50.7 7 53.3 6 54 4 0 49.9]65 54 .2 65 6 56.1 65 0 47.8 59 38.4 36.6 40.8 51 25.831.5 40.2 43.5 36 r.6|30 56 5 65 8 53.9 64 8 58.2 62 36.0 38 39.5 33 35.3i32 24.2'35 38.2 37.6 46.2 52 4 39.4 6 37.0 52 2 43 .2 53 47.2|53 48.8 55.6 64 2 39.6 53.0 68 59.2 71.5 75.9 72.4 73.0 74.2 71.3 70.1 73.8 75.2 6 72.3 2 67.2 .0 69 .6 65 72.2 73.6 66.7 73.6 74.1 70.4 4 73 62.2 9 73 0 74 6 69 273 3 70 9 73 28.6'32 .8 44.8 52 8 60 .8 72 I 8 59. 0 69. 9|64. 60. 79 2 77.4 77.0 75.5 80.3 75.0 81.0 74.6 76 6 75 4 73 .4 80 .1 72.6 80.4 71.4 75 .6 77 2 63 79 4169 74.6j67 72 3 70 73 3 65 75.4j65 77.2 68 75 8 69 74.8 64 75 5 53 1 50.7 4 58 2 44 7 33 5 56.1 .0 57 2 55.0 41 0 .0 56 5 55.2l42.l|37.2 52 251 3!59 2 58 9 46 .8 34 .9 56 .8 39 .6 56 7 6 62 8 56.0 41.8 31.0 56.5 41.4 56.2 76 77.4,63 69.3 61 8 65 1 57 72.4 60 67.4 56 70.159 l|65.2 56 2 65 .3 8 66 .5 0 74.6 66.6 57 73 80.4 68 4 57 6 48 8 43 6 44.2 36 6 48.3 38 47.0 37 46.4 38 47.0 31 6 45.6 37 47.9 37 47.7 46 0 48.2 34 70 .6 54 8 55 8 70 .6 57 72 .3 53 68.4 54 68.8 58 71 .4 58 6 67 .0 58 73.8 62 7 68 6 67 9 68 6 63 2 69 72 467 4 71 .4 56.7 41 .2 58.6 51 .2 58.4 43 .2 54.8 0 58.2 .4 56.2 .9 53.2 4 59.8 46 7 54 8 51 .6 60.8 79.2 76 76.5 74 78.6 75 76.3 77 6 76.9 74 4 78.0 76 0 77.276 9 75 .4 78 4 78 0 74 6'76.0 74 2 70.4 58 4 70.6 60 2 68.459 0 66.8 61 2 71 5 59 8 67.6j57 4164 .5152 3 65.0 60 6 70 4 63 8 69 8 63 I 1 46.0 27.4 48. 2^3 .3 44.2 43.8 0 43.6 43.4 47.1 51 .0 36 46.3 38 0 44.6 36 47.4 37 0 49.6 37.2 38.9 8 32 .3 50 .3 4 38.3 51.3 1 32.3 51.5 6 57.1 2 55.7 855 9 56.4 4 54.5 6 54.2 0 55.1 53.8 0 55.8 6 56 43.7 55.5 33 38.6 5 37 39 55.9 2 54.2 4 55.8 6 55.2 2 56.3 4 55.1 57.0 8 35. 34. 33 31 38 36 39 37 33 Mean Temperatures 37 4 57 .3 75 74 74 77 76 75 32.9 53.4 75 0 35 31.6 53 .6 75 .8 39.5 52 51 37.5 53 33.7 51 33.6 53 34.6 34 .0 50 35.8 54 6 44 5 54.4 33.9 52.1 8 55 .2 0 55.0 35.4 56 6 52.6 29.7 52 54.7 29 9 54 3j56.0 37.6 52 0 53 6 33 9j56.2 2,55.8 2 55.7 35.1 38 34.0 56 4 55 .4 36 4 55.935 0 55 .2 36 4 53 4 34 55.4 56.5 8 54.4 9 57 .2 .8 54.3 54.2 58.7 58.3 57.7 4 55 .5 53 52.3 50.8 51.4 55.3 8 51.9 .3 54 .6 .9 53.6 54.6 53.3 .6 52.9 9 51 56 7 53 63 75.2 58 74.8 57 74.8 76.3 56 58 73.2 75.8 74 74 0 56 74 8 57 72 76 74 74 74 75.1 73.8 76 76 78 76 .6 55 32 4 54 .9 74 .6 59 2 72.1 73.5 6 74 .5 57 75.4 58 72 .3 56 75.6 58 74 8 53 74.6 58 53.7 9 53.4 56.4 53.5175 9 53 .6 73 2 52 1 74 5'52 .1|75 3 56 5 74 2 54 7 75 1870- 1 1871- 2 1872- 3 1873- 4 1874- 5 1875- 6 1876- 7 1877- 8 1878- 9 1879- 80 60 1880- 1 1881- 2 .0 1882-3 1 1883-4 B 1884-5 8| 1885-6 1886-7 1837-8 1888- 9 1889- 90 5 56.5 55.3 7 55.7 6 57.1 8 57.6 58.1 57.8 6 58 .0 57.7 61.8 1890- 1 1891- 2 1892- 3 1893- 4 1894- 5 1895- 6 1896- 7 1897- 8 1898- 9 1899- 00 1900- 1 1901- 2 1902- 3 1903- 4 1904- 5 1905- 6 .2] 1906-7 .211907-8 .0 1908-9 .3 1909-10 42 6 31 3 43.8 41 .6156. 6 35. 6 48.640.655.0 32. 6 49.0 41.4 57.940 .1 4 47.0 33.4 55.4 36 .4 6 47.0 35 6 47.3 36 6 44.6 28 8 47 .2 41 .9155.7 29 0'47.4 33.2 56.6 39 l'47.1!39 .8 55 .2:31.5'52 .8 74.5 60 0 1919-20 .3 57.5 1910-11 .1 59.9 1911-12 8;59.0' 1912-13 9j58 .4 1913-14 .9 59 .4 1914-15 .7;58.2|l915-16 .5 57.2 1916-17 ,9'57 .7 1917-18 .3 60 .3! 1918-19 I 357 358 Climate of Baltimore County TABLE III. — MEAN TEMPERATURES, BALTIMORE, MARYLAND — Concluded Monthly and Annual Mean Temperatures ■s. 74 .5 57 8 48 1 70 8 60 6 49.0 37. 37 37 0 39 .0 54 6 58 6 63 .1 75 0 80 2 73 .9 32.3|38 4 44 8 55 8 67 2 75 1 77 0 74 1 36 6 32 4 44 5 53 6 63 8 76 7 76 7 74 8 70 4 57 4 46 4 45 34 .8^4 6 43 0 52 2 60 2 71 2 76 1 76 0 65 4 59 4 47 0 36 33 .0 41 .8 46 . 1 56 .4 61 .2 78 .7 77 .2 74 .7 73 .4 52 .7t« .4 37 34 5 35 6 39 8 51 6 64 5,69.7 77.4 76.8 69.6 58.0 45 .6 33 Mean Temperatures 35 8 43 7 54 2 36 .3 37 .7 46 1 55 7 65 5 75 0 78 34 1 36.7 34.7 35 2 35.1 42 3 54 3 36 3 43 8 53 .4 64.2 62.0 72 64.2 72 6 72.6 73 3 6 78 .0 69 8 57 3 75 4 67 1 55 3 48 3 40 .8 57 .4 38 .3 55 8 77 2 58 5 1821-30 45.1 35.3 55 0 35. 1<54 .0 75 2 55 8 1831-40 3 37 5 55 3[36 4 52 9 75 3 56 5 1841-50 6 77 4 75 .9,68 6 54 78.0 75.8 68.6 57.1' 35 7 42 7 54 6 63 9 74 0 78 6 76 6 69 8 57 .0 47 1 36 9 56 .0 35 9 53 7 76 4 58 0 1861-70 36 .6 41 .9 52 9,64 .6 74 .0 78 .7 75 .6 67 .1 57 .1 .7140.8 53.1 64. 2;72 8,77 .2 74 8 68. 7 58 6 38 35.1 33 33.5 3 34. 34. 0 32 7 34 5 44 .9 53 5[63 . 8 71 .4177.4 4 42.7 53.8 65.1 72.3 77.2 0 47 35 4 36.1 43 6 54 6 63.8 73 34 .2 35 .1 42 .7 53 5 64.2 72.9 34 8 35.6 43 2 54 0 64 0 73.2 I I I 5 78 1 77.4 77 7 44 1 75 9 69 6 57 0 46 .1 74.3:69. 1 57.2 46.1 75.8 68.5 60 2 5S 2 38 4 56 9 35 4 56 6 35 8 54.7 38 3 56 5 37 6 54 7 35 6 58 8 9 55 9 5 54 0 3 51 8 2 54 6 8 52 0 4 60 1 1920-1 4 60.1 1921-2 1 58 1 1922-3 4 57 3 1923-4 9 57 2 1924-5 6 57 7 1925-6 47 4 37 .7 55 8 36 2 53 8 75 7 57 .7 1851-60 5 36 .055 38.2 55 37 .8 55.3 3 36 35.1 4 35. 54.9 2 53.1 76 1 56 2(1871-80 4 52 7j74 .9 57 9 1881-90 35 3 53.1 75.2 57 6 1891-00 34.8 54.lj74.4 57 5 1901-10 9 46 .9 37 .2 55 .8 34 .7 53 .9 75 1 58 8 1911-20 76 .4 68.7 56.0 47.0 37.7 55.9 36.4 54 0 76 .0 57 2 1817-1870 75 2 68 8 57 8 46 2 37.0 55 4 35 8 53 5 75 2 57 6 1871-1926 75.8 68.8:57.0 46.6 37.3 55.7 36 o'53.8'75 6 57 3 1817-1826 I I I I I I I I I I A study of months and seasons in which the average temperature of the month rose decidedly above the normal or fell below it shows the following for Baltimore. Maryland Geological Survey 359 WARM MONTHS AND SEASONS Iu excess of 6° 6° 6° 5° 4° 4° 3° 3° 4° 4° 4° 5° 4° 3° 2° 3° 2° Year 1824, 1828, 1843, 1820, 1827, 1828, 1825, 1826, 1859, 1817, 1822, 1823, 1822, 1826, 1833, 1918. 1828, 1858, 1865, 1822, 1830, 1834, 1887. 1819, 1821, 1822, 1872, 1900. 1826, 1865, 1881, 1855, 1879, 1881, 1822, 1830, 1849, 1824, 1827, 1829, 1923. 1858, 1870, 1834, 1857, 1865, 1903, 1827, 1865, 1848, 1864, 1870, 1925. 1838, 1856, 1880, 1890, 1913. 1890, 1909, 1925. 1910, 1921. 1915. 1865, 1880, 1896, 1911, 1868, 1870, 1872, 1878, 1827, 1828, 1830, 1864, 1868, 1870, 1900, 1921, 1925. 1882, 1900, 1914, 1917, 1919. 1850, 1854, 1866, 1896, 1902, 1909. 1848, 1857, 1877, 1881, 1889, 1891, 1823-4, 1824-5, 1827-8, 1849-50, 1850-1, 1857-8, 1869-70, 1879-80, 1889-90, 1912-13. 1822, 1826, 1827, 1831, 1865, 1871, 1921. 1819, 1821, 1822, 1827, 1828, 1830, 1838, 1868, 1870, 1872, 1900. 1822, 1830, 1854, 1855, 1881, 1900. 1822, 1826, 1827, 1828, 1865, 1870, 1913, 1921. 360 Climate of Baltimore County COLD MONTHS AND SEASONS Month Defi- ciency more th&n Year - 0 1 fi91 1 Q.ATI 1 ftr»A 1 ft*V7 1 ftfi7 1 IGfiA 1019 1Q1 ft LnZl, IrvfU, 1?V>0, LoOi , loO/, loVM, iyU4T l.flZ, AyiO, loon 1 ■ i . hriln vi' 0 1 COO ICIrl Tfllfi 1 Q -£7 1C7S IOC" 1 0QE 1 CQQ 10/11 loZil, looD, looo, 15O0, lo/0, locSO, lo^D, 1533, lyui, lOfll ion^ lOOT March 6° 1836, 1843, 1856, 1872, 1885, 1916. April 5° 1841, 1857, 1874, 1875, 1907. May 4° 1820, 1841, 1843, 1861, 1882, 1907, 1917. June 4° 1836, 1862, 1903, 1907. July 3° 1862, 1888, 1891, 1895. August 3° 1836, 1861, 1866, 1874, 1903. September 4° 1835, 1840, 1863, 1871, 1879, 1917. October 4° 1819, 1820, 1834, 1836, 1838, 1841, 1844, 1859, 1863, 1876, 1888, 1925. November 4° 1820, 1838, 1839, 1842, 1844, 1873, 1875, 1880, 1901. December 5° 1831, 1840, 1845, 1872, 1876, 1880, 1886, 1904, 1910, 1917. Winter Spring Summer Autumn Year 4° 3° 2° 3° 2° 1855-6, 1866-7, 1880-1, 1892-3, 1903-4, 1904-5, 1917-18, 1919-20. 1836, 1841, 1843, 1857, 1874, 1875. 1836, 1846, 1862, 1886, 1891, 1903, 1904, 1907. 1836, 1842, 1844, 1876. 1836, 1841, 1863, 1875, 1893, 1904, 1907, 1917. Extremes of temperature. — A consideration of the cold and warm months and seasons leads naturally to a study of the extremes of tem- perature reached in Baltimore and its vicinity. The general condi- tions are shown in Plate XXII. These differ from the averages and range in the Baltimore records from a minimum of 7° below zero (Feb. 10, 1899) to 105° above (Aug. 6, 1918). The greatest variability in extreme conditions occurs in the winter months with a gradual decrease to more uniform conditions in the summer. At Baltimore during the hot spell of Aug. 5-9, 1918, all the existing records of high temperature were broken, while the lowest temperatures recorded were reached in the cold spell of February, 1899. The records at stations outside of Baltimore show similar extremes, but the values are differ- ent. At Woodstock the temperature was 103° in Aug. 1918 and — 14 in MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXII 5 10 15 20 25 30 5 10 15 20 25 5 10 15 20 25 30 5 10 15 20 2530 5 10 15 2025 30 5 10 15 20 25 30 5 «0 15 ?0 25 30 5 iQ '5 20 25 30 5 10 15 20 25 30 5 10 15 20 25 30 5 10 15 2025 30 5 10 15 2&2530 Daily march of temperature. Based upon daily observations for 30 years. A. Daily maximum temperature. B. Daily mean temperature. C. Daily minimum temperature. D. Extreme range of temperature. E. Average daily range of temperature. (After Fassig.) Maryland Geological Survey 361 Jan. 1893 and 1912; at Fallston 103° in Aug. 1918 and -14 in Feb- ruary 1899. The variability of temperature conditions during the last years of the nineteenth century and the first of the twentieth were exceptional. March, 1921, was the warmest March in 56 years while the summer of 1903 was the coolest and the winter of 1917-18 the coldest in a hundred years. The absolute extremes in temperature at Baltimore during the last 56 years (1871-1926) are given in the following table: ABSOLUTE EXTREMES OF TEMPERATURE 1871-1926 Absolute Max. Year Day Absolute Min. Year Day Absolute Range December 73° 1873 4 -3° 1880 30 76° January 74 1907 7 -6 1881 1 80 February 78 1874 23 -7 1899 10 85 March 88 1921 21 5 1873 4 83 94 1896 18 15 1923 1 79 May 98 1925 23 34 1876 1 64 June 101 1925 5 46 1913 9 55 July 104 1898 3 55 1891 8 49 August 105 1918 6 51 1890 24 54 101 1881 7 39 1888 30 62 October 92 1919 3 30 1876 16 62 79 1900 21 15 1880 22 64 78 1874 Feb. 23 -7 1899 Feb. 10 85 98 1925 May 23 5 1873 Mar. 4 93 105 1918 Aug. 6 46 1913 June 9 59 Autumn 101 1881 Sept. 7 15 1880 Nov. 22 86 Year 105 1918 Aug. 6 -7 1899 Feb. 10 112 The highest and lowest temperatures recorded during each month and year for the same period, 1871-1926, at Baltimore are shown in tables IV and V with the average values for each ten-year period and for the entire period. 362 Climate of Baltimore County TABLE IV. — MONTHLY MAXIMUM TEMPERATURES c a >-t ji o Ek i April May June July Aug. Sept. o Nov. S M Annual Extreme 1871 63 66 71 85 90 91 92 91 81 78 69 53 92 1872 56 61 65 88 89 94 97 96 94 80 63 55 97 1873 58 62 68 75 89 95 96 94 93 73 64 73 96 1874 69 78 72 68 89 98 96 97 90 78 71 67 98 1875 52 59 63 74 88 97 96 88 92 77 66 67 97 1876 71 65 69 75 88 95 99 90 88 77 76 56 99 1877 54 63 65 80 92 95 93 94 88 80 68 67 95 1878 57 63 72 79 85 92 98 92 87 80 61 61 98 1879 64 58 71 83 94 94 99 92 85 89 78 63 99 1880 65 67 76 80 93 95 99 91 91 81 69 56 99 1881 45 64 59 84 95 92 96 98 101 89 71 71 101 1882 59 59 69 82 83 97 93 90 88 78 73 51 97 1883 50 64 65 74 86 90 96 92 81 82 71 60 96 1884 52 68 64 80 89 93 95 94 93 89 71 66 95 1885 65 50 68 82 82 95 99 94 86 76 74 64 99 1886 57 67 71 88 88 89 92 92 91 82 73 52 92 1887 65 72 57 85 87 94 102 91 88 85 69 59 102 1888 50 60 74 90 86 94 94 96 84 74 74 58 96 1889 60 48 68 80 93 91 93 90 84 82 70 73 93 1890 73 74 77 83 87 93 98 95 87 78 73 59 98 1891 60 73 60 86 88 94 89 94 90 85 64 67 94 1892 58 57 65 83 87 94 99 95 88 83 70 64 99 1893 52 61 62 81 on 89 no 98 96 90 oo o« 84 67 no 1894 57 59 82 79 87 98 97 93 94 85 70 59 98 1895 60 62 72 86 95 97 95 96 96 74 77 61 97 1896 59 61 69 94 96 93 96 98 94 77 75 66 98 1897 60 56 72 84 84 95 94 90 97 90 75 66 97 1898 60 65 77 81 92 98 104 95 97 84 67 66 104 1899 59 60 74 80 90 98 96 97 94 78 72 67 98 1900 62 65 67 84 94 93 100 100 95 85 79 62 100 1901 64 49 74 86 83 99 103 93 92 81 65 65 103 1902 48 59 77 89 90 94 99 91 92 80 76 59 99 1903 57 71 72 91 92 88 96 97 89 83 75 52 97 1904 58 64 70 80 89 95 97 89 87 86 66 58 97 1905 64 49 80 81 87 95 98 90 88 87 71 60 98 Maryland Geological Survey 363 TABLE IV. — MONTHLY MAXIMUM TEMPERATURES — Concluded Means. 1871-1880.. 1881-1890.. 1891-1900.. 1901-1910 . 1911-1920.. 1921-1926.. 1871-1926 . c 08 ji a Murch April May June July e| 3 < 0. OB CO o O Nov. a 9 O Annual Extreme 64 61 65 87 94 94 91 96 94 80 65 68 96 74 54 86 80 84 90 93 91 90 79 63 66 93 57 66 80 87 89 98 97 95 86 85 71 69 98 61 70 74 89 90 94 94 98 82 80 78 62 98 58 67 83 92 85 95 95 90 96 90 64 58 96 62 64 74 74 95 99 98 98 89 78 71 61 99 59 58 72 80 89 93 94 92 94 85 76 71 94 68 68 78 84 91 97 98 98 92 77 76 63 98 72 57 75 85 94 96 99 97 94 85 79 63 99 58 59 60 89 85 90 95 96 93 80 76 58 96 71 58 64 76 92 86 93 98 94 86 75 70 98 57 64 78 85 86 94 99 98 83 76 70 49 99 52 61 78 80 94 96 94 105 82 82 69 67 105 64 59 75 73 93 95 102 94 95 92 73 68 102 58 53 76 82 84 97 93 91 87 85 72 68 97 66 73 88 80 90 96 96 94 96 78 75 60 96 61 74 78 89 89 93 95 92 95 91 "TO 72 61 95 64 54 80 84 90 100 99 96 86 82 66 65 100 60 56 75 80 85 96 95 100 94 84 76 66 100 55 67 73 88 98 101 97 93 92 76 69 59 101 64 57 76 85 87 92 102 98 92 87 70 51 102 60.9 64 2 69.2 78.7 89.7 94.6 96.5 92.5 88.9 79.3 68.5 61.8 97. 57.6 62.6 67.2 82.8 87.6 92.8 95.8 93.2 88.3 81.5 71.9 61.3 96. 58.6 61.9 70.0 83.8 90.2 95.8 96.6 94.8 93.3 82.5 71.1 64.5 98. 60.5 61.0 76.1 86.2 88.3 94.2 96.3 93.0 89.6 83.1 69.4 61.7 97. 62.1 60.1 73.0 80.8 90.3 94.3 96.5 96.7 90.3 82.6 73.7 63.8 98. 61.7 63.5 78.3 84.3 89.8 96.3 97.3 95.5 92.5 83.0 71.3 60.3 99. 60.1 62.1 71.9 82.6 89.3 94.6 96.4 94.2 90.3 81.9 71.0 62.4 97. 364 Climate of Baltimore County TABLE V. — MONTHLY MINIMUM TEMPERATURES c 3 n St ■ J3 | April >> l «S e = >-> July M 9 ■< c. o oa 3 o Nov. d o Q Annual Extreme 1871 14 10 36 42 51 62 60 63 45 40 28 5 5 1872 11 15 9 38 48 58 68 62 50 38 17 6 6 1873 -4 2 5 38 44 49 62 57 40 30 22 22 -4 1874 13 15 23 27 41 54 62 52 53 35 24 21 13 1875 -2 4 19 24 42 54 62 58 43 34 16 12 -2 1876 17 12 12 30 34 51 59 55 45 30 25 1 1 1877 1 18 9 32 41 55 64 63 48 41 25 22 1 1878 6 20 21 42 43 51 65 59 47 35 33 15 6 1879 0 12 24 29 43 52 60 56 40 30 20 13 0 1880 17 15 22 30 38 52 62 61 50 35 15 -3 -3 1881 -6 4 27 25 46 55 65 60 59 39 24 24 -6 1882 7 23 26 29 38 53 59 57 48 44 26 10 7 1883 11 22 16 30 45 55 62 59 46 40 23 17 11 1884 8 10 14 34 45 52 60 59 49 35 26 9 8 1885 10 3 12 32 44 56 56 53 46 38 32 15 3 1886 2 -1 15 34 45 52 59 58 50 36 26 15 -1 1887 7 21 21 30 51 52 67 55 42 32 25 16 7 1888 9 11 12 33 41 52 57 55 39 36 25 16 9 1889 20 3 28 34 43 52 61 58 46 34 28 23 3 1890 20 23 12 31 43 55 55 51 46 36 26 18 12 1891 21 16 16 30 40 47 55 54 51 33 18 17 16 1892 12 14 20 32 46 54 58 60 49 34 21 14 12 1893 1 11 16 ou 45 57 oo 57 44 31 99 18 i X 1894 18 8 20 30 43 47 56 57 45 36 24 7 7 1895 9 1 21 34 40 53 55 57 46 34 26 14 1 1 COA y c 0 i £ 31 47 04 61 ZA 4t> OD 29 1 A 14 5 1897 8 18 28 29 44 48 62 60 45 38 27 16 8 1898 17 10 27 26 40 55 57 59 52 34 24 14 10 1899 6 -7 26 29 47 55 59 58 42 34 31 9 -7 1900 10 8 12 30 40 55 58 61 50 36 28 15 8 1901 14 14 13 37 47 52 64 61 46 37 24 11 11 1902 17 13 20 35 43 53 62 55 48 34 32 18 13 1903 12 5 29 27 37 53 59 58 43 35 18 11 5 1904 2 5 20 27 43 50 57 55 40 31 23 12 2 1905 6 5 20 33 46 53 62 56 45 36 24 20 5 Maryland Geological Survey 365 TABLE V. — MONTHLY MINIMUM TEMPERATURES — Concluded c 3 ►a .2 9 h - s April May June July be < =. to -+3 O Nov. 8 Q Annual Extreme 1906 17 8 20 01 o ^ OO 63 51 33 13 Q O 1907 11 9 21 23 39 47 59 CQ Do 46 OO 66 29 9 1908 10 9 27 30 40 55 64 55 AT 47 Oft oy 22 oo 2.6 9 1909 12 17 24 28 41 56 58 CO DO AT 47 OK 35 32 9 9 1910 13 8 28 ATI n Tl 48 fil 57 CO 5o oo 61 *SO 1 o Q O 1911 20 20 14 97 41 =.7 Of 58 49 41 99 26 1 X 1912 -2 6 19 32 43 52 61 57 46 42 28 20 -2 1913 25 14 18 35 40 46 61 59 AT 47 OT 67 29 25 14 1914 5 8 15 31 43 55 57 57 A C 4d oo 66 26 5 5 1915 16 17 oo 23 32 43 48 61 D6 AC 4o oo oo 29 oo 16 1916 10 8 13 32 ro Do OU 59 46 40 9^ 13 Q O 1917 15 4 22 28 42 53 63 57 43 30 LO -2 o Li 1918 4 0 22 33 43 52 58 58 46 40 9ft 25 U 1919 11 22 29 25 46 54 60 58 51 A 1 41 ol 7 7 i 1920 9 8 18 32 43 54 56 58 49 orv 39 Ok AO 22 o o 1921 10 20 8 26 31 45 54 66 59 60 38 31 12 10 8 1922 13 24 34 46 59 61 59 47 37 29 16 1923 20 12 18 15 38 58 59 55 48 39 32 24 12 1924 7 18 26 28 45 53 60 58 45 36 26 15 7 1925 4 18 12 34 40 56 59 56 49 30 28 13 4 1926 8 15 18 30 43 49 60 59 51 36 26 11 8 Means 1871-1880 7.3 12.3 18.033.2 42.5 53.8 62.4 58.6 46.1 34.8 22.5 11.4 2.3 1881-1890 8.8 11.9 18.3 31.2 44.153.4 60.1156.5 47.137.0 26.1 16.3 5.3 1891-1900 11.1 8.4 20.2 30.7 43.2 .52 . 5 57.9 57 . 7 47.0!34.6 25.0 13.8 6.1 1901-1910 11.4 9.3i22.2 31.1 41.8 52.1 60.4 57.6 46.6 ,34.5 26.4 14.9 7.9 1911-1920 11.3 10.7119.3 30.7 43 1 52 4 59.8 57.7 46.8 38.1 26.6 16.3 6.8 1921-1926 10.3 15.2|20.7 28.7 42.8 54.8 60.8 57.7 50.0 36.0 28.7 15.2 8.2 1871-1926 10.0 ll.o|l9.7 31.1 42.9 53.1 60.2 57.6 47.1 35.8 25.7 14.6 5.9 366 Climate of Baltimore County FREQUENCY OF DAYS WITH FROST The frequency of occurrence of days with a temperature of freezing, especially in the spring and autumn is a subject of great practical importance in agricultural and commercial affairs. Light frosts occur, especially in low places, when the temperature records show a minimum of 35° or even 40°. This is due to the fact that the thermometers are placed in "shelters" above the ground; at the ground surface the tem- JM fit Mcm Am Mar J«M Jvl» Autt Scrr Oct Nov OtC Year. 3>- Fig. 16. — Greatest Daily Range of Temperature perature may fall considerably below that of the air but a few feet above the surface. This discrepancy is particularly marked when there is considerable moisture in the air. Early records of first and last frosts are deduced from thermometer readings but the actual observation of frost on the dates recorded has been used since the establishment of the Maryland Weather Service in 1892. The number of days with frost or a minimum temperature of 32° or below varies from year to year and from place to place. The greatest number of frost days recorded in a Maryland Geological Survey 367 single year was 143 at Woodstock during 1917. At the same station in 1913 the record was only 74 days. An average year or winter season in Baltimore County would probably have 110 to 115 days when the lowest temperature of the day will be below freezing and 15 to 20 cold days with a minimum temperature below 14°. The winter temperature in the northern part of the county is usually 4° to 5° lower than the temperature of the low areas along the Bay. This difference in tem- perature between the different parts of the county persists throughout the year but is less marked in the summer months. With these differ- ences in mind, it is possible to consider the duration of periods of con- secutive days in which the minimum temperature was below 32°. According to the Baltimore records the longest period of this char- acter was in the winter of 1917-1918 when the minimum temperature was 32° or below every day from December 25 to February 6, or 44 days. During a number of years the longest period was only 9 days while the average length of uninterrupted periods of freezing weather is 19 days. FREQUENCY OF COLD WAVES A cold wave in Baltimore County as defined by the U. S. Weather Bureau, is a fall in temperature of at least 20° in twenty-four hours, to a minimum of 20° in the winter months and a minimum of 28° in March and November. Such cold waves have occurred in Baltimore on the average about three times a year. During the period from 1871 to 1926 there were four seasons without a cold wave, namely 1873-74, 1885-86, 1889-90, and 1918-19 and six seasons. 1871-2, 1884-5, 1903-4, 1905-6, 1917-18 and 1924-25 which had as high as six waves. These cold waves are naturally most frequent in the winter months, but the greatest fall in temperature within twenty-four hours was recorded March 28-29, 1921 when the temperature fell' 57°. KILLING 1ROSTS AND THE GROWING SEASON Few climatic factors are of as much importance to the farmers as the average date of occurrence of the first "killing" or "black" frost in the autumn and the last frost in the spring since the interval between 368 Climate of Baltimore County these events is the average growing season. The dates for the first ''killing" frost of the autumn are shown in the following table: Killing Frosts Length of Growing Season Autumn Spring a .= ■■= = "o B ? > < ■ ■ fiJ mm 3 *«— = 0 H ■ •3 f| Q _ <■ B ►J ■ a ■3 la © — > 0 < © a •c C " s5 1 = O - ■ B = >• < a X Baltimore Oct. 1 Oct. 20 Nov. 22 May 12 Apr. 16 Mar. 19 279 187 174 Sept. 23 Oct. 27 Nov. 18 May 11 Apr. 13 Mar. 26 228 197 154 Woodstock Sept. 23 Oct. 14 Nov. 7 May 16 Apr. 19 Mar. 22 222 178 139 Fallston (Harford Co.)... Oct. 3 Oct. 18 Nov. 3 May 12 Apr. 18 Mar. 19 224 184 154 The foregoing dates, based on actually observed frosts do not indicate exactly the growing season for two reasons. A deposit of frost requires not only a freezing temperature but also a high content of moisture in the air in contact with the ground. The temperature may be below 32" without the formation of frost. The interval between the last and first occurrence of a minimum temperature of 32° is on the average 196 days in Baltimore or 9 days more than the average interval between frosts. The probability of an injurious frost sometime in April is approximately 68 per cent, as freezing temperatures have been recorded 38 times in 56 years. Twenty-seven of these occurred between the 1st and 10th and only 1 after the 20th. The second reason lies in the fact that the physio- logical activity in plants necessary to produce growth requires a mean daily temperature of at least 43 degrees. Such days may occur in every month of the year and have totaled on an average 266 days a year at Baltimore. The longest period with a mean daily temperature of 43° and above occurred in 1913 and contained 297 days; the shortest in 1886 and 1904 with only 244 daj's. The average growing season is therefore about 9 months with absolute freedom from frosts during 7 months of the \-ear. WARM DAYS IN SUMMER Extreme variations in maximum temperature are less marked than the variability in minimum temperatures. They are also of less importance Maryland Geological Survey 369 in agriculture but leave greater impressions because of their discomfort, especially in cities and large industrial plants. It is relatively easy to avoid or neutralize the effects of extreme cold but the enervation and discomfort of extremely hot humid periods are almost unavoidable except by those who can flee from them to the mountains and seashore. Unless the humidity is very high temperatures below 90° are not un- comfortable or enervating. This value is therefore taken as the critical one and the frequency of occurrence of days with higher maximum is chosen as the basis for the study of hot days in summer. Such days generally occur from June to September, though one or more hot days may occur in April, May, and October. The highest number recorded in one year was during the well-remembered summer of 1900 when 44 days with a maximum above 90° were recorded at Baltimore. This "hot spell" occurred late in July and in August and extended well into September. The temperature was above 90° over half of the days of July and August, reaching a maximum temperature of 99° to 100° on two consecutive days in July and six in August. Humidity The atmosphere enveloping the earth is constantly receiving moisture from the earth and giving it back in the form of rain, snow, and dew. This constant interchange is affected by changes in the relative tempera- ture and density of the air. The amount of water vapor which a given volume of air can contain is a quantity fixed by the temperature of the air; it rapidly increases with rise in temperature. Thus a cubic foot of air at 50° when saturated at sea-level pressure can hold about 4 grains of water vapor, at 70° 8 grains; and at 100° about 20 grains. By rating the amount of water vapor present at the point of saturation or dew-point as 100 the relative humidity of the atmosphere can be de- scribed in per cent. Thus if the air at 70° is saturated when it contains 8 grains of water vapor the relative humidity will be 50 when it has only 4 grains. Stated in another way — when the absolute humidity of the air is 4 grains the relative humidity will be 100 if the air has a tempera- ture of 50°, or 20 if the air is 100°. 370 Climate of Baltimore County Since the amount of water vapor held by the air varies with the temperature it is evident that there must be a more or less regular de- crease from the equator to the poles. At the equator the average amount of vapor may reach about 11 grains per cubic foot, or approxi- mately 20 tons per cubic mile. The atmosphere of Baltimore and vicinity with a mean annual temperature of 55° may contain (at satura- tion, or maximum content) about 5 grains per cubic foot or something like 9 tons per cubic mile. The temperature of the atmospheric en- velope also varies from the surface upward so that most of the water vapor actually present is in the air within 2 miles of the surface. Prob- ably nearly half of the total content is within the air strata not over a mile above the ground. If the atmosphere and earth were motionless there would be a steady decrease in the amount of water vapor from the equator to the poles; from the surface of the earth upwards; and from the oceans toward the interior of the continents. This general distribution is, however, modified by the inequalities of the earth's surface, their height and character, and by the winds. The moisture of the atmosphere, though invisible, has a benign influence on living conditions. The specific heat of water is so much higher than air that the moisture present tends to temper the tempera- ture and reduce extremes. Clouds and moisture-laden air screen part of the sun's heat from the earth during the day and reduce the radiation of heat from the earth during the night. Without its influence the changes in temperature through the day would be extreme everywhere as it is now in Death Valley and other arid regions. Without the move- ments of moisture-bearing winds there would be little or no rain or snow and tracts far from oceans and great lakes would be sunburnt, arid wastes. Notwithstanding the many essential benefits which it confers this same water vapor in the air adds much to man's personal discomfort. To it is due the oppressive, muggy weather when the temperature is high and the raw, penetrating cold when the temperature is low. A summer temperature agreeable when the air is dry becomes oppressively hot when the humidity is higher than 75 or 80. On the other hand, Maryland Geological Survey 371 during cold weather a temperature of 15° above zero with a similar humidity, as is the case in Baltimore and vicinity, causes suffering, while temperatures 35° lower are enjoyable and exhilarating in regions where the humidity is only 25 to 30 per cent. The relative humidity of the atmosphere cannot be told by the eye until it approaches the saturation point. Just before this point is reached the air may become unusually clear and distant points appear near at hand as on the brilliant days sometimes called "weather breed- Fig. 17. — Mean Hourly Relative Humidity. The hourly humidities are expressed as percentages, 100 per cent representing complete saturation. The light shades represent the lower humidities, or the dryer portions of the day and year; the heavy shades, the time of higher humidities. The dotted lines, S.R. and S.S. indicate the time of sunrise and sunset respectively. The diagram is based on the 30 months' record of a Richard hygrograph. (After Fassig.) ers." When the dew-point is past the moisture becomes visible in the form of clouds, fog, dew, rain, snow and frost. Which of these may occur depends upon many factors, such as the temperature, elevation, proximity to bodies of water, and the movements of the atmosphere. VARIATIONS IN HUMIDITY The humidity of the atmosphere at a given point varies greatly from day to day and hour to hour even in clear weather and the change is :'»7J Climate of Baltimore County especially marked during the course of a summer thunderstorm. Al- though the actual conditions may depart widely from the mean average conditions a study of the latter is helpful. From the continuous auto- jfmamj:asomdj Fig. 18.— The Mean Monthly Relative Humidity. The diagram is based on direct observations at two or three stated periods of the day during a period of 30 years; the average values were corrected for the diurnal variation, and expressed as percentages of total saturation. (After Fassig.) 187& 1880 1085 ItflA) I89S 1900 Fig. 19. — Variations in the Mean Annual Relative Humidity. (Expressed as percentages of total saturation. After Fassig.) matic records of the variations in relative humidity conditions made in Baltimore, Dr. Fassig has shown that the diurnal variation "is repre- sented by a simple curve with its maximum point at about 5 a.m. for the year, but varying between 4 a.m. and 7 a.m. according to the Maryland Geological Survey 373 season." "The minimum point, or the dryest time of day, occurs between 1.30 p.m. and 3.30 p.m." The average conditions of relative humidity by hours and months are shown in the accompanying figure. The monthly and annual means for relative humidity were also obtained from the Baltimore records for the period from 1871 to 1903 and his results are shown graphically in figures 18 and 19. These show that the normal amount of moisture for the entire year is about two-thirds of the total capacity of the atmosphere for water vapor, namely, 68.7 per cent. The mean monthly amounts vary from season to season, being greatest in the month of September (73.1) and least in the month of April (62.0). The monthly values for individual years vary considerably, the greatest range (28.5) occurring in October and the least (12.0) in Janu- ary. The variations in the mean annual relative humidity range from 70.5 to 64.0 without well defined cycles. ABSOLUTE HUMIDITY The absolute humidity or the actual weight of water vapor present from hour to hour, day to day, and year to year, has little apparent effect and varies in general with the temperature of the air. In general, there is a steady increase in the absolute humidity from January to July. The means obtained from Dr. Fassig's study of the records for five years from August, 1881 to July 1886 are given in the following table. MEAN ABSOLUTE HUMIDITY (Weight of the vapor of water in grains per cubic foot) Hours of Observation Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year 7 a.m 1 .41 1.58 1.78 2.72 3.89 5.56 6 50 5.98 5.29 3.83 2.26 1.74 3.082 1.47 1.66 1.78 2.71 3.80 5.50 6.12 6.06 5.53 3.87 2.36 1.82 3.222 1.60 1.71 1.84 2.78 4.02 5.51 6.11 6.16 5.48 4.06 2.49 1 91 3.267 7 p.m 1.57 1.72 1.91 3.01 4.20 5.79 6.68 6.38 5.79 3.96 2 47 1.88 3.437 11 p.m 1.54 1.72 1.82 2.93 4.08 5.82 6.71 6 38 5.61 4.03 2.48 1.83 3.327 Average 1.519 1 678 1.827 2 828 3 997 5.639 6 425 6.193 5.539 3.951 2.411 1.836 3.267 374 Climate of Baltimore County PRECIPITATION When, as through change in temperature, the amount of water vapor is more than the air can contain under the new conditions, the invisible vapor becomes visible in some such form as dew or rain. The conditions and mode of formation of these manifestations may be summarized as follows: General conditions: Whatever favors the lowering of temperature of the air favors the production of dew, fog, clouds, rain, etc. Dew: Formed by the cooling of the lower strata of the air and the warm earth by radiation during clear, cool nights. Frost: Formed by the same conditions as dew when the temperature is below freezing. Fog: Formed near the surface of the earth by the mixing of warm moist air with colder air; also by radiation. Clouds: Formed high above the earth by mixing of air currents of different temperature. Chiefly by the cooling of ascending warm moist air. The higher clouds consist of minute ice crystals which remain suspended in the air because of their relatively large surface and slight weight. Rain: Formed by the coalescing of minute particles of moisture into large drops too heavy to remain in suspension in the air. Snow: Due to the formation of crystals of ice which are too large to remain in suspension. Hail: Formed by the alternate partial melting and freezing of snow pellets falling through layers above and below freezing temperature. Precipitation in its various forms is essentially dependent upon the moisture in the air (the absolute humidity) and upon the temperature. Both of these factors, as has been shown in the preceding pages, vary from the equator to the poles and there is naturally a similar variation in the precipitation. Rainfall in the equatorial regions averages about 75 inches per year, and decreases towards the polar regions where the pre- cipitation, chiefly in the form of snow, is less than 10 inches per year. This decrease is by no means regular for the irregular surfaces of the continents and their distribution give rise to local variations in the distribution of atmospheric pressure, the direction of prevailing winds, and other factors which affect the rainfall locally. Maryland Geological Survey 375 INFLUENCES AFFECTING RAINFALL The major factors affecting rainfall which produce irregularities in its distribution are the relative positions of sea and land, irregularities in the land surface or its topography, and variation in atmospheric pressure. Oceans, seas, and continental lakes are the great sources of supply for the moisture in the atmosphere and it is natural that this, with the resulting precipitation, will be greatest along the coasts and least in the arid interiors of the largest land masses. Thus there is a steady decrease in the amount of the annual rainfall from the Atlantic and Gulf coasts towards the interior of the country from 50 to 60 inches along the coasts to 15 to 20 inches in the Rocky Mountain region. The influence of topography in modifying the rainfall is one of the most evident and easily understood of all the factors involved in precipitation. The warm, moist winds of the lowlands flowing inward are forced up the sides of mountains and are cooled by elevation so that they cannot hold all the moisture contained by the air when warm. Thus the windward sides of the mountains are as a rule marked by high precipitation and the leeward sides by dry cool air. The elevations in Baltimore County are not sufficient to show any appreciable differences such as occur along the Pacific Coast where the Coast Range and the Sierra Nevada Moun- tains rise rapidly from sea level to altitudes of over 10,000 feet. The influence of atmospheric pressure is, however, felt within the limits of the county but this is due to the passage of alternations of high and low pressure across the area and not to persistent local differences in specific localities. In general when the barometer is high the rainfall is poor and the skies are clear or flecked with clouds. When the barom- eter is low the skies are cloudy and rain is frequent. This is due to the fact that the winds flow from all sides towards the areas of low pressure and force the air at the center to rise and cool by expansion, to a point where it cannot hold all the moisture present. VARIATIONS IN PRECIPITATION The rainfall varies locally according to the seasons. This may be rather uniformly distributed month by month throughout the year, as 376 Climate of Baltimore County it is in Maryland, or limited to the summer months as in the tropics or to the winter months as in the states along the Pacific coast. Similar variations occur in the rainfall during the day. During the winter and spring months the precipitation is fairly uniform throughout the day while the showers and thunderstorms of the summer are most abundant in the hours of the late afternoon or in the early evening. The average hourly frequency of precipitation at Baltimore from January 1893 to the close of December 1902 is shown graphically in figure 20. The MOT 12J456789 10 11 Nop* 1 2 3 4 S 6 ' 8 9 10 II MPT Fig. 20. — Average Hourly Frequency of Precipitation. The heavy shades show the time of most frequent occurrence of precipitation during the day for ever3- month of the year. The small figures attached to the irregular curved lines show the average number of times precipitation was recorded per month at the times indicated. (After Fassig.) duration of precipitation also varies according to the seasons. The average rain period is a little less than eight hours in Baltimore. During the winter, spring, and fall when the storms are due to well defined cyclonic depressions, they last from 9 to more than 13 hours, but in the summer the thunderstorms and summer showers seldom last over two hours. The period of actual precipitation is not the same as that of the storm which causes it. Usually there are a series of showers sepa- rated by intervals of a few minutes or hours with little or no precipita- tion. This is less characteristic of a "northeast storm" where the rainfall is more persistent but even here there is a marked variation in the intensity of the rainfall. The Baltimore records indicate that there are Maryland Geological Survey 377 probably not more than three or four storms a year with an uninter- rupted rainfall of more than 24 hours. One of the longest continuous periods of actual precipitation recorded in Baltimore occurred in the spring of 1895 when rain fell for practically 102 consecutive hours. The total precipitation for the entire period amounted to 3.69 inches. The uniformity of distribution of precipitation is of more importance to the farmer than the total amount each month or year. In this respect Maryland is particularly fortunate. Droughts and excessive rainfalls are rare and precipitation is well distributed throughout the year. Days with an appreciable amount (0.01 inch or more) of precipi- tation average about 126 a year. They are most frequent in January and March and least frequent in September and October. From this average the departures are not excessive. To this number might be added the forty days a year which show light sprinkling rains or mists which have a beneficial effect on the growing crops. MONTHLY, SEASONAL AND ANNUAL AVERAGES Although there are many factors modifying the amount of precipita- tion from day to day and month to month it is customary to represent the general conditions at a specific locality by means of monthly, seasonal, and annual average amounts. This can be done where there are records of continuous observations for a long term of years but even these may be unduly affected by excessive rains, like that at Jewell, Anne Arundel County, on July 26, 1897, when nearly 15 inches were recorded during a local thunder storm. The average monthly precipita- tion at the various stations in and adjacent to Baltimore County are shown in the following table: 378 Climate of Baltimore County MONTHLY AND ANNUAL PRECIPITATION (Inches and Hundredths) Station a a Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year Baltimore 1871-1926: Maximum 6 81 7 or 7 94 8 70 7 26 8 .25 11 03 12 2s 10 52 6 S5 6 85 7 07 62.35 0 88 0 65 0 46 0 88 1 00 0 90 0 95 0 .64 0 09 0 05 0 .44 0 .37 31.57 >(„„ 3 40 3 .29 3 .74 3 31 3 49 3 .76 4 K 4 42 3 .61 2 S7 2 74 3 .19 42 47 Woodstock 1871-1926: 7 75 6 09 7 65 0 52 10 34 8 90 10 00 11 .28 9 38 10 23 9 83 9 29 57.77 0 .77 0 .53 0 .79 1 IS 0 57 1 .12 0 6S 0 as 0 .23 0 Is 0 36 0 63 28.02 3 .31 3 .12 3 58 3 13 3 71 3 .77 4 13 4 31 3 63 3 03 3 .84 3 14 41.79 McDonogh 1876-1906 (-'94-'98): 6 .78 6 04 • 00 5 60 7 59 7 .49 10 69 7 55 9 43 7 .22 8 .65 9 40 59.91 0 78 0 .09 1 .25 0 .76 0 6s 1 .81 1 94 0 31 0 .18 0 .34 0 .49 0 42 31.55 3 19 3 20 3 92 2 .70 3 48 4 .19 4 .42 3 .58 3 .82 2 96 3 .91 3 05 41 42 Towson 1909-1926 (-'19-'23): 7 40 5 52 7 39 7 82 5 00 5 94 6 67 13 41 7 02 5 97 4 20 5 23 49.32 1 61 1 23 0 81 1 40 0 99 0 .78 0 97 1 03 0 95 T. 0 70 1 62 34.60 3 77 2 72 3 03 3 64 3 15 3 36 3 90 4 78 3 07 2 82 2 48 3 28 39.90 Chase 1898-1904: Maximum 4 25 6 84 5 54 5 91 4 23 5 32 6 43 7 44 7 03 7 42 4 96 7 63 52.09 3 23 0 80 2 45 1 92 1 17 0 S3 2 16 1 84 2 00 0 53 0 91 1 15 37.22 3 13 3 81 3 98 3 37 2 72 2 94 4 10 4 27 4 22 3 49 3 76 4 09 42 88 Fallston 1870-1926: 8 26 7 01 8 75 8 52 10 41 10 21 12 37 15 63 12 95 8 06 10 27 8 14 70.17 1 20 0 80 0 84 1 28 0 54 1 05 1 21 0 95 0 23 0 23 0 47 0 40 35.15 3 73 3 o;; 3 97 3 52 3 81 4 03 4 63 4 87 4 08 3 41 3 33 3 61 46.52 Maryland Geological Survey 379 SEASONAL PRECIPITATION Winter Spring Summer Autumn Baltimore: 15 90 21 23 22 66 17.75 3 97 5 62 5 95 X fiO 9 88 10 54 12 83 9.22 Woodstock : 18 13 18 67 21 17 26.07 3 41 4 64 6 14 ^ . oy 9 57 10 52 12 21 9.49 McDonogh: Maximum 17 31 17 39 22 52 19.20 5 18 5 50 6 02 3 7^ o . / o Mean \ 9 44 10 10 12 19 9.69 Towson: Maximum 16 76 14 27 21 96 10.21 Minimum 6 95 5 69 7 01 5.26 Mean 9 77 9 72 12 04 8.37 Chase: 18 85 13 67 16 46 18.11 Minimum 4 99 8 56 7 43 8.28 Mean 11 03 10 07 11 31 10.47 Fallston : 19 67 23 85 24 21 19.42 Minimum 6 37 7 35 4 55 4.32 Mean 10 97 11 30 13 53 10.72 EXCESSIVE RAINFALL Since precipitation is the most variable of all the climatic factors the foregoing average values give little basis for prediction of probable values to be expected in any particular month, season, or year. In general the amount will be slightly less than the average, with occasional periods of excessive precipitation. When the latter may occur cannot be foretold. The table brings out the fact that during no month at any one of the stations has there been an absolute lack of precipitation. On the whole, it may be stated that there is some general relationship 380 Climate of Baltimore Couxty between the periods of excessive and deficient precipitation at the several stations and some suggestions of periodic cycles of wet and dry years. The interval between years of excessive precipitation is gen- erally between four and five. From the Baltimore records which are kept in great detail, Dr. Fassig- has inferred that the intensity of excessive rainfalls is more or less periodic but that there is no fixed relation between the rainfall of the year and the character of individual rains. Regions with high annual or seasonal precipitation do not necessarily have excessive rates of fall for short periods. Days with a fall of more than 2.50 inches are relatively few, on an average not over two a year. They are more likely to occur in the summer and early autumn months in connection with heavy thunderstorms and are not to be expected at other seasons more frequently than once or twice in ten years. The magnitude of the downpour in periods of excessive rains may be gathered from the statement that an inch of rainfall is the equivalent of more than 100 tons or 27,000 gallons per acre, or 7,255 tons per square mile. In such heavy rainstorms as that of July 12, 1903, when 2.69 inches fell in Baltimore in 30 minutes, the water falling within the city limits at that time has been estimated as over 17 million tons. DRY SPELLS Although Baltimore County is situated in an area where the rainfall is generally quite evenly distributed throughout the year, it occasionally has periods of many days in which there is little or no precipitation. Unless such dry spells occur during the periods of critical crop growth they are of comparatively slight importance. Periods of two weeks or more without rain or with less than one-tenth of an inch fall are not frequent in this vicinity, as ordinarily there are from ten to twelve days per month with rain of this amount. The longest consecutive period was 51 days in 188-4 when the total precipitation was only 0.39 inches for the period. The longest periods during the growing season were in the summer of 1893 (45 days with 0.55 inch), 1877 (34 days with 0.17 * Md. Weather Service, Vol. ii, p. 200 seq. MARYLAND GEOLOGICAL'.SURVEY BALTIMORE COUNTY. PLATE XXIII Fig. 1. — View of Gunpowder River near Loch Raven showing the hardwood forest on the Baltimore City Watershed Fig. 2. — View of Gunpowder River near Loch Raven showing the mixed hardwood forest on the Baltimore City Watershed Maryland Geological Survey 381 inch), 1881 (33 days with 0.16 inch) and the early spring of 1903 (36 days with 0.36 inch). Dry spells are most frequent in October, after the harvest season, but are comparatively not infrequent in May when a lack of moisture in the ground is a serious matter. WET SPELLS The average duration of rainfall at Baltimore is a trifle less than 8 hours. Periods of rain or snow continuing more than two or three days occur only once or twice a year although longer periods are on record. During a storm in April 1901 rain continued intermittently for seven days with a total precipitation of 2.03 inches and in May 1894 there was a period of 11 days during which rain fell 63 hours with a total precipita- tion of 4.45 inches. The periods of excessive rainfall occur more frequently in the summer than at other seasons. The number of rainy days in a normal year is 126 but in dry years there may be as few as 96 (1909) days and in wet years as many as 164 (1889). The normal precipitation is approximately 42.5 inches. SNOWFALL Records of the depth of snowfalls have been kept in Baltimore since 1883 and of the frequency since 1871. From these it appears that the average seasonal fall is 24 inches distributed through 6 months. The largest amount during any one winter was 51.1 inches (1898-99) and the least 4 inches (1918-19). February is the month of greatest snowfall, the amount ranging from 33.9 inches (1899) to 0 in 1884, the average fall amounting to less than 7 inches. Even in midwinter months of January and February about one-fifth of the precipitation is in the form of snow. The first flurries of snow come about the middle of November and the last about the middle of April. Flurries of snow have been noted as early as October 9 (1895, 1903) and as late as May 9 (1923). In 1925 a fall of 2.5 inches occurred on October 30; this is the earliest material snowfall of record. The latest material snowfall was 0.5 inch on April 14, 1923. During the 56 years from 1871 to 1926 382 Climate of Baltimore County the average number of days with any snowfall has been 24, the greatest in any one season 42 (1906-7), and the least 5 (1875-76). If only the days with at least one-tenth of an inch of snowfall are considered the average number is reduced to only 13, with seasons of only 2 (1877-78) or as many as 26 (1884-85). The heaviest snowfall of record fell January 27-29, 1922, 26.5 inches. The severest snowstorm occurred February 11-13, 1899 when 21.4 inches of snow fell. At the close of the storm Baltimore lay under a mantle of 30 inches which had been driven by the cold wind into snow drifts 10 to 20 feet deep. A fall of over one foot in a day occurred only five times during the 44 years from 1883-1926, viz., February 25, 1874, February 3, 1886, March 17, 1892, February 13, 1899, and January 28, 1922. The average duration of snowfall, like that of rainfall, is about 8 hours. Sunshine and Cloudiness The region of Baltimore City and County is one of abundant sunshine. The amount varies considerably from month to month but the auto- matic recorder installed in Baltimore shows that for a period of 10 years (1893-1903) the sun was shining near 60 per cent of the time possible, or an average of more than 7 hours a day. The winter months of least sunshine show about 40 per cent sunshine, the summer months as much as 80 per cent. Cloudiness is based upon an estimate of the amount of the sky covered at the time of observation. In general there is a steady increase in cloudiness from early morning to a maximum about 2 p.m. and then a somewhat more rapid decrease to midnight. When the sky is less than A covered the day is described as clear; fair or partly cloudy indicates a cover of from ,\r to A inclusive; cloudy when the sky is A or more covered. The relative frequency of days of each class are indicated in the accompanying figure from which it may be seen that each year about 33 per cent of the days are clear, 35 per cent partly cloudy, and 32 per cent cloudy. September and October have the highest percentage of clear days Maryland Geological Survey 383 and January, February, April, June and December the least. The number of clear days is rather uniform except in September and October. Cloudy or overcast days are most frequent in January and December, and partly cloudy days most frequent in June and July. Winds The velocity and duration of the winds may vary from hour to hour and depend on many factors. The records of a self-recording wind gage or anemometer at Baltimore during the 46-year period from 1881 to 1926 show that the wind velocity varies from hour to hour. The minimum velocity is between 2 and 5 a.m., from which it rises rapidly to a maximum between one and three in the afternoon, thence diminish- ing rather rapidly until eight or nine in the evening and thence slowly to its minimum about four in the morning. Unlike the diurnal velocities which vary with the rise and fall of the temperature, the annual changes show the lightest winds in the months of greatest heat while the highest average velocities occur in March and to a less degree in February and April. These annual changes are due to the increased cyclonic move- ments of the winter. When the general conditions are disturbed by the passage of well developed cyclonic or anti-cyclonic areas there are corresponding changes in the wind velocities. The highest velocity recorded at Baltimore since 1874 occurred during the storm of July 20, 1902, when the wind blew at the rate of 70 miles an hour for five minutes. This was one of the most destructive storms on record. THE MAGNETIC DECLINATION IN BALTIMORE COUNTY BT L. A. BAUER Introductory Values of the magnetic declination of the needle, or of the "variation of the compass" as observed by the Maryland Geological Survey and the United State Coast and Geodetic Survey at various points within the county are given in Table I. For a general description of the methods and instruments used, reference must be made to the "First Report upon Magnetic Work in Maryland" (Md. Geol. Survey, vol. i, pt. v, 1897). In the Second Report (Md. Geol. Survey, vol. v, pt. i, 1905) the various values col- lected are reduced to January 1, 1900. They are given now also for January 1, 1910 and 1925. Some later values for Baltimore are added. The First Report contains an historical account of the phenomena encountered by the surveyor on account of the many fluctuations to which the compass needle is subject. To these reports the reader is referred for any additional details. Meridian Line A meridian line for the use of surveyors was established by the Maryland Geological Survey on April 26, 1897, on the west side of the Court House grounds at the Countyseat, Towson. This was done by special request conveyed in the letter of the Chief Clerk of the Board of County Commissioners, dated April 6, 1897. A full report of the work was made by L. A. Bauer on May 15, 1897, and is on file at the Court House. The line was determined by astronomical methods correct within one minute. The monuments marking the two ends of the line, which because of the limited space could not be over 210 feet long, are granite posts, 6x6 385 386 Magn etic Declination in Baltimore County -a a a a A x x x x x £ £ x 5 5 71 5 * ..55 = J5 eJaS • cS PQ w cs c: ~ C500000KS©««0« . 4 w w « 0 c. ff 1 D) < 00 CM B 1 CO — 1" — 00 (0 CM %n CO 0 O CO CM CO to O O • co to t> to to. to to to to. to to to to to to O EC t - 3B D 1 *~ ~ CO to co O co s — CO CM 0 CO 10 •<* p _ 10 CO CO CO CO CO CO CO CO CO Qg CO CO 5g CO B O 6 3 ■5 O i-H CM CO — co 10 to s Q to CM FH O o> U3 to to to 1 - to — CM CO 00 O Q 5 OS to to »o tO to tO CO CO CO to to co CO CO a bA O CO — CO >- r. 0 ? 1 t- •«»< co CM OS to CO CO CO CO CO 10 >o CN O tO c S3 1O6I tO to to 10 to to to to ro to CO CO CO 0 to. CM O as CO OS to 00 CO to 0 > Ci to CM to — 0 c ~ f 00 CM CM c; co in — O O 10 > O to to CO CO CM to to to tO •O >o CO 0 lO Cs 0 CO CO CO CO CO ■V co to. to to — IC CO 00 CM CM to to CO ro to CO c - C -r as Ol — o> s 0) p 5 _~ 0 5 ~ X - X X X / 00 X y ■0 >j t^ 00 10 00 OS O O tO CO CM s go CO — tO •- lo- 1^ to to to Q to 1^ CO 0 to 0 Ci 10 0 0 •«)< CO 00 C to 00 1 - 1 - - •»*< — t- 0 C! CM CM CN CN CM CM CM CO 03 O a O! 0 - — OS C5 -■ cn CO CO CO CO CO CO CO EC CO co CO CO CO CO CO CO ■ t— 1 hh : J>* S3 ~ < K X X X X u u t- t- o o o u cS tt 5h 5h S E o c - = o *5 03 - -T g 5 a 0 a rS ad o o pq =3 & h CS - S" co 5 3 * pq pq 5 c ■ e> o »| 5 rot. = „ Ph d a -3 c =5 — ■ o >> o o c x a - - .'■ > 2 Si J; 33 oi " J. > A - o S K X j9 0 : - - "2 0 5 c M ej - ■O — 1 S v. — — = a z - s "5 s a Maryland Geological Survey 387 inches square and 4 feet long, set in concrete and firmly packed. They project about 6 inches above the ground. Leaded in the center of each stone is an inch brass bolt sunk its entire length of 3 inches into the top. The line passing through the centers of the crosses cut in these bolts marks the true north and south line. The north stone is lettered N M, the south one, S M and each stone bears the date 1897. (For further information see descriptions of stations and Table II.) Descriptions of Stations North Point, 1847. — The station was between the upper and lower North Point lights, Patapsco River. Baltimore, Fort McHenry, 1904. — Observations were made near the station of 1903 (see below) in the extreme eastern part of Fort McHenry. A second station was established near the center of Patterson Park, in east Baltimore. It is about 200 feet south of the band stand and on the terrace below it. It is 45 feet northwest from the edge of the driveway, 15 feet east of a scrub-oak 'tree, and 20 feet south of the foot of the slop- ing bank. The dome of the Bay View Hospital bears 88° 10'. 0 east of true north. A church spire bears 62° 49' east of truo south. Baltimoie, Fort McHenry, 1903. — The station of 1895 was occupied as closely as the meager description would permit. It is in the extreme southeastern part of Fort McHenry, between a locust tree and the sea wall, 40 feet from the tree and 41§ feet from a cross cut in the top of the sea wall. The station is marked by a stone slab about 4 by 12 inches on top, set flush with the ground and having a cross chiseled in the top. The mark used was the Lazaretto Point lighthouse, which bears 80° 17'.2 east of true north. The cupola of the City Hall bears 37° 20'.8 east of true north. A secondary station was occupied 32| feet from the principal station, in line to the city building cupola. It was marked by a small stone 4 by 5 inches on top. Baltimore, Patterson Park I, 1905-6. The station was reoccupied as nearly as could be determined. It is a little to the eastward of the center of Patterson Park, about 200 feet south of a shelter house and on a terrace below the same. It is 43.2 feet northwest from the edge of a 388 Magnetic Declination in Baltimore County roadway. This roadway leads south to the Luzerne Avenue entrance on Eastern Avenue. It is 13.8, 29.8, and 41.2 feet west-northwest, north by east, and northeast respectively, from small trees. The distance to the foot of the embankment to the northward is 20.5 feet (approxi- mately). The station is marked by a stone post 6 by 6 by 30 inches, lettered U. S. C. & G. S., 1905, and sunk flush with the sod. The nearest street-car line is on Eastern Avenue about 1000 feet south. Electric light wires pass over the shelter house. The following true bearings were determined: Dome of Bay View Hospital (mark) 88° 10'. 4 east of north Church spire to southeast 62° 47'. 8 east of north Baltimore, Patterson Park II, 1905. — The station of June, 1905, was reoccupied as nearly as could be determined from the description (within 4 feet perhaps). It is about 200 feet south-southeast of the Casino building, 80.9 feet northwest of a roadway, 64.6 feet east- northeast of a path, 21.9 feet east of a large maple tree, 48.6 feet northwest of another maple, and 40.2 feet southeast of a cypress. The station is not marked. The nearest car line is 1000 feet south on Eastern Avenue. The follow- ing true bearings were determined: Dome of Bay View Hospital (mark) 89° 0' 9 east of north Chimney in Highlandtown 69° 48'. 3 east of south Tip of stone structure in park lake 66° 50'. 5 east of south Baltimore, Patterson Park III, 1905. — Recent improvements to the park have rendered stations I and II less suitable for magnetic observa- tions. A new station was therefore chosen in the northeastern part of the park, about 600 feet northeast of a large stone building formerly used as a casino. This station is in the open field, 70 feet to the westward of driveway, 16 feet south of a small Cottonwood tree that stands alone and nearly on a line with an electric light pole 600 feet to the eastward (not in operation in the daytime) and the dome of Bay View Hospital. There is no disturbance of any kind in the vicinity and there are no street car lines within three-quarters of a mile. The station is marked by wooden peg flush with the ground. The following bearings were determined: MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXIV Fig. 1. — View of Patapsco River near Orange Grove showing the characteristic willow growth along the stream banks Fig. 2.— View of River Road near Avalon in the Patapsco State Forest showing the young forest returning under management Maryland Geological Survey 389 Dome of Bay View Hospital (mark) 87° 15'. 6 east of south Church of Sacred Heart spire 54° 55'. 6 east of south St. Elizabeth Church cross 42° 17'. 9 east of south Weather vane of park shelter house 7° 16'. 6 east of south Baltimore, Patterson Park IV. — The station established in January, 1907, was reoccupied. It is in the northeastern part of the park, in the open field, about 600 feet northeast of a large stone building formerly- used as a casino. It is 63.7 feet north-northwest from a sycamore tree near a driveway and 23 feet south of a small maple tree 6 inches in diameter. It is also in range with an elm tree about 230 feet to the eastward and the center of Lombard Street, Highlandtown. The station is marked by a marble post, 6 by 6 by 30 inches, set 2 inches below the surface of the ground, with top lettered U. S. C. & G. S. The following true bearings were determined in January, 1907: Dome of Bay View Hospital (mark) 87° 19'. 3 east of south Sacred Heart Church spire 55° 01 '.8 east of south Cross on St. Elizabeth's Church 41° 56'. 1 east of south Weather vane on park shelter house 7° 23'. 8 east of south Rosanne, 1844- — Near the Coast Survey triangulation station of 1844 which was on Prospect Hill, about 5\ miles west from the center of Baltimore city, and % mile north of Old Frederick Road, 18 feet from the northeast corner of Bogue's house, 68 feet from a cedar tree at the southeast corner of the house and 88.4 feet from a persimmon tree about east-northeast of the station, and in the carriageway leading from the front door of the house to the stable. The subsurface mark is an iron cone; surface mark is copper nail in an oak post. Baltimore, 1912. — Two stations designated A and B were occupied by Messrs. Fleming and Gait of the Carnegie Institution of Washington, at Homewood, the site of the Johns Hopkins University, about 2 miles (3 kilometers) north of Washington Monument, on knoll in sharp turn of Wyman Park Drive, about 400 meters southwest of grandstands on the athletic field. A is 183.5 feet (55.93 meters) northwest of fence at farthest point of turn in W3rman Park Drive, 116.5 feet (35.51 meters) from same fence to northwest, 112.0 feet (34.14 meters) nearly true south of stone boundary mark, and 502.6 feet (153.19 meters) from 390 Magnetic Declination in Baltimore County second stone nearly east of first. True bearings (counted continuously from 0° to 360° in the direction south, west, north, east) : Eastern apex of Cedar Avenue church roof 59° 49 ' 5 Cross on south end of roof of Lutheran church 89° 14'. 5 Top of city water standpipe, Roland Avenue 137° 51'. 3 Southernmost corner southeast grandstand 238° 49 '2 Stone boundary monument (second stone) 2.54° 16'. 0 B is on extension of line from cross on south end of Lutheran church through A 64.77 feet (19.74 meters) eastward. True bearings: South cross on roof of Lutheran church 89° 14'. 5 Church steeple with cross 99° 58'. 7 Towson, 1897. — In the ample grounds on the west side of the Court House. A meridian line was established at the time and marked by substantial granite posts. The observations were made over these posts. Finlay, 1846. — Near the Coast Survey triangulation station of 1844 which was about 9 miles northeasterly from Baltimore, 300 feet east of the old Harford Road, £ mile west of the Harford Road on Cub Hill on the old Finlaj' farm, now the property of Theodore Fastie. The north- east corner of an old log house, formerly a school house but now a black- smith's shop, is 253.71 feet from the station in azimuth 312° 53'. 5. The azimuth of the east gable of a stone barn on the Fastie place is 189° 27'. 5 and a large cherry tree is 126.85 feet from the station in azimuth 337° 14'. In 1896 the station was marked as follows: A glazed drain tile 4 inches in diameter and 30 inches long was sunk in the ground so that its upper end was 3 feet below the surface of the ground. It was set in cement and gravel and the center of the station marked by a 60d. nail. Above this was placed a chestnut post, its top even with the surface of the ground, with a 40d. nail marking the center. Bradshaw, 1897. — On the grounds of Colonel Taylor, east of Baltimore and Ohio station, 25 paces south-southeast of locust tree. Keisterstown, 1899. — In the large open field west of the Franklin school. Hyde's, 1897. — On Mr. Hyde's tract, back of the garden behind the store and railroad office, about 125 paces west of the railroad track. Maryland Geological Survey 391 Cockeysville, 1896. — On Mr. Cockey's property, a large open lot on right of road, near stone bridge. The station is about 500 feet west of road and 25 feet east of a clump of three willow trees. Parkton, 1899. — On top of the hill west of the railroad station and over the first boundary stone marking the property of the railroad company. This boundary stone is on the hill, about 20 yards north of wooden fence leading up the hill. Corrections for Secular and Diurnal Variations table ii. change in the magnetic declination at towson from 1750 to 1925 The following table is reproduced from page 482 of the First Report, mentioned above, without any alteration except that it has been extended to 1925 with the aid of data supplied by the United States Coast and Geodetic Survey. It will be noted that the table applies to the south meridian stone. To refer it to the north stone, 9' would have to be added to each of the figures, if the surrounding condi- tions have not changed since 1897. Year (Jan. 1) Needle pointed Year (Jan. 1) Needle pointed Year (Jan. 1) Needle pointed Year (Jan. 1) Needle pointed Year (Jan. 1) Needle pointed 1700 o / 6 03W 1750 o / 3 06W 1800 o / 0 54W 1850 o / 2 39W 1900 o / 5 SOW 05 5 54 55 2 45 05 0 54 55 2 59 05 6 08 10 5 41 60 2 27 10 0 55 60 3 19 10 6 32 15 5 26 65 2 10 15 0 59 65 3 38 15 6 52 20 5 08 70 1 52 20 1 06 70 3 59 20 7 05 25 4 49 75 1 36 25 1 16 75 4 20 25 7 34W 30 4 28 80 1 22 30 1 29 80 4 40 35 4 08 85 1 10 35 1 45 85 5 00 40 3 48 90 1 02 40 2 04 90 5 18 45 3 28W 95 0 57W 45 2 22W 95 .5 35W The declination is, at present, west over the entire county, and is increasing now at the average annual rate of 4 minutes. With the aid of the figures of Table II the surveyor can readily ascertain the amount of change of the needle between any two dates. For practical purposes it will suffice to regard the change thus derived to be the same over the entire county. It should be emphasized, how- ever, that when applying the quantities thus found in the re-running of 392 Magnetic Declination in Baltimore County old lines, the surveyor should not forget that the table can not attempt to give the correction to be allowed on account of the error of the compass used in the original survey. To reduce an observation of the magnetic declination to the mean value for the day of 24 hours, apply the quantities given in the table below with the sign as affixed : Month 6 A.M. 7 8 9 10 11 Noon 1 2 3 4 5 6 P.M. Jan -0M +0'2 +1'.0 +2M +2' .4 +1'.2 -l'.l -2' 5 -2'. 6 -2M -r.3 -0' 2 +0'2 Feb +0.6 +0.7 +15 +1.9 +14 -0.1 -15 -2 1 -2 5 -2.0 -12 -0 8 -0.4 +1.2 +2.0 +3.0 +2.8 +1.6 -0 6 -2.5 -3 4 -3.7 -3 3 -2.3 -1.2 -0.5 April +2.5 +3.1 +3.4 +2.6 +0.8 -2 1 -4 0 -4 1 -4.2 -3 6 -2.3 -12 -0 2 May +3 0 +3.8 +3.9 +2.6 +0.1 -2 4 -4.0 -5 0 -4 5 -3.6 -2.3 -0.9 +0.1 +2.9 +4.4 +4.4 +3.3 +11 -2 0 -3.6 -4 5 -4 5 -3 8 -2 6 -1.2 -0.2 July +3.1 +4 6 +4.9 +3.9 +18 -12 -3 4 -4 4 -4 7 -4.2 -2.8 -13 -0.3 +2.9 +4.9 +5.4 +3.7 +0.4 -2.8 -4 7 -5 1 -4 9 -3 7 -1.9 -0.6 +0.3 Sept +1.8 +2.8 +3.4 +2.5 +0.3 -2.7 -4 4 -4 6 -4.2 -4 0 -1 4 -0 3 -0 1 Oct +0.5 +16 +3.1 +2.8 +14 -1 0 -2 7 -3 3 -3.4 -2 4 -13 -0.4 -0 4 Nov +0.5 +1.2 +17 +1.8 +11 -0 5 -2.0 -2 7 -2.6 -1 8 -10 -0.2 +0 2 Dec +0.2 +0.3 +0.8 +1.8 +1.8 0 0 -1.6 -2.4 -2.3 -1.8 -11 -0.3 +0.1 Remarks Regarding Station at Towson The angle between the true meridian line and the southeast edge of Court House is, at the south meridian stone : 79° 50' E. of N. The latitude of the Court House may be taken to be 39° 23'. 5 and the longitude 76° 36'.4 W. of Greenwich or 23'.6 E. of Washington. To obtain true local mean time, or solar time, subtract from Eastern or Standard time, 6 minutes and 26 seconds. It is difficult to say whether the difference of 9' found in 1897 in the magnetic declination at the two meridian stones (see Table I), be due to some natural local disturbance or some artificial one It is hence essential in the adjustment and comparison of compasses that all observations be made at the same point and one beyond any artificial disturbing influence. Throughout this part of Maryland natural local disturbances are known to exist. THE FORESTS OF BALTIMORE COUNTY BY F. W. BESLEY, State Forester Introductory Baltimore County, the third largest in the State, has important forest resources. It ranks fourth in the value of its forest products and ninth in total wooded area. The proximity to Baltimore City, with its rapidly expanding industrial developments, furnishes an excellent market for all classes of forest products. The County lies in two physiographic divisions, the Piedmont and the Coastal Plain. Since only about one-tenth of the land area embrac- ing the southeastern section lies in the Coastal Plain, the surface is distinctly characteristic of the Piedmont with its rolling hills inter- spersed with a few valleys. The County is traversed by five lines of railroad, covering 120 miles, and by more than 1,000 miles of improved highway, rendering all sections accessible. Of the land area of the County, 28% is in forest growth. The forests are somewhat uniformly distributed in relatively small areas. The forest land is held almost exclusively by farmers in lots of 10 to 100 acres in connection with farms and interspersed with cleared lands. There are a few continuous forest areas of considerable size in the south- eastern part of the County in the Coastal Plain section, other areas LAND CLASSIFICATION Improved Farmland Wooded Area Waste Land Salt Marsh Land. . . 196,212 acres 55% 99,041 " 28% 55,650 " 16% 3,260 " 1% 354,163 " 100% Distribution of the Forests 393 394 The Forests of Baltimore County more limited in the northern section around Parkton, in the central part between Cockeysville and Owings Mills, and along the Patapsco River in the southwestern part of the County. The County has been settled for so long a time and land uses so well established that there has been for the past 50 years comparatively little change in the relationship bet ween cleared land and woodland, and there is not likely to be any decided change for many years to come. The forests are confined mainly to rocky ridges, steep slopes, and flats along streams. In a County of such high agricultural development, arable land and forest land are rather sharply defined. It is probably true, as claimed by land economists, that for the most economical use of land and the best development of agriculture in a hilly or rolling county, 25% of the land should be under forest cover, and so distributed as to break the force of winds, conserve water supplies, check soil erosion, and supply the wood and lumber needs of communities. It appears: therefore, with 28% wooded, Baltimore County presents nearly the ideal condition in forest distribution. STAND AND VALUE OF SAW TIMBER BY ELECTION DISTRICTS, TABLE I Dist. No. Total Land Area Wooded Area % Wooded Stand of Saw Timber in M Board Feet Stum page Value Acres Acres % Hard- wood Pine Total Hardwood »10 Per M Pine $10 PerM Total 1 1 13,940 4,537 32 10,890 30 10,920 108,900 300 109,200 2 28,750 8,744 29 23,120 23,120 231,200 231,200 3 16,020 3,559 22 9,055 20 9,075 90,550 200 90,750 4 37,580 8,624 23 22,925 170 23,095 229,250 1,700 230,950 5 28,290 4,487 16 11,260 435 11,695 112,600 4,350 116,950 6 22,870 7,089 31 10,170 10,170 101,700 101,700 7 52,670 8,142 15 12,570 60 12,630 125,700 600 126,300 8 41,273 9,207 22 26,760 26,760 267,600 267,600 9 16,842 3,861 23 13,360 13,360 133,600 133,600 10 30,980 6,120 20 15,750 15,750 157,500 157,500 11 42,930 14.413 34 33,470 1,265 34,735 334,700 12,650 347,350 12 1,703 508 30 480 480 4,800 4,800 13 6,004 904 15 2,712 2,712 27,120 27,120 14 8,151 2,447 30 4,508 100 4,608 45,080 1,000 46,080 15 23,458 16,399 70 25,115 6,680 31,795 251 , 150 66,800 317,950 371,561 99,041 26 222,145 8,760 230,905 2,221,450 87,600 2,309,050 Maryland Geological Survey 395 The 11th election district contains the greatest amount of standing timber, — only 8 of the districts contain any pine of merchantable size, and of this 76% is in the 15th district. The 7th and 13th districts contain the smallest percentage of woodland, each with 15%, followed closely by the 5th district with but 16%. The 15th election district contains not only the largest acreage of woodland, but also the highest percentage, — 70%, and the 12th contains much the smallest wooded area. Because of labor conditions and the low prices of forest products following the World War, numerous small areas were abandoned, becoming waste land, or in some cases returning to forest growth. The percentage, however, is small, and most of this land will likely be reclaimed within the next decade. Description of the Forests The forests of the county are almost entirely of the hardwood type. In the stands of timber, the hardwood constitutes 96%, while the pine only 4%. Rolling hills, with ridges, slopes, and valleys, produce three forest types, notably the ridge type, consisting of chestnut oak and scarlet oak as the prevailing tree species; the slope type, in which scarlet oak, black oak, and white oak of the upper slopes give way to the red oak, tulip, and hickory on the lower slopes; and the bottom type along streams, or low flat lands, consisting principally of red maple, ash, elm, birch, and sycamore. Practically all the forests have been cut over one or more times. Since the more valuable species have been cut the heaviest, constant cutting has caused severe deterioration of the stands. Chestnut, which was formerly the most prominent tree of the ridge type, has practically all been killed by the chestnut blight, and is now being replaced by a natural growth of oak, poplar, and hickory. Re- peated forest fires have also greatly changed the character and composi- tion of the forest, reducing greatly the proportion of the less fire resistant species, such as tulip poplar, hickory, and red oak, and causing serious deterioration in the forest as a whole. 396 The Forests of Baltimore County The destructive logging methods, practiced in years past, have also brought about changes in the composition of the forest. This is particu- larly noticeable where the timber is more accessible, and where the demand is greatest. The close cutting of the best species and the more valuable timber, leaving the inferior trees, has caused a marked deterio- ration in the forest in many sections. There are 91 kinds of trees found growing naturally, of which 7 are evergreens and 84 are deciduous trees. A large part of them are trees of commercial importance, and all are used to some extent. The list below contains species native to the county, which reach tree size. NATIVE FOREST TREES EVERGREEN OR NEEDLE-LEAVED TREES Common Xame Botanical Same1 Spruce Pine Pitch Pine White Pine Short Leaf Pine Red Cedar Hemlock Southern White Cedar Pinus virginiana Mill. Pinns rigida Mill. Pinus strobus L. Pinus echinala Mill. Juniperus virginiana L. Tsuga canadensis Carriere Chamaecyparis thyoides Britt. DECIDUOUS OR BROAD-LEAVED TREES Common Xame Botanical Name1 White Oak Chestnut Oak Post Oak Swamp White Oak Burr Oak Basket Oak Dwarf White Oak Red Oak Black Oak Scarlet Oak Pin Oak Willow Oak Black Jack Oak Shingle Oak Quercus alba L. Quercus montana L. Quercus stellata Wang. Quercus bicolor Willd. Quercus macrocarpa Michx. Quercus prinus L. Quercus pinoides Willd. Quercus borealis maxima Ashe Quercus velulina Lam. Quercus coccinea Muen. Quercus paluslris Muen. Quercus phellos L. Quercus marilandica Muen. Quercus imbricaria Mich. 1 The botanical names in this list are from the "Check List" by George B. Sudworth published by the U. S. Department of Agriculture. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXV Fig. 1. — View showing plantation of White Pine on the Baltimore City Watershed along Gunpowder River. Trees 10 years old Fig. 2. — View of mixed oak forest of mature trees near Ten Hills Maryland Geological Survey 397 Common Name Botanical Name1 Barren or Scrub Oak Quercus ilicifolia Wang. Chestnut Castanea dentala Borkh. Chinquapin Castanea pumila Mill. Tulip Poplar Liriodendron tulipifera L. Mockernut Hickory Hicoria alba Britt. Pignut Hickory Hicoria glabra Mill. Shagbark Hickory Hicoria ovata Britt. Small Pignut or Shagbark Hicoria ovata muttallii Sud. Bitternut Hickory Hicoria cardiformis Britt. Big Shellbark Hickory Hicoria laciniosa Sarg. Pignut Hickory Hicoria pallida Ashe Black Walnut Juglans nigra L. Butternut Juglans cinerea L. Black Locust Robinia pseudacacia L. Red Maple Acer rubrum L. Silver Maple Acer saccharinum L. Sugar Maple Acer saccharum Marsh. Ash Leaved Maple Acer negundo L. Beech Fagus grandifolia Ehrh. Red Gum Liquidambar slyraciflua L. Sour Gum Nyssa sylvatica Marsh. Wild Black Cherry Prunus serotina Ehrh. Fire Cherry Prunus pennsijlvanica L. Bird Cherry Prunus avium L. Choke Cherry Prunus virginiana L. Wild Plum Prunus americana Marsh. White Elm Ulmus americana L. Slippery Elm Ulmus fulva Michx. Sycamore Platanus occidentalis L. Sassafras Sassafras variifolium Kuntz. Persimmon Diospyros virginiana L. Basswood or Linn Tilia glabra Vent. Basswood Tilia neglecla Spach. Hackberry Celtis occidentalis L. Holly Ilex opaca Ait. White Willow Salix alba L. Pussy Willow Salix discolor Muehl. Black Willow Salix nigra Marsh. Red Bud Cercis canadensis L. Flowering Dogwood Cornus jlorida L. Dogwood Cornus alterni folia L. Blue Beech Carpinus caroliniana Walter. Shad Bush or Service Berry Amelanchier canadensis Med. Trembling Aspen Populus tremuloides Michx. Big Toothed Aspen Populus grandidentata Michx. Cottonwood Populus deltoides Marsh. Hop Hornbeam Ostrya virginiana Koch. i The Forests of Baltimore County Common Name Botanical Name1 Red Mulberry Morus rubra L. Paw Paw Asimina triloba Dunal. Witch Hazel Hamamelis virginiana L. Sweet Bay or Swamp Magnolia Magnolia virginiana L. Umbrella Magnolia or Umbrella Tree Magnolia tripetala L. Cockspur Thorn Crataegus crus-galli L. Red Birch Betula nigra L. Black Birch Betula lenta L. White Ash Fraxinus americana L. Black Ash Fraxinus nigra Marsh. Red Ash Fraxinus pennsylvanica Marsh. Green Ash Fraxinus pennsylvanica lanceolata Sarg. Fringe Tree Chionanthus virginica L. Hercules Club Aralia spinosa L. Staghorn Sumach Rhus hirla Sud. Wahoo or Burning Bush Evonymus alropurporia Jacquin Sweet Crab Mains coronaria Mill. introduced trees that have become common in the forest Common Name Botanical Name Honey Locust Gledilsia triacanlhos L. Hardy Catalpa Catalpa speciosa Warder Ailanthus Ailanthus allissima Swing. Empress Tree Paulownia tomentosa Steud. Osage Orange Toxylon pomiferum Raf. White Poplar Populus alba L. Important Timber Trees and Their Chief Uses Nearly all of the tree species found in the County are used to some extent, but taking only those which, by reason of their abundance and good qualities, have an extensive use, the list may be reduced to com- paratively few well recognized species. Oaks. — At the head of the list naturally stand the oaks which furnish 60 per cent, of the timber cut of the County. There is no class of wood that possesses strength and durability to such a marked extent as oak. The oaks may be divided commercially into two groups — the white oaks and the red oaks. White Oaks. — This group includes a number of different species classed by timber operators under the general name of white oak. The wood of the different species is very similar and difficult to recognize except by experts. For all practical purposes, the wood of one species is Maryland Geological Survey 399 as good as another. The principal species included in this group are the true white oak, chestnut oak, post oak, and swamp white oak. The true white oak furnishes about 80 per cent, of what is cut and sold as white oak, the chestnut oak about 12 per cent., and post oak and swamp white oak, the remainder. The wood of the white oak is especially tough and strong, and since it is so widely distributed over the County and constitutes so large a percentage of the merchantable timber, it is the most important of all of the tree species. It is used locally for general construction purposes, and is extensively exported from the County for car construction, framing, bridge plank, furniture wood, cooperage stock, railroad ties, piling, and a variety of other uses requiring high grade wood. Red Oaks. — A number of different species of oak are sold as red oak, including black oak, red oak, scarlet oak, Spanish oak, pin oak, and willow oak. Sometimes, the last two mentioned are classed as water oaks, and sold at a somewhat lower price. Red oak is less durable than white oak, and for most purposes does not command so high a price. Like white oak, it is heavy, hard, strong, tough, but not so durable on exposure. For interior uses, such as furniture, finish, etc., it is the equal of white oak, and sells for about the same price. Its chief uses are for general construction, car stock, railroad ties, planking, furniture, and interior finish. The greatest increase in use has been for railroad ties which take a large percentage of the cut. The wood of the red oak possesses all the requisite qualities for first class railroad ties, except its durability in contact with the soil. By treating the wood with a preservative, such as is in practice by all railroad companies, this obstacle is overcome, consequently red oak ties are now universally used. Tulip Poplar.— This species, commonly known as yellow poplar, is a tree found scattered singly or in small groups in the forest and is rarely found in anything like pure stands. The wood is of fine texture, light, soft, easily worked, takes paint readily, and holds its shape well, making it a favorite among wood users. It attains a larger size than any other tree in the County, and is found in the deep, moist soils of 400 The Forests of Baltimore County ravines and lower slopes. It is used locally for weather boarding, sheath- ing, and general construction. The better grades are exported for furniture stock and interior finish, cigar boxes, wagon bodies, etc. The smaller and medium-sized trees are cut extensively for pulpwood. Hickory. — Several species of hickory occur in the County and are used indiscriminately. The principal species are mockernut and pignut hickory. The wood has a highly specialized use for spoke timber and tool handles, for which it is fitted by its distinctive qualities of hardness, strength, toughness, and flexibility. It is a tree found sparingly in the forest and associated with the oaks, tulip poplar, and chestnut. While the wood is very valuable, usually only a small percentage of the tree is sufficiently clear straight-grained to be acceptable for its special uses, hence it is not considered as a desirable tree to encourage in the forest. As a fuel wood, it ranks very high. Locust. — This tree is abundant throughout the County, found on a variety of soils, and is the chief dependence for fence posts. It is a rapid growing tree of quick maturity, furnishing a valuable product, and is highly desirable for forest planting. In addition to its local use for fence posts, the wood is specially used for insulator pins, and was used extensively during the War for tree nails in the construction of wooden ships. Ash. — Although four species of ash are recognized in the County, it is probable that white ash constitutes more than 90 per cent, of the cut. It is a tree growing in mixture with other species in the forest, and is found on the moister soils along water courses. The wood is very heavy, strong, straight-grained, tough and elastic, and is used for car construction, furniture, vehicle manufacture, agricultural implements, tool handles, sporting goods, etc. The amount cut in the County is relatively small, and it is usually thrown in with other species, being cut for lumber and railroad ties, although occasionally selected logs are shipped for use in special wood using industries. Black Walnut. — Walnut brings a higher price per thousand feet than any other wood, and during the War immense quantities were cut and shipped out of the County for the manufacture of gun stocks and aero- MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXVI Fig. 2. — The product of a portable saw-mill, an operation in a 30-acre timber tract. I Maryland Geological Survey 401 plane propellers. It is a tree found along the edges of fields and ravines on the farm, rather than in the forest. Where it grows it is a short- stemmed, wide-branching tree having a low percentage of merchantable content, so that the values received are not high as compared with the length of time required to grow the tree to commercial size, and the amount of space that it occupies. The wood is fine-grained, hard, strong, durable, and easily worked. It is highly prized as a cabinet and furniture wood. Chestnut. — Chestnut was formerly the most abundant tree species in the County, but due to the ravages of the chestnut blight, — a fungus disease which became established about 1910, — it is no longer a species of commercial importance. It has been used more extensively for telegraph and telephone poles than any other species. Rapidity of growth, abundance, and adaptability for so many uses made it one of our most important timber trees. Its elimination from the forest has created a serious timber problem, affecting the pole supply especially, — a loss difficult to replace. The Lumber and Timber Cut The lumber and timber cut of the County has fallen off to about half of what it was in 1920. This is due in part to a depletion of the timber supply and partly to the appearance in eastern markets of lumber in large quantities from the Pacific Coast. Heretofore, the cut has been greater than the current growth. The reduction of the cut, with better care of the forests, will no doubt materially help in restoring the forest to greater productivity. There were 26 saw-mills operating in the County in 1925, which cut approximately 3,800,000 ft. board measure of lumber. These were mainly portable mills, operating but a few months in the year, but included also a few small stationary steam and water-mills, doing a small custom sawing business. The lumber cut consists almost entirely of hardwoods, — the amount of pine constituting but a small percentage. The several species of oak 402 The Forests of Baltimore Coun'ty constitute about 75 per cent of the cut, tulip poplar 10 p >r cent, and 15 per cent miscellaneous species. In addition to lumber, large quantities of railroad ties, including trolley ties, are produced annually. Oak is principally used, although with the general use of wood preservatives a number of other species, not naturally durable, are accepted for preservative treatment. The growing scarcity of old growth, high-grade timber has brought about more economical utilization. Choice logs from selected trees of black walnut, white and red oak, and tulip poplar are cut and shipped to veneer plants for manufacture into thin veneers. These thin strips of valuable wood, glued on to a cheap wood base, give the desired effects for furniture and cabinet work with the most economical use of material. In addition to furniture veneer many large sized poplar logs are made into veneer cigar boxes and baskets of various kinds. The demand for piling has fallen off very sharply since the War, but still constitutes an important product of Baltimore County's forests. This special use requires a strong wood in reasonabh' straight sticks. Oaks, including both white and red, constituted about the entire cut for this purpose. Piles range from 30-60 feet in length averaging about 35 feet, and are sold by the linear foot. Copper poles, so called, are used at the copper smelters in Baltimore in the process of reducing ore to the pure metal. They consist of poles of varjing length, although usually 30 feet long, and 3 inches, or over, at the small end, any kind of hardwood being taken. While this is strictly a local industry, there is a steady demand, amounting to several thousand tons annually. The increasing cost of coal and the difficulty of obtaining it has in- creased the market for cordwood. The high cost of cutting, however, has been a serious drawback, so that the amount cut and sold is not large, but the amount used as fuel wood on farms constitutes a large use, estimated at 15,000 cords. For this purpose all kinds of wood are used, much of it as waste material in the forest. It is estimated that the lumber and timber products cut from the forest and sold have an annual value of $500,000. Maryland Geological Survey 403 Forest Protection The principal reasons for the poor condition of the forests of the County are forest fires, destructive methods of cutting, pasturing the woodland, insects and tree diseases. Forest Fires. — The chief causes of forest fires are hunters, and fisher- men, brush burning, and railroads. Nearly all fires could be prevented with reasonable care. The Maryland Forest Laws impose heavy penalties upon anyone who sets fire to woodlands, not his own. Any owner who sets fire on his own land and allows it to escape to the injury of other lands is liable for the cost of extinguishing the fire, and for the damage that is done to adjacent property. Fire damage in Baltimore County has not been excessive, due to the isolated character of many of the woodlands, and also that most of the woodlands are on farms where a closer watch for fires is possible. Nevertheless, the annual loss from forest fires is considerable, and a fire that burns over any woodland does serious damage in reducing the productive capacity of the forests. The effects of fire are : (a) The burning of the leaves and litter on the ground which are needed to conserve the moisture, to protect the seed and to fertilize the soil. (b) The destruction of the seed, and young seedlings that have already started, and which are so essential for the renewal of the forests. (c) The burning of the cambium, or living wood, of young trees on the side most exposed to fire, causing the bark to peel off, thus exposing the wood to decay. The tree becomes stunted, decay enters the wood and gradually works its way up into the trunk rendering the tree practically worthless. (d) A severe fire in the brush, left by logging operations, often kills all the trees that remain, entailing a total loss of growing stock. Preventive Measures. — In the case of small woodlands, surrounded by cultivated land, the danger from forest fires is very much reduced. But where the woodlands are in large tracts, particularly where they border public highways or railroads, the danger is greatly increased. The most effective preventive measures are extreme care on the part of the owner and his employees engaged in work in the woods, and the elimination, so far as possible, of dead and down timber and dry tops. Where there is a particular fire hazard, such as along the borders of the 401 The Forests of Baltimore County roadways and railways, all inflammable material should be removed for some distance from the edges of the roadways, and along the rights-of- way of the railroads.2 Woods roads through the property should be kept clear of inflammable material to serve as fire lines, from which fires that occur may be more easily and more effectively combated. Destructive Cutting Methods. — In past years when timber was cheap, usually only the best was taken from the woodland, and that of the poorer species and poorer quality was left. This practice has continued for many years, nearly all of the forests having been cut over in this way, with the result that culled forests are the prevailing type. Most of the forests have been cut over two or three times, and under this system of always removing the best, rapid deterioration has followed. Not only that, but the remaining small trees of no merchantable value have been recklessly destroyed in taking out the larger timber, and there has been an excessive amount of waste in logging methods. The woods have been strewn with dead tops and brush, covering or weighing down the young trees, and at the same time greatly increasing the fire hazard. To correct such abuses and to restore forest productivity, the cutting should be made in such a way as to favor the most valuable species, and to eliminate, so far as practicable, the undesirable species and the crooked and defective trees even of the valuable species. This necessi- tates the careful selection of trees by the owner in any cutting that may be done. Especially in taking out trees for firewood, the poorer kind should be taken, thereby improving the character and composition of the woodland and leaving the more desirable trees for reproducing the forest. Grazing. — It is a common practice throughout the County to include the woodland in the permanent pasture. This has resulted in serious damage by creating conditions unfavorable to tree growth. The soil becomes hard and dry from the constant tramping of the cattle, the seed bed is destroyed, and the growth of the trees seriously checked, if not altogether stopped. The woodland becomes open and very much 2 Railroad companies are required by law to clear away inflammable material for a distance of 100 ft. from the track where the Forestry Department notifies them that a fire hazard exists. Maryland Geological Survey 405 understocked, due to the destruction of the young growth and it ceases to be of value for timber production. The small amount of pasturage is poor pay for the loss in the production of timber, and the result is that there is neither good pasture nor good woodland. Insects and Fungi. — No serious insect attacks have been reported from Baltimore County. While immense damage is done each year to shade trees, comparatively little damage is done to the trees in the forest. Here the insects seem to be held in check by their natural enemies. The one fungus disease that has been particularly destructive is the chestnut blight which has badly affected practically all the chestnut. This disease attacks only the chestnut, and there appears no danger of its spread to other kinds of trees. There is no practical method of control, and the chestnut, as a commercial tree species, appears to be doomed. Forest Management No county is more favorably located for the practice of forestry than is Baltimore, and few counties have suffered more from the lack of good forestry practice. The growing of timber is just as certainly crop production as is the growing of corn or wheat, and like any other crop from the soil, certain cultural operations can be conducted with much profit in increasing the final yield. These operations can often be so conducted as to bring in an immediate revenue, and at the same time improve growth conditions. The farmer in handling his woodlands is in the very best position to give them the careful management that is required to get the maximum results. The work in the woods should be as carefully planned as that in the fields, and with the same purpose in view, — to get the maximum yield. The selection of the trees for cutting should not be left to in- experienced farm hands, with no thought other than getting wood in the easiest way, and having no permanent interest in the land. Work in the woods can be done in the winter-time when other work on the farm is not pressing. Frequently, woods-work provides employment for farm hands during the winter months, when they could not otherwise be profitably employed. 406 The Forests of Baltimore County A woodland is fully productive when the ground is occupied entirely, that is, to the exclusion of any open places, by the best trees of the best species for which the soil is adapted. The proper density of the forest is, therefore, of prime importance, for not only will the greater volume of wood be produced when the crowns of the trees are close enough together to touch each other on all sides, but this crowding will produce tall straight trees with long clear stems that make the most valuable timbers. After trees attain their principal height growth, they will require a little free space around their crown to promote the greatest diameter growth. Starting then with a young thicket stand of any species, or with mixed species of trees, crowding is beneficial in that it forces the most likely ones into rapid height growth to keep them above their competitors, but the dense shade kills off the smaller lower branches that would otherwise make knotty timber. During the small pole stage (under 5 inches in diameter) the stand may be greatly improved by cutting out undesirable trees, such as black gum, red maple, beech, etc., when they are overtopping or crowding the more valuable species, such as the oaks, hickories, tulip poplar, etc. This is termed a "weeding" in a young stand and is similar to the same operation in the garden or cornfield, and for the same purpose. By working over the forest at frequent intervals, with the idea of always favoring the more promising trees, and removing the undesirable ones as soon as they begin to interfere with the trees selected for the permanent stand, it is possible to mould the forest into the form desired. Instead of a fully stocked young forest, the problem may be one of restocking and regenerating a badly burned and culled forest. In this case the important thing is to encourage a reproduction of the species best suited to the locality. Seed trees are generally present to begin with, and by keeping out fires a young growth will in most cases spring up rapidly. As the young growth develops such of the inferior trees as were left in the former cutting operations should be cut and utilized, so that they will cease to overtop and check the growth of the young saplings. By a gradual process of thinnings and improve- ment cuttings, the undesirable trees may be eliminated from the forest and a full stand of desirable trees secured for the final crop. Marylaxd Geological Survey 407 Another common problem of forest management is that of a forest in which there is a considerable amount of merchantable material that the owner desires to cut and turn into money, but, at the same time, he wants to get it out in such a way that the producing power of the forest shall not be destroyed, since he intends to hold the woodland for future timber crops. In most cases of this kind, there is already on the ground a good young growth, which, if properly protected, will insure a satisfactory second crop. The main consideration should be to frame the cutting contract (if the timber is not to be cut by the landowner) in such a way that the young growth will be saved. The usual practice is to specify a minimum diameter limit, to be measured at a certain height from the ground. In cutting to a diameter limit the inferior species, such as gums, red maple and beech should betaken, as well as the more valuable species, since it is very desirable to prevent these inferior trees from gaining any advantage in the stand which is to succeed the one that is being cut. Unless special care is taken in felling the trees, cutting roads, and getting out saw-logs, a great deal of this young growth will be destroyed. Some damage is unavoidable, but unreason- able damage should be guarded against in framing the contract, even if the price secured for the timber is a little less in consequence. There are precautions such as any careful business man would take, and they will pay well in the end. The destruction of the chestnut, caused by the chestnut blight, has introduced a new problem in forest management. Where the chestnut represented only a small percentage of the mixture, natural seeding from the other species has generally taken the place of the trees killed by the blight. In places, however, where the chestnut forms a large percentage of the trees in the forest, the killing of this species has created gaps that will take many years to fill up satisfactorily, through natural means, and the importance of artificial seeding, or planting, to fill up these open places is apparent. For this purpose, it will, ordinarily, be necessary to use trees that will stand a considerable amount of shade. For the high dry ridges, the planting of chestnut oak acorns will, probably, be most satisfactory, 408 The Forests of Baltimore County while on the slopes the planting of white pine seedlings is recommended. On the lower slopes and better soils, the planting of red oak acorns, or of white pine seedlings, is to be recommended. The extent to which conservative forest management may be applied in any case will depend upon a number of factors, chief of which are the danger of fire risk, and the market for the different kinds of forest products. If these conditions are favorable, there is the opportunity to practice forestry very profitably. Even if there is a serious fire risk, and the present market conditions are not favorable, the fact remains that nearly all of this land will be held for timber production, and since that is the case, why not make the lands as productive as possible, especially as so much can be done by way of improvement at little expense. The danger from fires will rapidly decrease, as people gener- ally come to appreciate the damage they do, and as the State makes more liberal provisions for forest protection. The market for timber products is sure to improve, so that timber growing is certain to become more remunerative. The landowners, who are taking care of their forests now, will be the ones who will have the timber to sell a few years later, when so much better prices will, undoubtedly, be secured. Forest Planting The forest survey of the County showed 65,650 acres, or 17% of the total land area of the County as waste-land, exclusive of salt marshes. This represents land upon which there is growing no crop of value, and includes swamps, gullied hillsides, and other unproductive areas. All of this land will grow timber if planted or seeded with suitable species of trees. There is such a wide range of valuable native species in the County, that it is possible to find kinds suitable for any conditions that exist, and for most of the waste-land, there is no more profitable crop that can be grown upon it than timber. Some of this land is suitable for permanent pasture, and will eventually be so used, but for a large part of it forest planting is the only solution of the problem. It is not alone on the waste-lands of the County that planting is MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXVII Fig. 1. — An original forest of mixed oak, hickory and tulip poplar, of which little is left, but showing what can be grown again if properly protected and managed Fig. 2. — View showing pine poles at White Marsh, Baltimore Count}' Maryland Geological Survey 409 practicable, but there is need for much forest planting on other lands, such as the reinforcing of depleted woodlands, the providing for fence posts and other timbers on farms, where the supply of these materials is lacking, the planting of strips for wind-breaks, the planting of lands now used for other purposes, that would bring better returns in a timber crop. Before planting is undertaken, the area that it is proposed to plant should be carefully examined with a view to selecting the best species, with reference to the soil, moisture conditions, and the purposes for which the timber is to be grown.3 Trees For Forest Planting. — Black locust (Robinia pseudacacia) , also called yellow locust, or simply locust, is a native tree of rapid growth, producing a heavy, hard, durable wood, highly prized for fence posts, and for this purpose exceeds in value any other species. It casts so little shade that grass and weeds will grow under the trees and com- pete for moisture and soil fertility. For this reason and also because of possible attack from the locust borer, it is advised to plant in mixture with other species, of somewhat slower growth, that will endure shade, and at the same time more completely shade the ground, such as white pine, or red oak. The trees should be spaced 6x6 feet, in alternate rows, with a row of white pine, or red oak, whichever is used in the mixture on the outside of the plantation. On good soils the locust will grow 2-4 feet in height in a year. Fence posts will be produced in about 15-20 years, leaving the other species to produce a timber crop some years later. One-year-old locust seedlings should, generally, be used for establishing the plantation. White pine (Pinus strobus) is found growing naturally along the Gunpowder River, and in the northern half of the County, and is suitable for planting in all sections, except the southeastern on the Coastal Plain. It is a rapid growing tree, averaging from one to two feet in height, each year, and produces a soft, even-grained wood, useful 3 The State Forester, Baltimore, Maryland, will upon request examine lands and prepare planting plans. Planting stock may be obtained from the State Nursery at small cost. 410 The Forests of Baltimore County for many purposes. It will produce saw timber in 30 to 40 years on good soil. White pine is subject to attack by the white pine weevil, — an insect that bores into the leader and kills it, often causing a forked stem. This species has been extensively planted in the County, in the Gun- powder watershed lands owned by Baltimore City, and appears to be making a most satisfactory growth. A spacing of 6 x 6 feet, using two year old seedlings, will generally give the best results on land that is free from undergrowth. A mixture of locust with white pine is recom- mended as most practical for fully utilizing the ground, using the same spacing, 6x6 feet, but with alternate rows of locust, which will come out for fence posts and stakes, when the pine needs mofe room. Red oak, (Quercus borealis maxima) is one of the common native trees, suitable for forest planting on medium to good soil. It is the most rapid growing of the oaks, producing a heavy, hard, strong wood, very useful on the farm for general construction purposes and for fuel wood. Red oak is fairly tolerant of shade, and therefore, useful for underplanting in woodlands in need of reinforcing. The best method of propagation is by planting the seeds, two or three in each hole, where the trees are needed. In establishing a plantation, a spacing of 5 x 5 feet is recommended when seed is used, and 6x6 when seedlings are planted. Other species that can be recommended under specific conditions: White ash, bottom lands or lower slopes. Tulip poplar, bottom lands or lower slopes. Black walnut, deep well-drained fertile soil. Shortleaf pine, dry upland soil. Loblolly pine, wet sandy soil of Coastal Plain. forest planting on the gunpowder watershed The City of Baltimore derives its water supply from reservoirs created in Baltimore County and for the purpose owns about 10,000 acres of land about half of which is under water. Beginning in 1912 the city adopted the policy of planting areas above the water line in forest trees and up to the present time has planted about 550 acres. A continuous Maryland Geological Survey 411 forest program will eventually bring all the city owned watershed above the flood line under a forest cover. The effect of this forest cover is to conserve the rainfall, prevent silting, beautify the landscape and provide revenues from timber growing. The plantations already established, consisting of ten or more differ- ent species, form a valuable demonstration of the value of each species for forest planting. BASKET WILLOW CULTURE The growing of basket willows is an important industry centered around Baltimore, particularly in the vicinity of Lansdowne, Patapsco, Rosedale, and Catonsville. There are 13 willow gardens in Baltimore County comprising a little over 46 acres. This acreage could be greatly increased with profit, as there are extensive areas in the County suitable for the purpose. The best gardens are on flat land which, however, is not water soaked during the growing season. Willows will grow on land that is wet during the winter and spring, but they must have reasonably dry surface conditions during the summer growing season. On the other hand, willows will not thrive on lands where the permanent water table is more than 6 feet below the surface. There are three standard varieties that are principally used, the Lemley, the American Green, and the Welsh. In Baltimore County there are 20.25 acres in Lemley, 21.50 in American Green, and 4.50 in Welsh. The net annual returns from willow gardens when established range from $75 to S200 per acre. Further information about willow culture is contained in a report of the State Board of Forestry entitled "Basket Willow Culture in Maryland," by Karl E. Pfeiffer, Assistant Forester. Summary 99,041 acres which is 28% of the land area of Baltimore County, is in woodland. This area is sufficient to supply the timber requirements, if maximum production can be secured. The woodlands are confined, generally, to the rocky ridges, steep slopes, or wet bottom lands — soils not suited for field crops. 412 The Forests of Baltimore County The forest lands are not producing more than one-half of their maxi- mum yield, due to forest fires, destructive cutting methods, grazing, and tree diseases, causing depleted woodlands. Adequate forest fire protection and good forest management would in a few years increase the timber production and forest revenues 50%. The demand for forest products is exceptionally good, transportation for such products to nearby markets especially favorable, resulting in good prices. The timber cut of the County has an annual value of S500,000 at the shipping points. There are 63,650 acres of waste-land in the County upon which nothing of value is being produced. Most of this area is suitable for forests, which, if planted to trees, will produce a good paying crop. The growing of basket willows is, probably, the most profitable use of many small areas of low ground along streams subject to overflow and too wet for other cultivated crops. MARYLAND GEOLOGICAL SURVEY BALTIMORE COUNTY. PLATE XXVIII Fig. 2. — View showing the result of a timber operation where the trees for cutting were marked by the State Board of Forestry, the small trees and young growth being fully protected for a second crop. INDEX A Age of structures, 191 Aiken, 75 Alaskite porphyry, 136 Alberton, 141, 154, 162, 260 Alberton anticline, 142, 146, 153, 186 Alum stone, 247, 248 American Tin Plate Company, 225 Amphibolite, 123 Analyses, 114, 120, 121, 130, 133, 135, 139, 149, 157, 159, 165, 172, 248 Ankowiac lime kiln, 249 Anticlines, 186 Arcadia, 72 Arcadia terrace, 86 Areal distribution of Arundel forma- tion, 203 Baltimore gneiss, 141 Cockeysville marble, 162 Patapsco formation, 205 Patuxent formation, 201 Peters Creek formation, 176 Raritan formation, 207 Recent deposits, 216 Setters quartzite, 211 Talbot formation, 215 Wicomico formation, 212 \Yissahickon schist, 167 Areas of different soils, 315 Artesian wells, 291 Artificial stone, 231 Arundel Corporation, 265 Arundel formation, areal distribution of, 203 lithologic character of, 203 organic remains, 204 stratigraphic relations, 204 strike, dip, and thickness, 204 Ashland furnace, 97, 223 Ashland Iron Compan}', 224 Atkinson quarry, 142 Atmospheric pressure, 348 Avalon, 112, 223 B Bacon Hall, 138 Baer flint quarry, 282, 284 Baker, J. E. and Company, 252 Baker and Connelly, 234 Baldwin, 162 Baltimore Brick Company, 274 Baltimore City anticline, 186 Baltimore City, incorporation of, 32 Baltimore County, agricultural con- ditions in, 305 artesian wells in, 291 building stones of, 228 climate of, 347 dug wells of, 290 early maps of, 22 forests of, 393 geographic research in, 22 geology of the crystalline rocks, 87 geological history of, 192 historical review, 21 magnetic declination in, 385 maps of, 22 mineral resources of, 219 ore banks in, 225 physical features of, 21 physiography of, 58 precipitation in, 374 road materials of, 238 settlement of, 28 soils of, 305 soil types in, 311 springs in, 289 structure of crystalline rocks, 184 temperature conditions in, 350 topography, 61, 66 water resources of, 288 Baltimore gneiss, 140, 141, 143, 146, 149, 150, 152 414 Index Bare Hills, 22, 107, 170, 189, 285 quarries, 254 syncline, 188 Basket willow culture, 411 Bauer, L. A., 385 Baugh Fertilizer Company, 224 Beaver Dam Marble Company, 163, 234,243 Beetree Run, 168 Belfast, 166 Ben Run, 141, 142, 146 Ben Run anticline, 153, 186 Bentley, 190 Berry, Edward W., 21, 200, 393 Bibliography, 38 Biotite gneiss, chemical analysis of, 135 Blue Mount, 108 dike, 109, 116 quarries, 252 Blunt quarries, 260 Bolton quarry, 251 "Bolus," 22 Bradshaw, 62 Branch quarry, 131 Brandywine formation, 79, 210 Bronzite, chemical analysis of, 121 Bruce, O. C, 305 Bryn Mawr gravels, 80 Buffalo Creek, 138 serpentine, 187 Building stones described, 228 Buried peneplains, 73 Burns and Russell Company, 271, 275 Burton sand pit, 249 Butler, 138, 143, 258 C Campbell quarry, 163, 245, 258 Canton, 224 Capitol Hill, 213 Carbonate ores, 225 Cardill, 109 Carpenters Point, 28 Carter, Win. F. Jr., 305 Caton Sand and Gravel Company, 267 Catonsville, 74, 80, 81, 82, 203, 211 Catonsville terrace, 82 Cedar Point furnaces, 223 Cecilian furnace, 224 Champion Brick Company, 275 Charlotte Hall, 80, 210 Chattolanee, 141, 186, 262 anticline, 142 Chesapeake furnace, 224 Chester loam, 316 Chester stony loam, 315 Chestnut Hill-Sweetair syncline, 189 Chestnut Ridge, 162 Chrome, 219, 284 Claremont, 279, 283 Clark, Win. Bullock, 37 Clay and clay products discussed, 270 Clay, operations in, 273 Clifton Park, 76 Climate discussed, 347 Coastal Plain discussed, 61, 200 terraces, 74, 76, 78 Cockeysville, 97, 167, 170, 187, 189, 247 marble, analysis of, 165 chemical composition of, 165 correlation of, 166 economic value, 162 igneous intrusions, 166 lithologic character, 163 quarries in, 229 thickness of, 166 section of, 164 Cold waves, 367 Congaree silt loam, 342 Congress Heights, 208 Conowingo, 178 Conowingo silt loam, 326 Cooks Lane, 251 Copper, 219, 287 Cowenton, 222 Cromwell Bridge, 156 Crystalline rocks, geology of, 97, 102 sedimentary origin of, 140 schists, origin of, 99 Cub Hill, 126, 153 Curley-Schwind quarry, 142 D Davis, 146, 162, 166 Davis tunnel. 130, 131 Index 415 Delight, 254 Diabase, age of, 139 analyses of, 138, 139 lithologic character of, 138 Dickeyville, 109, 251 Diopside, analysis of, 121 Dogwood Run, 153 Doe Run, 178 Dorseys Run, 136 Dover, 167 Dulaney Valley, 175, 181 Dyer quarry, 254 E Early maps of Baltimore County, 22 Elk Neck, 208 Elkton silt loam, 341 Ellicott City, 70, 134, 135, 220 granite quarries, 134, 229, 242 Emory Church, 168, 176 Epi-Carboniferous granites, 131 Erosion cycle, progress of, 64 F Falls Road quarry, 254, 255 Fassig, O. L., 347 Faulting, 190 Federal Hill, 205, 206 Feeney's quarry, 163 Feldspar, 276 Field stone, 238 Finksburg, 117 Flagstone, 237 Flint, 280 Folding, 186 Forests, distribution of, 393 management of, 405 planting, 408 production, 403 Fox Rock quarry, 240 Fowblesburg, 85, 86 Franklintown, 109, 251 Franklinville, 223 Frosts, 267 G Gabbro, analysis of, 114 areal distribution of, 107 economic value, 109 lithologic character, 109 intrusive relations, 108 weathering, 109 Gardenville, 109, 250 Gatch quarry, 242, 249 Gemmels, 176, 189 Geographic research, history of, 22 Geologic research, history of, 34 Geology of crystalline rocks, 97 Germantown, 201 Glenarm, 137, 141, 155 series, age of, 180 correlation of, 183 discussion of, 152 Glenarm-Towson anticline, 142 Glencoe, 108, 143, 145, 155, 167, 169, 187 Glen Falls, 63, 189 Glen Morris, 181, 182 Glyndon, 186 Gneiss, discussion of, 236 Gorsuch Point, 221 Govans, 153, 201, 203 Grange, 73 Granites, analyses of, 221 discussed, 123 for building, 232 Green, J. L., quarry, 282 Greenspring Valley, 142 Greenwood, 126, 155 Grey stone, 176 Growing season, 367 Guilford and Waltersville quarry, 131, 281 Gunpowder furnaces, 224 granite, 125 quarry, 247 Gwynns Falls furnace, 222 Gwynns Falls Stone Corporation quarry, 256 H Hagerstown loam, 330 Hall Spring, 143 Halethorpe, 203 Hamilton terrace, 81 Hampstead terrace, 86 Hampton furnace, 223 416 INDEX Harrisonville, 73, 84 Hartley augen gneiss, 124 Havre de Grace, 75, 178, 216 Hebbville, 73, 84, 112, 116, 162 Henryton, 179 Hereford, 64, 108 Herman, Augustine, map by, 24 Hernwood, 235, 249, 260, 261 Hess, 141, 154, 170 Hesse sand pit, 269 Hillsdale, 109, 251 Hilton quarries, 257 Historical review, 21 Hoffmanville, 168 Holbrook, 108, 116, 286 Hollofields, 30, 112, 154, 156 trap quarry, 252 Homewood, 76 Honeygo Run, 222 Hornblende gabbro, 110 Howard Park terrace, 82 Howardville, 116 Howells Point, 28 Hyde, 189 Hypersthene gabbro, 109 analysis of, 114 Humidity, 369 I . Igneous rocks, 106 Incorporation of Baltimore City, 32 Indian Run, 155 Iredell silt loam, 325 Iron ores, 221 Ivy, 143 J Jacksonville, 85 Jarretsville, 109 "Jew Bottom," 260 Johnycake Road, 120 Jonas, Anna L, 97 Jones Falls, 112 gneiss quarries, 229 quarry, 261 Joppa Iron Works, 222 K Kahl sand pit, 269 Keyport silt loam, 340 Kingsbury furnace, 222 Knoebel, 85 Knopf, Eleanora Bliss, 58, 97 Knopf quarry, 261 L Lake Montebello, 153 Lake Roland, 87, 90 Lancashire furnace, 223 Landsdowne, 203, 267 Laurel, 109, 142 furnaces, 224 Lazaretto furnaces, 224 Leonard quarry, 142 Leonardtown loam, 336 silt loam, 337 Limekiln Hollow, 168 Limestone operations, 240 Lindsay's kiln, 235, 249 quarry, 163 Link Sand Company, 267 Little Falls, 168 Loch Raven, 63, 84, 137, 166, 168, 175 quarry, 257 Locust Grove furnace, 224 Long Cam furnace, 224 Long Green, 162, 166 Long Creek Creek, 124 Longley quarry, 250 Loreley, 201 Louisa loam, 322 Lower Cretaceous formations, 200 Lumber and timber, 401 Lutherville, 73, 82 II Magncsite, 210 Magnetic declination, 385 Mallonee Brothers, 252, 259 Manchester, 87 Manor, 85 Manor loam, 320 stony loam, 319 Index 417 Mantua, 169 Maps of early Baltimore County, 233 Marble of Baltimore County, 233 Marble Hill, 167 - Martic overthrust. 191 Martin quarry, 251 Mason and Dixon Line, 37 Maryland Calcite Company's quarry, 247 Maryland furnace, 223 Maryland Line, 86 Maryland Quartz Company, 281 Mathews, Edward B., 219, 347 Meadow lowland, 62 McDonough, 124 McMahon Bros., 153, 246 Mecklenburg loam, 323 Melvale, 27, 28 Meridian line, 385 Meta-gabbro, 111 Milford trap quarry, 252 Minebank Valley, 160, 166 Mineral resources, 219 Mine Ridge Hill anticline, 192 Monadnocks, 87 Monkton, 82, 83, 141, 143 Montalto clay loam, 329 Montebello, 81 Morgan College quarry, 242 Mount Carmel, 168, 176 Mount Hope station, 113 Mount Washington, 116, 131, 153, 167, 187, 189, 190 Muirkirk Iron furnace, 221 Mutual Chemical Company of Amer- ica, 285 N Native forest trees, list of, 396 New Jersey United Clay Mining Cor- poration, 276 '■Niggerhead" rock, 239 Northampton furnace, 223 Nottingham Works, 222 Numsen Iron Works, 224 Nunn, Roscoe, 347 O Oakland, 127, 129, 179 Oakleigh, 161, 188 Oella, 112 Old Court Road, 138 Old Joppa, 222 Operations in building stone, 240 Orange Grove, 81, 112, 135 Ore banks, 225 Oregon, 167 furnace, 224 ore bank, 223 Overlea Sand and Gravel Company, 268 Owings Mills, 170 P Paleozoic fording, 192 Parkton, 168 Palners Island, 28 Parrs Ridge, 70, 71 Patapsco formation, areal distribution of, 205 character of materials, 205 organic remains, 206 stratigraphic relations, 207 strike, dip, and thickness, 207 Patuxent formation, areal distribution of, 201 character of materials, 202 organic remains, 202 stratigraphic relations, 203 strike, dip, and thickness, 202 Peach Bottom syncline, 179 Peat, 213 Peddicord quarry, 142 Pegmatites, 136 Peneplains, 68, 73 Peridotite, 114 Perry Hall, 203 Perryville, 75, 76 Peters Creek formation, age of, 179 areal distribution of, 176 economic importance of, 179 field relations of, 177 igneous intrusions, 180 thickness, 179 418 Index Phoenix, 63, 141, 153, 155 anticline, 146, 151, 180 Physical features of the county, 21 Physiographic provinces, 59 Physiography of the count}', 59 Piedmont Province, 62 terraces, 79 correlation of, 87, 89 origin of, 90 Pikesville, 84, 259 Pine Hill, 262 Pleasant Grove, 189 Pleistocene formations, 209 Point Lookout, 25 Pelesne Bros, sand pit, 268 Port Deposit granite, 27 Post-Glenarm granite, 125 Potomac Group, 201 "Powells lies," 22 Pre-Cambrian folding, 191 rocks, 140 Precipitation, 374 Pre-Glenarm granites, 124 Priceville, 167, 169 Principio Iron furnace, 221 Products Sales Company, 278, 283 Providence Hill, 166, 168 Putty Hill, 76 Pyroxene, 114 Q Quartz, 280 Quarternary ice age, 96 R Randallstown, 84, 85, 155, 189 Raritan formation, areal distribution of, 208 character of materials, 208 paleontologic character, 208 stratigraphic relations, 209 strike, dip, and thickness, 209 Raspeburg, 109, 249 Recent deposits, 216 Reckord, 108, 125 Relay, 63, 107, 207 Reisterstown, 85, 211, 245 terrace, 85 Richardson sand pit, 270 Road materials, 238 Robinson's kiln, 249 Rocky Point, 208, 209 Rogers, 155 Rogers Forge, 82 Rogers quarry, 263 Rognel Heights, 81, 116, 127, 128, 129 Roland Park, 116 Rosedale, 275 Rossville, 274 "Rust rock," 236 "Rustic" quarry, 258 Ruxton thrust fault, 187 S Sadler sand pit, 268 Saint James corners, 85 Saint John Church, 186 Sand and gravel, 263 operations for, 265 Sassafras gravelly loam, 332 loam, 334 sandy loam, 333 silt loam, 355 Saw timber, stand and value of, 395 Schleagel sand pit, 268 Schwartz sand pit, 269 Section of Cockeysville marble, 164 Setters formation, 161 Setters formation, age of, 161 analysis of, 155 areal distribution of, 153 chemical composition of, 157 economic importance, 155 thickness of, 161 Setters Ridge, 73, 82, 166 Serpentine, 114, 121, 236 Shamburg, 168, 190 Shoemaker quarry, 262 Soils of Baltimore County, 305 Soil types, 311 . Snowfall, 381 Snyder, J. M., 305 Soidiers Delight, 64, 108, 116, 118, 286 Sommers pit, 269 South Baltimore furnaces. 224 Sparks, 143 Index 419 Spring Gardens, 223 Stablersville, 168 Stemmer Run, 203 furnace, 224 Stern quarries, 254 Stevenson, 155 quarry, 202 Stickney furnace, 224 "Stony Forest," 109 Stream adjustment, 93 Stream gorges, 63 Stringtown, 167, 169 Structure, age of, 191 Sudbrook Park, 116, 118 Summerfield, 125, 279 Sunderland . formation, areal distribu- tion of; 211 character of materials, 21 paleontologic character, 212 physiographic expression, 211 thickness of, 212 stratigraphic relations, 212 Sunderland terraces, 76 Susquehanna silt loam, 339 Sweetair terrace, 84 Sunclines, 186 T Talbot formation, areal distribution of, 215 character of materials, 215 paleontologic character, 216 physiographic expression, 211 thickness, 216 stratigraphic relations, 212 Talbot terrace, 74 Temperature of the atmosphere, 350 Ten-mile Hill, 80 Texas, 141, 146, 181, 189, 235, 245, 247, 248 anticline, 153, 186 marble quarries, 229 Thompson sand pit, 248 Tidal marsh, 343 Timber trees and chief uses, 398 Timonium, 82 Tobin, 154 Todd Point, 238 Towson, 73, 74, 82, 414, 201, 203, 223 Trees for forest planting, 409 Trump, 86 Tucquan anticline, 190 Tyson, Isaac, Jr., 285 U Upper Cretaceous formations, 207 V Verona, 64, 154, 167 W Walbrook, 127, 128 Walker, 83 Warren, 153, 155, 156, 170, 175, 187 Washington, D. C, 77, 79 Waters quarry, 259 Water resources of the county, 288 Watson, Edward H., 219 Weatheredville, 251 Weisburg, 176 Westport, 203 Westport Paving Brick Company, 273 Wet spells, 381 Whitehall, 108, 123, 189, 252 White marsh, 213 Whetstone Point, 221 Whittaker's furnace, 223 Wicomico formation, age of, 214 areal distribution of, 213 character of materials, 213 paleontologic character, 213 physiographic expression, 213 stratigraphic relations, 214 thickness, 213 Wicomico terrace, 75 Williams, George Huntington, 36 Willo gardens, 411 Wilmington, 80 Winds, 383 Windsor Hills, 127 Wittingham quarry, 262 Wissahickon formation, age of, 175 analyses of 172 areal distribution, 167 420 Index economic importance, 171 character of the metamorphism, 174 chemical composition, 171 igneous intrusions, 175 lithologic character, 168 thickness, 175 Wissahickon types, mineral composi- tion of, 174 Woodberry, 109, 112, 130 trap rock quarry, 250 Woodensburg, 108, 116 Woodstock, 131, 141, 323 anticline, 142, 186 granite, 131 quarry, 229, 240 Worthington Valley, 141, 180 Wright's Mill quarry, 260 Y Veoho, 108, 117 Vox quarry, 282 Date Due L B Cat No. 1137 a™ . , scm Ma , 3 5002 00268 0598 Maryland Geological Survey. ^ Baltimore county. QE 122 B3A5 1376o1