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Introdl'Ctory 57 

Okooraphic and Geologic Relations 57 

riisTORiCAL Review 00 

Biblio<;rapiiy 60 

Stratigrapuy and Areal Distribution 85 

The Siluriau 8« 

The .1 iiuiata Formation 80 

Tlie Tiiscarora Formation 87 

The Clinton Formation 89 

Tl»e Niagara Formation 01 

Tlie Salina Formation 92 

The Devonian 94 

The Helderberg Formation *. 94 

The Oriskany Formation 98 

The Romney Formation 1 08 

The Jennings Formation 106 

The Hampshire Formation 108 

The Carbonifenms 109 

The Pocono Formation 109 

The Greenbrier Formation 110 

The Mauch Chunk Formation 112 

The Pottsville Formation 113 

The Allegheny Formation 115 

The Conemaugh Formation 118 

The Monongahela Formation 124 

The Permian 128 

Tlie Dunkard Formation 128 

The Pleistocene 130 

The Alluvial and other Late Deposits 130 

Structure 1 32 

The Orleans Anticline 132 

The Town Hill Svnollne 136 

The Stratford Ridge Anticline 138 

The Oldtown and Pratt Valley Folds 139 

The Polish Mountain Syncline 141 

The Tussey Mountain Anticline 142 

The Martin Mountain and Collier Mountain Anticlines 144 

The Big Spring Run Syncline 144 

The Martin Spring Branch Syncline 144 

The Collier Run Syncline 14 



The Evitts Mountain Anticline 145 

The Evitts Creek Syncline 146 

The Wills Mountain Anticline 148 

The Rawlings Syncline 149 

The Fort Hill Anticline 150 

The Georges Creek Syncline 150 

Dip, Strike and Pitch 153 

Faults 15S 

Structure Sections 154 

Interpretation of the Sedimentary Record 155 

General Character and Variation of Sediments 155 

The Early Paleozoic Period 155 

The Tuscarora Period 156 

The Later Silurian Period 158 

The Helderberir Period 1 59 

The OriBkany Period 160 

The Devonian Shale Period 160 

The Lower Carboniferous Period 163 

The Coal Measures Period 163 

Subsequent History 163 





Particular attention is given in the following pages to the strati- 
graphy, structure and areal distribution of the various formations 
exposed in Allegany county; the processes and conditions under which 
the sediments were deposited; and the forces that have operated in 
bringing about the present attitude of the strata. A brief review of 
previous work is given, and a bibliography is added. Only such gen- 
eral references to the paleontology, physiography and soils of the 
region have been made as are necessary to give a clear understanding 
of the geological features since these branches are more fully dis- 
eussed in other places. 


The situation and boundaries of Allegany county have been de- 
scribed in earlier pages. Although bounded on the north and west 
by straight lines whose combined length approximates only 50.8 
miles, the entire periphery is about 145 miles, the amount being very 
much increased by the tortuous channels of the Potomac river and 
Sideling Hill Creek. 

The county contains several mountains of importance. Naming 
them in order from the east, they are: Town Hill, Green Ridge, 
Stratford Ridge, Polish Mountain, Warrior Mountain, Tussey Moun- 
tain, Martin Mountain, Collier Mountain, Evitts Mountain, Nicholas 
Mountain, Shriver Ridge Mountain, Wills Mountain, Allegheny 
Mountain and Dans Mountain. The last two, which may really be 


considered as one mountain, and which are alluded to in this paper 
as the Dans- Allegheny Mountain^ form a part of the great Allegheny 
Front. Tussey Mountain dies out almost immediately after entering 
the county from Pennsylvania, and Evitts Mountain becomes oblit- 
erated nearly as quickly. Other ridges and hills of less geological 
importance are named on the map. 

The drainage of the county is wholly to the south. Among the 
more important streams entering the Potomac are the following: 
Sideling Hill Creek, Fifteenmile Creek, Town Creek, Martins Spring 
Run, Colliers Run, Evitts Creek, Wills Creek, Georges Creek and 
Stony Run. Among the other streams, lying wholly or partly within 
Allegany county, whose waters eventually find their way into the 
Potomac are Flintstone Creek, Murley Branch, Jennings Run, Brad- 
dock Run, Moores Run, Jackson Run, Hill Run, Elk Lick Run, 
Matthew Run, Neffs Run, Winebrenner Run, Staub Run, Wrights 
Run, Squirrel Neck Run, Koontz Run, Laurel Run, Bartlett Run, 
Mill Run, Rock Gully Creek, Maple Run, White Sulphur Creek, 
Piney Ridge Run. Flintstone Creek, Murley Branch and Maple 
Run flow into Town Creek; Jennings Run and Braddock Run flow 
into Wills Creek; Rock Gully Creek flows into Evitts Creek; White 
Sulphur Creek and Piney Ridge Run flow into Fifteenmile Creek; 
while all of the others named enter Georges Creek. 

The area covered by Allegany county forms an integral part of 
the Appalachian Province, hence an accurate and exhaustive study of 
the geology of the county can be made only by adequate reference to 
the conditions governing the complete geologic history of the entire 
province. The province itself is composed of three genetically re- 
lated physiographic divisions, the principal features of which have 
been brought about by geographic conditions that no longer exist* 
The eastern division is a part of the ancient continent of Appal acliia, 
a land-mass of uncertain area from which most of the sediments of 
the Appalachian Province were derived. The western limit of this 
division of the province is now represented by the Blue Ridge. 

1 Willis, Bailey. The Northern Appalachians, Geographic Monographs, vol. i,. 


Lying to the west of Appalachia there was a great inland sea in which 
the sediments from this ancient continent were gradually laid down. 
The littoral zone of this mediterranean sea having received many 
thousands of feet of various kinds of sediments, was from time to time 
affected by powerful organic movements, possibly not yet ceased, the 
result of which has been to bring the formerly almost horizontal 
beds into a greatly folded condition. This old littoral zone, now 
constituting the central physiographic division of the province, cor- 
responds to what is sometimes known as the Greater Appalachian 
Valley, using that term in its wider sense to include the area between 
the Blue Ridge and the Alleghany Front. Along the outskirts of 
the littoral zone the strata were much less influenced by the enormous 
forces which so disturbed the central and eastern divisions; and, 
although considerably elevated, they have, as a rule, been left in a 
more nearly horizontal position. This part which now forms the 
Alleghany Front and the Alleghany Plateau constitutes the western 
physiographic division of the Appalachian Province. 

Structurally, the area which is covered by the central and western 
physiographic divisions as above defined, is divided somewhat differ- 
ently. According to the structure, two divisions are recognized, but 
the line of separation falls much farther east. In Maryland, the 
western structural division known as the district of open folding is 
limited on the eastern side by North Mountain, while the western 
limit extends beyond the western borders of the state. East of North 
Mountain lies the structural division known as the district of close 
folding. In Maryland it occupies approximately the position of the 
Hagerstown Valley. 

Structurally, then, Allegany coimty lies wholly within a single dis- 
trict, that of open folding. Physiographically, it includes parts of two 
divisions, viz., the Greater Appalachian Valley and the Alleghany 
Plateau. Stratigraphically, it is not referable to any well-defined 
district or division. The stratigraphic features are, in a sense, much 
the same as for all of the area west of the great limestone valley. 
Furthermore, the various structural features, as well as the contacts 
of the various formations found in the county, extend in many 


instances without a break or disappearance for miles beyond the 
limits of the county. It will thus be seen that the county is not a 
geological unit and has not been so considered in this paper. How- 
ever, lying along the Potomac and favorably situated for the display 
of the structural, physiographic and stratigraphic features of a con- 
tinuous series of sediments, from the middle Silurian to the late 
Carboniferous or Permian, rich in easily accessible and well-preserved 
fossils, and containing also in the western part large deposits of 
economic importance, the county has for many years been known as 
a region of peculiar interest, and one deserving careful geologic 


The most prominent physiographic features of Allegany county 
have long been known. Natural facilities for a careful study of 
the rocks have always been good, and in addition, especially favorable 
opportunities have at times been provided by means of the various 
extensive improvements made for military and commercial purposes. 
During the middle of the eighteenth century military expeditions to 
Fort Cumberland and beyond necessitated the construction of a good 
road from the Atlantic coast to the Ohio valley. George Washington, 
in a letter to Colonel Bouquet, dated " Camp at Fort Cumberland, 
2, August, 1758," says that the first good road for commercial inter- 
course between the traders of Virginia and Pennsylvania and the 
Indians along the Ohio was by way of Wills Creek [Cumberland], 
which place had been selected by intelligent Indians who had been 
hired to choose the most favorable route of communication. He 
further states that the Ohio Company in 1753 opened the road at a 
considerable expense, and that in the following year his own troops 
greatly repaired it. In 1755 it was widened and completed by Gen- 
eral Braddock to near Fort Duquesne. Early in the present century 
the National Road was surveyed and constructed, the military road 
being in part utilized for this purpose. Later extensive surveys were 
made for the Chesapeake and Ohio Cajial and for the Baltimore and 
Ohio Railroad, the latter reaching Cumberland in the year 1842 and 




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the former in 1850. These surveys, references to which are given 
in the bibliography, added ranch to the general knowledge of the 
physiography and gave considerable detailed information concerning 
the character of the rocks and their folded condition, bnt there appears 
to have been little attention given to the purely scientific study of the 
geology of the area. 

During the autumn of 1831, Samuel Whyllys Pomeroy traveled 
through the county and made some hasty observations on the geology 
along the National Road, particularly in the vicinity of Cumberland 
and Frostburg (2). 

In " Some Notices of the Geology of the Country between Balti- 
more and the Ohio River, with a Section illustrating the Superposi- 
tion of the Rocks," by William E. A. Aiken, published in the 
American Journal of Science, volume xxv, 1834, we have one of the 
earliest attempts to explain the structure of the mountains and to 
correlate the various kinds of rocks (3). Unhappily, Mr. Aiken's 
observations in Allegany county were so meagre that many of the 
conclusions were necessarily faulty and little definite advance was 

In the same year, 1834, J. T. Ducatel, State Geologist, and J. H. 
Alexander, State Topographical Engineer, in a " Report on the Pro- 
jected Survey of the State of Maryland, pursuant to a resolution of 
the General Assembly," give general statements concerning the 
geology of the county (4). Mention is made of the mineral and 
warm springs near Flintstone, and of the Frostburg coal-field. Much 
of the information w-as taken from the collection of reports and 
letters of the engineers of the Chesapeake and Ohio Canal. 

In his " Report of a Geological Reconnaissance made in 1835 from 
the seat of government by way of Green Bay and the Wisconsin 
territory on the Coteau du Prairie, an elevated ridge dividing the 
Missouri from the St. Peters river," G. W. Featherstonhaugh gives 
considerable geological information concerning Allegany county (8). 
He traveled under the direction of the United States government 
and passed through the county while en route westward, evidently 
entering the county by the National Road. East of Cumberland he 


makes little mention of the rocks, but refers to fossils found in the 
limestone at Flintstone. This limestone he erroneously correlates 
with the Carboniferous limestone further west Shriver Ridge is 
mentioned as being composed of shale and limestone with " prodtida," 
" spirifer ^' and " cardia.'^ The Wills Creek gorge he describes 
with considerable detail, and gives a sketch of the same. A crude 
hypothesis for the anticlinal structure of Wills and neighboring 
mountains is also given. From Cumberland he went to Frostburg, 
thence down the Georges Creek valley to the Potomac, which he 
ascended beyond the mouth of Savage river, then returned along the 
Potomac to Cumberland. He speaks briefly of the Georges Creek 
coal area and believed that tlie coal-bearing strata were deposited 
after the movement which produced the folding to the east. 

About this time much interest l)egan to be manifested in the coal, 
iron, cement, and fire-clay of the coal basin. With the prospect of 
an opportimity to ship by rail and canal, a greater interest was 
aroused in the mineral wealth of the county, various mining com- 
panies were incorporated, and reports began to appear giving more 
or less accurate descriptions of the geology of this part of the state. 
Some of these papers show the result of original work; but not a few 
were only compilations from the writings of others. 

In a report dated October, 1836, to tlie Georges Creek Coal and 
Iron Company, one of the earliest companies to develop the mineral 
resources of the Georges Creek basin, J. H. Alexander and P. T. 
Tyson give two maps of portions of the Georges Creek area, one 
columnar section known as the ^' Dug Hill Section," one structure 
section and various oUier details (10). Two months later, Mr. 
Ducatel, the State Geologist, in his official report to the Governor 
of Maryland, included a description of the Frostburg coal-field in 
which the columnar section made for the Georges Creek Coal Com- 
pany is given. In this report there is also given a carefully prepared 
hachured map of die entire area on which the various streams, towns 
and mines are located and named. Frostburg is given on the map 
as Frost Town, and the coal area is called after it. 

During this year, 1836, the State Topographical Engineer, J. H. 

Maryland geoI/OGical survey 63 

Alexander, directed the execution of a chain of triangles with a plane- 
table survey over a part of the Georges Creek area. Tlie work of 
this survey was accomplished at individual expense, but the results 
were generously offered for the use of the state survey. 

During the same year, 1836, George W. Hughes made a report 
to the Maryland Mining Company in which he gives the result of 
an examination of the coal measures and iron ore deposits belonging 
to the company (9). The paper includes various analyses and 
columnar sections. 

In this year also, James C. Booth studied the area and published 
the results in a short paper entitled " Report of the Examination and 
Survey of the Coal-fields and iron ores belonging to the Barton and 
New York Coal Company " (7). The next year, 1837, further notes 
by Mr. Booth, as well as short reports by L. Howell and John Powell 
were published for the same company. 

On February 9, 1837, Professor Philip T. Tyson read before the 
Maryland Academy of Sciences and Literature a paper entitled " A 
description of the Frostburg coal formation of Allegany coimty, 
Maryland, with an account of its geological position " (12). Later 
this was published in the Transactions of the Society. With the de- 
scription of the area one columnar section and two structure sections 
are given. 

In the same year, D. B. Douglas spent three weeks in the coal- 
field. He made a columnar section and studied the physical and 
chemical character of the coals (15). 

The following year, 1838, Benjamin Silliman made a brief study 
of the area in the employ of the Maryland Mining Company (16). 

During the year 1840, the State Geologist, J. T. Ducatcl, made a 
study of the physical geography, geology and agricultural and mineral 
resources of Western Maryland (23). The results of his observations 
were published in the " Annual Report of the Geologist of Maryland, 
1840 " (23). This is a paper of 46 pages, 30 pages of which are, how- 
ever, taken up with a study of the area now included in Garrett 
county. Mr. Ducatel's report was the first published document of 
any considerable length which reviewed with reasonable accuracy the 


geology of the entire county. It includes the geology and physical 
geography with remarks on the actual agricultural condition, pros- 
pects and resources, as well as information concerning the mineral 
wealth of the county and the best means of developing it. Two 
columnar sections of the coal-fields, one structure section along the 
" Cumberland and National roads," and a topographical map of Alle- 
gany and Washington counties on the scale of 1:400,000 are given. 

The year 1842 is one of particular interest on accoimt of Sir 
Charles Lvell's visit to the county. In May of that year he passed 
through the county by way of the National Road, stopping at Cum- 
berland and Frostburg. In the vicinity of the latter phice a number 
of plants and marine shells were obtained from the coal measures. 
Among the shells, he mentions Bellerophorij EuomphaluSy NuculUj 
Loxonema and Producta — seventeen species in all. Of the plants, 
Bimbury, who described them, gives DanaeiteSj Neuropteris^ Pecop- 
teriSy Lepidodendron, Sigillaria, Stigmaria, Asterophyllites and 
Calamites — twenty species altogether (30). 

In 1844, the classic paper " A Report to the Navy Department of 
the United States on American coals applicable to steam navigation 
and other purposes," by Walter R. Johnson was published (27). 
Coals from several Maryland mines were among those studied. 

During the next few years little original investigation was carried 
on in the county, but this period marks the time of much of the 
valuable work done by the illustrious brothers, AV. B. Rogers, Direc- 
tor of the Geological Survey of Virginia, and H. D. Rogers, State 
Geologist of Pennsylvania, who published many reports giving valu- 
able information concerning the geology of their respective states, 
much of which information was extremely helpful in interpreting the 
geology of Allegany county. 

In 1852 reports were published by the Phoenix Mining and Manu- 
facturing Company which included a " topography of the mineral 
regions" by Professor Forrest Sheppard and a report on tlie topog- 
raphy and structure of the coal-field by Professor C. U. Shepard (33). 

Two years later, 1854, George AV. Hughes, President and Engineer 
of the Hampshire Coal and Iron Company, published a report dealing 
especially with the lands controlled by his company (34). 



In 1855, Robert G. Rankin published a report on the oconomic 
value of the serai-bituminous coal of the Cumberland basin (36). 
This is an excellent paper in which the author gives a description of 
the basin, analyses, use and origin of the coal and the facilities for 

In 1859 a great advance was made in the historical study of the 
rocks. Professor James Hall, State Geologist of New York, who 
was so exhaustively studying the Paleozoic fossils of his own state, 
made also from time to time large collections from several of the states 
to the west and south. In September, 1856, he visited Cumberland, 
made some geological examinations and studied the extensive collec- 
tion of Mr. Andrews. Later Professor Hall purchased Mr. Andrews' 
collection and continued his studies upon it. Three years after his 
visit volume 3 of the Paleontology of the State of Jfew York was 
published. In this volume sixty-three species are described from 
Cumberland and vicinity, many of which are figured. Several of the 
subsequent paleontological reports published under the direction of 
Professor Hall also contain descriptions and figures of numerous 
species from the same locality. 

The year 1860 marks the appearance of the state geological map 
by Philip T. Tyson, published in his official report as. State Agricul- 
tural Chemist (40). This map, which is on the scale of twelve miles 
to the inch, represents the first serious attempt to arrange in accurate 
detail the various geological formations in Allegany county. With 
the map there are three structure sections, one of which crosses the 
county from west to east near tlie Maryland-Pennsylvania line. 

During the summer of 1868, Professor James T. Hodge of Boston, 
studied the coal basin and made an extensive survey of the coal 
properties (47). In his report, published the following year, he gives 
much attention to property lines, but also discusses the coal region 
as a whole, including the drainage of the basin, access to the coal-bed, 
system of mining, area covered by the Big Vein and product of Big- 
Vein coal to the acre. To the property-owner this has been a most 
valuable work, but the report is now almost wholly inaccessible. 

In 1874, Professor James Hall published his paper on "The 


Niagara and Lower Helderberg Groups; their relations and geo- 
graphical distribution in the United States" (51). In this paper 
brief but valuable references are made to the relations of the groups 
as they occur at Cumberland. 

In 1878, under the direction of the United States Navy Depart- 
ment, B. F. Sherwood, Theodore Zeller and Henry L. Snyder made 
careful experiments on various coals, including the Frostburg coal 
(58). Particular attention was given to the physical structure of the 
coal, to its action while burning, to its heat-producing power and to 
the residual ash, clinker and soot. 

In 1878, Professor J. J. Stevenson published two articles in the 
American Journal of Science on the geology of portions of Pennsyl- 
vania, Maryland and West Virginia. In one article particular men- 
tion is made of the terraces in Garrett and Allegany counties, and in 
this article the causes of the present physiographic features are dis- 
cussed (60). The other article deals with the Upper Devonian 
rocks (61). 

The year 1882 was one of particular interest in the development 
of a correct knowledge of the structural geology of the county. 
Among the important publications which appeared during this year 
was a paper by Howard Grant Jones and one by Professor I. C. 
White. In Mr. Jones' paper a section west of Cumberland was 
given which was accompanied by a discussion of the correlation of the 
various rocks (72). Professor White later reviewed the work and 
rectified some of Mr. Jones' conclusions. Professor White's paper 
is the first publication showing conclusively the conformity and 
proper relations of the rock formations as found in the western part 
of Allegany county (76). 

It w^as during this year also that report TT of the Second Geological 
Survey of Pennsylvania was published (75). This report is by Pro- 
fessor J. J. Stevenson and deals with the geology of Bedford and 
Fulton counties, whicli lie immediately north of Allegany county. 
In this report frequent reference is made to Allegany county, and 

much of the general discussion concerning the Pennsylvania counties 
is directly applicable to it. 


In the Transactions of the American Institute of Mining Engineers, 
vol. xiv, 1886, R. S. Cook gives an account of the manufacture of 
fire-brick at Mt. Savage, which included a discussion of the occur- 
rence and composition of the clay and a description of the methods of 
manufacture (90). 

During the years 1883-4-5 considerable topographical mapping was 
done in Western Maryland and adjacent portions of West Virginia 
by the United States Geological Survey. The topographic party in 
the early part of the work was in charge of Mr. S. H. Bodfish. Later, 
Mr. Bodfish's health having failed, Mr. W. T. Griswold took charge 
of the party and remained in charge during the following two field 
seasons (86). During the year 1886 much of this work was examined, 
reviewed and prepared for publication by Mr. Merrill Hackett (87). 
Of the sheets surveyed at this time which include portions of Alle- 
gany county, only tliose covering the Piedmont and the Romney 
quadrangles have been published. 

In the year 1897, topographic work was resumed in Allegany 
county by the United States Geological Survey in connection with 
the ^Maryland Geological Survey, since which time the survey of the 
county has been completed. 

In volume 34 of the American Journal of Science, 1887, Professor 
J. J. Stevenson discusses the lower Carboniferous rocks of Pennsyl- 
vania, Maryland and the Virginias, and mentions various Allegany 
county localities (95). 

In the same journal and in the same year. Professor I. C. White 
discusses the probable causes which have brought about the deposition 
of rounded boulders at high altitudes on the eastern side of the AUe- 
ghanies and makes particular mention of the vicinity of Cumberland 

In the 42d Annual Report of the New York State Museum, 1889, 
Professor John M. Clarke discusses "The Hercynian Question," in 
connection with which he gives important notes on some of the for- 
mations in the region about Cumberland (101). 

During the year 1891, Bulletin No. 65 of the United States Geo- 
logical Survey was published. This is by Professor I. C. White on 


" The Stratigraphy of the Bituminous Coal Field of Pennsylvania, 
Ohio and West Virginia " (113). In this bulletin reference is made 
to the Coal Measures of Maryland, and the map which accompanies 
the bulletin includes the Cumberland-Georges Creek district. 

It was in May of this year, 1891, that the students in the Geo- 
logical Department of the Johns Hopkins University visited Allegany 
county imder the direction of the late Professor George H. Williams 
for the purpose of studying Appalachian geology. The results of 
their study are given in volume xi, number 94, of the University 
Circulars for that year (114). 

In 1893, in the Maryland World's Fair Book, entitled " Maryland, 
its Resources, Industries and Institutions," a general summary of 
the geology of the state was published by Professors George H. Wil- 
liams and William B. Clark of the Johns Hopkins University, in 
which the geology of Western Maryland is discussed at considerable 
length (144). With this publication there is a geological map of 
the state in which the areal distribution of the various formations 
and the structure of the rocks of Allegany county are represented in 
much greater detail and accuracy than on any previous map. 

In 1894, Mr. Howard Shriver, of Cumberland, published a short 
paper containing a catalogue of fossils found in the vicinity of Cum- 
berland (150). 

In the Fourteenth Annual Report of the United States Geological 
Survey, published during the same year, 1894, Joseph D. Weeks, 
under the title of " The Potomac and Roaring Creek Coal Fields," 
describes at some length the Cumberland-Georges Creek district, and 
gives a columnar section of the same (151). 

During the years 1894 and 1895, II. O. Hofman and C. D. Demond 
describe, in the Transactions of the American Institute of Mining 
Engineers, extensive experiments which were carried on by them for 
the purpose of determining the refractiveness of fire-clays (148). 
Various experiments were made with the Mt. Savage fire-clay, and in 
the paper a number of analyses are given. 

In 1896, the Piedmont Folio, No. 28 of the Geologic Atlas of the 
United States, was published by the United States Geological Survey 


(159). The geological work was done by Messrs. N. H. Darton and 
Joseph Taff under the direction of Mr. Bailey Willis, and was begun 
in the autumn of 1894. The quadrangle covered by this folio in- 
cludes a small area in the southwestern part of Allegany county, and 
the geology of the entire quadrangle is very similar to that of this 
county. Several of the formational names used in the folio have 
been adopted by the Maryland Geological Survey, and much of the 
discussion concerning the various geological features is directly 
applicable to Allegany county. 

In the early part of the year 1896, the Maryland Geological Survey 
was organized, and at the opening of the. field season began work in 
various parts of the state. Since then three volumes have been pub- 
lished by the survey under the direction of Professor William B. 
Clark, State Geologist. In volume I a general preliminary discussion 
of the various geological features of the state is given, including 
much new and valuable information concerning the stratigraphic, 
physiographic, economic and structural features of Allegany county. 

Volume n includes a description of the various building stones and 
of the geologic maps of the state, with particular mention of Alle- 
gany county. 

Volume III treats especially of the highways of the state, their 
present conditions and the material at hand in each of the counties for 





1. Shriver, James. An Account of the Examination and Surveys, 
with Remarks and Documents relative to the Chesapeake and Ohio 
and Lake Erie Canals. Baltimore, 1824. 116 pp., map. 


2. PoMEROY, Sam. Whyllys. Remarks on the Coal Region be- 
tween Cumberland and Pittsburg, and on the Topography, Scenery, 


etc., of that portion of the Alleghany Mts. [I^etter written Nov., 

Anier. Jour. Sci., vol. xxi, 1832, pp. 342-347. 


3. Aiken, Willla^m E. A. Some of the notices of the Geology of 
the Country between Baltimore and the Ohio River, with a section 
illustrating the superposition of the rocks. 

Amer. Jour. Sci., vol. xxvi, 1834, pp. 219-232, plate. 

4. DucATEL, J. T., and Alexander, J. H. Keport on the Pro- 
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Md. House of Delegates, Dec. Sess., 1833 (Annapolis, 1834). 
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7. Booth, Jas. C. Report of the Examination and Survey of the 
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9. Hughes, George W. Report of an Examination of the Coal 
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10. Duoatel, J. T., and Alexander, J. H. Report on the new 
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Another edition, 117 pp. 


11. Eldbedge, N. T. Report of the Special Agent sent to exam- 
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Trans, ^fd. Acad. Sci. and Lit., 1837, pp. 02-98, plate. 


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15. Douglas, D. B. Report on the Coal and Iron Formation of 
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16. Silliman, B. Extracts from a report made to the Maryland 
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17. Ebickson, Captain. Report of Captain Erickson, Civil Engi- 
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18. Sheppard, F. Report to the Potomac and Allegany Coal and 
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19. Silliman, B. Extract from a report made to the Maryland 
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20. Weld, Henry Thomas. A Report made by Henry Thomas 
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21. Alexander, J. H. Report on the Manufacture of Iron, 
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22. Anon. Charters of the Union Potomac Company and the 
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23. DucATEL, J. T. Annual Report of the Geologist of Maryland^ 
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Another edition, Svc, 59 pp. and 3 plates; also Md. House of Delegates, 
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26. BoGEBS, W. B. and H. D. On the Physical Structure of the 
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27. Johnson, W. R. A Report to the Navy Department of the 
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28. Lonsdale, W. 

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29. Lyell, Chas. Travels in North America, with Geological 
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Another edition. 2 vols. 12rao. London, 1845. 

Second English edition. London, 1855. 

German edition, translated by E. T. Wolff, Halle, 1846. 


30. BuNBURY, C. J. F. On some remarkable Fossil Ferns from 
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31. Taylor, R. C. Statistics of Coal. The geographical and 
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32. Johnson, W. R. The Coal Trade of British America with 
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33. Anon. Documents relating to the Phoenix Mining and Manu- 
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34. HiGGiNs, James. The fourth Annlial Report of James Hig- 
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36. Rankin, Robert G. A Report on the economic value of the 
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37. Lesley, J. P. Manual of Coal and its Topography, or 
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38. Phillips, G. Jenkins. Prospectus of the Balcarras Coal and 
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39. Rogers, H. D. The Geology of Pennsylvania. 2 vols. (vol. ii 
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40. Tyson, P. T. First Report of Philip T. Tyson, State Agricul- 
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Md. Sen. Doc. [E]. 
Md. House Doc. [C]. 


41. Hall, James. Paleontology. Vol. iii, Part I. Containing 
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42. Tyson, Philip T. Second Report of Philip T. Tyson, State 
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43. Daddow, S. H., and Bannon, Benj. Coal, Iron and Oil; or 
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I 44. Anon. Reports on the Iron Interests of the Cumberland Coal 
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45. Hall, James. Paleontology, Vol. iv, part I. Containing 
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46. Anon. Cumberland Bituminous Coal. 

Eng. and Min. Jour., voL viii, 1869, p. 153. 

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48. Tyson, P. T. Section of Cumberland Coal Basin. 

Proc. Amer. Phil. See, vol. xi, 1871, pp. 9-13. 


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51. Hall, Jas. The Niagara and Lower Helderberg Groups; 
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52. Merrill, Wm. E. Extension of the Chesapeake and Ohio 
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53. Anon. The Maryland Coal Company's Cumberland Coal. 

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54. FoNTAiNB, Wm. M. The Conglomerate Series of West Vir- 

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55. Anon. Assessed Valuation of Coal and Mining Corporations 
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56. SoHOOT, Chas. a. Tables, Distributions and Variations of the 
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57. Cook, Geobqe H. Keport on the Clay Deposits of Wood- 
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58. Sherwood, B. F., Zeller, Theo., Snyder, Henry L. Report 
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59. LowDERMiLK, WiLL H. History of Cumberland [etc.], with 
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60. Stevenson, John J. On the Surface Geology of Southwest 
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61. The Upper Devonian Rocks of Southwest Pennsyl- 

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62. Anon. Review of the Coal Trade of 1878. 

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63. Cain, Peter. Second Annual Report of Peter Cain, Inspec- 
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64. Fbazer, Persifor, Jr. Classification of Coals. (Read May 

Trans. Amer. Inst. Min. Eng., vol. vi, 1879, pp. 430-451. 

65. McCreath, Andrew A. Second Report of Progress in the 
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Rept. 2nd Geol. Survey, Pa. MM, Harrisburg, 1879. 

1880. . 

Q(j. Brown, Thomas. The Maryland Union Coal Company. 

Kng. and Min. Joiir., vol. xxx, 1880, p. 3. 

67. Dana, J. D. Manual of Geology'. 3rd edit. 

68. Fontaine, AVm. M., and White, I. C. The Permian or Upper 
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Kept. 2nd Geol. Survey Pa. PP. Harrisburg, 18S0, 143 pp. and 'AS plates. 

GJ). KiORDAN, O. Second Annual Rejwrt of Owen Riordan, In- 
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Md. House and Sen. Doc., 1880 [J]. 

70. Stevenson, J. J. Surface Geolog}' of Southwest Pennsylvania 
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71. Brown, T. Second Annual Report of T. Brown, Inspector 
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72. Jones, Howard Grant. Notes on the Cumberland or Poto- 
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Proc. Amer. Phil. Soc., vol. xix, 1882, pp. 11-110. 

73. Lesley, J. P. (The Cumberland or Potomac Coal Basin.) 
Remarks on the paper by Mr. Jones. 

Proc*. Amer. Phil. Soc., Phila., vol. xix, 1882, p. 110. 

74. Scharf, J. T. History of Western Maryland, being a history 
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75. Stevenson, J. J. Tlie Geology of Bedford and Fulton Coun- 
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2nd Geol. Survey Pa., Rept. T2. Harrisburg', 1882, 8vo., 382 pp., two maps. 

76. White, I. C. Notes on the Geology of West Virginia. A 
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Proc. Amer. PhlL Soc, vol. xix, 1882, pp. 438-446. 


77. Smock, J. C. The Useful Minerals of the United States. 

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78. Wilbur, F. A. Clay. 

Mineral Resources U. S., 1882. Washington, 1883, pp. 465-475. 


79. Brown, T. Report of T. Brown, Inspector of Mines for 
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80. Rogers, AVilliam Barton. A Reprint of Annual Reports 
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Sm. 8vo. Appleton, 1884. 

81. Smock, J. G. Geologico-geogi'aphical Distribution of the Iron 
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82. Swank, James M. History of the Manufacture of Iron in all 
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83. Weeks, Joseph D. Report on the Manufacture of Coke. 

Tenth Census, vol. x. Washington, 1884. 


84. Anon. General Mining News — ^Jkfaryland. 

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85. Armstrong, S. C. (Compiler). Coal. 

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86. Gannett, Henry. Administrative Reports. Topographic 
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87. Administrative Reports. Topographic work in 


6th Ann. Report U. S. Geol. Survey, 1884-1885. Washington, 1885, p. 8. 

88. Swain, Geo. F. Report on the water power of the Middle 
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Tenth Census, vol. xvi. Washington, 1885, pp. 513-660. 


89. AsHBURNER, Chas. A. Coal. 

Mineral Resources U. S., 1885. Washington, 1886, pp. 33-34. 

90. CooK, R. S. The Manufacture of Fire-brick at Mount Savage, 

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91. Lesley, J. P. Annual Report of the Geological Survey of 
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92. Peale, a. C. Lists and analyses of the mineral Sjirings of 
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House Misc. Doc., 49th Cong., 2nd Sess., vol. viii. No. 164. 

93. PuMPELLY, R. (Editor). i[ines and Metallurgical Establish- 
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Tenth Census, vol. xv, Mining Industries of the U. S. Washington, 1886, 
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94. Ashburner, Ciias. A. Coal. 

Mineral Resources U. S., 1886. Washington, 1S87, pp. 224-279. 


95. Ste\''enson, John J. Notes on the Lower Carboniferous 
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Amer. Jour. Sci., 3rd ser., vol, xxxiv, 1887, pp. 37-44. 

96. White, T. C. Rounded Boulders at High Altitudes along 
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Amer. Jour. Sci., 3rd ser., vol. xxxiv, 1887, pp. 374-381. 


97. Ashburner, Chas. A. Coal. 

Mineral Resources U. S., 1887. Washington, 1888, pp. 169, 171, 177, 263- 
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98. Day, D. T. Useful Minerals of the United States. 

Mineral Resources IT. S., 1887. Washington, 1888, pp. 739-742. 

99. ITall, James, and Clarke, J. M. Paleontology, vol. vii. 
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100. Swank, Jas. M. The Iron and Steel Industries of the 
United States in 1887 and 1888. 

Mineral Resources U. S., 1887. Washington, 1888. 


101. Clarke, J. M. The Hercynian Question. 

42nd Ann. Kept. N. Y. State Museum, pp. 408-437. Albany, 1889. 

102. Merrill, G. P. The Collection of Building and Ornamental 
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Smithsonian Kept., 1886, pt. II, 1889. 

103. Miller, S. A. North American Geology and Paleontology, 
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104. ScHucHERT, Chas. A List of Fossils Occurring in the 
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8th Ann. Eept. N. Y. State Geol. Albany, 1899, pp. 50-54. 

42nd Ann. Kept. N. Y. State Museum. Albany, 1889. pp. 396-400. 

105. Ward, Lester F. The Geographical Distribution of Fossil 

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106. AsHBURNER, Chas. A. Coal. 

Mineral Resources U. S., 1888. Washington, 1890. 

107. MacFarlane, J. R. An American Geological Railway 
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108. ScHARF, J. T. Report of the Commissioner of Land Office. 
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carefully prepared articles on Maryland's resources. . . . 1890. 

Md. House of Delegates, Dec. Scss., 1890, 8vo., 148 pp. 


109. Jones, John H. (Spec. Agt.). Census Bulletins of the Coal 
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Eng. and Min. Jour., vol. li, 1891, p. 238. 

110. Keyes, Charles Rollin. Paleozoic fossils of Maryland. 

Johns Hopkins Univ. Cir. No. 94, vol. xi, 1891, pp. 28-29. 

113. KiNNECUT, L. P., and Rogers, J. F. Fire-clay from Mount 
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Jour. Anal, and Appl. Chem., vol. v, 1891, p. 542. 

112. Watkins, J. Elfreth. The Development of tlie American 
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Report of the U. S. Nat. Mus. for 1889, p. 671. Washington, 1891. 

113. White, Israel C. Stratigraphy of the Bituminous Coal 
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BuU. U. S. Geol. Survey, No. 65, 1891. 

House Misc. Doc., 51st Cong., 2nd Sess., vol. xiii, No. 136. 

114. Williams, G. II. The Geological Excursions by University 
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Johns Hopkins Univ. Cir. No. 94, vol. xi, 1891, pp. 25-27. 

115. Williams, H. S. Correlation Papers — Devonian and Car- 

Bull. U. S. Geol. Survey, No. 80, 1891. 

Uouse Misc. Doc, r)2nd Cong., 1st Sess., vol. xix, No. 24. 


116. Anok. Fire-Brick Industry. 

The Iron Belt, Roanoke, Va., vol. iii, Nov. 1892, pp. 4-5. 


117. Babb, Cyrus C. The Hydrography of the Potomac Basin. 

Amer. Soc. Civ. Eng., vol. xxvii, 1892, pp. 21-33. 

118. Clark, Wm. B. The Surface Configuration of ^raryland. 

Monthly Kept. Md. State Weather Service, vol. ii, 1892, pp. 85-89. 

119. Jones, J. H. Coal. 

House Misc. Doc, 52nd Cong., 1st Sess., vol. i, pt. I, No. 340. 
Eleventh Census, Rept. on Mineral Industries, 1892, pp. 345-422. 

120. Lesley, J. P. A Summary description of the Geology of 
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121. Parker, E. AV. Coal. 

Mineral Resources U. S., 1889-90. Washington, 1892. 

122. Peale, a. C. Mineral Waters. 

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123. ScHARF, J. Thomas. The Natural Resources and advantages 
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124. Williams, G. H. The University and its Natural Environ- 

Johns Hopkins Univ. Cir. No. 96, vol. xi, 1892, pp. 54-56. 


125. Clark, Wm. Bullock. The Available Water Power of 

Monthly Rept. Md. State Weather Service, vol. iii, 1893, pp. 7-9. 

126. Physical Features [of Maryland]. 

Maryland, its Resources, Industries and Institutions. Pp. 11-54. Balti- 
more, 1893. 

127. The Leading Features of Maryland Climate. 

Monthly Rept. Md. State Weather Service, vol. iii, 1893, pp. 1-6. 

128. Gannett, Henry. The Average Elevation of the United 

13th Ann. Rept. U. S. Geol. Survey, 1891-2, pt. II. Washington, 1893, 
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129. Hill, K. T. Clay Materials of the United States. 

Mineral Resources U. S., 1891. Washington, 1893. 

130. Howard, A. B. First Annual Report of the Bureau <rf 
Industrial Statistics of Maryland. Annapolis, 1893. 


131. Keyser, W. Iron. 

Maryland, its Resources, Industries and Institutions, pp. 100-112. Balti- 
more, 1893. 

132. Parker, E. W. Coal. 

Mineral Resources U. S., 1891. Washingfton, 1893. 

133. Coal. 

Mineral Resources U. S., 1802. Washington, 1893. 

134. Peale, a. C. Mineral Waters. 

Mineral Resources U. S., 1891. Washington, 1893. 

135. Mineral Waters. 

Mineral Resources U. S., 1892. Washington, 1893. 

136. ScirPMANX, C. 11. The ^raniifactiire of Bricks. 

Cassier's Magazine, vol. iv, 1893, pp. 403-47. 

137. Spencer, S. B. Natural and Artificial Cements. 

Mineral Resources U. S., 1891. Washington, 1893. 

138. Stevenson, J. J. Origin of Pennsylvania Anthracite. 

Bull. Geol. Soc. Amer., vol. v, 1893, pp. 39-70, pi. II. 

130. Whitney, Milton. The Soils of Maryland. 

Md. Agri. Exper. Sta., Bull. No. 21. College Park, 1893, 58 pp., map. 

140. Agriculture and Live Stock [of Maryland]. 

Maryland, its Resources, Industries and Institutions. Baltimore, 1S93, 
pp. 152-217. 

141. Soils of Maryland. 

Monthly Kept. Md. State Weather Service, vol. iii, 1893, pp. 15-22, map. 

142. Williams, G. II. [The Appalachian Region and the Itin- 
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Geological Guidebook of the Kocky Mt. Excursion, Comte Kendu de la 
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143. Mines and Minerals [of Maryland]. 

Maryland, its Resources, Industries and Institutions. Baltimore, 1S93, 
pp. 89-153. 

144. Williams, G. H., and Clark, W. B. Geology [of ifary- 

Maryland, its Resources, Industries and Institutions. Baltimore, 1893, 
pp. 55-89. 

145. Willis, Bailey. The Mechanics of Appalachian Structure. 

13th Ann. Rept. U. S. Geol. Survey, 1891-92, pt. II. Washington, 1893, 
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146. Clark, Wm. Bullock. The Climatology and Physical Fea- 
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1st Biennial Rept. Md. State Weather Service, 1894. 

147. Gannett, Henry. Results of Primary Triangnlation. 

Bull. U. S. Geol. Survey, No. 122, 1894, pp. 64-65. 
House Misc. Doc., 53rd Cong., 1st Sess., vol. ix. No. 78. 

148. HoFMAN, H. O., and Demond, C. D. Some Experiments for 
Determining the Ref ractiveness of Fire-clays. 

Trans. Amer. Inst. Min. Eng., vol. xxiv, 1894, pp. 42-66. See also 1895. 

149. Parker, E. W. Coal. 

Mineral Resources U. S., 1893. Washington, 1894. 

150. Shriver, Howard. Catalogue of Fossils Found at Cumber- 
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151. Weeks, Joseph D. The Potomac and Roaring Creek Coal- 
fields in West Virginia. 

14th Ann. Rept. U. S. Geol. Survey, 1892-93, pt. II. Washington, 1894, 
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152. Baird^ G. W. Experiment to Determine the Economic 
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Jour. Amer. Soc. Naval Eng., vol. vii, 1895, pp. 329-331. 

153. Dana, J. D. Manual of Geology. 4th edit. 8vo. New 
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154. HoFMAN, H. O. Further Experiments for Determining tbe 
Fusibility of Fire-clays. 

Trans. Amer. Inst. Min. Eng., vol. xxv, 1895, pp. 3-17. See 1894. 

155. Kemp, James. The Ore Deposits of the United States. 8vo. 
343 pp. New York, 1895. 

156. Newell, F. H. Report of Progress of the Division of 
Hydrography, 1893-94. 

Bull. U. S. Geol. Survey, No. 131, 1895. 

House Misc. Doc, 54tli Cong., 1st Sess., vol. — , No. 318. 

157. Parker, E. W. Coal. 

16th Ann. Rept. U. S. Geol. Survey, 1894-95, pt. IV. Washington, 1895. 

158. RiEs, Heinrich. Technology of the Clay Industry. 

16th Ann. Rept. U. S. Geol. Survey, 1894-95, pt. IV. Washington, 1895, 
pp. 523-575. 



159. Darton, N. H., and Taff, Joseph. Piedmont Folio, Ex- 
planatory sheetf'. 

U. S. Geol. Survey, Geol. Atlas, folio 28. Washington, 1896. 

160. Parker, E. W. Coal. 

17th Ann. Kept. U. S. Geol. Surv., 1895, pt. III. Washington, 1896. 

161. Whitney, Milton. Texture of some Important Soil Forma- 

U. S. Dept. Agri.. Div. Agri. Soils, Bull. No. 5. Washington, 1896. Illus- 
trated, 23 pp., 35 plates. 

162. Willis, Bailey. The Northern Appalachians. 

The Physiography of the United States. 

Geographic Monographs, I. American Book Co., 169 pp., 1896. 


103. Clark, William Bullock. Historical Sketch embracing 
an Account of the Progress of Investigation Concerning the Physical 
Features and Natural Resources of Maryland. 

Aid. Geol. Surv., vol. i, pt. II, pp. 43-138. Baltimore, 1897. 

164. Outline of Present Knowledge of the Physical 

Features of Maryland embracing an Account of the Physiography, 
Geology and Mineral Resources. 

Ibid., pt. in, pp. 139-228. 

165. Mathews, Edward B. Bibliography and Cartogi'aphy of 
Maryland, including Publications relating to the Physiography, Geol- 
ogy and Mineral Resources. 

Ibid., pt. IV, pp. 229-401. 

166. NicoLLS, William Jasper. The Story of American Coals. 
8vo. 405 pp. Philadelphia, 1897. 

167. Parker, E. W. Coal. 

18th Ann. Kept. U. S. Geol. Surv., 1896, pt. V. Washington, 1897. 


168. Bauer, L. A. Report on the Survey of the Boundary-lino 
between Allegany and Garrett Counties. 8vo. 48 pp. Baltimore, 

169. Clark, Wm. Bullock. Administrative Report containing 
an Account of the Operations of the Survey during 1896 and 1897. 

M(l. Geol. Surv., vol. i, pt. I, pp. 25-43. 


170. Mathews, Edward H. An Account of the Character and 
Distribution of Maryland Building Stones, etc. 

Md. Geol. Surv., vol. i. pt. II, pp. 125-241. 

171. The Maps and Map-makers of Maryland. 

Md. Geol. Surv., vol. i, pt. Ill, pp. 337-188. 

172. XicoLiii, William Jasper. Above Ground and Bolow in 
the George's Creek Coal Region. (Published for the Consolidation 
Coal Company.) Sm. 8vo. 32 pp. Baltimore, 1898. 

173. Parker, E. W. Coal. 

19th Ann. Rept. U. S. Geol. Survey, 1897-98, pt. VI. 

174. White, L C. The Pittsburg Coal Bed. 

Amer. Geol., vol. xxi, pp. 49-60, 1898. 


175. Abke, Cleveland, Jr. A General Report on the Physiog- 
raphy of Maryland. 

Md. Weather Service, vol. i, pt. II, pp. 39-210. 

176. Clark, William Bullock. The Relations of Maryland 
Topography, Climate and Geology to Highway Construction. 

Md. Geol. Surv., vol. iii, pt. II, pp. 47-106. 

177. Newell, F. H., and others. Report of progress of stream 
measurements for the calendar year 1897, including papers by 
Dwight Porter, J. B. Lippincott and other hydrographers. 

19th Ann. Rept. U. S. Geol. Survey, 1897-98, pt. IV. Washington, 1899. 


With the exception of some scattering Pleistocene deposits, all of 
the geological formations exposed in Allegany county are of Paleo- 
zoic age. The Pleistocene deposits are too poorly defined to receive 
satisfactory mapping, but the areal distribution of the Paleozoic for- 
mations is indicated on the geological map in the Physical Atlas ac- 
companying this report, while their lithological features are shown 
on the columnar sections. 

The stratigraphic relations of the several geological formations, all 
of which are herein described, are shown in the following table: 



Pleistocene Alluvial, etc. 


Permian Dunkard. 

Carboniferous Monong^ahela, 




Alauch Chunk, 



Devonian Hampshire, 


Silurian Salina, 


The Silurian. 

ICau^h Chanli 





Pot ta villa 




Bum Dry 








Fig. 4. 


The Juniata foniiation, known farther north as the I^wer or Red 
Medina or Levant Red Sandstone, (TV b) receives its name from the 
Juniata river, Pennsylvania, along which it is typically developed. 
It includes the oldest rocks that appear at the surface in Allegany 
county and outcrops in only one locality. This outcrop is in the 
gorge just northwest of Cumberland where Wills Creek cuts through 
Wills Mountain. 

The formation is made up of dull red sandstones and shales inter- 
bedded without any regularity of succession. The sandstones are 
hard, fine-grained, quartzitic near the top, cross-bedded and mica- 
ceous. Some of the beds exposed are more than one foot in thick- 
ness, but most of them are less than six inches. A few of the beds 
contain small rounded or flattened pellets of brittle yellowish-green 




or reddish clay, the largest of which are usually less than one-half 
inch in diameter. 

The shale beds vary from less than one inch to six feet or more in 
thickness. In general, they are considerably thicker than the sand- 
stones, and the total thickness of shale in the exposure is much greater 
than the total thickness of sandstone. The shales, like the sandstones, 
are almost alwavs distinctly micaceous and weather readilv. 

The depth to which Wills Creek has cut into the formation is 580 
feet. However, 140 feet of this, computed according to the hori- 
zontal distance and supposed average dip, is concealed by the heavy 
talus derived from the overlying Tuscarora quartzite. Along the 
Baltimore and Ohio Railroad on the north side of Wills Creek the 
upper 370 feet is well shown, there being in all of this not more than 
twenty feet hidden. Here all of the remainder of the Juniata is 
concealed, but 140 feet below, on the opposite side of the creek, along 
the Cumberland and Pennsylvania Railroad, an additional exposure 
of thirty feet may be seen. With the exception of the 140 feet con- 
cealed, the measurements were all made with a st^el tape. 

Notwithstanding the good exposure of much of the formation, the 
various strata of shales and sandstones are more or less inclined to 
grade into each other, so that no satisfactory detailed section can be 
given. The top of the formation is considered as beginning with the 
highest distinct red shale bed, which is six inches thick where best 
shown. This may be seen in the small excavation at the spring on the 
north side of Wills Creek near the cast end of the Narrows, a few 
feet above the Baltimore and Ohio Railroad track. Here the red 
shale bands quickly become of little importance, and the whiteness 
of the sandstone gradually but rapidly increases, the Juniata forma- 
tion thus being separated from the Tuscarora by a transition zone of 
only a few feet in thickness.* 


The Tuscarora formation, perhaps nearly identical with the White 
Medina of the Pennsylvania and New York surveys, receives its 

^ For a discussion of contacts and transition zones, see Lesley, J. P., A Summary 
Description of the Geology of Pennsylvania, in three volumes. Vol. i, pp. 627 to 
6^9, Harrisburg, 1892. 


name from Tuscarora Mountain, Pennsylvania, where the formation 
is most typically developed. It is brought to the surface in five 
places in the county, viz., in Wills Mountain, where, lying conform- 
ably upon the Juniati^, it gives rise to the higher portions of that 
moimtain; in Evitts Mountain and in Tussey Mountain, of which it 
makes up almost the entire exposed surfaces; and in two small areas 
along the Baltimore and Ohio Railroad near Potomac Station, south- 
east of the southern end of Wills Mountain. The smaller of these 
last areas has been excavated about twenty feet in order to give a 
suitable grade for the railroad track. The larger area has a perpen- 
dicular exposure of more than one hundred feet above the railroad 
and extends to the southwest as a well-marked low ridge for a distance 
of nearly fivc^ hundred yards. 

The formation is made up of snow-white to light gray quartzite, 
frequently cross-bedded and consisting usually of medium-coarse 
quartz grains in a very hard siliceous matrix. In some of the beds 
scattering quartz pebbles are found, but these are never abundant, 
and usually are not larger than wheat grains. Yello^vish-green, hard 
clay pebbles of various sizes are sometimes found, but they are not 

With the exception of casts of Arthrophycus harlani, no forms of 
positive organic origin have been found in the Tuscarora of this 
county. Even Arthrophycus hai'luni is not abundant in any of the 
Allegany county exposures, although the faces of some of the upper 
beds along Wills Creek in the iS^arrows are pretty well covered by 
the casts. Casts of Arthrophycus are also shown, and possibly to a 
better advantage in the outcrops along tlie Baltimore and Ohio Rail- 
road near Potomac Station. This plant form was foimd in greater 
abundance in the upper beds, the lower beds apparently being nearly 
destitute of them. 

In general, the rocks are highly indurated and massive, and do not 
weather readily. In the Narrows and in Rocky (lap on Evitts Moun- 
tain, heavy talus slopes conceal the lower faces of the cliffs, while the 
overlianging walls of white rock give to these gorges a very rugged 
appearance. To some extent the same is true of the gap in Tussoys 


Mountain, but tliis gap is so near tlie point where the mountain 
pitches beneath the surface that the walls of the gorge are very low. 
The total thickness of the formation is shown only in the Wills 
Greek gorge in Wills Mountain. Here the thickness is 287 feet, a 
good measurement having been obtained by means of a line dropped 
from the top of the Narrows to the Tuscarora-Juniata contact at a 
point near the Baltimore and Ohio Railroad yard limits. 


The Clinton formation is identical with the Clinton rocks of the 
New York section, the name being first used by the New York 
survey on account of the excellent development of the rocks in that 
state in the vicinity of Clinton. This formation lie^ conformably 
upon the Tuscarora quartzite and immediately surrounds the areas 
covered bv the Tuscarora formation. 

The largest area flanks Wills Mountain on either side, and con- 
tinuing south-southeast beyond Cresap, encloses the smaller Tus- 
carora areas on the Potomac where that river makes a strong bend to 
the southeast. Another area lies to the northeast of Cumberland 
where, coming in from Pennsylvania, it flanks the southern end of 
Evitts Mountain. A third area lies further east and holds the same 
relation to Tussey Mountain northwest of Flintstone that the second 
area holds to Evitts Mountain. 

The Clinton is composed essentially of thin reddish and greenish- 
yellow shales, while sandstone beds, some of which are of considerable 
thickness, occur in it, and a few thin beds of limestone appear in the 
upper part. Two important beds of iron ore are also found in it. 
In the lower part, where light colored shales predominate, the several 
transition sandstones present are more or less quartzitic, but are of 
no very great thickness. These lower sandstones are best seen on 
the south side of AVills Creek at the east end of the Narrows. 

Near the top of the formation there is a light gray massive sand- 
stone generally about ten feet thick. This is well shown along the 
Baltimore and Ohio Kailroad al>out forty rods west of Brady, where 
the thickness is a little less than ten feet,* and where the sandstone is 


overlain by a six-inch bed of hematitic Iron ore, known as the upper 
Clinton iron ore. A sandstone which apparently corresponds to the 
above-mentioned sandstone was seen on the National Road northeast 
of Cumberland, a little west of the Sixmile House, one hundred yards 
west of the junction of the Johnston Road with the National Road. 

The limestones of the formation are seldom six inches in thickness, 
and are much inclined to occur in layers about two inches thick, 
intorbedded with shale bands of similar thickness. The limestones 
arc almost always highly fossiliferous. 

The shales occupy most of the lower part of the formation, besides 
a considerable space in the middle and upper portions. These also 
fnH]uently contain fossils. In color, they are usually a yellowish 
gret^n or olivQ where freshly broken, but the flat exposed surfaces 
fro(]uently have a marked scarlet color. Near the bottom of the 
formation the shales have more of a dull grayish browri appearance 
and are less fossiliferous. 

The lower Clinton iron ore includes two beds separated, where 
best seen, by six feet of greenish calcareous shale. The thickness of 
the lower bed averages about four and one-half feet and is 160 feet 
above the bottom of the formation, as shown on the Baltimore and 
Ohio Railroad southeast of Cresap between the two small Tuscarora 
exposures. The other bed, six feet higher, not fully exposed, shows 
a thickness of eight feet where observed southeast of Cresap, and is 
ten feet thick at Cumberland, north of the cement mill, where it is 
cut through by Wills Creek. All of the iron ore beds are fossilifer- 
ous, the upper bed of the lower ore being sometimes excessively filled 
with the various Clinton fossils. 

The following partial section was measured on the Baltimore and 
Ohio Railroad southeast of Cresap: 


Red iron ore band. (Not exposed to the top) 8 

Calcareous greenish shale 6 

Red iron ore band 4*4 

Fine brownish red and green arenaceous shale with several 

thin but compact sandstones or quartzites near the bottom, 160 

Clinton-Tuscarora contact 

Total amount exposed 178% 


Along the south side of Wills Creek, at the east end of the Narrows, 
the full thickness of the Clinton shows the following section: 


Shales and fossiliferous limestone, mostly concealed 33 

Reddish shale with a few thin limestone bands (more or less 
concealed and perhaps containing" the upper Clinton iron 

ore near the top) 29 

Fcssiliferons gray shale and blue limestone, with five and one- 
half feet of shaly sandstone near the bottom 28 

Concealed 57 

Keddish olive fossiliferous shale 24 

Concealed 238 

Fossiliferous iron ore (Lower Clinton ore) 10 

Rusty olive shale 17 

Fossiliferous olive-colored shale 85 

Rusty shale at top. Uneven bands of gray sandstone at bot- 
tom interstra titled with olive shales 36 

Olive-colored shales with thin beds of brownish gray quartzite, 27 

Clinton-Tuscarora contact 

Total thickness of Clinton 584 


The Niagara formation, the name of which is derived from Niagara 
Falls, New York, where excellent exposures of these rocks have given 
opportunity for their careful study, lies conformably on the Clinton 
and, surrounding the outcrops of that formation, occupies areas 
closely related to them in size, in shape, and in geographical distribu- 

The westernmost area lies as a narrow belt around the base of 
Wills Mountain and extends soutliward to tlie Potomac river near 
Potomac Station. The second area lies as a sharp loop around the 
southern end of Evitts Mountain with a narrow projection southward 
along its pitching anticline, while the third area is similarly situated 
about Tussey Mountain. 

In Allegany county the Niagara is pretty much concealed, the 
areas about Evitts and Tussey mountains affording no satisfactory 
exposures, while the Wills Mountain area shows only one complete 
section. This is on the Potomac river just west of the cement-mill 
near Potomac Station. The formation is made up almost wholly of 
thin limestones with shale partings. The shale partings become of 


considerable thickness in the upper portions where they predominate 
over the limestones. In the lower portions the limestones predom- 
inate and the partings are very thin. A few thin sandstones are found 
near the top interbedded with the shales and limestones. 

The thickness of the formation as measured along the south side of 
Wills Creek in Cumberland is 260 feet. The rocks are, however, 
mostly concealed and the upper and lower limits of the formation 
cannot be accurately determined. In the Potomac Station section 
the formation was found to be 317 feet thick, but owing to the con- 
siderable folding here the measurement may not be exact. The true 
thickness certainly approximates 300 feet, and this may with propriety 
be considered as the thickness for the county. The section as meas- 
ured by R. B. Rowe along the Baltimore and Ohio Railroad near 
Potomac Station is as follows: 

Niagara-Salina contact 

Black shales with layers of sandstone and an occasional layer 
of limestone 22 

Mostly dark blue limestone with shale partings. Very fossil- 
iferous at top, less fossiliferous near the bottom. Some 
folding, but the measurement is believed to be fairly 
accurate 225 

Dark blue limestone with thin shale partings. So much folded 
that the thickness can be only estimated 70 

Niagara-Clinton contact 

Total thickness of formation 317 


The Salina formation receives its name from Salina, New York, 
where it is typically developed. The rocks of this formation follow 
those of the Niagara conformity and are distributed about Wills 
Mountain, Evitts Mountain and Tussey Mountain in much the same 
manner as the two preceding formations. Along the eastern base of 
Wills Mountain the Salina has been cut through by the meanderings 
of the Potomac, thus throwing portions of the outcrop on the West 
Virginia side. 

The formation is composed of sandstones, shales and limestones. 
The sandstones predominate near the bottom and the limestones in 
the upper portions, while the shales are rather abundant throughout 





the formation. Cement rock of importance is found in the lower 
part. The location of the four cement beds of commercial value is 
given in the section below. 

The rocks of this formation are not well exposed except along 
Wills Creek in Cumberland, along the Potomac river near Potomac 
Station, and along Flintstone Creek at Flintstone. Much of the 
Wills Creek section can be made out only with difficulty, but the 
Potomac section is well shown. West of the cement mill in Cumber- 
land the red sandstone beds at the bottom of the formation can be 
readily seen, as can also considerable portions of the shales and lime- 
stones, including the cement series. Immediately north of Flint- 
stone, along Flintstone Creek, various lower beds are fairly well 
exposed. Around Evitts Mountain the rocks are almost wholly con- 
cealed. The Potomac section, the best exposed section of Salina in 
the county, measures as follows:' 

Salina-Helderberg" contact 

Gray papery shales, dark drab magnesian limestone, dark blue 
limestone and yellowish and green sandstones in various 
relations to each other and all thin bedded. Fossils 

(Ostracods) are present, especially near the bottom 450 

" Fourth '* cement rock. A twelve-inch band of limestone is 

found about five feet from the bottom 17 

Bluish gray shaly rock with some thin arenaceous and cal- 
careous beds 19^2 

'* Third " cement rock 1214 

Light greenish, fossiliferous shales with some calcareous and 

arenaceous layers 54 

" Second " cement rock 15 

Massive fossiliferous limestones alternating with thin cement 

layers , 15 

*• First " cemen t rock 6 

Bluish green shale with three and one-half feet of darker 

shale at the top. Fossiliferous 15 

Greenish gray sandstone .'{14 

Light brown disintegrated rock, probably limestone originally 8 

Greenish gray massive sandstone 7 

Bright yellow sandstone V2 

Thinly bedded greenish gray sandstone 214 

Dark, fine-grained shale 13^4 

Salina-Niagara contact 

Total thickness of Salina QM) 

' Section of R. B. Rowe. 

t)4 the geology of allegany county 

The Devonian, 
the helderbeeg formation. 

The Helderberg formation, so called from its typical locality, the 
Helderberg Mountains of New York, is considered by some geologists 
as the lowest Devonian formation, while others regard it as the 
highest Silurian formation. It follows the Salina of the Silurian 
with perfect conformity and, like all of the preceding formations, is 
exposed only in the central and west-central portions of the county. 
The easternmost and largest area, shaped like a much constricted 
letter W, lies to the east, west and south of Tussey Mountain, and 
by its prominent double bifurcation makes up a large part of Warrior 
Mountain and Martin Mountain. On the state line east of Tussey 
Mountain the Helderberg belt is less than one-half mile ^vide, while 
the width of the corresponding outcrop on the western side is con- 
siderably greater. Southward, owing to the pitching of the Tussey 
Mountain anticline, these bands gradually approach each other imtil, at 
a point near Rush, the two coalesce. Within less than one mile south- 
ward the area again becomes bifurcated, but this time, owing to the 
synclinal nature of the fold, the projecting parts are separated by 
the Oriskany formation, which immediately follows the Helderberg. 
Of the two southern Helderberg projections, the one furthest east 
is the more extensive, and includes within it Flakes Knob, the highest 
point in the county east of the Alleghany Front. This part of the 
area narrows southward, but caps Warrior Mountain to within almost 
a mile of where the mountain ceases to be a distinct topographic 
feature. The projection lying further west is much narrower than 
the one to the east, but continues almost as far south and acts as a 
capping for Collier Mountain. 

The next area of Helderberg lies further west and flanks the out- 
crop of Salina around Evitts Mountain ifi much the same way that 
the first area docs the Salina around Tussey Mountain. The bifur- 
cation at the north caused by the Evitts Mountain anticline is quite 
like that produced by the Tussey ilountain anticline. The forma- 
tion continues southward in one long, continually narrowing band to 
within one and one-half miles of the Potomac, where the Helderberg 


ending in a sharp point passes beneath the Oriskany to appear again 
at the roadside by the canal, where the Potomac has cut entirely 
through the overlying Oriskany and into the Helderberg for a dis- 
tance of fully a hundred feet The eastern part of this area forms 
much of the crest and western slope of Nicholas Mountain, while the 
contact line along the western side is clearly marked by a row of 
hills extending from the state line southward. This row of hills 
reaches almost as far south as does the Helderberg outcrop, but 
finally coalesces with Nicholas Mountain. 

East of AVills Mountain a belt of Helderberg averaging less than 
one-half mile in width comes into the county from the north, and 
extending southward along the western slope of Shriver Ridge, passes 
through the western part of Cumberland and across the Potomac into 
West Virginia. The Potomac in its very perceptible eastward bend 
nearly three miles above Cumberland, and again in the more promi- 
nent eastward bend about six miles above Cumberland, has carved 
out two small portions of this belt from the West Virginia area. 
These patches are mostly concealed, but their contact with the Salina 
is fairly well shown. Northward the Helderberg-Salina contact is 
largely concealed, but the limestone quarries which occur in the 
lower part of the Helderberg along the western base of Shriver Kidge 
afford a convenient means of judging the approximate western out- 
crop of the Helderberg. Shriver Ridge marks the eastern limit, as 
the contact lies on its western slope a short distance below the top. 

West of Wills Mountain there is a band of Helderberg correspond- 
ing in position to the eastern belt, but by reason of the perpendicular 
attitude of the strata, this belt is considerably narrower than the one 
on the eastern side. Following closely the general direction of AVills 
Mountain, it crosses the Potomac river at Potomac Station. Along 
the belt north of the National Road the Helderberg-Salina contact is 
usually not well shown, but tlie Helderberg-Oriskany contact is 
prominent, the latter being represented by the steep ridges to the 
north and south of Corriganville. South of the National Road 
neither contact is well shown, altliougli sliglit topographic features 
usually indicate their positions with reasonable accuracy. 


Another Helderberg area of considerable extent is exposed south 
of Rawlings. This forms the body of the steep isolated ridge known 
as Fort Hill, which extends southward along the Potomac for a dis- 
tance of about four miles. 

In addition to the above-mentioned areas, two very slight expos- 
ures may be seen along the AVest Virginia Central Railroad on the 
north and south sides of Monster Rock near Keyser, West Virginia. 
They are of little importance except in so far as they are of value in 
helping to work out the structure in that part of the county. 

Lithologically, the Helderberg is pre-eminently a limestone forma- 
tion. Argillaceous materials occur as impurities in some of the beds, 
but these are not important, and sandstones are almost wholly lacking. 
Thin bands of chert, which are white or yellowish-white in color, 
occur sparingly throughout the upper part of the formation. Most 
of the limestone in the upper part is heavily bedded, and much of it 
is highly fossiliferous. The lower part of the Helderberg is a dark 
blue thin-bedded limestone which in breaking gives a decided ring. 
This corresponds to the Tentaculite limestone of New York, which 
in Maryland is over 400 feet thick. In the field the contact between 
the Salina and the Tentaculite limestone is very marked because of 
the different weathering qualities of the two rocks. The Salina 
rock weathers into soil very completely, while the Tentaculite lime- 
stone leaves innumerable small, thin, dark blue slabs upon the surface. 

In Western Maryland the Tentaculite limestone is mapped as a 
part of the Helderberg formation. This is done because the litho- 
logical break between it and the Salina is very marked and can be 
followed in the field, as shown above, while there is no lithological 
break between the Tentaculite and Lower Pentamerus subformations, 
and the division for mapping purposes cannot be made here. Pro- 
fessor James Hall of the New York survey always insisted that the 
Tentaculite should be considered as a portion of the Helderberg, 
while Professor James D. Dana considered it as a portion of the 
Waterlime (Salina) formation. Since Professor Hall's death, even 
the geologists of the New York survey have been inclined towards 
Dana's view. The Tentaculite limestone of AVestcrn Maryland has 


not only a greater thickness but also a more abundant fauna than 
that of the New York region. 

This fauna, as will be shown in tlie more complete systematic 
reports, belongs to the Silurian and Devonian. It is too premature, 
at least, to assign all of the Helderberg of ilaryland to either the 
Devonian or Silurian svstems. 

The thickness of the formation is nearly eight hundred feet. The 
two partial sections given below are believed to represent the full 
thickness as well as a duplication of some of the middle beds as 
indicated. The Potomac section extends from the bottom of the 
formation to and includes a few inches of the coralline ledge. The 
thirty-six foot massive Htromatoj^ora bed of the Devil's Backbone 
section is believed to come in immediately above this, the other beds 
of the section continuing upw^ard in the order named to the top of 
the formation. 

The Devil's Backbone section, measured along the Huntingdon and 
Broadtop Eailroad east of Wills Creek is as follows: 

V eot. 
Helderberg-Oriskaiiy contact 

Concealed 42 

Light gray fossiliferous limestone Avith numerous layers, a 

very light-colored chert 22 

Light gray massive fossiliferous limestone. Breaks into rec- 
tangular blocks 16 

Shaly limestone 1 Vlj 

Bluish gray limestone, breaking into shaly fragments. 

Weathering indicates much argillaceous material 18 

Massive Stromatopora beds 36 

Shalv limestone, somewhat nodular 10 

Light gray massive limestone with upper part containing 

layers of light-colored chert 45 

Thinlv bedded limestone, the weathered surface covered 

with small bryozoans 16 

Dark blue massive limestone, very hard and difficult to 

break.. .Upper part tilled with Petitamerus (jaleatus 36 

Fine shaly fossiliferous limestone 16 

Massive dark blue fossiliferous limestone 40 

Slightly argillaceous, thinly bedded, fossiliferous limestone. 14 
(iray arenaceous fossiliferous limestone with l.iycrs oi 

chert V material 16 

Concealed to bottom of formation 

Total thickness of exposure at this place 328y2 


The measurements made at Potomac Station are as follows: 

Upper beds concealed. Very massive light gray limestone 

with a few feet of nodular limestone near the top. . 

Coralline layer near the top 95 

Mostly concealed, but sufficiently exposed to show that the 

beds are generally made up of thin grayish limestones. 

Some massive beds are present 240 

Generally thin-bedded, dark blue limestone, but with some 

heavy beds. Fossiliferous 148 

Thinly bedded, dark blue fossiliferous limestones with 

occasional papery shales 92 

Helderberg-Salina contact 

Total thickness of exposed Helderberg 575 


The Oriskany formation receives its name from Oriskany Falls, 
New York, at which place it is well shoAvn. In middle and western 
Allegany county the Oriskany, although thin compared with most of 
the other Paleozoic formations, on account of its zigzag course and 
usually more or less inclined position, covers a not insignificant part 
of the surface. To speak definitely, the Oriskany-Romney contact 
is more than one hundred miles in length, being considerably greater 
than that of any other contact line in the county. Coming in across 
the Maryland-Pennsylvania state line near Flintstone and going south- 
ward, the Oriskany constitutes the eastern slope of Warrior Mountain. 
Returning northward near Big Spring Run, it forms much of the 
western slope of Warrior Mountain. It enters quite largely into the 
structure of Martin Mountain and completely covers the central and 
southern portions of Collier Mountain, including the two projections 
near the Potomac. It also constitutes the western slope of the north- 
em part of Martin Mountain continuing beyond the state line. 
Branching south of the state line, one part returns southward and 
forms much of the eastern slope of Nicholas Mountain. It continues 
to the Potomac, but turning northward once more it helps to form 
the line of hills that flank Nicholas Mountain on the west, then again 
passes beyond the state line. 

A little further to the west a narrow strip along Shriver Ridge 
cuts across the county in a northeast-southwest direction through 


Cumberland. West of Wills Mountain a still narrower strip comes 
in from the north, runs approximately parallel with considerable por- 
tions of Wills Creek and Braddock Run, then bending to the east 
takes a more nearly north and south direction and passes across the 
Potomac near Potomac Station. Another area extends from Raw- 
lings, southwestward through Keyser, West Virginia. Geologic- 
ally, the outcrop is not discontinuous between these points, but a 
small part of it has been cut off from the county bv a bend in the 
Potomac river north of Monster Rock. A very small area is also 
found near the bend of the river east of Monster Rock, a short 
distance from Keyser, West Virginia, but this is greatly obscured by 
the comparatively recent river deposits. 

Tn addition to the above-mentioned areas, there are two others 
well shown east and northeast of Oldtown, besides one or more obscure 
patches in the bed of a ravine west of Corriganville. The smaller of 
the Oldtown areas covers less than half a square mile and outcrops 
immediately north of the Potomac and just west of the mouth of the 
South Branch. The other area forms Stratford Ridge, lying just 
west of the lower course of Town Creek. These last two areas are 
minor extensions or spurs of the much higher ridge south of the 
Potomac in West Virginia. 

The Oriskany formation in Allegany county consists of two well- 
marked lithological divisions which grade into each other. The lower 
part, resting conformably upon the Helderberg, is a blue-black chert 
in nodules and layers, separated by thin beds of dark gray arenaceous 
shale. This is the " chert lintel " of the Piedmont folio.* The upper 
part of the formation is a greenish gray, bluish gray, brownish gray or 
white sandstone, which is often calcareous. 

The chert in an unweathered condition is in hard, deep blue-black 
masses and show^s a great tendency to break into small-sized nodular 
or angular blocks with smooth conchoidal fractures. The unweath- 
ered surfaces have at times a pearly white appearance and the 
weathered specimens are almost invariably light colored. Specimens 
in which weathering has been carried on to an extreme degree usually 

> Geologic Atlas of U. S. Piedmont Folio, No. 28. 


show a yellowish hrown color and are more or less arenaceous and 
spongy. The Heldcrberg-Oriskany contiict line can often be easily 
followed by these chert fragments even if all other traces of the 
contact are gone. So numerous are the fragments in many places 
that in some well-cultivated fields they lie sufficiently close together 
to almost completely hide the surface of the ground. This is par- 
ticularly noticeable in some of the fields near the tops of Warrior 
Mountain, Martin Mountain and Nicholas iEountain. In the vicinity 
of Flakes Knob on AVarrior ifountain the chert beds have been worn 
entirely through, and on the top of this highest point the underlying 
limestone is exposed. Surroimding this high knoll is a heavy talus 
of the chert blocks. Near the top of Martin Mountain on the 
National Koad a good exposure shows the chert weathered to spongy 
blocks sufficiently soft to be easily cut with a knife. The same thing 
may be observed in other places, although usually it is not so well 
shown. West of Wills Mountain on the Georges Creek and Cumber- 
land Kail road and on the Eckhart branch of the Cumberland and 
Pennsylvania Railroad the same alteration has taken place, but some 
of the beds here show a more or less bright-colored banded structure. 
This is apparently due to a rearrangement of the ferruginous contents, 
thus leaving some portions with a peculiar bluish gray color, while 
other portions show yellowish, brownish or reddish parallel bands. 
No outcrop in the nortliern part of the county shows the full thick- 
ness of the chert, but the outcrop at the DeviFs Backbone compared 
with outcrops near Keyser, West Virginia, and near North Branch 
seems to indicate pretty conclusively tliat these beds thicken rapidly 

The upper portion, or sandstone member, of the Oriskany when 
wholly un weathered is usually hard and compact, and is at times 
rather inclined to resemble a verv arenaceous limestone. The texture 
is sometimes fine, but the rock is more often coarse-grained, and in 
the upper part of the formation one or more bands of conglomerate 
are always present. In the exposures near Keyser, West Virginia, 
the lower part of the formation is shaly, while the middle and upper 
portions apparently contain a greater percentage of coarse material 







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than elsewhere. Generally fossils are extremely abundant, occurring 
in irregular bands varying in thickness from one or two inches to 
several feet. The sandstone easily losing its calcareous cement, 
weathers readily to a very friable, dirty-buff, porous rock, in which 
condition large blocks can be easily shattered by a single blow of the 
hammer. In many places i^rotectcd from denudation, the rock has 
completely disintcgi-ated, leaving beds of dirty brownish-yellow sand. 
In this loose sand, under favorable conditions, well-preserved fossils 
may be procured. Pockets are frequently found in the less weathered 
rocks in whicli fossils free from the matrix are also beautifully pre- 
served. It is to these pockets that many collectors owe their finest 
cabinet specimens. 

Excellent exposures of the Oriskany are frequent, but the full 
thickness is not often shown. The thickness as measured on the 
south side of !^^onstcr Rock near Keyser, West Virginia, is three 
hundred feet, and at 21st Bridge, three hundred and forty feet; on 
the Williams Koad, two and one-half miles east of Cumberland, 
only one hundred and fifty-five feet are exposed. On the eastern 
slope of Warrior Mountain no good measurement could be obtained, 
but apparently the thickness there where best shown is less than at 
Cumberland. The following section was obtained along the West 
Virginia Central Railroad at the base of Monster Rock, opposite 
Keyser, West Virginia: 


Oriskany-Romney contact 

Fine-grained fossilif erous conglomerate 12 

Coarse sandstone with few fossils G 

Fine-grained fossilif erous conglomerate 4 

Coarse but slightly shaly sandstone 4 Va 

Coarse-grained fossiliferous sandstone 8 

Fossiliferous conglomerate 1 

Coarse fossiliferous sandstone 3^4 

Very fossiliferous coarse conglomerate V2 

Coarse-grained fossiliferous sandstone 12 

Fossiliferous sandstone, mostly coarse-grained 150 

Coarse shaly, almost non-fossilif erous, sandstone 251,'^ 

Black nodular chert 67 


Total thickness measured ' 300 

# • 


On the Williams Road, two and one-half miles east of Cumberland, 
the Oriskany section is as follows: 

Oriskan3'-Komney contact • 

Coarse sandstone, almost black and non-fossiliforons 2 

Much-decomposed yellowish sandstone with many fossils... 16 


Slightly fossiliferons conglomerate, the individual particles 

being of characteristic wheat-grain size 4 

Concealed 7% 

Very fossiliferons conglomerate % 

Concealed 2 

Blue calcareous fossiliferons sandstone 1% 

Coarse, much-weathered, fossiliferons sandstone 2>4 

Concealed 14 ^4 

Very coarse fossiliferons brown sandstone 3 

Fossiliferons conglomerate much like the wheat-grain con- 
glomerate above 1 

Brown fossiliferons sandstone 29 

Concealed 42 

Sandstone and concealed, mostly concealed 30 


Total thickness measured 156 

The Oriskany-TIelderberg contact is not shown here, and there is 
at Irnst 00 foot of chert still to add to the thickness. 

In the well-weathered Williams Road exposure the conglomerate 
bands are easily distinguished from the intervening finer material, 
but in the Monster Rock section, where the present face of the rock 
has been exposed only a few years, the lines of separation are much 
less clearly marked. This indistinctness, which is one of appearance 
rather than reality, is largely due to the bluish-gray color of many 
of the pebbles, as well as to the calcareous cement which is present in 
the conglomerate bands and in the finer sandy portions. 

In general, the individual pebbles of the conglomerate are fairly 
well rounded, usually of approximate wheat-grain size, and seldom 
larger than peas. In many places the rocks are densely crowded with 
fossils. This is particularly true of the fonnation in the vicinity of 
Cumberland, the locality from which Professor Hall has described 


80 many forms. Frequently the conglomerate bands partake of this 
fossiliferons nature, but the fossils are usually more abundant in the 

.» *i 

• * 
••• «•« • • 

• • t • • '^ 

' • • • • . 


finer portions. In Warrior Mountain the exposures are usually not 
good, and where exposed the fossils are less abundant, the sandstone 
there being less calcareous and highly compact. 

The Oriskany sandstone, although playing an important part in the 
composition of the mountains of Allegany county, owes much of its 
prestige, especially in the more calcareous areas, to the protection of 
the less easily disintegrating Oriskany chert beds. 


The Romney formation, corresponding in the main with the Mar- 
cellus and Hamilton formations further north, takes its name from 
Romney, West Virginia, where it is extensively developed. The 
passage from the Oriskany to the Romney is particularly abrupt, a 
distinct lithologic difference existing within a space of two inches. 
This contact is admirably shown on the Williams Road near the 
church two and one-half miles east of Cumberland, as well as on the 
north and south sides of Monster Rock along the West Virginia Cen- 
tral Railroad. It is also seen to good advantage on the Baltimore 
and Ohio Railroad one-fourth of a mile south of Rawlings, and on the 
same railroad about two miles northeast of Keyser, West Virginia. 
In various places along the east side of Warrior Moimtain the con- 
tact is disclosed, but the opportunities for studying it are not so good 
here as elsewhere. 

Next to the Jennings the Romney is the most widely distributed 
formation in the county. The largest area lies along the Potomac 
river in the vicinity of Oldtown. It includes the valleys of Big 
Spring Run and Saw Mill Run and much of the lower course of Town 
Creek and sends a narrow bolt northward along the eastern side of 
Warrior Mountain beyond the state line into Pennsylvania. "Further 
west along either side of the southern end of ^Martin Alountaiu there 
are small, elongated Romney areas which coincide approximately 
with the narrow valleys of Collier Run and Martin Spring Run. 
In the Evitts Creek valley a belt of considerable width comes into the 
county from Pennsylvania and passing southward is divided by a large 
Jennings area, the two Romney bands thus formed passing along 


■ i 


down on the higher slopes of the valley and continuing southward 
help to cover the Maryland projection west of the southern end of 
Nicholas Mountain. At the foot of Alleghany Front another area is 
shown which, like several of the succeeding formations, stretches as 
a somewhat narrow belt entirely across the county. Near Rawlings 
a prominent offshoot projects from this belt across the Potomac into 
West Virginia. On the eastern side of Monster Eock a slight, syn- 
clinal fold has preserved a very small area, but this is almost wholly 

In general the formation is an argillaceous fissile shale, intensely 
black and papery near the base, but more often of a drab color above, 
the upper part weathering into fine angular fragments. Owing to a 
lack of hard material, the formation is prominent in the valleys, where 
it forms low ridges or rounded hills. 

The sandstones and sandy shales of the formation are comparatively 
unimportant. However, on the Williams Road two and one-half 
miles east of Cumberland near the middle of the formation, there is 
a bed of brownish-gray sandstone weathering readily into irregular 
rhombs or lozenges, the whole being fifty feet thick. Thin irregular 
streaks of sandy shale are shown at various horizons below the middle 
of the formation on the Baltimore and Ohio Railroad in the cut im- 
mediately north of 21st Bridge on the West Virginia Central Rail- 
road. Northeast of Cumberland, between Shriver Ridge and Evitts 
Creek, there is a series of well-defined parallel ridges which appar- 
ently owe their preservation largely to shaly sandstone. In the Town 
Creek valley east and west of Saw Mill Run the various Romney 
ridges there appear to be quite free from sandstone. Most of these 
ridges show to good advantage the characteristic weathering of the 
upper shales. On the ridge west of Saw Mill Run two miles north- 
west of Oldtown, the exposed shales have completely broken up into 
fine irregularly angular, almost cubical blocks of various sizes usually 
considerably smaller than walnuts. These small fragments at this 
place are in such extreme abundance that they lie upon the surface 
of the ridge just within the angle of rest and in beds so deep and so 
frequently subject to gravitational movement that vegetation is lim- 
ited almost wholly to stunted pines. 


The intensely black shales at the bottom are very carbonaceous 
but do not contain coal seams. However, along Collier Run, where 
the lower beds can be easily reached, as well as along the road near 
the Warm Spring iron bridge one mile south of Flintstone, the shales 
have been fruitlessly worked with the idea that they might prove to 
be coal-bearing. 

About one hundred and fifty feet from the bottom of the formation 
there are several bluish-gray fossiliferous limestone bands. These 
are apparently never absent, although in the well-exposed Williams 
Road section none of them can be seen. This is perhaps due to the 
effect of weathering, as certain evidences indicate their probable pres- 
ence. These bands are individually rarely three feet, usually less 
than one foot thick, but the total thickness in the best exposed sec- 
tions is more than twenty feet. They are shown to good advantage in 
the West Virginia Central Railroad cut at 21st Bridge, one mile 
northeast of Keyser, West Virginia. They are found less clearly 
shown on the county road along the lower course of Martin Spring 
Branch east of the Oriskany fork at the south end of Martin Moun- 
tain, where a little of the limestone has been burned for fertilizing 
purposes. In various other places more or less limestone is shown 
but the exposures are not of sufficient importance to demand special 

One of the upper beds, about six inches thick, known as the Nauti- 
lus Ledge, shows great persistence, having been found at several 
widely separated localities. Another bed, usually from two to two 
and one-half feet thick, is honeycombed with concretionary nodules. 
These nodules, which are from one-half inch to four inches in diam- 
eter and generally more or less ferruginous, gradually weather free 
from their matrix and may be found in many localities scattered about 
in considerable numbers over the ground. 

Iron-ore pockets have been found in various localities along the 
eastern base of Warrior Mountain near the bottom of the Romney 
formation. Iron ore may also be seen between and slightly to the 
west of the two Oriskany outcrops northeast of Oldtown. There are 
indications of the ore elsewhere, but in no case can the exact horizon 


be deiSnitely located, nor can the full thickness at any place be learned. 
It is evidently very near or at the bottom of the Romney, and the 
theory has been advanced * that its presence indicated a possible local 
unconformity between the Oriskany and the Komney formations. 


The Jennings formation, closely related to the Chemung and 
Portage of the Pennsylvania and the New York Geological Surveys, 
is so called from its typical development in Jennings Gap and along 
Jennings Branch, Virginia. It follows the Romney with perfect 
conformity and has a considerably greater areal distribution than any 
other formation in the county. It occurs in four large areas. 
Farthest east is the much dissected strip east of Town Hill running 
from the state line southward beyond the Potomac river. A long 
irregularly shaped area west of Green Ridge extends entirely across 
the county; it is scarcely more than a mile in width in the southern 
part, but in the northern part, on the state line, it is about seven 
miles wide. Polish Mountain lies in the northwestern part of this 
area. In the lower part of the Evitts Creek valley and in the big 
bend ol the Potomac immediately south, there are two good-sized 
areas which for our purpose here may be considered as one. There 
is also a strip nearly a mile wide and about twenty-five miles long 
stretching northeast-southw^est across the widest part of the county on 
the eastern slope of Alleghany Front. 

The deposits of this formation are almost wholly arenaceous. In 
the lower and middle parts the thin layers of sandy shales and 
quartzose sandstones are interbcdded wdth no regularity of sequence 
or of thickness. In the upper part heavy quartzitic sandstones pre- 
dominate, but even here the sandy shales are in considerable abund- 
ance. In connection with the heavy quartzitic beds there are sev- 
eral more or less important beds of conglomerate, some of which are 
fossiliferous. Fossils also occur in the sandstones at various horizons, 
the fossiliferous beds being densely crowded, usually sharply defined 

> Darton, N. II. Notes on the Stratigraphy of a portion of Central Appalachian 
Virginia, Amer. GeoL, vol. x, July, 1892, p. 16. 


and seldom more than a few inches in thickness. The lower shales 
of the Jennings are thin and black, somewhat resembling those at 
the base of the Romney formation. The upper part of the Jennings 
is lithologically indefinite. The paleontological evidence indicates 
that the formation extends about six hundred and fifty feet above the 
hea\*iest conglomerate. This conglomerate is prominent in many 
parts of the county and from its situation so near the top of the 
formation can be used advantageously as a guide in tracing the upper 
contact. This conglomerate in Jennings Rim is thirty-five feet thick, 
the lower six feet of which is flaggy and contains only scattered peb- 
bles. The remainder is massive and is higlily charged with flattened 
or rounded white quartz pebbles of various sizes up to one inch or 
more in diameter. This conglomerate is apparently continuous over 
the coimty. It is well marked by a line of hills along the eastern 
slope of Alleghany Front and near the southern end of this line of 
hills four and one-half feet of the bed is shown. Whether or not 
this represents the entire thickness at this point could not be learned. 
At various intermediate points the conglomerate docs not show, but 
this is thought to be due not so much to its thinness as to more com- 
plete concealment. Remnants of the same conglomerate are seen 
along the top of Polish Mountain. It is not well shown on Green 
Ridge, although there is abundant evidence of its presence, but along 
the eastern flank of Town Hill it appeal's to be of considerable thick- 
ness. Along the Little Orleans-Oronoko Road near the western end 
of the big bend of tlie Potomac about three miles west of Little 
Orleans the abundance of loose conglomerate boulders indicates a 
considerable thickness there. The individual pebbles are quite large, 
equaling the largest found in Jennings Run. Above this big con- 
glomerate, as well as below it, there are thinner conglomerates which, 
although they may be of very varying thickness, are nevertheless 
generally present. They are usually greatly iron-stained, but when 
not so they much resemble some of the Carboniferous conglomerates. 
However, to one accustomed to observing them, the more flattened 
nature of the pebbles and the very characteristically smooth fracture 
across both matrix and pebbles at once distinguish the Jennings 
from the Carboniferous conglomerates. 


The thickness of the formation appears to vary within rather wide 
limits. Along Jennings Run it is thought to be between thirty-five 
hundred and four thousand feet, although no good measurement 
could be made. Along the Potomac near the mouth of Town Creek 
it is approximately five thousand feet. 


The Hampshire foraiation, approximately equivalent to the Cats- 
kill of the North, receives its name from Hampshire county, West 
Virginia, where it is extensively developed. In Allegany county 
these rocks are exposed in three areas as follows: First, in the eastern 
part where Sideling Hill Creek and the Potomac river have carved 
out small portions of the wide belt which underlies Sideling Hill 
further east. Since these several small patches are closely related 
structurally, they may here be considered together as one area. 
Second, a belt nearly three miles wide which runs northeastrsouthwest 
across the county forming the base of Town Hill. Third, a strip 
averaging perhaps one-half a mile in width which lies along the 
eastern face of Alleghany Front and stretches entirely across the 
county. The patches included under the first area are largely con- 
cealed by their own detritus. The rocks in the second area are well 
exposed only along the Potomac river and in the gap of FifteenmUe 
Creek. In the western area the rocks are shown to good advantage 
along Jennings Eun. They are shown to less advantage along Brad- 
dock Run, and in the Potomac gorge they are largely concealed. 

In composition the Hampshire is an extensive monotonous series^ 
of cross-bedded, flaggy and massive sandstones and fine-grained very 
fissile sandy and argillaceous shales. The shales are usually bright 
red or brownish red, although some gray and green or even yellowish 
shales are seen. These latter colors occur more frequently near the 
top of the formation, and this is particularly noticeable just outside 
of the county immediately east of the mouth of Sideling Hill Creek. 
The sandstone beds near the bottom are heavy, being in several in- 
stances more than twenty feet in thickness. The shales and sand- 
stones frequently merge gradually into each other, both laterally and 


vertically, and are interbedded without any constant order of suc- 

The thickness of the Hampshire along Jennings Eun is nineteen 
hundred feet. Along the Potomac river in the Town Hill syncline a 
measurement of nineteen hundred twenty-five feet was obtained. 
The Jennings Run measurement is believed to be quite accurate and 
the measurement in the Town Hill syncline approximately so. 

The Carboniferous, 
the pocono formation. 

The Pocono formation, named from Pocono Plateau, Pennsyl- 
vania, where it is well developed, is the basal member of the Car- 
boniferous and lies conformably upon the Hampshire formation of 
the Devonian. Of these rocks there are only three narrow areas 
shown in the county. One occupies a position along the eastern 
dope of Alleghany Front, capping a line of knobs which extend 
across the county. The other two, separated by the Fifteenmile 
Creek gorge, form the crest of Town Hill. 

Little study of the formation could be made on Town Hill, but it 
is known to consist largely of a very massive conglomerate in which 
the milky quartz pebbles are pretty well rounded. The size of the 
pebbles varies much, ranging up to three-fourths of an inch in diam- 
eter or even larger. In the western part of the county the litho- 
logical character of the formation is very different. The entire 
thickness is shown, although to poor advantage, on the Cumberland 
and Pennsylvania Railroad in the first tunnel east of Eckhart, where 
the thickness is two hundred and fifty-eight feet. In the Potomac 
gorge between Westernport and Keyser, West Virginia, there is an 
exposure of only thirty feet, but this may represent the entire thick- 
ness of the formation at that point. It has been so considered in 
the Piedmont folio.* 

In the Cumberland and Pennsylvania Railroad section the bottom 
of the formation extends sixty feet east of the east end of the tunnel, 

» Geologic Atlas of the United States, Piedmont Folio, Washington, IN'.kJ. 


while tlie top extends ninety feet west of the west end. The lower 
part of the formation here is a coarse, cross-bedded, grayish-green, 
micaceous sandstone. About one hundred feet above the bottom 
there is a four- or five-foot band of grayish, impure, friable sandstone 
frequently showing a prominent bluish coating. Scattering pebbles 
of various sizes up to two inches in longest direction are present. 
These are angular, subangular or well-rounded and of clear or smoky 
quartz, but seldom milky as in the conglomerate of the same forma- 
tion on Town Hill. At various horizons above this there are thin 
bands of fine conglomerate, the pebbles of which are inclined to be of 
the nature of milky quartz. Near the middle of the section there is a 
space of nearly thirty feet which is largely taken up with shales, some 
of which bear slight traces of plant remains. The upper part of the 
section shows mostly grayish-green or reddish-green micaceous, flaggy 
sandstones with some interbedded grayish, greenish, yellowish or 
reddish shales. 

In the Potomac gorge section the formation is made up of gray, 
cross-bedded sandstone with only a few widely scattered pebbles. 


The Greenbrier formation, so-called from Greenbrier county. West 
Virginia, lies conformably upon the Pocono and outcrops in Alle- 
gany county only in a single narrow band extending high up along 
the eastern face of the Alleghany Front from the Maryland-Pennsyl- 
vania state line southward through the county, cutting across the 
Potomac river almost midway between Westemport, Maryland, and 
Keyser, West Virginia. 

The formation consists mainly of limestone strata. Sandstones and 
arenaceous limestones are most prominently developed in the lower 
part. Shales preponderate near the middle while the upper part is 
mostly composed of highly fossiliferous and more nearly pure lime- 
stones. Many of the lower arenaceous beds show a peculiar banding 
on the weathered surfaces apparently as if they were highly cross- 

The formation is well shown in only one place in the county, viz., 


at the mouth of Stony Run below the water-tank on the West Virginia 
Central Railroad, two miles southeast of Westernport. Even here 
some of the beds are hidden. In the only other places in the county 
where one might hope to get good sections, viz., along Braddock Run 
and along Jennings Run, the formation is largely concealed by soil 
and by talus from the heavy Pottsville sandstones and conglomerates 
above. As a result no measurements can be made in the northern 
part of the county, but judging from measurements in various places 
outside of the state, it seems quite certain that the formation grows 
continually thinner northward from Stony Run.* Much interest 
is attached to this formation because it is in great measure the Appa- 
lachian representative of the great Carboniferous limestones of the 
Central Mississippi states. 

At the mouth of Stony Run the following section was made: 

Fe.t. Inclics. 
Clreenbrier-^Iaiich Clivink contact 

Heavy dark bluish gray fossiUferous limestone 4 6 

ArgiUaceous shale. FossiUferous, especially in the upper 
part. Drab colored on fresh surface, but inclined to 
show as a dull red shale on account of its prominent 

ferruginous surface coating 8 

Massive bluish fossiUferous limestone 7 

Concealed 10 

Massive bluish fossiUferous limestone 1 6 

Massive bluish, highl3' fossiUferous limestone, weathers 

very irregularly 3 6 

Thinly bedded fossiUferous limestone with thin bands of 

olive-green fossiUferous shale 10 10 

Concealed 9 

Keddish brown, much disintegrated sandstone 9 

Concealed 20 

Heavy, pinkish green, mottled, slightly fossiUferous lime- 
stone 2 6 

Concealed 11 

Ked sandy shale with thin green layers near top and 

bottom 3 

Greenish red shaly arenaceous limestone 1 

Concealed 3 

Ued sandy shale with a few thin shaly defined green argil- 
laceous bands 32 

» Lesley, J. ?. A Summary Description of the Ocoloiry of Pennsylvania in Three 
Volumes, vol. iii, part i, pa^e 1791, Ilarrisburg, 1895. See also the Geologic Atlas of 
the United States, Piedmont and Franklin Folios. 


Feet. Inches. 
Concealed 6 

Ked shaly sandstone 1 6 

Massive sandstone in streaks or layers of pink, green and 

white 6 

Red arenaceous shale 10 

Ked shaly sandstone 9 

Calcareous, pinkish gray sandstone 2 6 

Concealed 7 

Shaly sandstone '..... 1 6 

Mostly concealed, some shaly sandstone showing 20 

Very arenaceous pinkish green limestone 26 

Concealed 5 

Bluish arenaceous limestone 7 

Concealed ^ 

Below tliis comes a coarse grayish sandstone which is considered 
as marking the top of the Pocono, thus giving for the total thickness 
of the Greenbrier at this place two hundred and twenty-seven feet. 


The Mauch Chunk formation, which is very similar to the Canaan 
formation of the Piedmont quadrangle, receives its name from Mauch 
Chunk, Pennsylvania, where the formation is well shown. Like the 
preceding formation, it is exposed in Allegany county only along the 
eastern face of the Alleghany Front. This formation, together with 
the underlying Greenbrier, lies obscurely in the depressions extend- 
ing in a line across the county between the heavy crest of Alleghany 
Front and the Pocono knobs a little lower down on the eastern face. 

The Mauch Clniuk is composed chiefly of red arenaceous and argil- 
laceous shales, the argillaceous shales being a bright red and par- 
ticularly prominent in the lower part. A little above the middle of 
the formation there lies in one almost continuous body about one 
hundred feet of soft, flaggy, fine-grained, reddish-green to brownish- 
red sandstone. The sandstones are very generally micaceous, as are 
also many of the middle and upper shales. 

Between the Mauch Chunk and the Greenbrier there is a greenish 
brecciated sandstone which near the mouth of Stony Run is four feet 
thick. At the top of the Mauch Chunk there is also a four-foot transi- 
tion band of highly brecciated reddish arenaceous limestones above 






which lie the lower flags of the succeeding Pottsville formation. This 
breccia ted limestone can be seen to best advantage on the Cumber- 
land and Pennsylvania Eailroad one hundred twenty rods east of 
Barrelville. It is apparently continuous southward, since a similar 
brecciated limestone at the same horizon may be seen outcropping on 
the Keyser-Piedmont wagon road on the West Virginia side of the 
Potomac about one and one-half miles below Piedmont. 

The total thickness of the formation in the Potomac gorge east of 
Westemport is about eight hundred feet. Along Jennings Kun, 
twenty-five miles to the northeast, the space occupied by the Mauch 
Chunk and Greenbrier combined is approximately nine hundred 
and thirtv feet or about one hundred feet less than the combined 
thickness of the two formations in the Potomac gorge. 


The Pottsville formation, which is approximately equivalent to the 
Blackwater formation of the Piedmont quadrangle, receives its 
name from Pottsville, Pennsylvania, near which place it is exten- 
sively developed. It is this formation which, at its easternmost out- 
crop in the county, makes the bold crest of Alleghany Front, and dip- 
ping westward passes beneath the surface and forms the massive 
floor of the Cumberland-Georges Creek coal district. It is to this 
formation more than to any other that is due the preservation of the 
present area of the coal-field. By its resistance to erosion it has 
governed the position of Alleghany Front, and although its eastern 
edge is greatly notched by Jennings Run, by Braddock Run and by 
the Potomac river, the latter having, indeed, cut into the formation 
westward across the synclinal axis, the formation nevertheless retain-^ 
its full thickness throughout almost all of the area in Allegany 
county west of the easternmost Pottsville outcrop. The formation 
is slightly cut into by Georges Creek near the southern end of the 
coal basin, but passes beneath the creek bed a few yards north of the 
Cumberland and Pennsylvania car-shops in the northern suburbs 
of Westernport. 

Messrs. N. H. Darton and Joseph A. Taff, in their general de- 


scription of the Blackwater formation with which the Pottsville so 
closely agrees, mention the following important characteristics of the 
area in the northeastern part of the Piedmont quadrangle: "In 
the vicinity of Piedmont the uppermost and lowest sandstone beds 
are conglomeritic and are one hundred and ten and thirty feet thick 
respectively, while the medial sandstone is fine-grained and only 
fourteen feet thick." ' The triple character of the formation can 
be readily made out by means of the many extensive outcrops of 
sandstone and conglomerate ledges; nevertheless there is no really 
good exposure of the whole formation found in the county, the 
softer strata being very largely concealed. Furthermore this, like most 
of the other Carboniferous formations, shows exceedingly rapid 
changes within short distances, so that a measurement in one locality, 
even if favorable conditions prevail, will but poorly suffice, so far as 
details are concerned, for an area only a short distance away. 

It is perhaps for this reason alone that such wide discrepancy is 
observed in the details of all published sections made near the Potomac 
in the southern part of the Georges Creek basin. The following sec- 
tion, constructed from measurements made at various places, is be- 
lieved to represent with reasonable accuracy the general character of 
the Pottsville formation in that vicinity: 

K«»et. Inches. 
PottsviUe-Allegheny contact 

Massive sandstone 20 

Coal, Irequently impure or accompanied by black or gray 

shales [Westernport or *' Two-foot " coal] 2 

Shale and heavy sandstone 85 

Shale with coal streaks 30 

Flaggy sandstone and shale 12 

Coal 1 C 

Impure fire-clay 8 

Flaggy sandstone 14 

Coal [Bloomington or '* Railroad ** coal] 1 <) 

Shale 2 

Shale, flaggy sandstone and concealed 80 

Coal and coaly shale 3 

Black, yellow and gray arenaceous shales 7 

Greenish flaggy sandstone 30 

Pottsville-Mauch Chunk contact 

Total thickness of Pottsville 296 

«Geoloi,'ic Atlas of the United States, Piedmont Folio, Washlni,'ton, 1896. 


No good measurement of the Pottsville can be obtained in the 
northern part of Allegany county, but the following section has been 
measured a little north of the state line near AVellersburg, Somerset 
county, Pennsylvania, in the gap of Gladdens Kun through Little 
Allegheny Mountain : ' 

Fc"C*t. IiR-hes. 
Massive sandstone 75 

Mount Savagfe coal 4 

^[ount Savage tire-clay 7 (i 

Conglomerate sandstone 125 

Dark, shaly sandstone 10 

Shale 1 

Coal and shale 8 

Impure fire-claj'^ 10 

Dark shales with iron ore 20 

Massive sandstone 35 

Total tliickness 288 2 

Along the Baltimore and Ohio Railroad west of Piedmont, West 
Virginia, is a coal seam popularly known as the Railroad Seam, which 
has been named the Bloomington coal, and near the top of the forma- 
tion is a two-foot seam named the Westernport coal. 


The Allegheny formation, identical with the Allegheny river series 
of Pennsylvania, immediately follows the Pottsville, and like it, 
underlies most of the Georges Creek basin. It outcrops on the east- 
ern side of the basin high up on tlie western slope of Dans and Little 
Allegheny mountains. In a simihu* manuer its western edge shows 
along the eastern slope of Savage Mountain, but of this last outcrop 
Allegany county includes only a small portion near the Maryland- 
Pennsylvania line. The entire thickness of the foimation is shown 
in the southern part of the basin on the hillsides along the Potomac 
but northw^ard the formation disappears beneath the bed of Georges 
Creek one mile below Barton. 

The formation consists mainly of irregularly interbedded shales 
and sandstones with several coal seams of greater or less importance. 

1 White, I, C. Stratii^raphy of the Bituminous Coal Fields of PeiiDsylvania, Ohio 
and West Viri^inia, V. S. G. S. Bull. No. 05, p. 18(), Washington, 181U. 


At the base is the poorly exposed Bliiebangh seam which has been 
opened at Warrior Run. About 35 feet above this, is the Parker seam 
shown in various parts of the coal basin and supposed to be the equiva- 
lent of the Clarion coal of Pennsylvania. About the center of the 
formation is the Davis or Six-foot coal, the most important of all the 
coals in this formation. It is supposed to be the equivalent of the 
Lower Kittanning of Pennsylvania. About 30 feet beneath it streaks 
of coal may usually be found which together compose the unworked 
Split-six. At the top of the formation is the Thomas or Three-foot 

Most of the sandstones are thinly bedded and disintegrate easily, 
80 that the face of the outcrop is generally hidden by a gently sloping 
cover of loose shale and soil delimited by the more massive Potts- 
ville sandstone below and the heavy Mahoning sandstone above. 

The following section was measured near the Franklin gravity 
plane a short distance from the mouth of Savage river: 

Sandstone, apparently the Mahoning- 

Concealed 25 

Sandy ferruginous shale 00 

Sandstones and concealed 50 

Sandstone, flaggy near top 60 

Shale 6 

Coal [Davis or ** Six-foot "] 6 

Concealed :J0 

Flaggy and shaly sandstone 61 

Coal [Parker] 1 

Shale 19 

Conglomeritic sandstone of Pottsville 

Total thickness of Allegheny formation 318 

A more detailed section was obtained as follows near Franklin 
village on Georges Creek. 

Massive sandstone, apparently the Mahoning 

Greenish shal}- sandstone. A coal vein near the top 

[Thomas] 55 

^lassive sandstone 24 

Ferruginous shale, showing spheroidal weathering' M 

Fine black and brown shales 8 

Grayish green, slightly nodular shale 10 

Fine grayish green shale 4 

Arenaceous shale 9 

Greenish sandstone and shale 26 




Shaly sandstone 6 

Fine shale and concealed 9 

Shaly sandstone , 13i/^ 

Concealed 30 

Coal [Davis] 6 

Sandstone, shale and concealed 7 

Flag-gy sandstone IG 

Massive sandstone 4 

Shale 2 

Coal [" Split-six "J 3 

Concealed 90 

Total thickness of Allegheny formation '^2514 

Professor I. C. White, in Bulletin 65 of the United States Geo- 
logical Survey, gives the following measurements for the vicinity of 

Feet. Inches, 
r Coal 2 

Coal, Upper Freeport [Thomas] .. J Shale and bone.... 1 

[ Coal 2 5 

Concealed 10 

Shale, bluish 10 

Coal, Lower Freeport 2 

Fire-clay 2 

Concealed 10 

Sandstone, hard 2 

Sandstone, shaly 5 

Shales, sandstones and concealed 55 

f Bituminous slate . . 5 
Coal, Upper Kittanning < ^ , 2 7 

Dark shales and concealed 10 

Massive sandstone, gn^ay 50 

Shales, drab 5 

Coal, slaty .... 1 
Coal, bony .... 8 

Coal, Upper Kittanning [Davis]. ^ Coal, good .... 1 4 

Slate, hard .... % 

Coal, good .... 2 65 6% 

Fire-clay, sandy 3 

Shales, with nodular iron ore 2 

Fire-clay, impure 4 

Flaggy sandstone 20 

Concealed 25 

Fire-clay, sandy 10 

^''l&g'g'y sandstone and sandy shales 25 

Concealed and sandy shales 40 

Total 307 6% 


In the northern part of the coal basin the thickness cannot be 
learned, nor is there a good exposure anywhere along the lines of 
outcrop on the eastern and western borders of the basin. 

Near the mouth of Geoi^s Creek, as seen beneath Mr. MerrilFs 
mine, there is a coal seam almost thirty feet below the "six-foof 
The section obtained at Mr. Merrill's mine for this part of the forma- 
tion is as follows: 

CJoal [Davis] 

Shale 9 

Sandstone and shale 11 

Shale 4 

Shaly sandstone 1 

Shale 4 

Coal [" SpUt-six "] 3 


The Conemau^h formation, so-called from Conemaugh river, Pa., 
follows the Allegheny in regular order and lies within the area out- 
lined by that formation. In the northern part of the basin the Alle- 
gheny has been cut deeply by Jennings Run and its tributaries, while 
at the southern end Georges Creek has made a long incision into it, 
the bifurcation extending northward to within one mile of Barton. 

The Conemaugh, formerly called the " Barren Measures," is largely 
a shale formation. A sandstone, sometimes rather massive, is gen- 
erally found near the bottom. This is apparently equivalent to the 
Mahoning sandstone of Pennsylvania. A second sandstone occa- 
sionally quite massive, is found twenty or thirty feet below the top. 
The latter sandstone is generally not less than twenty feet thick and 
is sometimes conglomeritic, especially in the lower parts. Two hun- 
dred yards east of the Hofman mine opening an exposure above 
and below the railroad switch gives a thickness of thirty-eight feet 
with neither the top nor bottom shown. A few rods east of Eckhart 
on the National Road near the Cumberland and Pennsylvania Rail- 
road, thirty feet of the sandstone is exposed, but here also the top 
and bottom are concealed. Likewise, immediately east of the long 
railroad bridge near Detmold Run, fourteen feet is exposed, and in 


the village of Miller, east of Lonaconing, twenty-five feet is shown, 
but in each case the top and bottom are hidden. This sandstone is 
flaggy near the top and, like most of the other Coal Measures sand- 
stones, is highly charged with iron, contains much mica and is highly 

A sandstone which is frequently conglomeritic is found a little 
below the middle of the formation. Thirty-six feet of this conglom- 
eritic sandstone is shown to good advantage at Barton on the hillside 
south of the Potomac tramway. 

The shales are chiefly argillaceous, and the coals, of which there 
are several, are usually impure; one coal seam of some importance 
known as the " Four-foot " or Barton coal is approximately 250 feet 
above the bottom of the formation. Irregular beds of iron ore are 
frequent and two or three limestones are present. A limestone bed, 
perhaps the thickest limestone of the formation, is poorly exposed on 
the Potomac gravity plane about 235 feet below the top of the 
formation. It is bluish-black in color, slightly fossiliferous and six 
feet thick. It measures as follows: 

Feet. Inches. 

Massive limestone 1 6 

Shaly limestone 6 

Massive limestone 8 

Shaly limestone 4 

Massive limestone 3 

Another limestone was found in a ravine at the roadside one mile 
west of Mount Savage. This is apparently about one hundred feet 
higher than the limestone at the Potomac Plane. The measurement 
of the entire exposure here is as follows: 

Feet. Inches. 

Black shale 10 

Very coaly .shale 3 

Black, somewhat coaly shale 1 8 

Impure coal 2 8 

Black shale with very thin coal streaks 4 

Coaly shale 1 1 

Coal, apparently all good 2 4 

Shale, dark above, gray in lower part 1 5 

Clay 7 

Massive, bluish gray, argillaceous limestone 2 1 


Feet i nches. 
Massive light gray argillaceous brecciated limestone 1 9 

Very argillaceous limestone 4 6 

Soft weathered shale 4 

Iron-ore band 4 

Black coaly shale 2 


Thirty feet below this section there is a thin highly ripple-mai keil 
sandstone exposed in the road-bed two hundred yards west of the coal 

For a complete section of the entire formation no more detailed 
section can be given than that published by Professor P. T. Tyson * 
many years ago, as obtained from measurements made on the 
eastern side of Dug Hill near Lonaconing, the hill having received 
this name on account of the excavations made especially for these 
measurements on Laurel Run and on Mill Run. It is not easv to 
decide just which stratum of Professor I'yson's section coincides with. 
the lower limit of the Conomaugh, but the section as given below is 
believed to have its lowest measurement within a few feet of the 
contact. Although on account of the variability of the strata the 
measurements mav seem to have been taken more in detail than nee- 
essary and less attention given to recording the degree of purity of 
the various coal seams and iron-ore bands than may be desirable for 
economic purposes, nevertheless the section will perhaps always re- 
main an important one for this division of the Coal Measures at Lona- 
coning. In the absence of good exposures elsewhere it has in the 
past been largely depended upon as a guide for other parts of the coal 

The section is as follows: 

Feet. Inches. 

" Big Vein " coal [from Dug Hill measurements] 

Shale with iron ore at the top 12 

Fire-clay 3 

Limestone 1 6 

Shale 15 6 

Sandstone, fine-grained 29 

Shale 27 6 

» Proc. Amer. Phllos. Soc. xi, 1871, pp. 9-13. 


»3«afci-"'***f>- •>Mrfc_. 


I. a.— VlliW OK " IIIG VEIN '■ COAL. IN OCKA^ 


Feot. Inches. 

Coal 2 6 

Shale 4 

Shale with iron ore at the top IG 8 

Shale, ferruginous 1 

Coal 3 9 

Shale 1 

Coal 1 

Shale, with three bands of iron ore 2 6 

Fire-clay with iron ore :i 

Shale 6 

Coal 1 

Shale with iron ore 7 

Fire-clay with iron ore nodules 2 

Shale 6 

Coal 1 6 

Shale 2 6 

Fire-clay with two bands of iron ore 5 6 

Sandstone 1 c 

Shale with four bands of iron ore 6 6 

Shale with two bands of iron ore nodules 6 6 

Iron ore 7 

Shale with iron ore 4 3 

Coal 6 

Shale with iron ore 6 

Coal 1 6 

Shale 2 

Coaly shale 2 3 

Shale with iron ore 2 2 

Coal 2 1 

Shale 6 

Fire-clay with iron ore 2 8 

Shale with iron ore 4 10 

Shale, ferruginous 2 6 

Iron ore 1 6 

Coal 3 

Shalv sandstone 2 

Shale 4 C 

Coal 2 6 

Limestone 3 

Fire-clay 3 6 

Coal 8 

Shale 1 6 

Shale, ferruginous 1 6 

Shale 1 

Coal 1 3 

Shale 1 3 

Coal 1 fi 

Shale 1 r, 


Feet. Inches. 
Coal 1 6 

Shale, brown 2 8 

Shale, arenaceous and nodular 5 

Shaly sandstone 8 

Shale 4 6 

Coal 1 6 

Fire-clay 7 4 

Shale, ferruginous 5 

Shale with nodules 7 

Shale, ferruginous 2 

Shale 1 

Sandstone 39 

Shale 15 

Fire-clay with iron ore 3 

Limestone 6 

Fire-clay with iron ore 2 

Shale 10 

Sandstone [from measurements on Laurel Run] 44 

Coal • 8 

Shale 10 

Limestone 2 2 

Sandstone 23 6 

Shale 6 

Hard black band 6 

Shale, very ferruginous 6 

Shale [from measurements on Mill Run] 4 6 

Coal, shaly, hard, good 5 8 

Fire-clay, sandy 4 

Ore in shaly fire-clay 6 

Limestone 6 

Sandstone 33 

Shale 9 6 

Fossilif erous ferruginous shale 11 

Total thickness of strata now considered as Conemaugh, 495 6 

An excellent section recently obtained by Professor Charles S. 
Prosser of the Maryland Geological Survey gives the thickness of the 
Conemaugh on Phoenix Hill two miles below Barton as approximately 
630 feet. This section is as follows: 

Feet. Inches. 
*• Big Vein " coal 

Black shales with thin layers of sandstone 41 6 

Concealed in part 93 6 

Thin-bedded sandstone with coal streak at base 10 

Black clay shales 4 ft 


Coal 2^4 in. \ Feet. Inches. 

Black clay shale. . . ly^ 

Coal 7 

Black clay shale. . . 2 ft. 
V/Oax •.........••• xx 

Black clay shale. .. 7 \ The Franklin or so-called 

Coal 3 ( " Dirty Nine-foot " 10 

Black clay shale. . . 5 

Coal 5 

Black clay shale. . . 2 4 

Coal 2 6 

Fire-clay and shales 24 

Brownish sandstone 2 6 

Concealed 23 

Coal 3 

Concealed 15 

Drab to yellowish shales 16 6 

Coal 9 

Sandy shales with iron nodules 14 9 

Mostly concealed 38 

Shales 17 6 

Bituminous shale 1 6 

Shales with limestone concretions 21 

Concealed 25 

Shales and sandstone 28 9 

Brownish gray compact sandstone 1 

Concealed, probably containing Barton or " Four-Foot " 

coal 37 6 

Yellowish gray shales 2 

Coal 4 

Shales and thin-bedded sandstones 28 6 

Thin-bedded sandstones and shales 6 

Impure fire-clay and shales 10 

Yellowish sandy shales 20 

Bluish to yellowish shales 23 

Massive sandstone 12 

Concealed 20 

Coal 1 9 

Fire-clay 2 6 

Yellowish shales with iron nodules 15 6 

Massive sandstone 1 

Concealed 20 3 

Olive to yellowish shales 11 6 

Concealed, with sandstone blocks 8 9 

Massive sandstone 3 9 

Concealed and sandy shales 21 

Coneniaugh-Allegheny contact 

Total thickness of Conemaugh 630-f 



The Monongahela formation received its name from the Monon- 
gahela river, along which stream it is well developed. The floor of 
the " Big Vein " coal distinctly marks the base of the formation, 
while its npper limits in the few small areas where the full thickness 
still remains is marked by the roof of tlie Koontz (Waynesburg) coal. 

The formation has been much dissected by erosion and, retaining 
only a minor proportion of its former distribution, is broken into 
many distinct areas. The most extensive of these lies around and 
largely to the south of Frostburg. Its northern end lies upon and 
helps to make the high transverse divide which separates the drainage 
of Jennings and Braddock runs from that of Georges Creek, and has 
thus survived the cutting that has so seriously affected the northern 
and southern portions of the basin. This area is very irregular in 
outline. It extends southward to Lonaconing, and one narrow area 
reaches northward to within almost half a mile of Mount Savage. 
Three of its prominent westerly projections extend across the county 
line into Garrett county. An oval area of small extent lies upon the 
county line about one and one-half miles southwest of Frostburg as 
an outlier of the above-mentioned larger area from which it has been 
cut off by the branches of Winebrenner Kun, a tributary of Georges 
Creek. Xorth of Frostburg and west of the Cumberland and Penn- 
sylvania Kailroad there is an area of considerable size which is sepa- 
rated from the larger area to the south by the headwaters of Jennings 
Run. A rapidly disappearing remnant of Monongahela, covering 
perhaps twenty acres, caps a prominent hill north-northwest of Mount 
Savage, one-half mile south of the state line. The area is oval in 
shape and the greatest thickness above the " Big Vein " is less than 
seventy-five feet. 

In the southern part of the basin east of Georges Creek there are 
several isolated areas. The largest of these, lying southeast of Lona- 
coning, covers less than three square miles and retains the full thick- 
ness of the formation. Xone of the others reach an area of two 
square miles and none show the full thickness. Several areas lie 
west of Georges Creek south of Koontz Kun, but only one of these, 


the small one west of Moscow, is wholly within Allegany county. That 
just west of Lonaconing is one of the largest and retains the full 
thickness of the formation. 

The Monongahela formation is composed almost wholly of easily 
disintegrating materials. Only rarely do the sandstones become 
sufficiently thick and massive to form noticeable topographic features, 
although in Washington Hollow near Eckliart and on the hillsides east 
of the village of Miller many loose sandstone boulders were found 
which are quite massive and conglomeritic. The surface of the hill- 
sides covered by the Monongahela is smooth and gently sloping. The 
characteristic topographic feature commonly known as the " bench," 
which is so frequently seen above the Big Vein, is due generally to 
the relatively easy weathering properties of the coal and to the hard- 
ness of the heavv underlvine: sandstone. 

Near the top of Westernport Hill above the Franklin tramroad 
is a micaceous sandstone about twenty-five feet thick. This is near 
the middle of the formation and apparently varies greatly in char- 
acter. Other thinner sandstones are interbedded among the shales, 
but their exact location is generally not easy to determine. 

The shales of the Monongahela are arenaceous and argillaceous and 
vary in color from a light gray through green and brown to an intense 
black. Iron-ore bands are not infrequent, and in the lower part of 
the formation they are sometimes of considerable thickness. 

The number of persistent limestones is not definitely known. Some 
of those which in places show good exposures are evidently so len- 
ticular in character that they can seldom be safely correlated with 
those in distant areas. In the mine shaft sunk by the Borden Min- 
ing Company three miles south of Frostburg, two limestones were 
found about forty and fifty feet above the " Big Vein " coal. In the 
Consolidation Coal Company's pumping shaft not far distant two 
limestones were also found, one thirty-three feet above the " Big 
Vein," while the other was more than two hundred feet above. An 
additional limestone bed is exposed near by but a few feet above the 
mouth of the shaft. One mile north of Frostburg along the upper 
railroad track near the Xew York mine, loose boulders of a massive 


limestone are shown which indicate a stratum not more than fifty 
feet above the " Big Vein '* coal. Likewiaei in the vicinity of the 
Koontz mine, a variable limestone is found about forty feet above 
the " Big Vein," and one-half mile west of Vale Summit in a ravine 
on the west side of the Georges Creek and Cumberland Railroad a 
limestone is found at about the same horizon. Near the new furnace, 
one-half mile west of the New Detmold mine, a three and one-half 
foot bed is shown one hundred and five feet above the " Big Vein/' 
while near the top of Westemport Hill loose limestone boulders indi- 
cate a bed there occupying about the same position. 

The limestones frequently appear brecciated on weathered sur- 
faces, are usually slightly fossilif erous and are almost invariably dark 
in color when fresh. 

Owing to the detritus which covers the well-weathered hillsides in 
the northern and in the southern ends of the basin, good sections of 
the Monongahela can be obtained only near the central part Meas- 
urements made by Professor Tyson near Lonaconing, and by the 
Consolidation Coal Company at their pumping shaft, include all of 
the strata now considered as Monongahela, and since the Borden 
Mine shaft has passed through the lower half of the formation, we 
have three good measurements in as many different places. The 
measurements obtained at Borden Shaft are as follows: 

Feet. Inches. 

Top of shaft 

Hard gray sandstone 6 6Vi 

Shale 12 6 

Coal [Tyson] 3 4 

Shale 8 5i/, 

Sandstone 2 4 

Shale and sandstone 5 2 

Sandstone 1 

Shale 7 

Limestone 2 

Shale 2 9 

Limestone and shale 7 8 

Shale 8 9% 

Coal and shale [Redstone] 8 3 

Fire-clay 1 4^ 

Black shale 18 2V, 

Sandstone 4 


Feet. Inches. 

Shale 2 7 

Elkgarden or " Big Vein ** coal 12 6»4 

Total thickness exposed 110 9% 

In the Consolidation Coal Company's shaft, which is situated about 
two miles south of Frostburg, the measurements are: 

Feet. Inches. 
Top of shaft 

Unconsolidated surface material 8 5 

Limestone with boulders 5 7 

Siliceous fire-clay 3 11 

Sandstone 10 

Shale 4 10 

Sandstone 1 8 

Shale 20 

Coal 5 

Shale 5 8 

Sandstone 14 2 

Shale 38 

Coal ^ 10 

Shale I [Tyson] 3 

Coal ] 1 8 

Shale 16 

Sandstone 4 

Shale 25 

Sandstone 1 

Coal 2 6 

Shale 18 

Sandstone 10 

Shale 9 6 

Limestone 5 6 

Shale 7 8 

Coal and shale [Redstone] 7 4 

Shale 18 9 

Sandstone 1 2 

Coal and shale 3 7 

Elkgarden or ** Big Vein " coal 9 6 

Total thickness exposed 239 4 

Professor Tyson's measurements are as follows: 

Feet. Inches. 
Shale above 

Coal 6 

Limestone with shale 12 

Fire-clay 13 9 

Concealed 3 9 


Feet. Inches. 
Shale with iron nodules 27 3 

Shale 27 9 

Fine-grained sandstone 3 6 

Shale 2 6 

Coal with two inches of shale 4 3 

Fire-clay 10 

Coal 3 6 

Fire-clay 3 

Coarse shaly, micaceous sandstone 51 

Shale 42 6 

Coal 4 6 

Shale 2 

Coal 1 

Shale 4 9 

Coal 10 

Shale 1 3 

Shaly sandstone 1 

Ferruginous shale 4 8 

Elkgarden or " Big Vein " coal 14 

Total thickness of Monongahela at Lonaconing 238 9 



Several of the highest hills near the central part of the coal basin 
are capped by strata which are equivalent to the Diinkard series of 
Pennsylvania. The largest of these areas, on which Frostburg is situ- 
ated, caps the irregularly shaped divide which separates the head- 
waters of Georges Creek, Braddock Run and Jennings Run. An area 
of considerable size lies to the north of Lonaconing and another lies 
to the west. Both extend into Garrett county. A much smaller 
area lies to the south. A dumbbell-shaped area lies west of Ocean 
and a small oval patch lies north of Upper Ocean. A fair-sized area 
lies also between Ocean and Vale Summit. 

Stratigraphically the Dunkard formation conformably follows and 
includes everything above the Monongahela. The higher slopes of 
the hills on which the formation lies are in every case well rounded 
and show almost no natural outcrops. Shales and limestones are 
known to be prominent, sandstones are present but apparently not 


important, and coal-beds, although shown in some places, seem to be 
of little consequence. The shales have a dull reddish-green color, but 
were seen only where considerably weathered. The lowest limestone 
observed is exposed in the Cumberland and Pennsylvania Railroad 
cut near the Consolidation Coal Company's pumping shaft two miles 
south of Frostburg. This is composed of an upper dark massive fossil- 
iferous layer twenty-eight inches thick and a lower, somewhat shaly 
bluish-gray stratum forty-three inches thick. About 300 feet above 
this, on the hill east of the pumping shaft, there is an abandoned 
limestone quarry in which the partially exposed limestone containing 
small scattering fossils seems to have a thickness of about six feet. 
Fifteen feet higher there is another thinner limestone as indicated 
by loose blocks on the surface. A very argillaceous limestone seven 
and one-half feet thick is exposed about 250 yards north of the Frost- 
burg tunnel. This seems to be several feet above the bottom of the 
Dunkard formation and possibly lies at the same horizon as the one 
seen in the railroad cut near the pumping shaft. 

But little can be said of the coal seams in the Dunkard formation, 
and so far as known none are more than twelve inches thick. One 
bed having this thickness is exposed a few feet above the limestone 
north of the Frostburg tunnel. Others w^ere seen at this place, but 
they were of much less thickness. Near the pumping shaft two coal 
seams are known to lie more than .300 feet above the bottom of the 
formation, but their thickness could not be learned. 

No detailed section of the formation can be given, but its greatest 
thickness is about four hundred feet. 

The Permian character of these strata has been maintained by some, 
and thev are classified as Permian in Volume One of The Marvland 
Geological Survey in conformity Avith the results obtained by Pro- 
fessors Fontaine and White in their study of similar strata in Penn- 
sylvania and West Virginia. Their work in the higher strata there 
has shown a gradual decrease and final disappearance of coal, a great 
change in plant life and important changes in physical conditions. 
Lithologically, in Maryland, the Dunkard appears but little different 
from the higher Coal Measures except in the lesser importance of ita 


coal seams and possibly in the greater abundance of its limestones. 
The fossils thus far found in the formation are not numerous and 
have not yet been described. All of those collected have been confined 
wholly to minute fonns found in the limestones. The plant form 
Pecopteris elliptica described by Bunbury, is thought to have come 
from the Dunkard formation, but this is not certain.* 

The Pleistocene. 


Well-rounded boulders and coarse gravels of quartzite and con- 
glomerate are found in the western part of the county scattered 
loosely upon the hillsides, extending at Cumberland as much as 300 
feet above the Potomac river, or a little more than 900 feet above 
tide. At Piedmont, West Virginia, where the river bed is 300 feet 
higher, similar boulders have been found as much as 1060 feet above 
sea-level. These and other deposits of like nature have been de- 
scribed and discussed bv Professors J. J. Stevenson and I. C. White, 
both of whom consider them of glacial or post-glacial age.' 

At a considerably lower level in several places along the Potomac 
river deposits of clay, coarse gravels and boulders are found which 
sometimes show coarse stratification. This is particularly notice- 
able in the vicinity of Cumberland and in some of the Baltimore 
and Ohio and West Virginia Central Railroad cuts between Cum- 
berland and Westemport, as well as along the Baltimore and Ohio 
Railroad near the eastern part of the county between Paw Paw, West 
Virginia, and the mouth of Sideling Hill Creek. The gravels and 
boulders are usually well-rounded and polished and consist for the 
most part of fragments of Paleozoic materials such as are found in 

' Fontaine, Wm. M., and White, I. C. The Permian, or Upper Carboniferous, Flora 
of West Virginia and S. W. Pennsylvania. Second Geological Survey of Pennsyl- 
vania, Report PP, p. iii, Harrisburg, 1S80. 

'Stevenson, John J. On the Surface Geology of Southwest Pennsylvania and ad- 
joining portions of Maryland and West Virginia. A. J. S., vol. xv, 1878, pp. 245-250. 

White, I. C. Rounded Boulders at high altitudes along some Appalachian Rivers. 
A. J. S., vol. xxxiv, 1887, pp. 374-381. 


the immediate vicinity. Near the railroad tunnel just north of 
Paw Paw the stratification may be seen to excellent advantage, the 
deposits there extending upwards as much as sixty feet above the bed 
of the Potomac river. Some of the materials found here have evi- 
dently been carried a considerable distance, since among them are 
chert fragments, evidently from the Helderberg formation, the near- 
est outcrop of which is more than ten miles distant. Distinct strati- 
fication may also be seen in a few favorable places between Cumber- 
land and Westemport. 

It may be of interest to describe in this connection a fossiliferous 
limestone-chert breccia found by the author between Cumberland 
and Westernport. Professor I. C. White has described an appar- 
ently similar deposit along Patterson Creek in West Virginia, but 
does not mention the presence of fossils.' The two deposits possibly 
have the same origin. The breccia is made up of small angular, 
slightly water-worn, frequently flattened fragments of chert and 
limestone, evidently derived from the Helderberg formation on which 
it is foimd. The cementing material is lime. It is hard but vesicular 
and forms no little portion of the entire mass. 

As yet only a small collection of this breccia has been examined, 
but among the fossils thus far found the following have been identified 
by Professor H. A. Pilsbry: 

Pupa {Bifidaria) armifera, Say. 

ZenUoides minusculus, Binn. 

Strobilops, probably virgo, Pils. or afjinis, Pils. 

Ilelicina occulta, Say. 

II elicodiscus lineatus, Say. 

Polygyra hirsuia. 

Polygyra albocahris, Say (?). 

Polygyra, speci(*s undetermined. 

The breccia is apparently of quite recent origin, and there is some 
reason for believing that it may be forming at the present time. 
Professor Pilsbry says that Ilelicina occulta is one of the most abun- 

' White, I. C. Rounded Boulders at high altitudes along some Appalachian rivers 
A. J. 8., 3d series, vol. xxxiv, 1887, pp. 374-381. 


dant and characteristic fossils of the Iowa loess and is now almost 
extinct, being confined to a few very restricted though widely sepa- 
rated areas, and that it has not hitherto been known to occur in Mary- 
land, either recent or fossil. The other species have been previously 
recognized as living in Maryland. 



The Orleans anticline, known in Pennsylvania as the Whip Cove 
anticline, enters- Allegany county from the north near the point where 
Sideling Hill Creek crosses the state line. It may be considered as 
including the area covered by the Jennings formation east of Town 
Hill. The several small patches of Hampshire that have been carved 
out by the meanderings of the Potomac river and Sideling Hill 
Creek along the eastern side may also be considered with this anti- 
cline, although the easternmost parts of the areas might perhaps be 
more conveniently considered with the Sideling Hill syncline outside 
of the county. 

The exact position of the main anticlinal axis on the state line is 
concealed, but it is apparently east of Sideling Hill Creek and the 
Second Geological Sun^ey of Pennsylvania from data collected in 
that state has so indicated it. West of the creek the dip was ob- 
served in various places in the bottom of the ravine which runs nearly 
parallel with the state line. Two hundred yards west of the creek 
there is a very perceptible anticline, although the exact position of the 
axis is concealed. The west limb of this anticline dips quite regu- 
larly 27° to 28° W. East of the axis the dip is complicated. At a 
point one hundred yards west of the creek the dip is 38° E. This 
rapidly decreases eastward to almost zero, then as rapidly increases 
again to 50° E., which in turn quickly decreases to zero, this last 
measurement having been obtained in the bed of Sideling Hill Creek. 
East of the creek along the state line the rocks are concealed. 

The anticline running nearly parallel with Town Hill extends en- 
tirely across the county, including the two larger West Virginia areas 


that have been carved out by the sinuosities of the Potomac river. 
In general the fold is composite, as is indicated by the presence of 
various small anticlines situated near where the main axis evidently 

On the National Road, about one mile south of the state line, the 
various attitudes of the strata are well shown and three anticlines are 
there disclosed. The evidence seems to indicate that the main axis 
crosses the National Road about one mile west of Sideling Hill 
Creek. At this point there is a very perceptible anticline, the west 
limb dipping 43^ W., the east limb dipping 14° E. This last dip 
changes within one-half mile east to 21° W., and this a little further 
east is followed by an anticline, the eastern limb of which dips 52° E. 
At the edge of the county, where the road crosses the creek near the 
Hampshire-Jennings contact, the dip is 36° E. West of the main 
anticlinal axis as located, the dip rapidly swings around, from 43° W. 
through zero to 46° E., but one-half mile west there is another anti- 
cline with the west limb dipping 4° AV. Continuing westward the 
dip is slight until the Jennings-Hampshire contact four miles west is 
reached, near which place there is a small anticline with east and west 
limbs dipping 60° E. and 41° W. respectively. This is followed by 
strata dipping more and more gently westward. 

Southward from the National Road the anticline turns a little more 
to the east, passing only a few rods west of the great bend in Sideling 
Hill Creek, where the east limb dips 48° E. and the west limb 61° 
to 85° W. Continuing southward the axis crosses Fifteenmile Creek 
three-fourths of a mile west of Little Orleans, the village which sug- 
gested the name here used in descriinng the anticline. Where the 
axis crosses the creek the east limb of the anticline dips 14° E., the 
west limb 50° W. The dip of the east limb gradually increases east- 
ward until at the mouth of the creek the dip is 90°. On the Potomac 
river, one-fourth mile north of Little Orleans, a dip of 54° W. is 
shortly followed to the east by a dip of 78° W. Beyond this, east- 
ward, the dip passes somewhat rapidly through zero to 57° E., near 
which attitude the strata remain until within two hundred yards of 
the mouth of Sideling Hill Creek. Here there is a small syncline 


with west limb dipping 44*^ E. and east limb dipping 63*^ W. At 
the mouth of the creek the dip is 34*^ W. On Fifteenmile Creek, 
west of the main anticlinal axis, the strata dip on an average about 
40° W. until near the Jennings-Hampshire contact, where there is 
a syncline with east and west limbs dipping 40° W. and 38° E. respec- 

South of Fifteenmile Creek the axis extends in a more southerly 
direction and cuts across the West Virginia projection about one mile 
west of Doe Gully tunnel on the Baltimore and Ohio Eailroad and 
almost parallel with it. Where the anticline is first crossed by the 
Potomac south of Fifteenmile Creek its limbs dip 82° W. and 63° E. 
Along the river west of the axis the dip of the strata changes gradu- 
ally, decreasing to 47° W. at the Jennings-Hampshire contact near 
the big bend in the river. East of the axis also the dip is pretty 
regular, passing gradually through 74° E., 64° E., 44° E., 64° K, 
42° E. to 66° E., the last measurement, 66° E., having been made 
one mile east of Doe Gullv at the end of the bend in the river. The 
strata through which Doe Gully tunnel is cut dip 63° E. near the 
north end and 64° E. near the south end, the strike being 34° E. in 
a line with the tunnel. In the West Virginia area west of the tun- 
nel, as well as in most of the Maryland peninsular area immediately 
to the south, the dip is not shown. However, going up the Potomac 
from the south end of the tunnel, the dip can be pretty frequently 
made out. The anticlinal axis having turned considerably to the 
west of its usual direction, crosses the river about one mile below 
Bairds on the Baltimore and Ohio Railroad, where the limbs of the 
anticline dip 74° W. and 46° E. Along this east and West section of 
the river, as in the one near Doe Gully Station, no secondary folding 
can be observed. The dip of 74° W. gradually increases to 82° W., 
then slowly decreases to 61° W. at the bend of the river near Bairds. 
East of the axis the dip gradually passes through 42° E., 64° E., 43° 
E., 36° E., 39° E., and 54° E., the latter dip, 64° E., being shown 
at the Jennings-Hampshire contact as well as farther east at the bend 
in the river. 

Apparently taking more nearly its general course of S. 26° W., 


the axis passes across the next West Virginia area where its position 
is hidden but is shown again on the Potomac between Bairds and Mag- 
nolia in a much confused condition. Here five anticlines appear. 
The main axis is situated somewhere west of the canal tunnel north 
of Paw Paw and apparently crosses the river about one-half mile west 
of the timnel. West of the axis the dip oscillates rapidly, 69° being 
the dip of the steepest strata observed. East of the axis the dip is 
less changeable, although considerable fluctuation occurs. Imme- 
diately above the opening at the northern portal of the canal tunnel 
a small asymmetric anticline is exposed which dips 44° W. and 28° E. 
The tunnel, which is three thousand four hundred and forty feet long, 
runs nearly with the strike, but at the south end this anticline is not 
seen, the dip being 36° E. At the north end, where a very large 
amount of rock has been removed in order to provide a suitable ap- 
proach to the tunnel, a most magnificent slickenside surface of more 
than one thousand square yards is exposed. The surface has a slant 
of 52° W. and, although imcovered more than half a century ago, it 
is everywhere marked by the usual slickenside striation and still 
retains a high polish. 

In the Hampshire formation at the bend in the river at Magnolia 
the dip is 78° E. Going westward the dip gradually grows less until 
it reaches 21° E. at a point about three-fourths of a mile west of the 
easternmost part of the bend. On the Maryland side of the river op- 
posite the north end of the Paw Paw tunnel on the Baltimore and Ohio 
Railroad there is a strong anticline, the east line of which dips 30° E. 
The dip of the west limb could not be determined. At each end of 
the tunnel the dip is 41° E. Across the river from Paw Paw at the 
edge of the canal a small anticline is exposed. It is also shown a 
short distance further north at the canal, and is presumably identical 
with the one seen at the north end of the canal tunnel. 

Almost three-fourths of a mile west of Paw Paw on the county road 
there is a fold which apparently locates the axis of the main anti- 
cline. The west limb has a dip of 80°, which gradually decreases to 
40° one-fourth of a mile further west. The dip of the east limb is 
71° and this decreases to 40° within a distance of eighty rods. South 


of the county road the anticlinal axis apparently becomes much de- 
flected to the west, although this cannot be definitely proven. 

Along the river on the south side of the county only one obscure 
anticline was detected and this is about one hundred rods west of the 
point where Little (/acapon river enters the Potomac. The west 
limb dips 6Q^ W., but gradually and uninterruptedly grows less 
steep. The dip of the east limb is not known, but opposite the mouth 
of Little C^acapon the dip is 32° E. In the absence of other evidence 
the Orleans anticline is considered as passing across the river and out 
of the county along the position of this, the only observed anticline 
in the region. 


The Town Hill syncline, extending entirely across the county, has 
the general direction of N. 25° E., and may be considered to embrace 
the area covered by the two long narrow belts of Pocono at the top 
of Town Hill, the flanking area of Hampshire in the hollow of which 
the Pocono rests, together with that part of the Jennings included in 
the western slope of Green Ridge. So far as can be observed, this 
syncline is but little complicated, being particularly simple and sym- 
metrical where cut through by the Potomac river. On the National 
Road near the eastern Pocono-Hampshire contact the dip is 24° W. 
Going eastward the dip slowly increases to 48° W., this observation 
having been made near the fork in the road about one mile west of 
Piney Grove. Near here the dip quickly changes through zero to 
52° E., which position the strata retain a few rods west of Piney 
Grove post-office. From this point eastward the strata rapidly regain 
their westerly dip and at the post-office the dip is 57° W. One-fourth 
of a mile further east the dip is 23° W. This is soon followed by 
a fold, the presence of which is indicated by the position of the strata 
one-half mile east of the post-office where the dip is 25°-30° E. 
Beyond this the influence of the Orleans anticline becomes paramount. 

On the Xational Road, west of the top of Town Hill, one small 
symmetrical anticline is seen with limbs dipping 28°. This is one- 
half mile west of the Pocono-Hampshire contact. Continuing west- 

aeoLOoiCAL survev. 




ward this is followed by a regular easterly dip, gradually changing 
through 28° E., 38° E., 45° E., 32° K, 53° E., 35° E., and 50° E. 
The dip of 38° E. was measured at the side of the creek between 
Town Hill and Green Ridge, that of 32° E. is shown on the summit 
of Green Ridge near the Hampshire-Jennings contact, while the 
measurement of 50° E. w^as obtained near the bridge over Eif teen- 
mile Creek. A few yards west of the creek the dip is 70° E., and 
further west the strata are more and more influenced by the Pratt 
Valley folds. 

Along Fifteenmile Creek, as well as along the county road which 
runs nearly parallel w^ith it, good exposures are frequent. West 
from the axis, which is in the center of the Town Hill Gap, the strata 
gradually become more steeply inclined until at the top of Green 
Ridge, where the creek road enters the ridge road, the dip is 40° E. 
Two miles south of this point attitudes of 50° to 54° were found on 
the WTstern slope of the ridge. East of the axis the dip of the strata 
is more complex. Within three-fourths of a mile from the center of 
the gap the dip changes from zero to 44° W. Between this point and 
the Hampshire-Jennings contact further east, two secondary anticlines 
appear. As a result of these the dip changes from 44° W. to 55° 
E., then to 35° W. and again to 32° E., the latter dip indicating the 
position of the strata near the Hampshire-Jennings contact. A few 
rods east of this contact line the dip is 38° E., after which the influ- 
ence of the synclinal axis ceases to be felt. 

Near the southern end of Town Hill various observations were 
made which compare favorably with measurements obtained further 
north. On the Okonoko-Orleans road one and one-half miles north 
of the southern limit of the Pocono a dip of 56° W. was observed. 
Three-fourths of a mile south and a few rods west of this exposure a 
dip of 49° W. is shown. One hundred and twenty-five yards further 
west the dip is 21° W. Along the county road leading from Town 
Hill to Green Ridge there are various exposures. One in the bed 
of the ravine shows a dip of 61° E., and a few rods further west a dip 
of 49° E. was seen. This quickly decreases to 38° E., but at the top 
of Green Ridge the strata dip 52° E. Continuing northwestward 


down to and along Town Creek the dip is generally quite steep^ 
being much of the time considerably more than 50° E. and in several 
places 90°. 


This anticline clearly asserts itself in the two Oriskany exposures 
east and northeast of Oldtown, and a good exposure locates the posi- 
tion of the axis. About one mile east of Oldtown on the canal near 
the water level, the dip on the west side of the axis is 30° W. Tho 
strata here are bent into a nearly symmetrical arch almost one hun- 
dred feet high, although on the east side near the canal level the 
strata quickly become steeper and plunge beneath the surface with a 
dip of 63° E. In the long narrow strip of Oriskany to the northeast 
of this the position of the area corresponds to that of the axis of the 
anticline. Here the rocks of the Oriskany formation being largely 
free from covering, show the anticlinal nature of the ridge distinctly. 
Almost at the extreme northern limit of the area where the county 
road and a small tributary of Town Creek cut across the ridge a dip 
of 12° was measured on the west side of the axis. Farther east where 
Town Creek cuts into the eastern side of the Oriskany the strata 
have an apparent overturned dip, the attitude there being 70° W* 
This seems to swing back through 90° very soon, as only a few rods 
further east a good exposure shows a dip of 44° E. Continuing east 
along the creek toward Green Kidge the strata wherever exposed show 
a strong dip, but at some places where the rocks are concealed there is 
an undoubted undulation, this fact being rendered evident by a dip 
of 70° W., observed near the angle formed by the creek as it turns 
west-northwestward from Green Ridge. Two miles south of this, 
where Town Creek makes an abrupt turn to the east, the dip near the 
Jennings-Romney contact is 53° E. This graduallv increases east- 
ward to 62° E., which observation was made where the creek turns 
southward. Along the West Virginia side of the Potomac, both east 
and west of the Stratford Ridf^e axis minor folds are shown, but on the 
Maryland side the strata are' worn down and conocaled in such a 
manner that these minor folds are not very apparent and, indeed, their 


influence seems to die out almost immediately after passing across the 
river into Allegany county. A few yards east of the mouth of the 
South Branch the dip is 15° E., but this gradually increases without 
serious interruption to 90° near by, at which attitude the strata remain 
for much of the distance between the mouth of South Branch and 
the Jennings-Romney contact. Between this contact and the mouth 
of Town Creek the dip is about 55° £. Nearly one-half mile west 
of the main axis a fold of some importance is seen on the West Vir- 
ginia side, but it is concealed in Maryland. The limbs dip 15° E. 
and 25° W. 

One-half mile south of the north end of the Stratford Ridge area 
along the county road running parallel to and west of the axis a dip of 
21° W. was foimd. North of this area, where the creek cuts across 
the Jennings-Romney contact zone, the dip is 65° E. This increases 
to 81° E. about one-fourth of a mile nearer Green Ridge, but de- 
creases to 22° E. near where the creek turns south parallel to Green 

The effects brought about in the formation of the Stratford Ridge 
anticline are no doubt felt considerably further north than the Oris- 
kany area extends, possibly even reaching for a considerable distance 
north of the creek, but owing to the paucity of exposures the true 
conditions cannot be made out. 


In the extensive area of Romney shales east, west and north of 
Oldtown the extreme poverty of exposures prevents any precise de- 
scription of the structural details, but such definite observation as can 
be made shows that the strata are considerably folded. Whether or 
not these folds are very persistent or important in any way is not 
known. As a consequence, therefore, the structure sections for this 
part of the county have been made upon data that is necessarily 
somewhat conjectural, but the general condition of the strata is evi- 
dently that of gentle and frequent undulation and they have been 
so represented. 

Pratt Vallev may be roughly considered as including the compara* 


tively low area lying between Polish Mountain and Green Kidge north 
of the lower course of Town Creek. With the exception of the ex- 
posures along the Kational Road the conditions for studying the 
exact features of the stnicture in this area are eveti more meagre than 
in the Oldtown area. The valley is very densely wooded, and over a 
considerable portion of the area the only means of gaining any knowl- 
edge of the underlying formation is to examine the loose shales lying 
in the cavities left by uprooted trees. On the National Koad three 
hundred yards east of Pratt post-office a beautiful, almost symmetrical, 
anticline is seen. The w^est limb dips 40° W. and the east limb dips 
44° E. For nearly onehalf mile west of this the dip gradually de- 
creases, finally reaching as low as 6° W. at a point about four hun- 
dred yards west of Pratt post-office. West of this point the dip 
increases more and more under the influence of the Polish Mountain 
syncline. About one-third of a mile east of the axis an exposure 
shows the strata dipping 30° E., but two hundred and fifty yards 
further east they dip 85° W. Beyond this for nearly a mile the strata 
are concealed. When next seen the dip is to the east. South of the 
National Road no distinct traces of these anticlines can be found, 
although various measurements on Town Creek and northward on 
some of its branches indicate much variation of dip with the probable 
presence of several folds. 

At a point two miles west of Pratt two anticlines near each other 
are poorly shown on the National Road. Their limbs, so far as can 
be obser\'ed, dip nearly symmetrically at 30° to 40°. At a point 
almost one-half mile west of this the dip is 45° E., but three hundred 
yards further west the dip has decreased to 35° E. East of the two 
anticlines, which in fact may be considered as flexures of one main 
anticline, the dip changes rapidly until Fifteenmile Creek is reached. 
Starting with a dip of 30° E. the dip undulates through 90°, 50° E., 
40° E., 87° W., 35° W., 70° E., 50° E., 45° E., the last measure- 
ment being one hundred fifty yards west of Fifteenmile Creek. The 
dip of 35° W. and 70° E. shows a crumpled anticline about five him- 
dred yards west of the creek. We thus have at least three separate 
and distinct positions along the National Road in Pratt Valley where 
anticlines are developed. 


By comparing this valley with the corresponding area north of the 
state line in Pennsylvania, it will be observed that the positions of 
the Pratt Valley anticlines correspond quite closely to the positions 
of important anticlines in Bedford coimty as worked out by the Second 
Geological Survey of Pennsylvania/ Beginning with the eastern- 
most, these anticlines are known as the Broad Top anticline, the 
Snyders Ridge anticline and the Shavers Creek anticline. In the 
absence of opposing evidence it seems, with the information at hand, 
that we may say without probability of serious error that the above- 
named anticlines as traced out in Pennsylvania extend into Maryland 
and, crossing the National Road at or near the points suggested, con- 
tinue an indefinite distance southward, being apparently seriously de- 
flected and possibly entirely dissipated by other more or less important 
folds before reaching the Potomac river. 


This syncline follows the trend of Polish Mountain and is the 
gradually shallowing prolongation of the much more prominent 
Clearsville syncline of Pennsylvania. On the National Road the 
dip on the east side of the synclinal axis approximates 20° W., while 
on the west side it is about 40° E. On the Williams Road, about 
two miles south of the National Road, the strata on the east side of 
the syncline are concealed; but on the west side between Town Creek 
and the crest of the mountain the dip varies from 22° E. to 30° E. 
Near the south end of the mountain various observations were made, 
but onlv those on the western side of the axis are trustworthy. Thev 
indicate the average dip to be very nearly the same as that shown 
on the AVilliams Road. Further south the syncline becomes lost 
amidst the confusion of other folds. No rocks higher than those of 
the Jennings formation are contained wnthin this syncline in Alle- 
gany county. Along the top of the mountain a heavy conglomerate 
is shown south of the Williams Road, but where the mountain is 
crossed by the National Road the conglomerate has apparently been 

'Stevenson, J. J. Geology of Bedford and Fulton Counties, Report T2, Second 
Geological Survey of Pennsylvania, Harrisburg, 1882, 


worn completely away, although its former position is shown by a 
few scattering but much weathered boulders. This conglomerate 
capping is apparently the same as the heavy conglomerate seen in 
many other places in the county near the top of the Jennings, and in 
Pennsylvania where the opportunities for studying the rocks of this 
syncline are better than in Maryland, the Pennsylvania Geological 
Survey has similarly located it and has correlated it with the Che- 
mung Upper Conglomerate/ 


Within that structural division of the Appalachian system of which 
Allegany county forms a part, the folds of predominating importance 
are usually those long anticlines which are of sufficient magnitude to 
bring up the Silurian rocks. Of such anticlines Allegany county 
has three that are well developed. All of these enter the county 
from Pennsylvania, but in each case the position of the anticline be- 
comes entirely obliterated or very much disturbed before reaching the 
Potomac river. The Tussey Mountain anticline is the easternmost 
and most quickly obliterated one and at the state line occupies the 
position of Tussey Mountain. Continuing nearly southward across 
the National Road and then more nearly southwest the anticline 
bifurcates, one branch following the direction of Warrior Mountain, 
the other that of Martin Mountain. 

Xear the state line where the Tuscarora of Tussey Mountain is cut 
through by Flintstone Creek the dip on the west side of the anticline 
is 18^ W. Although not well known, it is apparently about the same 
on the east side. Further east the strata where not concealed show a 
varying dip, the Clinton being much folded there. Along Flintstone 
Creek northward from Flintstone for half a mile or more the general 
dip is 40° to 50° E. One and onehalf miles west of Flintstone 
Creek on the National Koad a dip of 40° E. is shown. One-half 
mile further west the dip is 5° W., the intervening area apparently 
representing the position of the main anticline. Further west, as far 

> Stevenson, J. J. Geolopy of Bedford and Fulton Counties, Report T2, p. 81, 
Second Geological Survey of Pennsylvania, Harrisburg, 1883. 


as the abandoned limekiln in the Helderberg formation, three miles 
west of Flintstone, the dip varies from 20^ to 30° W., but the ex- 
posures are not good. Along a small ravine, about one mile south 
of the National Road and running neariy parallel with it, various 
measurements indicate the general attitude of the strata to be much 
the same as along the National Road. However, further east along 
the Murley Branch road considerable confusion of dip exists and this 
is found to be due to the presence of a minor fold nmning parallel 
with Murley Branch. The exact position of the axis of this minor 
fold is best seen a little more than half a mile east of Rush on the 
Williams Road. A few feet of the red sandstone near the bottom 
of the Salina is there shown in a small anticline whose liml>s have a 
dip of 15°. The same anticline with a similar exposure of Salina is 
brought to view on the ravine two hundred yards south of this. It 
cannot be traced further south. The anticline is not well shown 
northward from the Williams Road, but its presence is sufficiently 
indicated to enable one to trace it for a distance of more than two 
miles. The Tussey anticline bifurcates in the vicinity of Rush, and 
the Murley Branch fold is no doubt one expression of the beginning 
of bifurcation. 

On the county road leading west-northwest from Rush, various out- 
crops indicate a much disturbed condition of the strata. At least 
four anticlinal flexures cross the road within a mile of Rush. The 
positions of the axes of these folds cannot be actually seen, but their 
presence is sufficiently indicated by various exposures along the road. 
The dip at Rush near the iron bridge over ^Nfurley Branch is 55° 
to 75° E. 

In the double southern extensions of the Tussey anticline but few 
measurements of the attitude of the strata can be obtained. The 
Warrior Mountain branch can be easily traced to within a mile of the 
Potomac. Along the eastern side on the county road running near 
the Oriskany-Romney contact the dip varied but slightly, 27° E. 
being the greatest dip observed and 17° E. the lowest. The dip 
along the western side is much the same. 

In the vicinity of Twiggtown the western projection of the Tussey 


Mountain anticline in turn becomes bifurcated, the western projection 
of this bifurcation forming the Collier Mountain anticline with east 
and west dips of about 40°. 


The Martin Moimtain anticline occupies the position of that moun- 
tain and has been formed by a bifurcation of the larger anticline 
south of Rush Ridge. The dip varies from 35° to 60°, the two limbs 
having approximately the same inclination. Near the Potomac the 
dip is less, scarcely reaching 25° on either side. 


This syncline, which is formed by the gradually separating branches 
of the Tussey Mountain anticline, occupies the triangular Romney 
area west of the southern end of Warrior Mountain and includes 
within it a considerable portion of the valley of Big Spring Run. 
The rocks are almost wholly concealed, but along the Potomac river 
the observations indicate that the strata are considerably, although not 
deeply, plicated. 


This is a narrow syncline lying between Martin Mountain and 
Collier Mountain, and extends from the Potomac river northward 
to within about two miles of Twiggtown. It occupies the position 
of the long narrow Romney area in which Martin Spring Branch 
lies, and is in general appearance much like the Collier Run syncline 
which lies to the west of Collier Mountain. The dip on either side 
varies between 20° and 45°. 


Collier Run syncline stretches across the county in a general north- 
east-southwest direction. In its southern and middle portions it is 
flanked by Collier Mountain and Nicholas Mountain and is marked 
by a long narrow strip of Romney shales within which Collier Run 
lies. Near the headwaters of Collier Run, Nicholas Mountain and 
Martin Mountain gradually coalesce and become one synclinal ridge, 


Xieholas Mountain losing its identity and its name. Martin Moun- 
tain, still capped by Oriskany rocks, continues northward beyond 
the state line. 

Along Collier Run the dip of the syncline on either side is steep 
and seldom less than 30° near the llomney-Oriskany contact. It is 
generally more than 40°. More varying measurements, as might be 
expected, were obtained in the Romney exposures, but since the 
measurements usually express only unimportant local conditions they 
need not be given here. On the Potomac at the Romney-Oriskany 
contact on the east side of the syncline the dip is 39° W. At the 
corresponding point on the western side it is only 20° E., but in- 
creases farther Avest. The synclinal nature of Martin Mountain, 
where crossed by the National Road, is well indicated by the many 
measurements obtained, the dip on the east side being from 60° W. to 
80° W., while on the western side the dip is much less, it being not 
more than 35° E. 


This anticline enters the county from Pennsylvania and is dis- 
tinctly marked for a short distance by Evitts Mountain. On the 
National Road, and for three or four miles further south, it is not 
well marked topographically, but south of the Williams Road the axis 
of the anticline gradually takes the position occupied by Nicholas 

Near the southern end of Evitts Mountain a branch of Evitts 
Creek has cut deeply across the Tuscarora quartzite and has disclosed 
to good advantage both limbs of the anticline. On the west side of 
the Tuscarora-Clinton contact the dip is 54° W. On the eastern side 
at the corresponding point it is 18° E. On the county road running 
aroimd the southern end of the mountain a measurement of 50° W. 
was obtained on the west side and 22° E. on the east side. On the 
National Road the position of the axis seems to be just east of where 
the Johnson Road enters the National Road from the south. Ininu*- 
diately at this ])oint of union the dip is 30° W. Or.e hundred yards 
further west in the outcrop of red sandstone near the bottom of th(^ 


Salina the dip is 67° W. Continuing westward the dip in the Hel- 
derberg limestone undulates through 54'' W., 70° E., and 72° W. 
Fifty yards east of the Johnson-National road fork the dip is 21° E. 
Nearly one-half mile further east the Hinckle Road enters the Na- 
tional Eoad from the south, at which point the dip is 32° E. One- 
half mile east of this where a county road from the north enters the 
National Road the dip is 17° E. Still further east, in the lower part 
of the Salina, the dip is 25° E., but increases shortly to 35° E,, then 
rapidly to 78° E., then decreases to 30° E. near the middle of the 
Helderberg. East of this the dip gradually increases until near the 
position of the Collier Run syncline. On the Hinckle Road near 
the bottom of the Salina the dip is 18 E., gradually increasing south- 
eastward to 36° near the Romney-Oriskany contact. Three-fourths 
of a mile south of the National Road on the Johnson Road the dip is 
42° E., while further south, near the fork in the road, it is 34° E. 
East of this for half a mile the prevailing dip is less than 15°. On 
the Williams Road the anticlinal axis appears to be almost in the 
bottom of the valley on the western side of Nicholas Mountain. Here 
a small sharp anticline is exposed. East of this anticline, as far as 
Collier Run, all of the outcrops show an easterly dip of the strata, 
the dip varying^ from 7° to 34°. West of the anticline, as far as 
Evitts Creek, all of the outcrops show a westerly dip of the strata, 
the dip varying from 50° to 72°. Along the Potomac river the dip 
on the eastern side of the axis varies from 20° E. to 42° E., while on 
the western side the range of dip is from 15° W. to 54° W. 


The Evitts Creek valley, together with the low-lying West Virginia 
and Maryland areas to the south, practically includes all of the Evitts 
Creek syncline. It is bounded on the east by a row of Oriskany 
hills which extend from the state line southward to near the Potomac 
river, where the hills become gradually absorbed by Nicholas Moun- 
tain. Shriver Ridge, in Maryland, and Knobly Mountain, in West 
Virginia, both protected by Oriskany sandstone, lie along the western 


In that part of the syncHne which lies north of the Potomac river 
outcrops are frequent. Along the National Road, and along the 
Baltimore and Ohio Railroad, this is particularly true. In addition 
to these a county road about one mile south of the National Road 
discloses the attitude of the strata in many places, and on the eastern 
side of the syncline along the AVilliams Road a good series of ex- 
posures is also shown. In addition to these, many other more scat- 
tering and less easily located exposures were found. With but rare 
exception these exposures all show that the axis of the syncline is 
thrown far toward the eastern part of the valley, as is also Evitts 
Creek in much of its course. North of the National Road and west 
of Evitts Creek the dip is to the east in every place observed and in 
some instances the easterly dip continues a considerable distance east 
of the creek. Along the eastern side of Shriver Ridge the dip is 
30° E. to 35° E., although about one and one-half miles south of the 
state line a measurement of 44° E. was obtained. One mile south 
of the state line on Evitts Creek the strata stand upright, as they were 
observed to do also two miles south of the state line. On the Na- 
tional Road about one-half mile east of the creek the dip is also 90°, 
but this may be a very local feature, since between this point and 
Evitts Creek there are two anticlines. Where Evitts Creek crosses 
the National Road the dip is 27° W. East of Evitts Creek on the 
Williams Road at the Jennings-Romney contact the dip is 70° W. 
Continuing eastward the dip varies through 50°, 65°, 72°, and 69°, 
the last measurement having been obtained near the Romney-Oris- 
kany contact. Going south from Cumberland, then east along the 
Baltimore and Ohio Railroad, the dip, with insignificant exceptions, 
remains from 15° E. to 20° E. until within about one-fourth of a 
mile of the mouth of Evitts Creek, where a small amoimt of folding 
is observed. Just west of the creek the dip is 16° E., but the only 
observations in this locality east of the creek show a considerable 
dip to the west. In view of these facts it seems quite evident that the 
main axis of the syncline crosses the Potomac river at or near the 
point where Evitts Creek enters it. 

In that part of the syncline whir»h is occupied by the large west- 


wardly projecting area west of the southern end of Nicholas Mountain 
no good outcrops were seen, the surface there being almost wholly 
covered by river-washed materials. 


This anticline, like the Evitts Mountain and Tussey Mountain 
anticlines, is distinctly marked by a ridge of Tuscarora quartzite. It 
enters Allegany county from the north and continues in an approxi- 
mate S. 30° W. direction as a prominent topographic feature for a 
distance of more than ten miles. The eastern limb of the anticline 
has a moderate dip. The west limb dips steeply. Near the Tus- 
carora-Clinton contact line along the east side the prevailing dip is 
less than 30° and shows but very little variation, while along the 
corresponding contact line on the west the dip approaches and some- 
times exceeds 70°. 

The structure of the moimtain is most admirably shown in the 
Wills Creek gorge known as " The Narrows," where, acting like a 
veritable saw and keeping pace with the gradually rising strata, the 
creek has cut for itself a narrow passage across the mountain and has 
thus disclosed on either side a rocky arch of magnificent proportions. 
Here immense talus slopes extending upward more than five hundred 
feet, are overhung by high precipitous walls of massive white 
quartzite. Toward the east end of the gorge, where the talus is less 
prominent, the strata may be seen to descend slowly, the dip increas- 
ing to 24° E. at the Tuscarora-Clinton contact. At the western end 
of the gorge the dip is precipitous, the well-exposed Tuscarora strata 
there plunging beneath the surface with a dip of 72° W. 

South of the National Road, Wills Mountain becomes gradually 
deflected from its general course of S. 30° W., and for some distance 
before reaching Cresap runs nearly due south. At Cresap the Tus- 
carora passes beneath the surface, and with its disappearance the 
mountain becomes obliterated. 

As a result of the eastward deflection of the southern end of Wills 
Mountain, some minor folding has been brought about along the Po- 
tomac river southeast of Cresap, where the upper beds of the Tns- 




carora are raised to the surface in two sharp anticlines. One of these 
anticlines has exposed almost one hundred feet of the Tiiscarora and 
can be traced for nearly five hundred yards in a general south-south- 
west direction. The smaller anticline which lies a short distance 
southeast of this is not sufficientlv individualized to be distinctly 
traced lonp:itudinally and is scarcely more than sufficiently prominent 
to bring the Tuscarora to the surface. 

In the northern part of the county east of the Tuscarora-Clinton 
contact line east of Wills Mountain the dip increases slightly but 
rarely roaches more than 40° E. AVest of the axis the dip in the 
Clinton wherever exposed is great. Further west in the ITelderberg 
and Oriskany formations several excellent exposures give a prevail- 
ing dip of 90°. This is admirably shown at the " Devil's Backbone " 
near CVrrigaiiville, as well as at either end of the low enlongated 
hill lying just west of the " Narrows." 

Near the state line, a short distance west of the long narrow Oris- 
kany area there is a slight fold which in some low places brings the 
Oriskany to the surface again. Immediately west of this the dip 
is steep, but continuing westward it gradually grows more nearly hori- 

South of Braddock Run the high pitch of the strata is fully as 
prominent as further north and the excellent exposure at Potomac 
Station shows the strata in much the same attitude as at the "Devil's 


By the Rawlings syncline is designated that small, poorly defined 
stnictural region which lies to the north and east of Kawlings and 
which is marked by a southward projection of the Romney forma- 
tion across the Potomac river into West Virginia. The upright 
strata of the Oriskany and the ITelderberg may be considered as occu- 
pying the eastern side, while on the w^est the limits are poorly de- 
fined except near Rawlings, w^here the father steeply dipping Oris- 
kany strata are wtII shown. Good exposures are almost wholly lack- 
ing, but a study of the areal geology in connection with the topogra- 


phy leads at once to correct conclusions as to the general synclinal 
nature of the fold. 


The high isolated Oriskany-Helderberg hill extending southward 
from Rawlings for a distance of more than four miles ia a rapidly dis- 
appearing remnant of the Fort Hill anticline which extends from 
Rawlings to Keyser, West Virginia. The anticline has been much 
obscured by the corrosive action of the Potomac river and much of it 
now lies on the West Virginia side. Along the western side the 
prevailing dip of the Oriskany strata is from 70° W. to 90° W., 
although south of Monster Kock, in an exposure near the West Vir- 
ginia Central Railroad bridge, an overturned dip of 65° E. may be 
clearly seen. Near Rawlings, where the Oriskany passes beneath 
the surface, the west limb dips 28° W., while a little further south 
the east limb dips 42° E. At Monster Rock the anticline is quite 
narrow and near Rawlings it comes to a point. Midway between the 
two the width is considerably more than a mile. 

In the projecting area occupied by Monster Rock the east limb of 
the anticline is seen to dip gently to the east for a short distance, but 
before passing beyond the river the strata rise again with a dip to the 
west. The little syncline thus produced is worthy of notice, as it is 
apparently the prolongation of the Rawlings syncline which, passing 
along down the western side of Knobly Mountain in West Virginia, 
re-enters Allegany county near ^lonstor Rock as indicated. 


The Frostburg syncline is defined on the east by the Wills Moun- 
tain and Foot Hill anticlines already described. The western limit 
is west of Savage Mountain beyond the borders of Allegany county, 
hence need not receive further mention here. The full width of this 
syncline, of which only the eastern and central portions lie in Alle- 
gany county, remains approximately ten miles throughout its entire 
course across the state. This measurement, however, is not to be 
confused with the width of the high valley lying between Savage 


Mountain and Dans-Little Allegheny Mountain which occupies 
scarcely more than one-half of the synclinal fold. The axis of the 
syncline has been designated with considerable detail by means of 
the various mining operations in the coal basin. Its general direction 
is N. 28° to 30° E. passing through Franklin, Barton, Moscow and 
Lonaconing. It lies a little to the west of Westemport and passes 
through the immediate vicinity of Mount Savage. 

Steeply-dipping Silurian and Devonian strata occupy the eastern 
border of the syncline, but gradually growing less steep westward 
from Wills Mountain they disappear one by one beneath the high- 
lying Carboniferous strata of the coal basin. 

In the gap tfirough which Jennings Run flows, where many of the 
strata, particularly those of the Hampshire formation, have an excel- 
lent exposure, the gradually decreasing inclination of the beds may 
be clearly seen. Numerous good exposures further south along 
Braddock Run and still further south in the Potomac gorge also aid 
materially in arriving at correct conclusions concerning the structure 
of this part of the county. 

At the Jennings-Hampshire contact in the Jennings Run gap the 
dip is 68° W. At the Hampshire-Pocono contact the dip has gradu- 
ally decreased to 28° W. At the Pocono-Greenbrier contact it is 
17° W., while at the Mauch Chunk-Potts ville contact the dip is only 
13° W. Further west the dip continues to gradually grow less. 

In the Potomac gorge and along Braddock Run the favorable places 
for observation cannot be concisely described but the measurements 
obtained correspond closely to those made along Jennings Run. 

These measurements were all obtained near the level of the streams 
mentioned, hence following the various formations upward to the posi- 
tions which they occupy in the higher parts of the Alleghany Front 
the dip is foimd to increase slightly. Opportunities are not good for 
learning definitely how much this increase is, but it is kno\vn that 
the Pottsville dips from 10° W. to 22° W. where best exposed along 
the high crest of Dans-Little Allegheny Mountain. 

Outcrops of strata in Allegany county suitable for accurate meas- 
urement of the dip are rare west of the synclinal axis. Southward 


from the state line the Allegany-Garrett line gradually approaches 
the position of the synclinal axis, hence the western limb of the syn- 
cline is but poorly represented in Allegany county. It seems, how- 
ever, that the steepness increases somewhat less rapidly west of the 
axis and the prevailing dip of the Pottsville in the northwest comer 
of the county is thought to be not greater than 12° E. to 15° E. 


Certain facts of prime importance in the study of Appalachian 
structure which have abundant illustration in Allegany county and 
which have been brought out to some extent in the description of the 
individual folds demand particular mention. These relate to dip, 
strike, and pitch. It was observed that the three principal anticlines 
in the county, viz., the Tussey ^fountain anticline, the Evitts Moun- 
tain anticline and the Wills ^fountain anticline all have moderate 
easterly dips. The same is not true, however, of their westerly dips. 
The west limb of the Tussey Mountain anticline, so far as is shown 
in Allegany county, happens to have apparently about the same dip 
as the east limb, but the west limb of the Evitts Mountain anticline 
has a dip more than twice as great as the east limb, while the dip of 
the west limb of the Wills Mountain anticline is almost three times 
as great as the dip of the east limb. A similar condition is observed 
to prevail in connection with many of the less important folds, hence 
we may say that the Allegany county anticlines tend to develop limbs 
sloping gently to the cast and i?teeply to the west. Expressed in terms 
of synclines, we may say that the synclines tend to develop steeply- 
sloping limbs on the east side of their axes and gently-sloping limbs 
on the west side. Those facts are in accord with observations made 
throughout almost the entire Appalachian region, and it is upon these 
facts that many able geologists have based the theory that the de- 
forming force which produced these folds came from the southeast. 
These facts alone seem inadequate to prove the truth of the theory, 
but that the initial force did really originate in that direction has 
been pretty generally accepted by geologists. 

The strike of the beds, as in most other parts of the Appalachian 


region, varies within rather narrow limits. The Tnssey ^fountain 
anticline and the Evitts Mountain anticline extend approximately N. 
27° E., while the Town Hill syncline, the Collier Eun syncline, the 
Wills Mountain anticline, and the Georges Creek syncline all have 
a direction approximately N. 30° E. Observations in many other 
places show that in no case worthy of special note do the beds lie at 
great variance to the general direction given. 

Xearly all of the folds show more or less axial pitch and this pitch 
is downward to the south almost without exception. The exact na- 
ture of this pitch along many of the folds cannot be easily computed, 
but from field observations on the major anticlines it seems that even 
in extreme cases the pitch scarcely reaches five degrees. It is to this 
pitching of the folds that much of the characteristic structure of the 
Appalachian Region is due. The effect of the pitch on the areal 
distribution of the formations is best illustrated in Allegany county 
by the Evitts Mountain anticline. At the state line on the north the 
axis of this anticline is indicated by the tongue-shaped area of Tus- 
carora quartzite. Southward the Tuscarora narrows and disappears 
beneath the later Clinton formation. The Clinton continuing south- 
ward upon the axis also narrows and disappears l)eneath the succeed- 
ing Xiagara formation. This in like manner is followed in regular 
order by the Salina, the ITelderberg and the Oriskany. The pitch in 
the southern part of the county is slight, as is evidenced by the emer- 
gence of the Helderberg again where the Potomac has cut across 
Nicholas Mountain. Similar areal distribution of formations brought 
about by pitching of the folds may be observed in almost every fold 
west of Town ITill. In much of the Georges Creek syncline this is 
not quite so apparent, but in the northern part of the county the up- 
ward pitch to the north becomes perceptible, and as a result the coal 
measures all come to the surface within some fifteen miles north of 
the state line. 


Faulting is rare and the amount of vertical movement is never great. 
Only the more thinly beddinl strata present instances of faulting 


worthy of note, and none of the observed faults have more than a 
local extent. 

In the Jennings formation along the Williams Road on the hillside 
near the eastern edge of Cumberland there is a fault whose throw 
seems to be considerable, but no definite idea as to the exact amount 
of displacement could be gained. 

On the Baltimore and Ohio Railroad west of Cedar Cliff, about 
three miles south of Cumberland, a small, clearly faulted anticline 
is seen in the red shaly sandstone bands near the bottom of the Salina 
formation. The throw here is only a few feet. 

Other faults occur, but so far as observed they are of no special 
moment except in the general relation which they bear to the more 
important structural features of the region. 


On the structure-section sheet (Plate XVT) twelve structure sec- 
tions are given. They represent the strata as they would appear 
along the sides of trenches cut across the county on the section lines 
and extending downward to the position of sea-level. All of the sec- 
tions extend in the direction X. 60° W., S. 60° E. which is approxi- 
mately perpendicular to the prevailing strike. The relative posi- 
tions of the various section lines have been chosen with especial ref- 
erence to lines along which most favorable conditions for field obser- 
vations were found, combined wherever possible without sacrificing 
accuracy with such positions as best reveal the various structural 
changes. For this reason the distances between the section lines vary. 
Those crossing the eastern and central portions of the county are ap- 
proximately two miles apart, while the distances between those lying 
wholly within the western part of the county average about four 

On the structure-section sheet the straight line at the upper edge 
of each blank space represents the section-line along or near which 
the field observations were made; the straight line on which the sec- 
tion rests indicates the position of sea-level; while the undulating line 
at the top represents the surface configuration along the section-line. 

maryland geological survey 155 

Interpretation of the Sedimentary Record. 

general character and variation of sediments. 

The three chief topographic phases of sedimentation indicated by 
sandstones, shales and limestones are well represented in Allegany 
county. Keviewing briefly that which has been given in detail in 
earlier pages, we find that four formations, the Tuscarora, the Oria- 
kany, the Pocono and the Pottsville, are entirely or largely composed 
of heavy sandstones; that nearly the whole of the Ilelderberg and 
the Xiagara, as well as much of the Salina and the Greenbrier are 
made up of limestones; and that all of the other Paleozoic forma- 
tions consist more or less completely of soft shales and thin-bedded 
limestones and sandstones. 

Marked changes in the character of the formations as they extend 
across the county are observed in only a few instances. The Oris- 
kany and the Jennings thicken considerably toward the west, the 
Greenbrier thickens to the south and the Pocono apparently thickens 
to the north. Lithologically the Pocono on Town Hill differs ma- 
terially from the Pocono in the western part of the county. In the 
east it is very massive and coarsely conglomeritic wherever observed, 
while in the western portion it is much less massive and is free from 
heavy conglomerate. The other formations do not change except in 
minor particulars, and as these changes have been mentioned else- 
where they need not be repeated here. 


In early Cambrian time a long strait extending from the region of 
the Gulf of St. Lawrence southward to Alabama occupied approxi- 
mately the position now occupied by the greater Appalachian valley. 
It separated a mountainous Archean continent known as Appalachia 
from a comparatively low-lying land area covering the Central States 
region. During Cambrian time erosion greatly reduced the height 

' For the discussion of this period as well as for much that follows the author has 
drawn liberally £r«»m the writinirs of others, especially of the members of the Appa- 
lachian division of the United States (ieoloirical Survey and of the State Geological 
Survevs of Pennsvlvania and New York. 


of the Archean continent and the detritus thus obtained was de- 
posited to the westward while the sea gradually transgressed eastward. 
Xear the close of the Cambrian period the western land area began to 
sink and the strait gradually widening westward to Wisconsin and 
beyond the ilississippi formed a great mediterranean sea. Conditions 
were then poorly suited for the transfer of land-derived sediments, and 
a long period of limestone deposition set in. In course of time a dis- 
turbance of conditions took place and the limestone deposition gave 
way to a widespread distribution of shale. The deposition of this 
shale, besides indicating an uplift of the eastern land from which the 
sediments were derived, marks also a recession of the shore line and 
a probable shallowing of the sea. This shale, known in Maryland as 
the Martinsburg formation, was followed by a series of reddish shales 
and sandstones — the Jimiata formation in Maryland — the upper part 
of which is exposed in Allegany county. With the history of this 
formation the immediate geological history of Allegany county be- 
gins. As shown on a previous page, the sandstones of the Juniata 
multiply and thicken toward the top and thus indicate a steady ap- 
proach to conditions of shallow water deposition. 


With the advent of the Tuscarora period a decided change in the 
factors of decomposition w^as introduced. The lithologic characters 
of this formation, which have been described on a previous page, 
indicate that the sediments were laid down in shallow water. How- 
ever, to say that the Tuscarora formation is a product of shallow w^ater 
deposition is only a meagre introduction to the explanation of the 
conditions involved. Dr. A. C. Spencer, in his paper on *^ The 
Geology of Massanutten Mountain in Virginia," has given a clear 
summary of the probable factors which operate to bring about such 
concentration and deposition of materials, and has discussed these 
factors in the light of sediments in the Massanutten area similar to the 
Tuscarora of Marvland. lie savs " The concentration of the more 
resistant products of rock-decay for the formation of extensive sand- 
stones is a process of great complexity. During the early part of a 


topographic cycle when denudation exceeds decomposition, the numer- 
ous rapid streams deliver to the sea large quantities of coarse materials 
of mixed composition which may be partially sorted by the waves 
and somewhat widely distributed by marine currents; but as drainage 
becomes more mature there \vill be a tendency for stream-derived 
detritus to accumulate at the mouths of large rivers, often without 
much wave-washing. In either case the deposits will be more or less 
heterogeneous, and the same will be true of the deposits derived by a 
transgressing sea from a land surface covered by a deep residual 
mantle. Such coarse-grained heterogeneous deposits would be con- 
fined to a rather narrow littoral zone, but brought a second time 
under the action of the weaves by a slight elevation of the land, they 
would be re-soi*tod, the less resistant components would be largely 
ground up and removed as fine silt and the zone of coai"sc sediments 
would be moved seaward. At the same time the rivers might be 
bringing fresh material, but wath continued slow, or int(M*mittent rise 
of the land accompanied by marine planation, these and the older 
surviving materials becoming mingled, the final result would be a 
mass of sand and pebbles composed almost entirely of quartz." * 

The uniform nature of the quartzite indicates a time of comparative 
quiescence and but one source of material. The period was perhaps 
initiated by a gradual but rapid uplift of the land accompanied by a 
shallowing of the sea which prevailed until the close of the period. 
As to the position of the shore-line at this time with reference to 
Allegany county but little is known except that it was in all proba- 
bility a considerable distance east of the county. Southward in West 
Virginia and northward in Pennsylvania the formation is consid- 
erably thicker and in each of these areas the deposits are inclined to 
be coarser than in Alh^gany county, this being particularly true in 
Pennsvlvania. Whether the less(»r thickness of the fonnation in AUe- 
gany county is due to local or remote causes is not known. A shal- 
lowing of the sea may have deflected the currents or a deepening of 
the sea may have lessened their power, in either of which cases much 
of the sediment would have been deposited elsewhere. 

• Spencer, A. C. The Geoloicy of Maesanutten Mountain in Virginia. Wasbinj;- 
ton, 1897. 



With the advent of the Clinton, conditions very similar to those 
immediately preceding the Tnscarora seem for a time to have pre- 
vailed. The red shales, with alternating sandstones, were again 
introduced, but they are more thinly bedded than those of the Juniata. 
That the Tnscarora represents only temporary invasion of pure 
quartzose materials which intemipted the deposition of red clays and 
sands may be possible. The topographic cycle may have advanced 
sufficiently slowly to allow the waves of marine planation to cut their 
way across the old littoral deposit and to reach again the region of 
uncovered crystalline rocks. If detritus was obtained in this way 
the waves would perhaps be unable to properly sort it but might be 
able to deliver the lighter materials to strong currents and thereby 
bring about the distribution as w^e find it. Whatever may have been 
the conditions it seems evident that the subsidence soon became suf- 
ficiently great to bring about decidedly new conditions. With the 
deposition of the upper part of the Clinton formation, limestone and 
iron ore were both introduced, the iron being of comparatively little 
imj)ortance in the Juniata except as a coloring matter, while the lime- 
stone is wholly absent. 

Concerning the >^'iagara period. Professor James Hall says that the 
condition of the ocean seems to have been favorable to the production 
of corals and crinoids and to the deposition of calcareous beds of 
magnesian character, the sea being comparatively shallow.' In Alle- 
gany county the calcareous beds have been in part replaced by argil- 
laceous sediments apparently indicating occasional changes in marine 
currents at this time. The corals and crinoids were acted upon with 
considerable energv' by the weaves, as is indicated by the immense 
quantity of broken and worn fragments thrown heterogeneously 
together and cemented by the calcareous mud produced by a more 
complete trituration of some of the materials. 

These finely comminuted deposits, profusely filled with fragments 
of organic remains uniformly deposited over wide areas, sliow an un- 

' Twenty-eiirhth Annual Report of the New York State Museum of Natural History. 
The Fauna of the Niairara (iroup. Albany, 187i>, p. 101. 


disturbed transition upward, and tlie abundance of carbonate of 
lime coming into the sea and entering into the secretions of the various 
marine organisms indicates the presence of much calcareous material 
easy of access. The Silurian limestone was evidently the source of 
this material, as it had no doubt been raised above the level of the sea 
in various places and thus brought under the influence of aerial 

The lower portions of the Salina add further proof of the shallow 
water conditions. The red sandstone of that formation, with its salt, 
gypsum and fish remains, as found further north, was certainly laid 
down in reasonably shallow^ w^ater and in all probability in more or 
less land-locked bays. At any rate, although no \erj great struc- 
tural disturbance appears to have taken place at this time, the condi- 
tions affecting marine life appear to have been very greatly changed. 
In Allegany county no fossils have been found in the red sandstone 
and the presence of salt and gypsum has not been proven, but the 
conditions of deposition are believed to have been much the same as 
fui-ther north. Whatever mav have been the condition, it is evident 
that when the Helderberg period was initiated the organic life which 
came with it was very unlike that w^hich prevailed during the time 
immediately preceding the shaly sandstone deposition.' 


From the general character of the Helderberg fossils it would 
seem that the depth of the water at this time w^as perhaps not far 
different from that of much of the later Silurian period, but one thing 
of especial note is the almost entire absence in the Helderberg of 
niochanical detritus, such as sand and clay. Apparently the surface 
configuration of the land was very subdued. Possibly conditions of 
base-level erosion now prevailed such as had existed during Lower 
Silurian time. If such were the case the streams, being weak, would 
be unable to transport the heavier detritus in suspension, but might 
continue to carry much calcareous matter in solution. The adjacent 

' Clarke, J. M. The Ilercynian Question. Forty-second Annual Report of the 
Trustees of the State Museum of Natural History. Albany, 1«S1), p. 436. 

• • • . • ' 


seas then being free from muddy sediments but highly charged with 
carbonate of lime would be in favorable condition for the growth of 
animal organisms such as the Helderberg contains, and extensive 
limestone beds would be formed from the detritus produced by them. 


With the advent of the Oriskany a great change in the character 
of the sediments again took place. As has been stated elsewhere, the 
formation is made up of highly fossiliferous sandstones and conglom- 
erates separated from the Helderberg proper by a transition zone 
of interbedded limestone. We have already seen how the coarse 
quartzitic detritus which contributed the sands of the Tuscarora may 
have been gradually stored up on a pre-Tuscaroran Coastal Plain. 
The events in the concentration of materials to supply the sands and 
pebbles of the Oriskany were perhaps much the same. As in the case 
of the Tuscarora, an upward earth-movement evidently initiated the 
principal factors of final distribution. Simultaneous with this the 
shallowness of the sea became sufficientlv accentuated to admit of the 
currents acting with much energy, thereby enabling them to transport 
hcavv materials for considerable distances. 

The supply of carbonate of lime continued throughout the period in 
sufficient abundance to admit of prolific marine life. In many places 
the formation is a mass of shells and casts and the abundant cementing 
material is often so prominently calcareous that a perfectly fresh 
specimen has much the appearance of a tnic limestone. 


The Romney, Jennings and Hampshire formations are largely 
composed of fine sediments, and may here be treated together. Ac- 
cording to Mr. Willis, the lowlands of the early Devonian were gen- 
eral from Xew York to Georgia, continuing low in tlie southern 
Appalachian area throughout the Devonian, but northward becoming 
considerably elevated, produced mountains probably several thousand 
feet high, the degradation of which supplied the later Devonian 
sediments.' Near the close of the Oriskany period the area covered 

•Piedmont Folio, U. S. Geol. Survey, 1896. 




by Allegany county seems to have been elevated and possibly to a 
sufficient extent to allow of some erosion, although this is not proven. 
However, in Virginia and Pennsylvania, local non-conformities exist 
between the Oriskany and the Romney, and it seems probable that the 
changes in Allegany county were in harmony with the movements 
which brought about the non-conformities to the north and south. 
The lower shales, resting with sharp contrast upon the Oriskany, are 
extremely fine and highly carboniferous. Various hypotheses have 
been given to explain the manner of deposition of these fine sedi- 
ments. It would seem that a gentle subsidence after emergence 
might so affect the currents that, sweeping swiftly over the arenaceous 
beds they might thoroughly wash away any superficial coating which 
may have previously collected there. The land surface was no doubt 
low, and thus for a long time not in a condition to supply coarse 
detritus. H. D. Rogers, in his admirable paper on the origin of the 
Appalachian strata, long ago suggested that these black sediments 
possibly accumulated in a very widely spread sea marsh or marine 
savannah, the carboniferous part of the shales being the result of plant 

The argillaceous portions evidently came from a low-lying land 
surface. During the removal of the heterogeneous Coastal Plain 
detritus which furnished the materials for much of the Oriskany 
formation, the land surface farther inland was low and imaffected by 
rapid streams and gradually became covered with a coating of chemi- 
cally disintegrated materials awaiting future transportation. Dis- 
turbances which we know occurred near the close of the Oriskany 
period may have easily brought about conditions favorable for the 
slow removal of this residual mantle. 

A general but perhaps slight depression allowed the deposition of 
the limestone near the bottom of the Romney, following which 
shallow water conditions with only minor interruptions continued 
until after the beginning of the Carboniferous time. 

»Koi,'er8, 11. D. The Geolo^ry of Pennsylvania, vol. ii, p. 791. Philadelphia, 1858. 



In Allegany county there is little apparent difference between the 
highest Devonian and the lowest Carboniferous sediments except in 
color and coarseness. In each case the sediments are almost wholly 
of quartzose materials and indicate shallow water and mountainous 
land conditions. Cross-bedding, ripple-marks and thin coal seams all 
attest a preparatory step toward the marshy condition of the Coal 

The limestones and shales following the Pocono formation indicate 
a degradation of the Devonian mountains and an almost unvarying 
relation of land and sea. That the land appeared above the surface, 
however, in places not far from the Allegany county area seems 
proven by ^ the bands of- limestone-shale breccia at the Greenbrier- 
Mauch Chunk and the ^fauch Chunk-Pottsville contacts. 


Following the limestones and shales of the lower Carboniferous 
period massive conglomerates, sandstones, shales, limestones, coals, 
fire-clays, etc., were laid down in rapid but irregular succession. The 
features of this deposition being much the same throughout a large 
part of the Appalachian region, a detailed discussion of the period 
need not be entered upon here. The general conditions which pre- 
vailed may be stated in the following words: " During middle and 
later Carboniferous time there ensued that general vertical movement 
of the eastern land area and the region of the interior sea which 
resulted in the withdrawal of the sea to the Mississippi embayment. 
The movement was not simple; it was composed of many episodes of 
uplift and subsidence, among which uplift preponderated. In the 
repeated oscillations of level the sea swept backward and forth over 
wide areas. It received from the Coastal Plain the coarse quartz 
detritus which had accumulated during previous ages, and the waves 
and currents of the shallow sea spread the concentrated sandstones 
and pebbles in beds which alternated with materials of less ancient 
derivation. The Carboniferous strata include shale and sandy shale, 
derived more or less directly from lands of moderate elevation, and 


also the coal beds, each of which marks the prolonged existence of a 
marsh in which the peat-making plants grew. When the mnrsh sank 
beneath the sea the peat beds were buried beneath sands and shales,, 
and the peat, by a process of distillation, became coal." ' 


In the review of the sedimentarv record we have seen how eleva- 
tion and subsidence followed each other with varying rapidity while 
the large volume of Paleozoic sediments was being deposited. It 
seems probable that during this time some lateral pressure was also 
exerted upon these sediments, producing incipient anticlines and 
synclines. It was not, however, until near the close of Paleozoic 
time that structural changes of exceptional magnitude were mani- 
fested throughout the entire Appalachian province. The strata 
which had been deposited upon each other in an approximately hori- 
zontal position were then squeezed and folded to an enormous degree, 
the forces being applied laterally in a direction perpendicular to the 
course of the present mountain ranges. How long this compression 
continued is not known. Suffice it to say that the earliest Mesozoic 
records show a new axis of drainage and that most of the rivers, in- 
stead of flowing to the west as the Paleozoic rivers had done, were 
then flowing to the east. 

That there has been vertical upward movement of importance since 
the close of Paleozoic time is evidenced by the development of well- 
marked physiographic features, such as the Cretaceous and Tertiary 
peneplains and the various river terraces found along the streams of 
the county. 

« Piedmont Folio, V. S. Geol. Survey, ISHC.