MEMOIRS OF THE GEOLOGICAL, SURVEY OF INDIA. MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA VOLUME XLII Published by order of the Government of India. CALCUTTA : SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY OF INDIA, 27, CHOWRINGHEE ROAD. LONDON: MESSRS. KEGAN PAUL, TRENCH, TRUBNER & CO. 1917 CONTENTS. PART I. The Burma Earthquakes of May 1912. By J. Coggin Brown, M.Sc., F.G.S., Assistant Superintendent, Geological Survey of India. InrRODUCTION SUMMARY OF THE Seodcs ; GENERAL ACCOUNTS OF THE EARTHQUAKES SECTION I. RECORDS OF OBSERVATIONS. CHAPTER I.—EPICENTRAL AND SEVERELY SHAKEN AREAS Mandalay and District Maymyo : Northern Shan State : Southern Shan States and Kuvantl Ruby Mines District Kyaukse District Myingyan District Meiktila District Yamethin District CxHaApTerR IT.—OTuHER AREAS IN BURMA Bhamo District . Myitkyina District Katha District Shwebo District . Upper Chindwin District Lower Chindwin District Sagaing District Minbu District Magwe District . Pakokku District Toungoo District Thayetmyo District Northern Arakan District PaGeE. 1 5 7 io) | or oo or Oo ovonstnn il CONTENTS. Pack Akyab District . ‘ . . : - . 68 Kyaukpyu District. ‘ , ; , ; 69 Sandoway District . > é ; ; 7 69 Prome District . ‘ ‘ : ; r : 70 Tharrawaddy District : . . . : 70 Henzada District ; ‘ 5 : . é 71 Pegu District . ‘ ‘ : ‘ ° 71 Hanthawaddy Diswiot: \ : . ‘ . 71 Maubin District . : : , ; . 73 Bassein District . : : m 4 . 73 Myaungmya District . , ; : ‘ a 73 Pyapon District . ‘ ‘ Z ‘ , ; 74 Amherst District a ; ; ; ; p 74 Mergui District . . , ‘ ‘ ‘ ‘ 74 Chin Hills . ‘ : 4 " i 5 ‘ 74 CHAPTER IIT.—OruHER AREAS OUTSIDE BURMA. ; 3 ~ ; 75 Yunnan. ‘ “ ‘ : ; " : 75 Bengal. . . : . ; ‘ , 75 Siam P : : ' ‘ ‘ ; x 76 SECTION II. THE TIME OF THE EARTHQUAKE AND RATE OF PROPAGATION OF THE SHOCK. CHAPTER LV.—Tive oF EARTHQUAKE. RATE OF PROPAGATION . . 81 Tue Isoseists. Inrensrry AND CHARACTER OF THE SHOCK . ‘ ‘ . : ; . i 87 Depru or Focus E . ; , “ = 102 ELEMENTS OF WAVE Sows . : 4 ; 102 ExtTraA-INDIAN SEISMOGRAPHIC Beccuns ; : x 103 CHAPTER V.—GEOLOGICAL CONDITIONS IN RELATION TO THE EARTH- QUAKE . : ¥ ‘ 3 b é 7 104 CAUSE OF THE Naber: 4 4 n a i 110 EARTHQUAKE SOUNDS . ‘ , e ‘ ¢ lll VISIBLE UNDULATIONS OF THE Ginines ? 2 4 3 114 EFFECT ON SPRINGS AND WATER-SUPPLY 4 > 115 Cuaprer VI,—EAr.ier SHocks or 18rH, 21st AND 22ND May, 1912 ‘ 117 AFTERSHOCKS . : ” . . " 7 ; 124 CuAPTeR VII.—TxHE EARTHQUAKE AND BUILDING CONSTRUCTION . 132 BuRMESE ARCHITECTURE . : : 3 A P 135 INDEX . 3 3 : ‘ . ° 3 i ‘ . 139 CONTENTS. ii PART II. The Structure of the Himalayas, and of the Gangetic Plain, as elucidated by Geodetic observations in India. By R.D. Oldham, F.R.S. PAGE. CHAPTER I.—INTRODUCTORY . { ; ; ; : ‘ 5 1 CHapTer I,—Tur NatuRE AND INTERPRETATION OF THE GEODETIC EVIDENCE Fs ; r é £ j % 10 Cuaprer I1].—Tun IMAGINARY RANGE AND TROUGH . i ‘ ; 36 CHAPTER IV,—THE UNDERGROUND ForM OF THE FLOOR OF THE GANGETIC TROUGH . p ‘j A ‘ 3 , 3 ; 65 CHAPTER V.—THE SUPPORT OF THE HIMALAYAS . : ee : : 99 CHAPTER VI.—SUMMARY AND CONCLUSIONS é ‘ ‘ ‘ . 119 INDEX TO GEODETIC STATIONS . s “ s : 3 143 GENERAL INDEX ; ; . 4 5 3 : ‘ Z 5 149 CALCUTTA SUPERINTENDENT GOVERNMENT PRINTING, INDIA 8, HASTINGS STREET MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA VOLUME XLII, PART 1. ? THE BurMA EARTHQUAKES OF MAy 1912. By J “Coacrn Brown, | <«~} - M.Sc., F.G.8., Assistant Superintendent, Geological Survey of India. 3 \ Published by order of the Government of India CALCUTTA: SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY OF INDIA, 27, CHOWRINGHEE ROAD ' LONDON: MESSRS. KEGAN PAUL, TRENCH, TRUBNER & CO. BERLIN: MESSRS. FRIEDLANDER UND SOHN. 1914. Bice Thiee Rupees ot 4. MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA. Vor. Vou. Vou. Vot. Vou. Vou. Vot. Vot. Vot.. Vo. Von. Vou. ; Vor. Von. _ Vot. Vou. Vor. Vot. Vot. I. II, IIl. XXI. XXII. XXIII. Pt. 1, 1856 (owt of print) : Coal and Iron of Talchir.—Talchir Coal-field.— Gold-yielding deposits of Upper Assam.—Gold from Shué-gween. Pt. 2, 1858 (owt of print) : Geological structure of a portion of Khasi Hills.— Geological structure of Nilgiri Hills (Madras), Pt. 5, 1859 (out of print) : Geological structure and physical features of districts of Ban- kura, Midnapore, and Orissa.—Laterite of Orissa.—Fossil fish-teeth of genus Ceratodus, from Maledi, south of Nagpur. Pt. 1, 1860 (out of print) : Vindhyan rocks, and their associates in Bundel- kand. Pt. 2, 1860 (out of print) : Geological structure of central portion of Nerbudda District.—Tertiary and alluvial deposits of central portion of Nerbudda Valley.—Geological relations and probable age of systems of rocks in Central India and Bengal. 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( “g0ba6 ) sla Bart ee Libary Published by Order of the Government of India CALCUTTA : SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY OF INDIA, 27, CHOWRINGHEE ROAD. LONDON : MESSRS. KEGAN PAUL, TRENCH, TRUBNER & CO. BERLIN ; MESSRS. FRIEDLANDER UND SOHN, 1914 - ie iO a ae ' he ae CONTENTS. INTRODUCTION . 5 : ; : : SUMMARY OF THE SHOCKS = GENERAL ACCOUNTS OF THE EARTHQUAKES . 3 ; PART I. RECORDS OF OBSERVATIONS. CHAPTER ],—EPICENTRAL AND SEVERELY SHAKEN AREAS Mandalay and District Maymyo ° ° . . . Northern Shan States . A Southern Shan States and Karenni Ruby Mines District Kyaukse District ° Myingyan District ; ; . é ‘ Meiktila District . Yamethin District “CHAPTER I[J.—OTHER AREAS IN BURMA Bhamo District . ° ° Myitkyina District Katha District Shwebo District PF Upper Chindwin District Lower Chindwin District Sagaing District . . : , : ° Minbu District ° . : . ; ‘ Magwe District. : ° : ° . Pakokku District . f - > : ° Toungoo District . ‘ : : ; : Thayetmyo District ‘ ‘ : : . Northern Arakan District ° ‘ ; x Akyab District ‘ “ ° . . ; Kyaukpyu District 2 , . . . Sandoway District ° ° ° ° ° Prome District ° ° . ° Tharrawaddy District . . . . ii CONTENTS. Henzada District . . , : ‘ ‘ Pegu District ° ; . ‘ ; ‘ Hanthawaddy District Maubin District . Bassein District . Myaungmya District Pyapon District Amherst District Mergui District Chin Hills. ‘ CHapTerR IIJ.—OTHER AREAS OUTSIDE BURMA Yiinnan 2 . x ; ; . ‘ Bengal : . . Siam . 7 é ; , . ‘ PART II. CHaprer IV.—TIME OF EARTHQUAKE. RATE OF PROPAGATION Tue Isosnists. INTENSITY AND CHARACTER OP THE SHOCK ‘ . c : 4 ; C DeptH oF Focus A A R “ a ELEMENTS OF WaAvrE Morion Extra-INDIAN SEISMOGRAPHIC RECORDS PF P CHAPTER V.—GEOLOGICAL CONDITIONS IN RELATION TO THE EARTH- QUAKE CAUSE OF THE EARTHQUAKE . : . A ? EARTHQUAKE SOUNDS VISIBLE UNDULATIONS OF THE GROUND . EFFECT ON SPRINGS AND WATER-SUPPLY CuapteR VI.—EARLIER SHOCKS oF 18TH, 2Ilst AND 22ND May 1912 x 3 . . > 3 : ‘ AFTERSHOCKS A 4 ‘ ‘ " z Cuapter VII.—TuHe EartHQquaKE AND BuripinGa CONSTRUCTION . BurMeEsSE ARCHITECTURE , " , : InprEx Z Z S ; , ¢ : mi “i ‘ PAGE, on oe QOaaan 81 87 102 102 103 104 110 111 114 115 117 124 132 135 139 be Tan & & LIST OF PLATES. . Village monastery or “ Pongyi-kyaung’’ of the Northern Shan States. Showing how the framework is supported on wooden piles. Typical Shan Pagodas. Method of Pagoda construction. To illustrate the instability of such struc- tures during earthquakes. . Section of a typical brick nogged bungalow. Elevation of a typical brick nogged bungalow. . Sketches showing damage to various buildings in Taunggyi. . Map showing positions of the chief faults in the Northern Shan States. . Map showing the approximate positions of the Isoseists and Axial Epicentre of the Burma earthquake of May 23rd, 1912. . Seismograms of the earthquake of May 23rd, recorded at Simla. Omori Instruments. . Seismograms of the earthquake of May 28rd, 1912, recorded at Colaba ob- servatory, Bombay. Milne and Vertical Movement Instruments. . Seismograms of the earthquake of May 23rd, 1912, recorded at Colombo and Kodaikanal. Milne Instruments. . Seismograms of the earthquake of May 23rd, 1912, recorded at Colaba ob- servatory, Bombay. Omori-Ewing Instrument. > The ta» oo os a on es > she nas aaa POE Se Saha id MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA. THE BURMA EARTHQUAKES OF MAY 1912, BY J. COGGIN BROWN, M.Sc., F.G.S., Assistant Superintendent, Geological Survey of India. INTRODUCTION. In his survey of the geographical distribution of recorded earth- quakes, F. de Montessus de Ballore, referring to Burma and adjoin- ing regions, has remarked,— “* Aussi les tremblements de terre sont- ils fréquents et redoubtables dans tous ces pays. Malheureusement, les informations séismiques sont encore bien insuflisantes dans le détail, et il n’a jamais été fait d’observations systématiques.’’(!) Beyond the dates of a few earthquakes which occurred in Burma during the latter part of the 17th and in the 18th century, and the meagre details of the effects of two or three of them .as collected and recorded by T. Oldham in 1883 (?), practically no accurate information exists about the seismic disturbances which universal traditions of the Burmese people assert to be frequent and severe in many parts of their country. That these traditions are likely to be true is suggested by the intense folding of the mountains of the province, and by a con- sideration of the more recent geologic events to which the area has been subjected. In these accounts of the earthquakes which were felt throughout Burma during the latter part of May 1912, and which were also felt in Siam and in the Yiinnan province + F. de Montessus de Ballore. Les Tremblements de Terre. Geographie Séis- mologique. Paris, 1906, p. 192. * Thomas Oldham. b guessed. ‘Two distinct shocks. No damage was Sadon. caused. Captain Fennel, [.A—Time 9 a.m., guessed. The rock on which Sima-Nmaikrang Road. he was seated rocked from N.W. to 8.E. Katha District. The Sub-divisional Officer—Two distinct shocks were felt about scan 9 a.m. Exact time not noted. Duration not more than 1 minute. Maung Po Tu, Advocate-—Time exactly 9 A.M., according to railway time. Apparent direction S.W.—N.E. No sounds of any kind were noticed before, during or after the earthquake. Katha. Station Master—The station office clock stopped at 8-55 a.m. Nabo. No damage was caused. The Sub-divisional Officer—He was out walking and felt a shock a little after 9 A.M. (uncorrected time), but B k. : i 1 rey sas was informed by the villagers of Legyin that 58 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. an earlier movement took place between 8-30 and 8-45 A.M. Direction of second shock from W.—E. Duration about 10 seconds. No sound phenomena were observed. The shock was very distinctly felt and the villagers experienced feelings of nausea. Banmauk sub-division is extremely hilly and sparsely populated. It contains only three masonry buildings, two police stations and a treasure vault, none of which were damaged. Maung Gale, Sub-divisional Officer, Maung Tha Byaw, Maung Tun, and Mauny Khin, Traders.—Time 8-50 A.M., wn- corrected. Three distinct shocks lasting 2 minutes. No preliminary tremors, but the subsequent vibrations lasted 4 minute. Direction S.W.—N.E., observed by hanging lamp which swung as much as 13 inches out of the perpendicular. There was a rumbling sound heard during the main occurrence. Two walls of the Wuntho township office, which is built of the usual brick nogging in wooden frames, were cracked and the plaster came off another wall in two places.. Both cracked walls are parallel, cours- ing N.—S. In the E. wall the cracks occurred about 10 feet apart, on the S. side of the centre posts. Commencing from the edge of the posts they ran diagonally upwards at an angle of about 60°, to a height of about 5 feet from the ground, and right through the wall. A crack some 6 feet in length also appeared in the cement floor running in a 8.W. direction. M. Molid Khalil, Sub-Postmaster.—A great shock occurred at 9 am., by telegraph time. Direction N.—S, Duration 1 minute. He thinks that the quake was divided into 3 or 4 separate shocks. Wuntho. Wuntho. Maung Pyu, Myothugyi of Pinlebu Township, Maung Po Lu, Myothuggi of Pinlebu, Maung Lu Gyi, Ywasaye of Kauksin, Pinlebu Township — Time 9 A.m., guessed. No prelimi- nary or subsequent tremors and no sound pheno- mena. One shock distinctly felt from $8. to N. Duration about 1 minute. Cooking pots and cups fell to the §8., in Kauksin and Kyaukingon villages and hanging lamps swung as much as 18 inches from N. to S. U Ne Myo, Schoolmaster—Time 9 A.m., by a watch compared with railway time. No previous or subsequent vibrations were felt but a rumbling sound was heard. ‘Two distinct shocks lasting 2 minutes. Direction 8. to N. Pinlebu. Kawlin. mor ere OTHER AREAS IN BURMA. 59 Shwebo District. Mr. W. V. Wallace, Deputy Commissioner, Shwebo.—He felt a shock while writing in the office room of his house at almost exactly 9 a.m., on the morning of the 23rd May. He took out his watch to see how long the shock would last, but as he did so the violence of the earthquake ereatly increased, with the result that a lot of plaster fell off the walls of a room upstairs, and the noise gave him the impression that the brick nogging was falling out, so he got up to leave the house. He then found that the earth was distinctly rocking from N. to S., as it caused a dinner waggon to sway in that direction to such an extent that some glass was flung on to the floor. Upstairs it was found that the plaster had fallen off the S. sides of the bathroom walls only, and that a door facing E. and W. had to be forced open, as the door frame had evidently been slightly pushed out of the perpendicular. The only noise detected was the creaking of the building itself. The duration was perhaps 40 seconds. Very little damage was done in Shwebo town, a few old and badly built brick buildings showed small cracks. Shwebo. Upper Chindwin District. The Sub-divisional Officer —Distinctly felt a shock about 9 A.M, Kindat. on May 28rd. Duration about 4 seconds. The Sub-divisional Officer. —A distinct shock about 8-30 a.m. It began with a slight tremor lasting 30 seconds, followed bya very distinct shock lasting about 10 seconds, which was succeeded by after tremors for another 20 seconds. Direction N.—S. The children who were walking in the streets began to lose their balance. There was no damage to life or property. The Sub-di-is onal Officer —Distinctly felt shock at 9-30 a.m. Time merely guessed. About three distinct shocks were felt. No prelimimary tremors and no sound phenomena. Direction S.E.—N.W. Mr. E. P. Dove, Executive Engi- neer, Public Works Department, did not feel the shock. Mingin. Kalewa. Lower Chindwin District. E. A. Passanha, Telegraph Master —A continuous distinct shock started at 8-55 a.m., and lasted for 1 minute Monywa. nae ° * - 55 seconds by telegraphic time. Judging §0 COGGIN BROWN: THE BURMA BKARTHQUAKES OF MAY 1912. from the swaying of trees and the motion of water in fire buckets it moved from N. to S. No objects were overturned, neither was any damage caused to the building. Maung Po Mya, Senior Sub-Assistant Surgeon.—Time 8-30 AM. Duration ? of a minute. A very distmet shock from N. to S. Near the hospital the top of a pagoda, with its “ hti,’ was broken off. Mr. Francis, Storekeeper, Public Works Department.—Time 8-55 A.M. by telegraphic time. Direction N. to S. Duration about 2 minutes. This observer has lived in Monywa for 20 years but has never felt such a severe and continuous shock before. No damage was done to his house as it is a wooden one, but the clock was stopped and crockery fell down. Cracks 2 or 3 inches in width and extending over 15 feet in length, were noticed subsequently in a brick building in the town. A small crack about ,},th inch in width and 10 inches long appeared in the N. wall of the Roman Catholic Chapel. Old people were unable to stand without support. J. Mahadala Moodlier, Station Master.—A_ severe shock occurred at 8-55 am. The station clock was stopped. Duration 1 minute 55 seconds. Direction N.— S., from the movement of trees and buildings. All the railway buildings are constructed of wood, therefore no damage was done. In a brick building a gaping crack 2 or 3 inches wide was caused. The Roman Catholic Church was cracked near the entrance. The station master has never felt such a severe shock in his life, and the inmates of his house “lost all confidence and they were very giddy.” Mr. Gordon W. Lepper, Geologist, The Burmah Oil Co., Ltd.—Time 9 a.m. by uncorrected watch. Intensity IV—V Rossi-Forel scale. The bungalow shook as if affected by a gale. He ran out and found his servants hastily wetting from below the bungalow. The shocks lasted at least 30 seconds, and he instinctively held on to the compound fence, while the ground seemed to be moving to and fro in a horizontal plane. He then returned to the bungalow and placed a basin of water on the table. Extremely feeble shocks (intensity I, Rossi-Forel scale), continued for 5 minutes or more after 9 A.M., and again at intervals until about 10 a.m. These aftershocks were extremely feeble, hardly noticeable. Monywa. Monywa. Monywa. Kani. 3 & g 7 aa OTHER AREAS IN BURMA. 61 Sagaing District. The Station Master.—Time 8-50 A.M. Duration about 2 minutes. The station clock was not stopped. The station buildings and the wagons in the yard could be clearly seen shaking. As most of the quarters in this station are built of wood they sustained no damage, but brick buildings suffered slightly. These latter comprise the locomotive workshops, the engine shed and the divisional offices. The brick walls broke here and there, some partitions fell down and large cracks were caused in several places. Maung Bah, Station Master—Time 8-55 A.M. Station clock Natyekan. stopped. Duration 2 minutes and 5 seconds. Mr. C. S. Pennel, Deputy Commissioner.—Time exactly 8-57 a.m. on May 23rd. Several clocks with pendulums stopped at the hour mentioned. These clocks were regulated with that of the telegraph office. At outstations in this district the timing was more or less guess work and variously reported as 9 and 9-30 a.m. A loud rumbling sound resembling that of heavy carriages driven quickly on a metalled road preceded the shock, which lasted for 1} to 2 minutes, and was followed by 7 or more shocks during the course of the day. Apparent direction from N.E. to S.W. judged from the fall of loose objects and the swing of hanging lamps. Brick buildings and pagodas suffered through- out the whole district. Walls running E. to W. were cracked towards the perpendicular. Several pagoda tops were knocked off and the “htis”’ of others were bent. Ornaments on tables and brackets were knocked down, and water jars containing water overturned. A Jost fan was thrown from its pedestal, the direction of its fall being N.—S. In the towns of Sagaing and Myinmu all these effects were noticed, also free swinging objects swung consi- derably from N.E. to 8.W. Houses swung in an alarming manner and stucco ornaments on the top of brick buildings were dislodged. Mr. G. F. S. Christie was in a moving train and felt Ywataung. Sagaing. nothing. Minbu District. Mr, Soloman, Sub-Assistant Surgeon.—Time between 9 and 9-30 AM. Chimney of a hanging lamp fell and Minbu. ; smashed. Duration 5 seconds. 62 COGGIN BROWN : THE BURMA BARTHQUAKES OF MAY 1912. Mr. Grey, Headmaster, Government High School.—Time between 8-30 and 9 a.m. He did not notice the shock personally but the teachers in the school ex- perienced it. Apparent direction N.—S. Minbu. The Sub-divisional Officer—Reported that various people in the Minbu. town felt the shock very slightly. Mr. Morris, The British Burma Petroleum Co.—He was seated at his desk about 9 A.M., when the chair moved gently backwards and forwards and he experienced a feeling of nausea. Mr. Francis, Head Clerk, Deputy Commissioner's Office.—Noticed that one of the Duthagon pagodas was crack- ed by the shock. The Sub-divisional Officer—Reported that various people in the Salin. town felt the shock “ very slightly.” Minbu. Minbu. Township Officer.—-Time about 9 A.m. (guessed). ‘Two or three dis- tinctly felt shocks from $.W. to N.E., which disturbed hanging objects but caused no damage. Head Clerk, Sub-divisional Officer's Office —Time 9-15 Am. by watch compared with the post office clock three days previously. A distinct shock with previous vibrations and aftershocks. No damage was caused. Salin. Salin. The Assistant Township Officer and Maung Pe, Zema Quarter.— Time 9-15 a.m. by a watch compared with the post office clock. Distinct shock, which lasted 1 minute. Direction N.W. to S.E. Hanging objects moved but no damage was done. After the shock was over a great noise, something like the firing of a cannon, was heard. No aftershocks were noticed. Maung Tha Do, Advocate, Sagu ; Ywathit Headman, Kyauksan ; Maung Zan Pe, Advocate, Sagu ; Kumaruppa Chetty, Sagu ; Maung Tun Mya, Sagu; Maung Po Twin, Sagu—Time at Sagu, 8-47 a.m. by a clock compared with that of the telegraph office. Two distinct shocks were felt each of which lasted 5 minutes (!) with an interval of 1 minute between. They “ appeared to go first from north-east to, south- west and then from south-west to north-east.’ Plates on a table fell away towards the S.W., and suspended lamps swung in the Salin. Sagu and neighbour- ing villages. OTHER AREAS IN BURMA. 63 same direction. Some people felt dizzy owing to the shock. When the earthquake was over a great noise like a cannon being fired was heard three times from the N.E. Maung Ba Nyun.—Time about 8-10 a.m. Three distinct shocks, which lasted about 5 minutes. No preliminary tremors. Direction observed from the motion of hanging objects, was E.—W. The Township Officer—Time about 9-12 a.m., by a watch compared with post office time. A second shock took place at 9-14 a.m., and lasted until 9-17 a.m. Vibrations felt for a minute after this latter shock. The first one appeared to come from the N., and the second from the W. Nothing was overturned and no damage was done. Maung San Hlaing, Head Clerk ; Maung Thet Nan, Burmese Medical Practitioner—Time about 9 a.m. (guessed). Duration about 5 minutes. The shock appeared to move from W. to E. Hanging objects continued to move for about 10 minutes. No preliminary tremors, sound pheno- mena or aftershocks. Ngape. Pwinbyu. Sadoktaya. Magwe District. Mr. W. Robson, Chief Clerk, Deputy Commissioner's Office.-— Time 8-55 a.m. according to telegraph office time. Duration 2 minutes. He was seated in a chair in an upper room reading, when the floor began to rock and he became giddy and sick. He rushed downstairs, found the house rocking and children holding on to posts for support. His house is 100 yards from the telegraph office and opposite it. Ten minutes after the shock the signallers came over and enquired whe- ther he had felt it, as they themselves had not done so. They only knew of it by the telegraph master of Taungdwingyi asking whe- ther they felt it or not, and also by the Rangoon telegraph office making the same enquiries. No damage was done to the house, nor were any things upset. Head Accountant, Deputy Commissioner's Office—Time 8-55 A.M. He noticed that his house was shaking and hanging lamps were swinging to and fro. Mahomed Esoof, Head Revenue Clerk, Deputy Commissioner's Office —Time 8-50 a.M., according to tele- graph time. He felt two distinct shocks. The Magwe. Magwe. Magwe. 64 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. first lasted about 15 seconds with tremors for some 20 seconds after- wards. The second lasted longer than the first and took place some 10 or 15 seconds afterwards. Apparent direction from E. to W., judging from the motion of water in a wide-mouthed jar filled to the brim. Both he and his wife suffered afterwards from giddi- ness. Nothing was upset in the house and no damage was caused. Mr. de Facieu.—Time about 8-45 or 8-50 a.m. He was on the Magwo. veranda of the Deputy Commissioner's court- house, and distinctly felt the building sway several times in about 2 minutes. There was no accompanying sound, neither were any objects in the building displaced or overturned. He thinks that what he felt were more like tremors than distinct shocks, and very unlike any earthquake he has ex- perienced before. Not a building in the town was damaged or cracked. The effect of the shock was to induce in several persons a feeling of slight nausea. Hospital cook, and Sub-Assistant Surgeon, Military Police Hos- hee pital.— Both felt a slight shock about 9 A.M, Direction from E. to W. It was not experi- enced by the Civil Surgeon who was in a launch on the river. Mr. W. Ripley, Sub-divisional Officer—A distinct shock at 9-30 : aM. on the 23rd May. No _ preliminary PRrrcwe S Yabe tremors were felt, but several smaller tremulous vibrations were distinctly felt after the main- shocks. Time of duration from 10 to 20 seconds. Direction S. E. —N. W., judged by water, by the movements of objects and shadows of trees, etc., at the time of the shock. Water bottles and hats said to have fallen and overturned. No particular sounds were noticed before or afterwards. On the 16th, very peculiar sounds were heard towards the N., by villagers and himself, at a place called Inywagyi in the Myothit township, in the morning and afternoon. When the villagers were questioned they said they had never heard such peculiar rumblings before, and could not under- stand them. They were of long duration and not very loud. Mr. H. Marsland, Public Works Department.--He was riding on a pony between these two places and did not shee ae Myothit and fee] anything. No buildings, Government or private, in the Magwe district were damaged. The shock must have been very slight in Magwe, as a masonry building, which had partially collapsed a month or so before, whilst it was OTHER AREAS IN BURMA, 65 under construction and which he had condemned as dangerous to human life, some of the walls being at angle to the vertical, was not affected in any way. Mr, Ray, District Superintendent of Police.—Time soon after 9 A.M. Duration about 2 minutes. He was seated in a chair on the ground floor of a house. He felt the concrete floor move in waves, and the swaying was so severe that another officer who was standing had to sit down. They both experienced a sensation of nausea. Two very distinct periods were noticed. Maung Ba Pe, Head Clerk, Sub-divisional Office —Time about 9 A.M., by a watch compared with telegraph office time. Duration about } minute. Direction from N.E. to S.W. as estimated from the swaying of pagodas. Not noticed by people on the move. Hanging objects were set swinging. No aftershocks. I made numerous enquiries amongst the European and American officers of various oil companies in Yenangyaung. Most of those who were on the oil-field felt a slight shock and saw the derricks moving, whilst others who were in office felt nothing. Captain A. P. Sandeman, I1.A., Warden.—Time about 9 a.m. He was in office at the time when it began to rock as in a high wind. He rushed out, but no damage was caused. Experienced nasuea. Mr. W. E. Smith, Ayent, The Nath Singh Oil Co.—Time about 9-20 A.M. Distinct shock felt by all the office staff. Duration about 5 seconds. No articles were moved or dismantled and no damage was caused. Mr. Fred. W. Spicer, Field Accountant, The Burmah Oil Co., Lid.— Time 8-56 a.m. by local time (standard time unknown). He was sitting at his desk in a large single-roomed bungalow raised from 1 to 3 feet from the ground on piles, when the house swayed twice. The motions had an interval of 1 or 2 seconds and were sufficiently violent to give him a momentary qualm of sickness. Mr. Basil E. Macrorie, Geologist, The Burmah Oil Co., Ltd.—He looked at his watch when the shock was over, It indicated 8-55 a.m. It is difficult to say Taungdwingyi. Taungd wingyi. Yenangyaung. Yenangyaung. Yenangyaung, Yenangyaung. T ure ¢ Nyaunghla, F 66 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. how long the shock lasted. Possibly he only felt it for 5 seconds, but it may have been as long as 10 seconds at a maximum. 7 Pakokku District. Mr. H. H. Young, Refinery Manager, The Burmah Oil Co., Ltd.— The shock was felt at 8-52 a.m. He noted the time immediately by his watch, but unfortunately he has no standard time to go by. There was one distinct shock which lasted about 55 seconds, preceded by a slight wind and followed by complete stillness. It was distinctly felt and appeared to come in waves, its apparent direction being from W. to E., judged from the agitation of water in a tank set in the ground, and also from the swinging of balance weights set to flue doors. One slight crack, running nearly straight up and down, was caused in the brickwork of an oil still. Earthquake tremors are almost weekly occurrences at this place. Yenangyat. Toungoo District. Mr. Walter. C. Sherman, Government Telegraph Office—Time 9-3 am. by the telegraph office clock, which is said to be fairly accurate, but “of course there may have been a difference of a minute or two each way.” Dura- tion a good 6 or 7 seconds, accompanied by a peculiar droning sound. He was in the telegraph office which is a wooden build- ing 15 feet off the ground. It shook and swayed a good deal. Direction N.—S., judging from water spilt from fire buckets kept on the veranda floor. It was rather distinctly felt by people in upstairs buildings. Others on the roads at the time said they felt a pecu- liar sensation and some experienced a feeling of nausea, Only one building to his personal knowledge suffered slightly, a masonry wall facing N. cracked from the ceiling downwards. No aftershocks were experienced. Mr. W. R. Fry, Municipal Engineer—Time 9-5 a.m., by an uncorrected watch. No preliminary vibrations or unusual sounds. Duration a little over a minute, Direction E.—-W., judged from the movement of water in a small tub near his office table, part of the liquid from which was spilled. He did not hear of any buildings being cracked in Toun- ‘Toungoo. Toungoo. OTHER AREAS IN BURMA, 67 goo. According to Mr. A. H. Geyer, Deputy Commissioner, no damage was done in Toungoo or the district, Maung Po Tin, Sub-divisional Officer —A severe shock was felt at 9 A.M., lasting a full minute. With his family he went downstairs and when on the ground they continued to feel the shock. A brick wall of the house in which the township judge, Maung Gale, lives, was slightly cracked from top to bottom. The water in the Sittang river was disturbed, the waves moving from E. to W. Mr. A. Williamson, Sub-divisional Officer—Time 9 a.m., not accurately observed. Duration 2 minutes, a rough guess. To an unscientific observer the whole phenomenon appeared a wave-like motion, gradually increas- ing to a period of highest intensity and then dying away again. Direction mainly N. and §., as estimated from the swaying of a punkah. The only sounds noticed were the raitling of doors and windows and the creaking of joists. He was writing at the time, and the preliminary tremors were quite sufficient to make it im- possible to continue. The clerk to the Sub-divisional Ojficer—The cupboard in the office threatened to fall over on to him. From its position, this indicates a more or less N.—S. direction for the shock. Some joists fell from a house in the bazar but they were very rotten. Two long cracks were caused in the plaster of the Sub-divisional Officer’s house, which is a comparatively new laterite building. They run straight up and down in the E. and W. walls of one of the rooms. Pyu, Kyaukkyi. Shwegyin. Thayetmyo District. Mr, R. C. W. Symms, Deputy Commissioner.—He did not feel the shock on the ground floor of his house. People on the first storey noticed it about 8-45 a.m, Glasses on tables shook and doors rattled. The direction was from N. to S. apparently. No damage of any kind was done in the Thayetmyo District. The Civil Surgeon —Time 9-5 a.m. Duration 30 seconds, Observer sitting indoors at the time. One slight quake was felt, strong enough to move his seat a little. No unusual sound phenomena were heard. Thayetmya. Thayet myo. F2 68 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912, The Sub-divisional Offcer——-Time 9 A.M. uncorrected. No preliminary vibrations. Duration 1 minute, and direction W.—E. Mr. R. C. Rogers.—Time 8-30 a.m. He was sitting in a one- storied house and felt a continuous shock from K. to W. It lasted for quite a minute and felt as if a large animal was rubbing itself against the posts of the house. It caused the writer and the policemen, who were with him, to feel giddy. U. Asaya, Pongyi—Time 8-47 a.m. No preliminary vibrations. Continuous shock, lasting about 1 minute. Allanmyo. Tawmun, Sinbaungwe. A belated report from a Burmese official —Time 8-15 a.m. Duration ; 5 seconds. Direction N.—S. Minhla. A belated report froma Burmese official—Time 9 a.m. Duration 3 minutes. No preliminary tremors. Apparent direction N. W.—S. E. Mindon. Northern Arakan District. Mr. W. H. Thom, Deputy Commissioner.—He did not feel the earthquake personally, but the clerk of the police station recorded a slight shock lasting 2 seconds at 10 a.m. This time is said to be taken froma clock compared with the one in the telegraph office. Other people said that they felt the shocks at about 2-30 p.m., but when asked some weeks afterwards could not state the exact date. With regard to these time observations, the followmg pertinent remark of the Deputy Commissioner is worth quoting :—‘‘ The latter time is merely guess- work as most of the people in these parts have not even seen a clock and have no idea of time.” No damage was done in Paletwa or district. Paletwa. Akyab District. Mr. J. D. deVine, Meteorological Observer.—Time 8-55 to 9 a.m. pe Duration 23 seconds. Writer was standing on ; a staircase and felt two distinct shocks from N. to 8. Doors and windows rattled and hanging objects swung. There were no other sound phenomena. OTHER AREAS IN BURMA. 6Y The Sub-divisional Officer—A slight shock was felt in the town and in parts of the sub-division. ‘There were no effects.” Maung Saw U. Kaing, Sub-divisional Officer—He noticed a slight shock which lasted for about a second. The Sub-divisional Officer —No shock ex- perienced. Saw Ban U., Advocate, and Tha Tun U., Head Clerk.—Time 9 A.m., by unchecked watch. About 7 distinct shocks were felt, lasting from 40 seconds to 1 minute and followed by a few vibrations. Maung San Aung.—Time about 9 a.m., unchecked. Direction and duration not noted. No damage of any kind was caused. Mr. A. R. Morris, Sub-divisional Officer, and the Township Officer-—Both reported that the shock was not felt. The Sub-divisional Officer.—Two distinct shocks were felt, one at 9 A.M., and the other at 9 P.M. he Kyaukpyu District. Akyab. Minbya. Naungdaw. Buthidaung. Kyauktan. Poonagyun. Rathedaung. Maung Myat Tun Aung, Deputy Commissioner.—Reported that the earthquake of May 23rd, was hardly felt in Kyaukpyu. ‘‘ Someone said that a slight shock was felt in the afternoon.’? No damage of any kind was caused. The Sub-divisional Officer, Public Works Department.—He did not feel the shock himself, but reported that a gang of men employed at Pyade noticed it. Kyaukpyu. Kyaukpyu. Sandoway District. The Civil Surgeon.—Time betwen 8 AM. and 10 AM. He was working in the Jail office, and felt the shock travelling from S.S.W. to N.N.E. Both the jailor who was standing near, and the deputy jailor seated at another table in the same room, felt the movements, which the writer regarded as a series of small shocks lasting 6 or 8 seconds’ Five prisoners sitting on the ground just outside the office did not notice anything. The shock was not felt in the hospital or in the Civil Surgeon’s house. Mr. J. D. Hamilton, Sub-divisional Forest Officer, reported that he did not feel the earthquake. Sandoway. 7Q COGGIN BROWN: THE BURMA KARTHQUAKKES OF MAY 1912. Mr. P. Vajravelu, Accountant, Public Works Department.—Time about 8-30 aM. He was seated in a chair facing 8S. and felt a slight shock lasting for a few seconds, running from W. to E. Both the chair and a table moved, the former in a lateral direction. He was informed a few minutes later by an outsider that an earthquake had been felt im the town. Maung Po Thwai, Tracer, Public Works Department.—Time between 8 and 9 o'clock in’ the morning of May 23rd. He was sitting on an easy chair and noticed that the direction of the movement was from W.—E. A few seconds later he thought the direction was reversed and then the former motion was resumed again. Mr, J. A. de Rozario, Supervisor, Public Works Department.—Did not feel the earthquake of the 23rd May. Sandoway. Sandoway. Kyecintali. Mr, N. A. Times, District Superintendent of Police.—He felt a shock, but it was so slight that he did not take any particular notice of it. Mr, J. C. Brown, Telegraph Master—He did not notice any shock on the 23rd May, and failed to elicit any definite information regarding the earthquake in the town. It was not felt by anyone residing on the tele- graph station premises and no damage of any kind was caused. ryt Taungup. Taungup. Prome District. Post Master.—-Time about 9 a.m., two slight shocks were felt in ae quick succession on May 23rd, 1913. No further particulars are available. Tharrawaddy District. Major F. R. Nethersole, 1.4., Deputy Commissioner—He was seated at 8-30 a.m. (time guessed), in the upper storey of a wooden building which faces N., when the oscillation appeared to be from side to side, i.e, E.—W. Duration about 15 seconds. No sound phenomena were observed. The Sub-divigional Officer—Zigon is 48 miles to the north of Tharrawaddy. Time 8-45 a.m. Duration 20 seconds. Tharrawaddy. Zigon. OTHER AREAS IN BURMA. "1 Henzada District. Mr. OC. W. Allen, Divisional Forest Officer—Time 8-53 A.M., by a clock set to railway time. One shock which lasted for about 30 seconds. Direction seemed to be W.—E.. No sound was noticed. It was distinctly felts by the Forest Officer, by his wife and by the Extra Assistant Conservator of Forests who were all sitting upstairs at the time. The whole house moved with a swinging motion, and water in a basin in the room was disturbed. Henzada. Pegu District. Mr. W. Howell. Station Master —The station clock stopped at 8-52 a.m. A very severe shock and two of a lesser nature were felt. They succeeded one another without a break and lasted for about 50 seconds. From the swinging of lamps and hanging flower-pots, the direction appeared to be from N.S. No damage was done. Mr. Ormiston, Deputy Commissioner..-He was informed that the earthquake took place about 9 A.M., but was out riding near the town and felt nothing. Mr. T. Lister, Assistant Commissioner, was talking in the road at the time to Sheikh Safdar Hussain, Extra Assistant Commissioner. The latter sat down in the road, while Mr. Lister said he felt trembling in the knees as one does on landing after a long sea voyage. He heard no accounts of objects being displaced. As regards injury, he mentions that his own house is extensively cracked, being built on made soil (the banquette of the old town wall), but it showed no fresh cracks after the earthquake. The Sub-Postmaster.—Time 8-47-56 a.m. on May 23rd, lasting about 3 minutes. No damage was caused. Pegu. Pegu. Myitkya. Hanthawaddy District. Lieut.-Col. S. L. Aplin, I. A., Deputy Commissioner.—He | felt a very slight shock which was only just percep- tible at his house in Leeds Road, Cantonments, Rangoon, at 8-55 a.m. on the 23rd May. The time is from a watch which was lying before him on the table at which he was seated at the time, and which was within 2 or 3 minutes of the correct time according to the clock on the Chief Court, Rangoon, Rangoon. 72 COGGIN BROWN: THE BURMA BEARTHQUAKES OF MAY 1912. which he believes is usually correct. The electric lamp above his table swung from side to side but nothing else appeared to have moved. There were no cracks in the building nor was any object overthrown. Mr. H. Thompson, C.S1., I.C8., Deputy Commissioner.—He was a mile or two from Insein in the open and noticed nothing. The shock is reported to have been felt in different parts of the district at or shortly before 9 A.M. No accurate observations were recorded, but hanging lamps and other suspended objects were noticed to swing E.—-W. No sounds were heard, and no damage of any kind was caused. Capt. E. Butterfield, I.A., Sub-divisional Officer —The shock was noticed at places all over the sub-division, and appeared to be a long slow wave. In no case was any noise observed and nothing was thrown down except balanced instruments at Seikkyi. No damage was done. In Sittan village, one Maung Kyaw, son of the headman, reported that he was writing letters at the time, seated facing N. and felt himself impelled forward and almost overbalanced. The shock lasted 2 minutes. Various European employees of the Burmah Oil Co., Ltd., reported that the oil was observed distinctly swinging in the tanks at the time of the earthquake. The Manager, British Burmah Petroleum Co.’s Refinery.— reported that nothing was noticed at Thilwa. Insein. Kyauktan. Syriam. Thilwa. The Lounship Officer—Time 9-10 a.m., by a clock compared with the telegraph office time. No damage was done. The Lownship Officer, and Maung San Yon, Pleader.-Time 8-50 a.M., by a watch compared with telegraph time a week before. There were 3 shocks, the first being distinctly felt and lasting a minute. At intervals of about a minute two other shocks were felt. Hanging lamps moved or shook slightly and a few persons got giddy. There was no sound. Mr, James Turley, Chemist, Indo-Burma Petroleum Co., Ltd.—Time Seikkyi. 8-58 A.M., by the candle-house clock. Time not ' verified. One distinct shock. Direction N.N.W.— S.S.E.. Duration about 10 seconds. The candle machine weights, Kayan. Thougwa. OTHER AREAS IN BURMA. 73 the lamps and the pans of a chemical balance were set swinging in the above mentioned direction. The swinging of the weights and lamps was approximately 2 inches. The pendants supporting the pans of a chemical balance were shaken off the knife-edges, but falling in a confined space, nothing was to be learned from the direction of fall. No aftershocks. Mr. J. Thompson.—Clock stopped, and water in the river was seen to move in waves from a few points to the E. of N. towards the 58. Seikkyi. Maubin District. Capt. A. B. Roberts, 1.A., Deputy Commissioner.—He felt no shock personally, but reported that it was felt slightly in Danubyu and Yandoon about 9 A.M. on May 23rd. No damage was done and very few people noticed it. In the S. of the district it was so slight that only one or two people felt it. Standard time is not kept, and 9 A.M., the time quoted, is a rough guess. No particulars were noted by anyone and nothing was overturned. Maubin. Bassein District. Mr. W. F. Grahame, Deputy Commissioner—None of the people consulted by the Deputy Commissioner felt any earthquake shock during the month of May. He did not experience any himself, nor did he hear of anyone in the district who did. It is interesting to note that the Sub- divisional Officer of Bassein reported that an earthquake shock was felt there on the night of 22nd February 1912, at 8-10 P.M., the duration of which was 2-3 seconds. The Deputy Commissioner is very sceptical regarding the occurrence of this alleged shock. Bassein. Myaungmya District. Mr. F. L. J. Williamson, Deputy Commissioner —Reported that no earthquakes were felt in the Myaungmya district Myaungmya. ‘ : in May 1912, so far as he could ascertain. 74 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. Pyapon District. Major H. V. M. Langtry, I.A., Deputy Commissioner.—Reported < that no earthquake was felt in the Pyapon iat district on May 28rd, 1912. Amherst District. Mr. J. D. Frazer, 1.C.S., Deputy Commissioner —Time 9 A.M., Shght shocks were experienced in Moulmein Moulmein. erate ; and Kawkareik. The Civil Surgeon.—Time 8-50 a.m., on May 23rd, 1912. A slight shock was felt by observer while working in his office. Moulmein. Mergui District. Mr. G. P. Andrew, Deputy Commissioner —The shocks were not felt elsewhere than in Mergui town and no damage was caused. Mr. J. F. Leslie, Secretary, Municipality, and U. Paduma, Head Upazin of Taw Kyaung, Alegyun, Mergui.—Time, just about 9 a.m., followed almost immediately by a second shock. Both were slight and their duration was not noted. Direction thought to be N.—S. Hanging lamps commenced to swing about, but nothing fell or broke. No sound was heard. Only people who were at rest felt the shock. Mergut. Mergui. Chin Hills. The Assistant Superintendent, Chin Hills —The shock was so slight that it was almost imperceptible, so much so that very few noticed it. The Assistant Superintendent.—Reported that no shocks were Tiddim. felt in his sub-division. Lhe Assistant Superintendent.—Reported that no shocks were felt Haka. in his sub-division. Falam. OTHER AREAS OUTSIDE BURMA. 75 CHAPTER I. OTHER AREAS OUTSIDE BURMA. Yiinnan Province, China. Mr. C. D. Smith, H.B.M.’s Consul—Reported that the earthquake was felt in Téng-yiieh, a few minutes before 9 a.M., as noted by the Commissioner of Customs shortly after the shock. Two separate shocks were distinctly felt, occupying perhaps a minute and a half from the beginning of the first to the end of the second. This is, however, a mere guess. The shocks appeared to move in an approximately N. and 8. direc- tion judging from the motion imparted to water in a bath tub. The first seemed to be the shorter in duration and the lesser in intensity. No sound phenomena were noted, and the Consul was unable to obtain any information as to the effects of the quakes, though no damage appeared to have been done. Mr. Roshigliosi, Assistant in Charge of Customs, Chinese Customs Service.—He did not feel the shock personally as he was out of doors at the time, but it was noticed by various other people. It was divided into 3 parts, the first was the most distinct and lasted 2 or 3 seconds. The apparent direction was N.—S., as judged by the pendulum- like swinging of hanging lamps. No unusual sounds were noticed. The time is given as 445 p.M., but as this is stated to be a mere guess, and it was not until the middle of August that Mr. Roshigliosi wrote his account, furthermore, obtaining his inform- ation from Chinese sources, I am of the opinion that this may be definitely stated to be a mistake. Téng-yiich. Ssumao. Bengal. Mr. A. H. Clayton, Deputy Commissioner. —No earthquake was perceived in the Chittagong district on May 23rd, 1912.(*) 1Earthquake shocks were reported at the following Indian stations on May 23rd, 1912 :-— Chittagong. Rawalpindi. : : ; : _ 4-53 a.m. (Indian Standard Time.) Drosh a ‘ ; ‘ ; ; 5 oy Chitral . ; : : . = . 448-,, Gulmarg (Kashmir) 7 oo hed 5 ~ 5, The intensity of these shocks does not seem to have been greater than IV—V on the Rossi-Forel scale. ‘They appear to have been quite local in origin and to belong to the series of small shocks which are continually being felt in the Himalayan region. 76 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. Siam. The following account appeared in the ‘* Bangkok Times ’’ of May 23rd, 1912 :— ** Bangkok experienced a slight earthquake shock this morning which lasted for three or four seconds. The very slight duration of the shock notwithstanding, it was noticed over quite a large area. At Bankolem the electric lamps were all swinging, and from different business houses situated along the east bank of the river we have received the same report of lamps and electric fans swing- ing. At the Royal Railway Department the shock was distinctly noticed and two of the clocks stopped, the time being 9-10 am. At the Post and Telegraph office the time of the disturbance is given as 9-9 A.M. The sorting staff in Post Office No. 2 at work on the English mail, noticed the disturbance, and it is evident the tremors were not confined to one parti- cular spot, as reports from the west side of the river, Bangsue military quarters, the Ordnance Depart- ment at Bang Nga and the Police School at Sapatum all report having experienced the tremors. At the police station near Wat Buparam the earthquake was noticed by people in the streets. At Messrs. Harry A. Badman’s city store the lamps in that part of the building nearest the Chakkri Palace were all set swinging, while those in the other half of the building were sta- tionary. The last earthquake recorded in this country as far as our knowledge goes was on the Ist January 1887. Paknam.—lt was at first thought that possibly an explosion had taken place at Paknam, but a_ telephone message to that place brought news that everything was all right and no tremors whatever were noticed there. Petriu—aA telephonic enquiry to Petriu has elicited the fact that nothing untoward was noted in that district this morning. Chiengmar.—A telegram received this morning states that a slight shock was experienced in that city on the 21st May. The tremors this morning were more severe and lasted longer. The time of the shock is given at 9-5 a.m. OTHER AREAS OUTSIDE BURMA. 77 Bangkok, later.—The boys in school as well as some members of the teaching staff noticed the earth movements, which produced a feeling of giddiness. One of the shipping firms state that the fans in their office swung nearly a foot out of the perpendicular. At the Railway works at Makasan a number of workmen complained of gid- diness and sickness.’’ The following account appeared in ‘‘ The Siam Observer’’ of May 28rd, 1912 :— ‘An earthquake of some force was experienced here (Bang- kok) this morning, the first shock bemg felt at 9-8 a.m, It lasted for just on three minutes. In the Observer building the shock was felt with considerable definite- ness. Pictures swung on the walls and hanging lamps gyrated. In other houses full water jars shook so that some of their contents was spilled, while the telegraph and telephone wires above the streets swung several inches. A feeling of giddiness was the first indication of the quake experienced by most. This passed off as the tremor became more definite. During the first minute wooden buildines swayed distinctly, and even in stone buildings such as the Chartered Bank and Post Office No. 2, the shock was strongly felt. We learn that the direction was from the south-east. An old resident informs us that the last shock felt here was on either November i7th or IS8th, 1886, when tiles fell from the roofs of houses in old Raheng, while in Bangkok the wood work of the houses strained and creaked. This quake occurred about 11 A.M., and was much more severe than this morning’s quake. A local lady informs us that the tables and chairs in her house moved across the floor at the height of the shock this morning. The tremor was less noticeable on the river, although it was distinct- ly felt on one or two ships at anchor.”’ Concerning the effects of the earthquake at Tachin the fol- lowing report appeared in the ‘ Bangkok Times of May 24th, 1912, dated Mahachai, May 23rd :— ‘©The shock was of a very deliberate nature, severe enough to set the trees swaying, every hanging object swinging violently, and to stop my clock. The duration of the 78 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. shock must have been at least one to one and a halt minutes as I had time, first to realize what was going on, then to cross the room and to note the time (9-5 A.M.), steady a hanging lamp, rest myself and watch the lamp resume its oscillations. It was a curiously nauseating sensation and caused one occupant of my house to vomit.’’ In the “ Bangkok Times ’’ of the 25th May 1912, the following further reports appeared : — ““As the reports come in from the outlying Monthons it appears that the seismic disturbances of Thursday morning occurred practically all over the country. We have received telegrams or letters from correspondents in Monthon Bayat (Chiengmai, Chiengrai and Nakon Lampang), Monthon Ratburi (Petchaburi), Monthon Nakon Sri Thammaraj, Monthon Nakon Chaisi (Maha- chai) and Monthon Krung Thepe. The reports from Chiengmai and Tachin have already appeared. Apparent- ly, two distinct shocks were felt in the far north. Our correspondent im Chiengmai reported a slight shock on Tuesday morning as well as on Thursday. Chiengrai also experienced two shocks. No telegram has come to hand from our Puket correspondent, and presumably the shock was not felt there. The later telegrams to hand are given below. Lakon Lampang.—The earthshock was distinctly felt here. Clocks were stopped in a number of houses. No dam- age is reported. Nakon Sri Thammaraj.—We only experienced a cyclonic thun- derstorm here. There was no earthquake. A number of roofs were slightly damaged. Petchaburt.—No earthquake shock was noted here on Thursday, Chiengrat.—There was an earthquake shock here yesterday (Thursday) morning and another, and minor one, this (Friday) morning.’’ His Britannic Majesty’s Consul in Chiengmai in a letter to the Assistant Superintendent, Southern Shan States, Keng Tung Sub- division, reported that shocks were felt there on May 2lst and 23rd, OTHER AREAS OUTSIDE BURMA. 79 Correspondent in the ‘ Rangoon Gazette.’—Time 8-45 A.M. on May 28rd, 1912. The shock lasted some seconds. The bungalow rocked and creaked to such an extent that the writer thought it safer to get outside. It also caused a good sized wave, very similar to that caused by a steamer going up a narrow river, to run along the banks of the creek on which the house is built. Mongpai is situated in Lat. 19°30': Long 98°30’, approx. Mongpai, Siam. * a fae r ¥ a < Fi 5p Ot Bare Map) oe on TIME OF BARTHQUAKE AND RATE OF PROPAGATION OF SHOCK. g] PART II. CHAPTER IV. THE TIME OF THE EARTHQUAKE AND RATE OF PROPA- GATION OF THE SHOCK. It has not been an easy matter to obtain reliable time observa- tions of the earthquake, in fact the difficulties met with have been greater than those usually encountered in such enquiries. The epicentral area itself is situated in a_ sparsely populated portion of the Northern Shan States, and although crossed by a branch of the Burma Railways, has furnished but little trust- worthy evidence. Both for the adjoining, and for more distant regions, I have received various time data exhibiting different degrees of accuracy, and the sources from which they have come may be divided as follows :— 1. Letters from district officials and others. 2. Reports from station masters and from post and telegraph offices. 3. Automatic records of self-registering instruments in India. The records from the first category are the most variable. In a few cases, it is definitely stated that the watch or clock from which the observation was made, had been compared with that of the nearest telegraph office or railway station, but in others, the time is merely guessed, or no details of any kind are given. It might be supposed that in telegraph offices which receive a daily signal, or in railway stations where the constant running of trains demands due attention to a time-table, some considerable measure of accuracy would be approached. Such a supposition is erroneous, the causes being errors in the clocks themselves, and failure on the part of recorders to appreciate that exact time was required of them. Standard Time is generally used in Burma. According to information supplied to me by the Commis- sioners for the Port of Rangoon, it is 5 minutes G Standard Time. 82 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. 20 seconds ahead of Rangoon Mean Time, which is 6 hours 24 minutes 40 seconds (96° 10’) in advance of Greenwich Mean Time, whereas Burma Standard Time is 6 hours 30 minutes (97° 30’) in advance of Greenwich Mean Time. The official guide book of the Burma Railways states that Standard Time is kept at all the stations on the lme. An enquiry addressed to the Traffic Manager of the railway in Rangoon confirmed this, and _ elicited the further information that the railway administration receives a daily time signal from the Rangoon telegraph office. Railway Time. The Indian Telegraph Guide states that all telegrams are timed by Standard Time which in India is 5} hours, and in Burma 64 hours, in advance of Green- wich Time. I have been informed by the Deputy Superintendent of Telegraphs in Rangoon that this Standard Time is kept at all Burma telegraph stations, and that the time signal is obtained daily from Calcutta. Telegraph Time. The present investigation only adds confirmation to the opinions ' expressed by Oldham in 1899 and Middlemiss Great irregularity of . C : : ~ es sebardsd fines, in 1910, that in the outlying provincial districts in India, ‘‘ uniformly co-ordinated time is not yet recognised as a necessity, and therefore in spite of the well- meant daily signal it is not as a matter of fact, kept.’’(1), (2) After making a thorough examination of the times given in ees an 2. the descriptive part of this report, I have tidod in Gatotitationa. come to the conclusion that for the purpose of seismological calculations, the great majority of them from scattered places in the province are worthless, as the differences even in times which are said to have been compared with Standard Railway or Telegraph Time in the same towns, are often very apparent and mutually irreconcilable. Fortunately, in Mandalay, the chief city of Upper Burma, and in Maymyo, which is the summer headquarters of the Government * R. D. Oldham : Report on the Great Earthquake of 12th June 1897. Mem., Geol. Surv., Ind., Vol. XXIX, p. 53, et seq. * C. 8. Middlemiss : The Kangra Earthquake of 4th April 1905. Mem., Geol. Surv., Ind., Vol. XXX Viit,-p: 285, TIME OF EARTHQUAKE AND RATE OF PROPAGATION OF SHOCK. 83 of the province, a closer approximation is visible, as can be seen from the tollowing list :— Mandalay Time. | Standard. Observer, 8-57 Nostandard{stated “ - | Meteorological Reporter. 8-55 No standard stated Secretary to Municipality. 8-56 Clocks stopped Deputy Superintendent, Signal Office. 8-55 Railway Time Sub-Postmaster, Police lines. 8-55 | Post Office Clock Baad Sa , Hospital. 8-55 | Station Time . ; . . | Station Master, Myohaung. 8-55 Mandalay Clock Tower. . | Mr. Eades, Zigon. From this list other times which are uncorrected or which are obvious guesses, are omitted. The time given by the Meteorologi cal Reporter cannot be correct, for the clocks in the Mandalay telegraph office had stopped at 8-56 a.m., which was doubtless some time after the first violent movement had affected them. Turning now to Maymyo, the following list gives the more exact times which have been gathered together :— | Time. Observer. ——_— pow 8-55 °° exact ”’ | Director of Telegraphs. between 8-56 and 8-57 . : 2 - | Postmaster. 8-55 . 2 : . | Deputy Superintendent, Manda- | lay, Signal Office. SS The Postmaster in Maymyo informed me that his clock is regu lated by “‘ gun time.’’ I thereupon communicated with Capt. A. Thorp, the officer under whose orders the daily gun was fired in Maymyo and who replied as follows :— “The gun-is supposed to be fired in accordance with the time kept by the railway station clock and I send a watch to be checked by it every morning, but as the station clock is a very indifferent one, the amount that the watch (a very good timekeeper) differs from it varies 4 or 5 minutes every day. I do not alter the watchr daily so can only say that gun time is approximately railway station time. 1 have no record now (July 7th, 1912) how much difference there was on 23rd May........ , sO that I am in a position to say that by gun time the earthquake on May 23rd _ took place a few minutes before 9 a.m,” @ 2 g4 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912, Under these circumstances no reliance whatever can be placed on the times quoted by the Postmaster in Maymyo or on any others based on “gun” or railway time there. There remain the times given by the Director and the Deputy Superintendent of Telegraphs, and it need only be pointed out that they are in agree: ment with similar data from Mandalay. Most of the station masters in or near the epicentral tract sent the times at which the station clocks stopped, or approximate cuesses, evidently to the nearest five minutes. As examples Hsum- hsai, Nawnghkio, Gokteik, Pyaunggaung, Kyaukme, and Bawgyo may be quoted. The time records from the Southern Shan States and the Ruby Mines District are rejected for the same reasons. As far as can be ascertained from the data at my disposal ‘tents eines therefore, the earthquake was felt in Mandalay mont ot siete at 8-55 am., Burma Standard Time, on_ the morning of May 23rd, 1912, m Maymyo a few seconds earlier, and in the epicentral area a few miles to the east of this, slightly earlier still. The probable time of commence- ment of the shock therefore as accurately as can be determined, lies between say 8-54 and 8-55 B.S.T. Burma possesses one seismograph whichis of the Omori type and is installed in Rangoon College. Other instrumental records were derived from the seismographs of the Milne type in the meteorological observatories of Caleutta (Alipore), Kodaikanal in the Palni Hills and Bombay (Colaba), and from the Omori-Ewing seismographs in the same stations at Bombay and Simla. According to Middlemiss :— Instrumental Records. “If recent criticism of seismographic records is to be trusted (as to which specialists in this branch of science can alone speak with particular know- ledge), the Milne seismograph trace, which is very small and often blurred, cannot be trusted to show all those minute sub-divisions of regularly reecur- ring period and amplitude which the larger forms working with a large natural period of swing, register by means of a needle point on smoked paper, and which give an open or large scale diagram. The so-called preliminary tremors as seen in long-distance seismograms written by the Milne instrument, are, however, fairly well differentiated from the large movement which follows. The splitting of the preliminary tremors into two groups, first and second, is also believed by many to be sufficiently recognisable. However that may be, the beginning of the large movement is the only definite point that can be reasonably correlated with the sensible TIME OF EARTHQUAKE AND RATE OF PROPAGATION OF SHOCR. 85 earthquake wave or shock as felt in its progression from place to place over the surface of the affected area.’’(+) The data obtained from the Indian seismographic records are as follows :— Rangoon.—The Omori seismograph installed in the Rangoon College.—The shock commenced on the morning of the 23rd May at 8 hours 54 minutes 10 seconds, and lasted till 10 hours 3 minutes 30 seconds (B.S.T.). The shock was severe from 8 hours 54 minutes 10 seconds till 9 hours 13 minutes 30 seconds. The clock whose pendulum swings from east to west stopped as soon as the shock commenced. Through the courtesy of the Principal of the Rangoon College, I have been allowed to examine the original record taken by this instrument, but I do not think that any further evidence can be safely deduced from it, owing to the violence of the motion consequent upon the short distance of the station from the epicentre, and the unsatisfactory condition of the clock. Kodaikanal.—A_ good record was obtained from the instrument of the Milne type in this observatory (PI. No. 10). (All times given in this and subsequent data are referred to Greenwich Mean Time.) Time of commencement of Preliminary Tremors, 2 hours 29-0 minutes. i Pv re s Long Wave, 2 hours 29-5 minutes. »» 93 Maxima, 2 hours 39-9 minutes. Maximum Amplitude, 13-5=5-4 mm. we s Do ote oy ie s é i4:5=5-8 mm. xe 95 a yy: A oe ae i “ 16-0=6-0 mm. End, 6 hours 15-2 minutes. Duration, 3 hours 46-2 minutes. Alipore (Caleutia).—The record from the Milne instrument in this observatory was not satisfactory. Owing to air tremors the time of the commencement of the preliminary tremors cannot be given. The large movement is stated by the meteorological reporter to commence at 2 hours 26:1 minutes (7), but I think that this is very much open to question, after an inspection of a copy of the record. Owing to the boom moving throughout the trace, the time of maximum and the amplitude cannot be deduced. The movement ended at 6 hours 1°9 minutes (?). Sensibility, 1 mm-=-0°38 of tilt. 1 C. 8. Middlemiss : Loc. cit., pp. 290 and 291. See also Publications of the Earthquake Investigation Committee in Foreign Languages No. 24, p. 26. La Science Séismologique, by Le Comte de Montessus de Ballore, ‘p. 40. 86 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. Simla.—The following data were obtained from the two instru- ments of the Omori-Ewing type in Simla (PI. No. 8) :— A = East and West component. B=North and South component. Time of commencement of Ist Preliminary Tremor, A=2 hours 28-4 minutes. ”? 9 9 6 ea ” ” B=2 ”» 28-5 ” APO - Svan < e A=2 ,, 31-3 od ” 9 > 99 9 is B=? «4... tae a >) ae ” ” Long Wave, AMZ. 4s 35-6 79 ik $s sscipeoptani Bend Spe ag Owing to the style touching the stops, the time and displacements of the maxi- mum amplitude cannot be given. Time of approximate end of moyement, A=4 hours 36 minutes. 1B YN: Loam ye 93 ” ” ” »» 95 duration, Atere «ye AO Ss ” ” ” ” ” B=2 2: 8-5 > On the seismograph trace (Pl. No. 8), the following corrections to the minute marks are necessary to find Indian Standard Time :— Instrument with boom, E.—W. —2:‘7 minutes. N.S... -—22 - ” > 99 Bombay.—The following data were obtained from the Omori-Ewing instrument in Bombay (PI. No. 11) :— Time of commencement of the Preliminary Tremors, 2 hours 28-9 minutes. 2nd Phase ss D6 BOR na Large Waves, Dm DOM 6 99 99 93 99> 33 99 99 9? 99 %> The maximum was lost as the zero shifted and the pen lay against the W. stop, Approximate end of the movement, 4 hours 42-7 minutes. On the seismogram a smaller disturbance is noted which took place on the previous day, commencing at 23 hours 14-7 minutes. The Milne instrument in Bombay gave the iollowing figures (Pl. No. 9) :— Time of commencement of the Preliminary Tremors, 2 hours 28-9 minutes. ,, 2nd Phase Preliminary Tremors, 2 hours 33-6 minutes. 99 2? 29 93 Se ra "3 Large Waves, 2 hours 38-6 minutes. The Maximum (Ist) is timed at 2 hours 42-5 minutes. Ee > (2nd) , between 2 hours 43-3 minutes and 2 hours 44-1 minutes. For hours prior to the quake the trace is disturbed by small tremors and hence the previous quake is masked. ‘Two thicken- ings showing maxima, however, can be indicated at 22 days 23 hours 18°6 minutes and at 23 days 0 hours 3°9 minutes. ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 87 The vertical motion and tilt record from Bombay is as follows :-— The commencement of the Burma quake is timed at 2 hours 29-1 minutes, of the previous day at 23 hours 12°3 minutes. » ¥3 % " The times of commencement as recorded by this instrument are almost always earlier, but in a few cases they are either simul- taneous or slightly later than the commencements recorded by the horizontal pendulum seismographs (PI. No. 9). For the purposes of this calculation I take 8 hours 54 minutes Rate of Propagation 15 seconds, as the probable time for the be- of the Shock. ginning of the shock at the epicentre. The times of commencement of the large movement im the Indian seismographic records of the earthquake are as follows :— Hours. Minutes. Seconds. Bombay . ‘ ‘ : ° e~-9 8 24 Simla : . é ‘ waned +) 39 We therefore have :— ee, i , Re Distance in Seconds —— —— miles from during 4 oe on ‘ epicentre. transit. suse Ng second. Bombay : | 1,561 849 1-83 ae | te ae Simla 1,350 684 | 1:97 asi Sonne (REL, OS, | bawt | Mean mie | 1:90 The times given are all reduced to Burma Standard Time. I am indebted to my colleague Mr. C. 8. Fox for the calculation of the distances given above. THE ISOSEISTS. DISTRIBUTION OF INTENSITY AND CHARACTER OF THE SHOCK. The intensity of an earthquake is best inferred from the records of instruments designed for the purpose, and stationed in the districts over which the shock is felt. Owing to the absence of such instruments in Upper Burma we have to fall back upon the more general method, by estimating mtensities from the effects 88 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. of the quake upon mankind in general, upon structures of all sorts, and upon movable objects which they contain. The plotting of the isoseismal curves upon the map has been carried out almost entirely from the collated reports of various individuals who experienced the shock in different parts of Burma, and, following the custom hitherto adopted in similar investigations in this country, use has been made of the modified Rossi-Forel scale, The curves of course enclose zones of equal intensity, and in passing from one to the next we proceed through belts of greater intensity until the pleistoseismic area, or that portion of the earth’s crust which is immediately above the seat of the dis- turbance, is reached. Indeed, one of the many reasons for deli- neating intensity systematically is to locate this position and to make known any fault with which the earthquake may be connected, The study of the distribution of intensity may lead to the recognition of deep-seated portions of a fault not recognisable at the surface, or reveal other dislocations which happened at the time of the shock, by the sudden release of molecular strain in neighbouring portions of the region, or, again, auxiliary faults which bear some relationship to the main system. I.—Microseismic Shock—recorded by a single seismograph, or by some seismographs of the same pattern but not by several seismographs of different kinds; the shock felt by an experienced observer. (This number of the scale is now obsolete owing to improvements in seismo- graphs. ) Il.—Eatremely Feeble Shock—recorded by seismographs of differ- ent kinds; felt by a small number of persons at rest. Ill—Very Feeble Shock—felt by several persons at rest; strong enough for the duration or the direction to be appreciable. 1V.—Feeble Shock—telt by persons in motion; disturbance of movable objects, doors, or windows ; cracking of ceilings. V.—Shock of Moderate Intensity—felt generally by everyone ; disturbance of furniture and beds; ringing of some bells. Vi.—Fairly Strong Shock—general awakening of those asleep ; general ringing of bells; oscillation of chandeliers ; stopping of clocks; visible disturbance of trees and shrubs. Some startled persons leave their dwellings. VIL.—Strong Shock—overthrow of movable objects; fail oi plas- ter; ringing of church bells; general panic, without damage to ‘Lhe Rossi-Forel scale. ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 89 buildings. (Owing to poor material and construction in India damage to buildings is considered to begin here.) VIUL.—-Very Strong Shock—tfall of chimneys, cracks in walls of buildings. IX.—Ezatremely Strong Shock—partial or total destruction of some buildings. X.—Shock of Extreme Intensity —-great disasters, ruins, disturbance of strata, fissures in the earth’s crust, rock falls from mountains. A revised and simplified scale was adopted by the Commission appointed to investigate the California Karth- Acaivetentoenietiene quake of April 18th, 1906. Degrees VIII, IX and X agree with the above. The first seven are as follows :— I.—-Perceptible—only by delicate instruments. Il.—Very Slight Shock—noticed by a few persons at rest. I1.—Slight Shock—of which direction and duration were noted by a number of persons. 1V.—Moderate Shock—-+reported by persons im motion; shaking of movable objects ; cracking of ceilings. V.—Smart Shock—-generally felt ; furniture shaken; some clocks stopped ; some sleepers awakened. VI.—Severe Shock—general awakening of sleepers ; stopping of clocks, some window glass broken. VII.—Violent Shock—overturning of loose objects; falling of plaster ; striking of church bells; some chimneys fall. There are many uncertain features about both schemes. The personal factor of course enters very largely, for different observers interpret the same event in different ways. The Commission point out that the stopping of clocks is a very uncertain criterion of intensity, a statement well substantiated m the present case too. Again, with regard to degrees VI, VII, VIII and IX of the Rossi- Forel scale, in which damage to buildings is relied upon for an estimate, two important factors are given which tend to vitiate the conclusions arrived at as to comparative intensity. These are, the great variability of the structures themselves, and the nature of the ground upon which they are built. The scale was probably designed originally for regions where brick and masonry — struc- tures prevail; in California wooden structures are by far the most Disadvantages of the scale. 99 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. common. The same is true for Burma probably to a greater degree still. “Wooden houses by reason of their greater elasticity, are usually much better adapted to withstand the wracking movement of an earthquake shock than are brick and masonry walls. The intensity as inferred from a region of wooden buildings, would therefore, in general appear to be less than that for a region of brick or masonry structures. Even among the latter, and among the brick chimneys of wooden houses, which are so generally used as indicators of intensity, there is a great variation in strength due to the variation chiefly in the character of the mortar used in their construction.’’(') The prevailing custom in the district towns of Burma is_ to build houses with wooden frames, the panels of which are filled in with brick-work. This adheres to the wooden framing with ereater or lesser cohesion depending upon the character of the ori- sinal structure and the age of the work. Now although intensity inferred from damage to wooden buildings appears to be less than that computed from the partial destruction of brick structures, it must not be forgotten that panels of fairly loose brick nogging, especially those fillmg in the frames of high parts of end or parti- tion walls, do not require much shaking to bring them down. Another point to which the Californian Commission draws atten- tion and which is of interest to us m Burma, Fissures in the ground deals with the question of fissures in the as a measure of inten: SAL " sity: ground, taken as a criterion of the highest erade of intensity and placed in grade X of the Rossi-Forel scale. As a matter of fact the value of such a criterion entirely depends on the circumstances under which such a fissure is formed. Those which are due to actual rupture on a fault-plane are significant of the highest degree of disturbance, but cracks which occur in the bottoms of alluvium-filled valleys, or near a stream, or cracks which are associated with earth or rock- slides, when the slide was imminent and merely precipitated by the shock, are superficial phenomena and do not actually indicate so high a degree of intensity as X on the Rossi-Forel scale. The subject will be referred to in a_ later paragraph in connection with fissures caused by the Burma quake near Kyaukse. Again, ‘1 The California Earthquake of Isth April 1906. Report of the State Earth- quake Investigation Commission. Vol. I, Pt. 1, p. 161. ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 9] the detailed study of numerous earthquakes has made it abund- antly clear that on river bottoms and valley floors, especially when the latter are water-logged, buildings are more susceptible to damage than similar structures built on solid rock. The regions affected by this earthquake comprise some of the most thinly populated country in the Indian Empire, indeed everywhere in Burma the popu- lation is under 100 persons per square mile. In addition to this, the most severely shaken area lies within the wildest and most thinly populated portion of Burma, that is to say in the western regions of the Northern Shan States, and about their borders with Mandalay and the Ruby Mines Districts and with the Southern Shan States, etc. It has for this reason been found necessary to group together the lower members of the Rossi-Forel scale as shown below, a practice already established by Oldham(') and Middlemiss(?) in the accounts of the great shocks of 1897 and 1905. For the same reason | am unable to draw the curve which encloses the small area over which an intensity of LX was reached. A grouped — scale aclopted. | a Pb Grouped members of the Rossi-Forel scale. | Definition taken here. Ce II and IIL - $ : : . i | Felt by a few sensitive people lying down or favourably situated. IV and V . : i . < . | Generally noticed, no damage. Shaking of beds, ete. Vl and VII | Universally felt. Upsetting of small loose objects. No damage | except in rare instances, to burnt brick structures. Small cracks ; and damage to sun-dried brick / and mud buildings. The resulting curves are shown on the map. It is not contended that they are highly satisfactory, or comparable Paws only approxi ith the elaborate delineations given on recent maps of the great earthquake-shaken regions of 1 Qldham : Loe. cit., p. 42. 2 Middlemiss : Loc. cit., p. 303. 92. COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. the world, From the northern and eastern portions which he about or across the frontier and are inhabited by wild tribes, I have obtained no information. Moreover, had facilities existed for visiting these areas or obtaining information from them, it is doubtful if anything of much value would have been obtained, owing to the flimsy nature of the bamboo houses in which the greater part of the population exists. As it happened, | had to abandon any attempt to tour through the regions in question, owing to pressure of work elsewhere, but I am convinced that very little has been lost. The curves have been drawn in accordance with what little is recorded and only an equal amount of value can be attached to them. Isoseists VIII and IX. (1)—Descrtprion AND GENERAL LNTENSITY. The innermost isoseismal line shown on the map (PI. No. 7) encloses an area of approximately 36,000 square miles, over the ereater portion of which the shock reached an intensity of VIIE on the Rossi-Forel scale. (As mentioned in a previous paragraph, suflicient information does not exist to permit of the delineation of the line enclosing the area over which an intensity of IX was reached, but it must be a small area lying mainly about the Kyaukkyan fault and roughly coinciding with the central portion of the oval enclosed by line VIIL.) The longer axis of this oval runs in a general north and south direction, and the area includes the whole or greater part of the districts of Mandalay, Sagaing, Kyaukse, Meiktila, Yamethin, Shwebo and the Ruby Mines, small portions of the districts of Bhamo, Lower Chindwin and Myingyan: practically the whole of the Northern Shan States of Hsipaw (with Tawngpeng and Monglong) and Mongmit: parts of North and South Hsenwi, Lawk Sawk, Mongkung and the group of smaller States in the south-west corner of Southern Shan States overlooking the Burmese plains. It embraces the city of Mandalay, the towns of Maymyo, Mogok, Sagaing, Shwebo, Mongmit, Lashio, Hsipaw, Kyaukse, Thazi, Meiktila, Yamethin and Taunggyi, and numerous smaller places. Maymyo itself probably lies just outside the borders of the area of intensity IX, all the other places experienced the lower degree of intensity, namely VIII. Area and boundaries. ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 93 Two railway lines traverse the area: (1) The main line of the Burma Railways from Rangoon to Mandalay, Parts of the. a and its continuation on the other side of the Sa * Trrawaddy from Sagaing to Myitkyina. Enter- ing to the south of Yamethin and leaving just to the north of Shwebo, the line cuts across the western part of the oval, more or less parallel to its long axis. This line and the telegraph which runs alongside it were entirely un- damaged. (2) The other line is the Shan States branch of the Burma Railways which runs from Mandalay to Lashio over the upper part of the oval from south-west to north-east. Although it rises from the plains in a series of zigzags overhung by preci- pices of very folded strata, and crosses several well known faults, the line was only damaged to the east of Maymyo on the “plateau ” itself, where it crosses the great Kyaukkyan fault. This fact adds confirmation to the view already arrived at from a study of the distribution of the intensity, namely that the earth- quake was connected in some way with this fault. The railway lines were bent into a smooth curve close to the actual line of the fault, while cuttings and earth banks in the vicinity had slipped and blocked the line. To the north and south of this poimt and in the neighbour- hood around, the greatest intensity of the quake was experienced. Cracks in the cliffs near Myinpyu gave out streams of mud and water which were voluminous enough to overwhelm and_ partially destroy Shan houses. Fresh cracks opened in the eround on the Myinpyu hill, and from Kyaukkyan in the Namma circle to Seikpyu, At the latter place a hot spring dried up. Near the northern end of the fault, land and rock slips took place and completely blocked up the Nam-pan-se stream for a time, after which the water forced its way through the barrier. This stream flows along the course of the northern end of the Kyaukkyan fault for some 4 or 5 miles before crossing it. Other landslips happened in various places; indeed, I was informed that the dust from them was visible for days along the Kyaukkyan fault, and gave rise to the belief amongst the Shans that a volcanic eruption had taken place. The creat diversity of architecture within this region tends to complicate deductions regarding the intensity. Throughout the most shaken area, practically no stone or brick edifices exist outside the Variety of Architec- ture. 94. COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. towns, with the exception of those of a religious character,—the Buddhist pagodas of varying ages and styles. In towns like Maymyo buildings are composed of :— Brick nogging. Brick in lime mortar. Brick in mud mortar. Sun-dried brick in mud. Bamboo mat and thatch. On the whole, it seems best to characterise the damage here as moderate, with the proviso, gained from a careful study of the results of the shock, that the damage would undoubtedly have been very much greater if more houses had been built of stone and brickwork in lime of the ordinary type. Practically every pagoda which I saw had crumbled or been shaken down for the greater part of its height. Every fair-sized brick buildmg in Maymyo suffered more or in less damage. Good examples of solid brick and FH abanie., sige cil masonry structures existed in the kitchens of the British Infantry barracks; many of these were very badly cracked and shattered, and most were injured to some extent, affording an illustration of the probable result if the station as a whole had been built after the same fashion. The garage of Government House which was also a strongly built brick building was completely shattered. Brick nogging buildings fared much better. Lower panels sometimes cracked and_ high eable panels rocked out of their frames, causing considerable damage as they fell. Plaster from walls and ceilings was shaken off, and bricks, especially along the tops of walls, were often loosened. Complete destruction was conspicuous by its absence, and this I believe is to be put down to the elasticity of the wooden frames of the brick nogged bungalows. The brick chimneys which are a feature of the bungalows in Maymyo suffered greatly. In most cases they fell or were so badly cracked that dismantling was imperative. Considerable damage was caused to roofs and ceilings by falling chimneys. As was only to be expected from its lack of cohesion and strength, work composed of brick in mud mortar, and sun-dried brick in mud was badly shattered and cracked by the shock, ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 95 The bungalow used as a rest-house near the Gokteik railway station was shattered and rendered uninhabitable. Land- ships took place in the gorge itself, and large rocks fell from the roof of the cave through which the stream in the bottom of the gorge flows. Two landslips occurred near the tunnels beyond the station, while the viaduct itself was very slightly displaced. From a perusal of the detailed accounts of the damage in Mandalay, it might be thought that the shock reached a higher intensity there than in Maymyo, but two considerations have led me to the opposite conclusion. Mandalay is built on a thick cushion of alluvium which fills in the bottom of the Irrawaddy valley, and it is well known that actual sinking of the ground in such situations, can wreck and injure buildings independently of any clastic vibration communi- cated to them from the ground, and on the motion of which the intensity of the shock itself depends. Damage at Gokteik. Damage in Mandalay. Again, the age and construction of the buildings which collapsed in Mandalay compare very unfavourably with those of the newer and better built ones in Maymyo, situated as they are on the plateau of the Shan States. Witnesses declare that it was very difficult to stand during the shock in Mandalay. The ground between the fort wall and the moat was cracked in places. Three quarters of the brick structures im the city were more or less cracked, and nearly every pagoda and brick monastery was damaged. At Hsipaw the railway medical store and various places of business were badly damaged. In Mogok and Taungeyi brick nogging buildings suffered in the same way as in Maymyo. In both these towns every masonry structure seems to have been more or less damaged. Collapsed and shattered chimney stacks were common, and cracks in walls over doors and windows, especially in north and south and in cross partition walls, were very generally caused. Considerable damage of a similar kind was caused to the Govern- ment buildings in Meiktila. Cracks opened in alluvium for a length of 150 feet, and gave forth sand and water near the Zawgyi river to the south of Kyaukse railway station. Throughout the area enclosed by isoseismal VIII the majority of the Burmese and Shan pagodas were wholly or partially broken down. Damage at other a places. 96 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912, Accounts of the damage in other places can be found in the first part of this report. (2) CHARACTER OF THE Suock. The preliminary tremors which precede a great earthquake seem to have been absent or of unusually short duration. The shock itself is described as very severe by most observers, and the dura- tion is given generally as 1—1} minutes, Some witnesses state that the shock was divided into three distinct periods, but others do not mention this peculiarity. The following are among the more characteristic descriptions of the shock :— (1) Appeared to be a shaking underfoot rather than a distinct wave motion. (2) Like the sensation experienced in a big building in which a high speed engine is running. (3) Like a child’s cradle being roughly pushed backwards and forwards. (4) Like a ship at sea. (5) The earth seemed to be in ripples as if disturbed by waves of great frequency. (6) It required a considerable muscular effort to stand: women were thrown to the ground. (7) Saw the earth moving towards him in waves about 1 foot high and 2 fect distant from each other. (8) Unstable articles like lamp-glasses and wine glasses over- turned; hanging lamps thrown out of their supports ; brick chimneys crashed through ceilings. Windows rat- tled backwards and forwards. (9) Clocks jerked forwards ; bottles and ornaments thrown down ; books shot out of book cases. (10) Ground rose and fell like the waves of the sea; pagodas crumbled as though sliced with a knife; trees swayed and ground cracked. Sounds were very generally heard throughout the area both before and during the shock, and are compared to low rumblings and to distant thunder. Although there is much contradiction, general opinion places the direction of the shock in Mandalay and Taunggyi as approximately north and south. In Maymyo there is evidence of motion at right angles to this. Conclusion. ISOSEISTS. DISTRIBUTION OF INTENSITY, ETC. 97 The shock certainly appears to have been split up into 3 or 4 separate periods, each with a maximum intensity of its own, but diverse surface conditions, and, perhaps, subconscious personal idio- syncracy, have obscured this in some places. Isoseists VI and VII. The area circumscribed within the grouped isoseists VI and VII amounts to approximately 82,900 square miles, and like the later grouped areas IV and V, and II and III, it is bounded by a smooth curve joining up the somewhat isolated places from which accounts were received (Pl. No. 7). The detailed accounts of the shock have already been given, and it only remains to summarise them briefly here. As a glance at the map will show, these grouped _isoseists contain the headquarter towns of Monywa, Katha, Bhamo, Myingyan, Pakokku, Toungoo, the southern part of the State of Karenni, and a belt of country comprising the eastern portions of the Northern Shan States: and the central portions of the Southern Shan States. Unusual sounds were still heard in some places, and many buildings were cracked, but not sufficiently to cause even partial destruction or the widespread fissuring of all brick structures as found in the area of higher intensity. Cracking of walls though common m some places, is by no means universal and has generally taken place near doors or windows. An occasional brick nogeed panel has dropped out, plaster has often fallen, and old pagodas have had part of their tops carried away. The shock seems now to have lost a good deal of its sudden- Description of the Ness and to have become more even and prolonged. shock. It is described as follows :— Area and bounda- ries. Cracking of build- ings. (1) The observer could not follow a straight line in walking and lost the sense of height in stepping. He became intensely giddy and experienced the sensations associ- ated with sea sickness. High trees swayed. A wooden bungalow creaked and groaned and dogs rushed out and barked. (2) Cooking pots and cups were thrown over, hanging lamps swung. H 9g COGGIN BROWN : THE BURMA BARTHQUAKES OF MAY 1912. (3) The earth distinctly rocked. Plaster fell and glass was thrown to the floor. (4) Trees swayed, water in fire buckets moved. Pagoda tops broken off. General panic. (5) House rocked, inmates rushed out in alarm. Children could not stand unsupported. The jerky motion of the central area was converted into more undulose waves, which seem to have been responsible for the wide- spread nausea, sickness and giddiness, which is an ever recurring statement in the reports from the districts where an intensity of VI—VII was experienced. Isoseists IV and V. The area enclosed within this isoseist is only shown on the north, west and south-west of the epicentral tract, for in the other directions it comprises the frontier regions of Burma with the Chinese province of Yiinnan, and the Kingdom of Siam. These regions are very difficult of access, sparsely inhabited and devoid of postal communications except along one or two widely separated routes. Towards the north it embraces parts of the Myitkyina and Katha districts, on the west and south-west the greater portion of the central basin of Burma including parts of the Pakokku, Minbu, Magwe and Thayetmyo districts, running down into the districts of Prome and Tharrawaddy, into Pegu and the Irrawaddy and Sittang deltas. This is the area where the shock appears to have been felt by the majority of the people, but where no damage was caused, except in one or two cases where it is expressly stated that the structure in question was old and rotten. first was | Maymyo. | very sharp, and brought down a lot of | | plaster which had been used to j-atch up | the damage done | y the great shock. Do. 15th . | Midnight | Loikaw. Do. 16th . | 12-5 (Midnight) : ; ; . | Mandalay. 3 shocks. Duration 6 seconds. Strong | | enough to throw down loose o’ jects. | | Awakened observer from a deep sleep. | | 12-10. Duration 3 seconds, 2 shocks. | | Slight. 12-15. Duration 3 seconds. 1 | shock. Slight. Do. do. 12-11 aM. . | Momeik. Do. do. Midnight | Mogok. Do. 18th | 4 A.M. Quite severe but caused no serious Do. | damage. Do. 26th . | 9-25 a.m. Momeik. | CE ee TIE SN ES ee cee In addition to the list of shocks given above, more general reports were received from other places and are given on the next page. K 130 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY 1912. Mandalay, May 27th, 1912.—‘‘ There is scarcely an hour, day or night, without its slight shock or tremor, Since I started writing this letter I have felt 3 distinct tremors, and it is not imagination for mortar dust has at the same time been falling from the cracks in the plaster.”’—(‘ Burma Critic.”’) Mandalay, June 10th, 1912.—‘‘ We are daily having slight earth- quake tremors here since the severe shock experienced a fortnight ago, and those living in pucea [brick] houses are having an anxious time.’’—(‘‘ Rangoon Gazette.’’) Maymyo, June 4th, 1912.—‘‘ Earthquake shocks of very slight intensity, but some of curiously long duration, considering their weakness, continue to recur once or twice during the 24 hours and people still consider it ‘wise to sleep under canvas fearing lest an- other severe one may follow.’’-—(“‘ Rangoon Gazette.’’) Maymyo, June Ist, 1912.—‘* Earthquakes still continue at re- gular intervals, but none of the shocks are very bad ones and no further damage has been done. A general exodus from the station is taking place as a result of the continuance of the trouble.’’— (‘‘ Rangoon Gazette.’’) Maymyo, June 11th, 1912.—‘* We still have an earthquake shock now and then, chiefly at night, but none are very violent and no one takes much notice of them.’’—(*‘ Rangoon Gazette.’’) Nawnghkio (North Shan States).—Slight shocks were being felt up to July 4th (date of the letter), and were sometimes accom- panied by a low rumbling noise. Taunggyi.—‘* Since then (the main shock of the 23rd May 1912), there have been shocks, mostly slight, with occasional severe ones every day, and although the disturbance would seem to be over earth tremors are still felt.’’ Southern Shan States, South-Eastern Sub-division.—‘‘ After this (May 21st 1912) shocks were experienced for about 20 days.’’ Southern Shan States, Western Sub-division.—‘‘ For the succeed- ing 20 days or so there were other shocks, usually slight.’’ Southern Shan States, Yawnghwe.—‘‘ For several days after May 23rd, 1912, small shocks were noticed.’’ Ruby Mines District, Mogok.—‘‘ No record has been kept of the subsequent shocks in Mogok and Thabeikkyin, but for about a month afterwards shocks of different intensities were experienced from time to time,”’ AFTERSHOCKS 131 Sagaing District, Sagaing—‘‘ No detailed record of aftershocks was kept but they continued nearly every day for a month.’’ Shwebo District, Shwebo.—‘* During the next few days there were almost imperceptible tremors at intervals.’’ Maymyo, August 12th, 1912.—‘* The earthquakes are very slight, so slight that many people do not even notice them.’’—(‘‘ Rangoon Gazette.’’) For data regarding most of the aftershocks in Maymyo I‘ am indebted to Dr. Finlayson, Geologist to the Indo-Burma Petroleum Co., Ltd. Unfortunately he left the station on June 8th and I was unable to find anyone ready to complete the list which he had started. He wrote that the times were taken from a watch correct with the 12 o’clock (midday) gun. As regards aftershocks during the night, the fainter ones, which must have been frequent, would not arouse sleeping persons. The stronger ones were suffi- cient to awake and disturb light sleepers. All the effects were noted and recorded in Messrs. Steel Bros. brick bungalow. Most of the after tremors would fall in degrees I and II of the Rossi-Forel scale and two or three of the tremors in degree III. Reports appeared in the Burma press of July 27th, 1912, ; oe concerning two slight earthquake shocks felt The Bassein Earth- . : : quake of July 26th, ™m Bassein on the previous day, one at 1912. 1-54 a.m. and the other at 3-20 a.m. Later, the Meteorological Observer in Bassein reported that an earthquake took place at 1-59-58 a.m., and lasted for one second. He was awakened by the shock which had a shaking movement and caused hanging objects to swing slightly. No unusual sounds were noticed. I do not think that these shocks were in any way connected with the movements faking place in Upper Burma. They are re- garded as purely local and originating either in the Irrawaddy delta or the rocks below it. They belong to the same category as the two Calcutta earthquakes of 1906 described by Middlemiss.’ Aftershocks in May- myo. 1 Two Calcutta Earthquakes of 1906, C. S. Middlemiss. MJer., Geol. Surv., Ind., Vol. XXXVI (1907-08), pp. 214-232. 132 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. CHAPTER VII. THE EARTHQUAKE AND BUILDING CONSTRUCTION. The damage caused to brick and stone buildings was far more severe than to those of wood, or of wood and laa and masonry brick nogging. Although as a rule left stand- ing, most of the mjured brick and stone walls contained numerous large and small cracks (Pl. No. 5). In a few very bad cases walls collapsed or the top parts near the roofs were shaken away. Cracking was most prevalent near lines of weakness caused by the presence of windows, doors and_ arches, but did not as a rule cross the bricks themselves, following rather the mortar binding them together. Wooden structures suffered much less than those of brick and stone, though judging by the damage to loose objects contained in them, they felt the shock to much the same extent. The indigenous Shan and Burmese houses were hardly injured at all. They are practically earthquake proof. The high panels in brick nogging walls, and the gables in similar positions were frequently shaken out and the lower ones cracked, but where the keying of the frames was well done and in good condition, with the exception of minor damage to plaster ceilings and to chimneys, little further injury was caused. It may be taken for granted that nearly all the brick chimneys of houses in the severely shaken areas were damaged. Some seemed to have been lashed off whole at their junctions with the roof. Others appear to have crumbled away and cases were observed in which chimneys although standing had been twisted around through quite large angles, while others were shattered or cracked in all direc- tions. Not only was such cracking found in those portions of the chimneys projecting above the roof level, but it often extended down into the flues, which were also occasionally broken away from the walls of the house. The situation of the site and the character of the mortar used in construction probably account for these bewildering variations. Wooden houses. Brick nogged houses. Brick chimneys. eee ee ee Ee THE EARTHQUAKE AND BUILDING CONSTRUCTION. 133 CONCLUSIONS. Although the mouern type of bungalow in Maymyo (Pls. Nos. 3 and 4), stood the shock remarkably well, it is perfectly evident that much of the damage which was caused, both here and in other towns, could have been avoided by judicious construction, if the lability of the district to disastrous earthquakes could have been foreseen. That such a danger exists is now only too apparent. It is a comparatively easy matter to bwild houses at ‘Slightly —_-modifil’ g reasonable cost which are to all intents birck nogged bunga- low necessary. and purposes earthquake proof, yet I do not consider it expedient to advocate any consider- able departure from the broad lines of the general type of brick nogged bungalow a sketch of which is appended (Pls. Nos. and 4). In the first place it is useless to urge the construction of earthquake-proof buildings while earthquakes are isolated occurrences, hardly remembered a few months after they have taken place. The prejudices of custom, helped out by the more immediate demands of economy and convenience, have already proved themselves powerful enough to override considerations of absolute safety in districts which have experienced the most appalling results of the strongest earthquakes. Furthermore, the ordinary type of brick nogged bungalow with a few modifications seems to me fitted to withstand shocks of the intensities des- cribed in these pages. I shall therefore content myself by bringing forward the results which the present investigation has revealed in this connection, by means of which I believe a further margin of safety may be added to the peculiar type of house, which the special local conditions in Upper Burma have brought into existence. Perhaps the best description of a resistant type of wooden structure, which might be combmed with the designs of the bungalows of towns like Maymyo and Taunggyi, is that which the Californian Earthquake Commission put forward as a result of their researches. It is as follows :— ‘The building should be of wood, and a wooden sill should be bolted to a deep-laid concrete foundation, the top of which should be but little above the level of the ground. It should be ceiled with wood within. Shelves for dishes should be closed in Californian — earth- quake-proof bungalow. 134 COGGIN BROWN: THE BURMA EARTHQUAKES OF MAY 1912. with doors, or should at least have strips along the front edges. The chimneys should be laid with cement mortar and boxed from a foot or two below the roof to the top, and the parts above the roof should be braced with iron rods. The lower the structure the less strain it will be subjected to. Such a building would be practically proof against earthquakes having an intensity below X on the Rossi-Forel scale.’’(') It is also poimted out that steel frames and reinforced concrete structures are eminently well adapted to resist earthquake shocks of high intensity. The reinforced concrete roofs of the military hospital m Maymyo did not fall or crack. Some of the girders moved and crushed the walls under them, but this would have been avoided if bed plates had been frovided. The frames of brick nogged houses then should be as low, solid and strongly keyed together as possible. The upper panels of walls and gables should be filled in with wooden boards. The brick work of lower panels runs less chance of being rocked out during a shock, but it should be firmly bound together, and some means devised of clamping it to the woodwork in a better way than is the custom at present. Plaster on inside walls, and ceilings, and plaster or stucco on the outside of houses, should be avoided as far as possible. Attention should be paid to the foundations on the lines indicated above. Any break between the foundations and the upper structure of a house, as inthe case of a wooden building erected on brick or masonry pillars is dangerous. On the other hand, foundations like the long teak post, let deeply into the ground as is often done in the construction of bungalows in Burma, ensures a considerable element of safety.(*) Reinforced concrete. Construction of modi- fied bungalow. The present method of constructing chimneys must be a perpetual menace in a situation liable to earthquake shocks. It is recommended that chimneys be built as light and low as possible, that the brick courses be braced together with iron rods used as clamps, and that they should be, as far as practicable, provided with casing boxes or a coating of cement. Present chimneys a source of danger. 1 Loc. cit., Vol. 1, Pt. LU, p. 358. 2 See Montessus de Ballore: La Science Seismologique, p. 485. | : | BURMESE ARCHITECTURE, 135 Chimney pots, galvanized iron pipes and stove pipes are to be preferred to brick structures. During the Californian earthquake their efficiency was conclusively demonstrated, for in the San Mateo county where a survey was made, 90 to 95 per cent. of such chim- neys passed through the earthquake without harm, whereas no less than 88 per cent. of the brick chimneys fell. To avoid the great damage caused by the pitching of solid masses of masonry on to roofs, or to the cracking of chimney flues both above and below roof level, some modification of the patterns in use at the present time is highly desirable.(?) That houses built of burnt bricks in mud mortar or of unburnt sun-dried bricks in lime or mud mortar, are Fe eae sun- totally unsuited to withstand earthquake shocks of high intensities, is a self-evident fact which needs no emphasis here. BURMESE ARCHITECTURE. The following notes on Burmese architecture are taken almost entirely from the report of Mr. F. O. Oertel reproduced in the ‘‘ Upper Burma Gazetteer.” (*) They will explain how it is that no native buildings, except those connected with the religion of the country, suffered any severe damage. Sumptuary laws have in Burma, from very ancient times, re- es stricted the use of all durable building materials ae native build- such as brick and stone masonry, and all = architectural adornments to religious and royal edifices. The people live now, as probably they always did, in single-storied huts, raised a few feet above the ground and constructed of bamboo frame-work with split bamboo floors and and mat partitions. The richer people use teak posts and boarded partitions instead of bamboo. The roof is thatched, tiled or in some cases covered with wooden shingles (Pl. No. 1). There are three distinct types of religious buildings in Burma which may be classified as follows :— 1. Solid pagodas, or topes enshrining relics, such as the Shwe Dagon Pagoda, Rangoon. 1 Since these lines were written I have seen the designs of a good type of earth- quake-proof chimney which is now built in Maymyo by the Public Works Department . 2 The Upper Burma Gazetteer, Vol. II, Pt. 1, pp. 168-175 136 COGGIN BROWN: THE BURMA BARTHQUAKES OF MAY i912, 2. Carved and ornamented wooden monasteries (pongyt kyaungs) including the royal paiace at Mandalay, rest-houses (zayats), wooden shrines, theins, tazaungs, and the like. 3. Masonry temples, such as the Ananda and others, peculiar to Pagan and other old sites in Upper Burma. We are only concerned here with buildings of the first class, the wooden structures of class 2, escaped with very little mjury, while an examination of the ancient Pagan temples which I made two months after the earthquake, proved that they suffered little or no damage. Pagan temples un- injured. The common classification of solid pagodas (which are unques- tionably the direct lineal descendants of the Cl ssifi ‘ati VO- . . + . y P da en P88" ancient Indian Buddhist stupas), or zedis, is as follows :— | 1. Dat-daw Zedi, those containing relics of a Buddha or Rahanda. 2. Paribawga Zedi, those containing implements or garments which have belonged to the Buddhas or sacred person- ages. 3. Dhamma Zedi, those containing books or texts. 4, Udeiksa Zedi, those built from motives of piety, and con- taining statues of the Buddha or models of sacred build- ings. The last two classes are by far the most numerous, and the devastation which the earthquake caused to such buildings in the Shan States and Upper Burma was confined to these groups. Most of the Burmese pagodas are constructed of brickwork and . covered with stucco. Their peculiar method Construction of Bur- f — b f h ded mese pagodas. of construction can be seen from the appende drawing (Pl. No. 2). Stone and laterite have also been used but this is very rare. The outside is usually whitewashed, and in some cases richly gilt as well. They are slender conical piles, the chief peculiarity of which is the inward curvature of the contour on both sides. Shan pagodas are very much more slender in the spire than the Burmese ones. They retain the hti or umbrella which the Siamese pagodas discard. All the larger pagodas stand on a wide, open BURMESE ARCHITECTURE, 137 platform. On this, surrounding the main shrine, are a number of smaller pagodas, shrines or tazaung-pyathats. The Burmese divide important pagodas into twelve parts :— le 3, chs 3. . The “) The The The >. The The The The . The . The . The base with the surrounding pagodas, or shoe. three terraces, called pichaya. bell. inverted thabeik or alms bowl. twisted turban or baung-yit lotus flower or kyalan. plaintain bud. brass plate for the htz. Ati. artificial flowers or seimbwin. vane. bud of diamonds or seinbu. A less elaborate division is into four parts :— 1. The square masonry or brick work terrace. 2. A high plinth of a boldly moulded stepped contour, generally of elaborate polygonal form in_ plan. 3. The bell-shaped body of the pagoda, divided into two por- tions by an ornamental band. .. The spire, consisting of a number of rings; a lotus leaf band, with a bead moulding in the centre and leaves above and below, pointing in opposite directions; a terminal carrot-shaped cone, surmounted by the gilt metal-work crown, or ftv. This is generally made of pierced iron-work, and consists of several rings rising in diminishing stages, and finished off with a long iron rod. When not completely broken down the pagodas were often smashed off at the top or middle of the bell- shaped body. rE ae agate oP Se See cond apt INDEX. A Page. Aftershocks < . 124, 131 * distribution of 124 ‘ list of . . 124, 129 Akyab 68, 69, 100 Alipore seismograph trace 84, 85 Allanmyo 68 Amherst ; 74 Anisekan 33, 118, 128, 129 Arakan, Northern 68 Architecture, Burmese 135 Assam 6, 99 B Ballore Montessus de I, 102, 134 Bampon . : 44 Bangkok ; .76, 77, 78 Banmauk ° 57 ‘“ Barisal guns ”’ - 113 Bassein . : " ; ; a é 73, 99 3 earthquake of July 12th, 1912. . 131 Bawgyo : ; ; ; ‘ ‘ 35, 84 Bayat Monthon : : : . . . 78 Bengal ; : . : : ‘ . 75, 100 Bhamo . ; ; ; ‘ : yur 8, 5d, 92, 97, 105, 111, 112 Bombay Sasrieoaagh traces 84, 86, 87, 122 Buildings, brick : . 132 * brick nogging ° . 132 ss construction of, in natn ts the acninees 132 m wood F : 132 Bungalow, Californian Senthqrtckosntok . « 133, 134 » modified brick nogging . 133, 134 Burma-China frontier ‘ 105 Buthidaung 69 140 INDEX. Caleutta earthquakes Californian earthquake commission Charleston Chaung Magyi fault series Chiengmai Chiengrai Chimneys, brick Chindwin, Lower er Upper Chin Hills Chitral Chittagong . Concrete reinforced . Davison, C. Drosh : Dutton, C. E. Earthquake of May 18th, 1912 : YASG 5 : y x 5 ee 2s ee : $3 » 23rd, 1912, cause of rate of propagation sound phenomena > 3 %”> 9° °° ” > ” time of et . Falam . 3 Z Faulting of the Northern Shan States ; ‘ Fissures in the ground Fluviatile deposits . - ; : J . Focus, depth of : ; , , : . Fox, G, S. 8 A 2 - " ; . Page. ‘ 131 89, 90, 115, 133 6 105 . 108 . 106, 109 76, 78, 122 78, 122, 126 . 133, 1385 5, 59, 60, 120 59, 92 74, 100 75 75, 100 134 INDEX, 141 G Page. Geological structure, Northern Shan States : ‘ P : $ 104 Gokteik , : ; , . . . ; : . 8, 35, 84, 95 » gorge . : F s : . . , : ; 109 » viaduct ; : : ; < : ; : . ; 35 Griesbach, C. L. : : , ; ” , . ; : . 105 Gulmarg : ‘ : : ; : ‘ ; ; : . 75 H Haka . . . . . : . : . : ; : 74 Hanthawaddy : ; ‘ : . 2 : ; 71 Heho . , . ; : . . . . ‘ ‘ ; 42 Henzada ; ‘ . . . . . . . : . 71 Himalayas. : . . ; . : : : : . 76, 107 Holland, Sir T. H. . ; : . . ; . . . ; 110 Hpawng-aw . . ; ; ; . ; é ; ‘ 109 Hsenwi, North . . : , ; . , , F . 37, 92 - South ; ; : ; ; . j ; . . 87, 92 Hsipaw . : : A : : : : . . 8, 36, 37, 92, 95 Hsum-hsai . : . , . . . 7, 34, 35, 36, 84, 109, 111 I Insein . . 2 , : , , ; . ; ; ; 72 Intensity, distribution of F : ; ; ; E . : 87 Intensity, scale of Californian Commission 7 ; : ; : 89 _ 5 modifications of . : ; : , . ; 91 Inwagyi . ; , ; ; : . ‘ : ; . 113 Irrawaddy alluvium . , ; : F . 9, 95, 99, 104, 106, 107 se river. E : ; ; : . ; . 93, 98, 105 Isoseists, general deductions from. ; ‘ : : 2 : 101 5 H-Hi... : . : : ; , , P ; 99 S IV-V.. . , : : : ; : . ’ 98 3 VI-VU . : . , : . ; : : ‘ 97 - VIII-IX, character of the shock , : . . 3 96 Pe VIII-IX, general description . ; F : ; . 92 K Kalaw . : : , ps , . : : . ; . 8, 44 Kalewa . ' : ; ; ; P : ; ; : . 59 142 Kamaing Kangra . Kani Karenni Katha Kawlin . Kayan Kela Ke-laung stream Keng Tung Kindat . Kodaikanal seismograph trace . Kodaung Hill Tracts Krung Thepe Monthon Kutkai . Kyahnyat Kyaukkyan fault Kyaukkyi Kyaukme Kyaukpyu Kyaukse Kyauktan (Akyab) . Kyauktan (Hanthawaddy) Kyeintali Lacustrine deposits . Lashio La Touche, T. HL. D. Letter regarding earthquake Lisbon Loczy, L. von Loikaw . Loilem Madaya . Magwe Mahachai , Malay States . INDEX. Page. . . 57 . . ° ° e 6 . ° : 5, 60,120 45, 97, 111, 119 57, 97, 98, 111 58 72 Vt ; . 34, 109 44, 78, 98, 119 ; 59 84, 85, 128 48, 49 78 37 ; : . ‘ 47 34, 36, 93, 104, 109, 111, 124 -. 67,122 . 86, 84 ; : : : : ‘ 69 5, 50, 92, 95, 104, 105, 111, 115, 120, 123 : , 69 72 70 L ; 106 oer, 92, 93, 118, 126 34, 104, 105, 107, 109, 110 3 6 105 45, 111, 119, 129 42, 43, 44, 123, 125, 126, 127, 128 M ’ 19 5, 8, 52, 92, 95, 121 feo eds TS 10] Mandalay Martin, L. Maubin . Mawkmai Mayagon Maymyo Meiktila Mergui Mica Schist series Middlemiss, C. S. Minbu Minbya . Mingin Minhla Mogaung Mogok » gneissic series Momeik . Mongkung Monglong Mongmit Mongnai Mongpai Mongpan Monywa Moulmein Myaungmya Myingyan Myinpyu Myitgne gorge Myitkya Myitkyina Myittha Myohaung Myothit Naba Nakon Chaisi . INDEX. 143 Page. 2, 5, 8, 9, 82, 83, 91, 92, 93, 95, 104, 105, 108, 111, 114, 117, 118, 123, 124, 125, 126, 127, 128, 129, 130 6 ; 76 , 44 ‘ ‘ 5 : ; : é 3 ; ’ 538 2, 7, 20, 32, 33, 34, 82, 92, 93, 94, 104, 109, 111, 114, 117, 118, 123, 124, 125, 126, 127, 128, 129, 130, 131, 133, 135 5, 8, 52, 92, 95, 121 74 ; : : : ; 109 82, 84, 91, 102, 103, 104, 105, 106, 131 61, 98, 111, 112 69 59, 125 68 : ; : ; ‘ ‘ 56, 111 8, 45, 92, 95, 111, 114, 120, 124, 125,126, 129, 130 . : ‘ ; 9, 105, 108 . 45, 47, 120, 125, 126, 127, 128, 129 ; 92 36, 92, 119 92 44 79, 122 : 44 59, 60, 97 74, 105 . 73, 99 5, 61, 92, 97, 121 36, 93 108 , 71 : 56, 93, 98, 111 . 50, 51, 121, 123, 125, 128 19, 20, 114 64, 113 144 Nakon Lampang . » Sri Thammaraj Namhsan Namma . Nammaung Nammeik Nampandet Natmauk Natogyi Natyekan Naungdaw Nawnghkio New Madrid Ngape Northern Arakan Nyaungbaw beds Nyaunghla Nyaunghmaw Oldham, R. D. Oldham, T. Ordovician rocks Pagan Pagodas, construction of Paknam Pakokku Paleozoic rocks Paletwa Palni Hills Panglong Pegu Petchaburi Petrui Pinlebu . Plateau Limestone » > crushing of Poonagyun Page. 78 : . 78 36, 111, 114, 119 93 47 47 43 63 51, 121 61 3 : : 69 7, 33, 34, 35, 84, 130 15 63 68 108 65 121 82, 91, 103, 110, 116 P 1 . 106, 108 136 136 76 ‘ 66, 97, 98 105, 106, 107, 108, 109 68 : 84 * 37 5, 71, 122 78 76 58, 111 106, 108, 109 106 69 Popa Prome Puket Pyabwe . Pyapon . Pyaunggyaung Pwinbyu Pyinmana Pyintha flexure Pyu Rangoon : Rate of Propagation Rathburi Monthon . Rathedaung Rawalpindi Reid, H. F. Riviera Rossi-Forel scale Ruby Mines INDEX. 145: Page. 52, 121 70, 98 78 3, 54 74, 99 35, 84 63 54, 116 108 67, 122: R 5, 8, 63, 71, 81, 84, 85, 93, 100, 1238, 135 87 78 69 75 110 5, 60, 75, 88, 90, 91, 92, 117, 120, 131, 134 5, 8, 45, 84, 91, 92, 104, 105, 111, 120, 124, 130 Sadoktaya 67 Sadon 57, 125 Saen “ : : ; ‘ ; 37 Sagaing . 5, 8, 61, 92, 93, 107, 111, 120, 125, 130 Sagu 62, 111, 112 Sagyin ‘ 105 Salin 62, 111, 112 Sandoway 69 San Francisco 6 Sedaw fault 108 Seikkyi . 72, 100 Seikpyu ' , 115 Seismograph records 84 3 » extra-Indian . ‘ , js j ; 103 5s ,. of aftershocks . ‘ , ; . ; : 124 Shaun Plateau . . 105, 107 5 » rocks of 106. 146 INDEX. Page. Shan States, Northern. . 5, 33, 81, 91, 92, 97, 104, 111, 118, 124, 130 5 - - faulting of . ‘ ° . . . . 107 Southern ‘ ; . 5, 38, 84, 91, 92, 97, 104, 111, 115, 117, 119, 124, 130 Shwebo . ; ; A “ ; ' : . 5, 59, 92, 107, 120, 125 Shwegu . 3 A ~ é A x é ‘ omopee Ls LED Shwegyin : : ‘ A ‘ ° ‘ ‘ ; P . 67 Shweli river. i. , f i. ‘ : ; A ; 47 54, 115, 116 > 9? Shwemyo . ‘ ‘ ‘ : ‘ . : Siam . - * : ‘ : : 1, 8, 75, 98, 99, 100, 101, 122 Sima. ' ; : . . > ‘ . ; ‘ ‘ 57 Simla seismograph traces ; ‘ ‘ ‘ ‘ ; 84, 86, 87, 123 Sinbaungwe . ‘ ; 5 . , : ; : ‘ ‘ 68 Sinhe . R ‘ . . : . : . : . 38, 42 Singaing F ; : ‘ ‘ : , ‘ ‘ , ¢ OL, 12) Sittang river . : é ‘ ‘ ‘ ee ‘ ‘ ‘ 98 Sonora . < é 3 ‘ j ‘ } : : ; ‘ 6 Springs affected ; . : : ‘ ‘ ; ; Ff ‘ 115 Ssumao . ‘ : ; : i , ‘ , ; , . 75, 100 Suess, E. ; : : : “ P : ; . : . 107, 110 Syriam . : ; ‘ : x ‘ : ‘ : : ; 72 Tagaung = < ‘ : . ‘ : . , , : 47 fan aa = Sa x ; ‘ : . . : . : { 6 Taungdwingyi : ‘ ‘ . : ‘ : ‘ ‘ 63, 65, 121 Taunggyi . 5, 38, 92, 95, 115, 117, 119, 128, 124, 125, 126, 127, 128, 130, 133 Taungup ‘ : : : : ; . ‘ : : ‘ 70 ‘Tawmun ; 5 ; ‘ ‘ ‘ : ; . , ‘ 68 Tawngpeng . ‘ i : ‘ ; : : ‘ . 36, 92, 119 3 system . , : ‘ : . ; ‘ : : 106 Téng-yiieh : é ; . . ; ‘ ‘ ‘ . 75, 98 Thabeikkyin . P ‘ ; 2 ; : ‘ ‘ 45, 46, 47, 130 Tharrawaddy . . ‘ < P . , ? : : . 70, 98 Thayetmyo . , ‘ é ‘ ‘ . ; : , . 67, 98 Thazi . 5 ; ; ‘ ‘ : ; . . : 52, 53, 92 Thekemyaung ‘ : , ‘ : ; . ‘ 3 ; 64 Thilwa . , ; ; ‘ . . : . ‘ ; ‘ 72 Thindaing . Hi ; , ; ‘ ; = , ‘ 47 Thongdaung . : . ; : ‘ , . : : ; 33 Thongwa . ‘ ‘ : re Sy — ; j ; : 72 INDEX. 147 Page. Tibetan plateau 107 Tiddim . 74 Time of earthquake 81 ,, Standards 8] Tonbo fault : ; 108 Toungoo 5, 8, 66, 97, 111, 122 U Undulations of the ground, visible . : . ; ; : , 114 W Warrabum ; : 56 Water supplies affecte 115 Wave motion elements 102 Wetwin . 34, 109 Wuntho 58, 111 Y Yabe - : - ; ; Fe . A A : ; 64 Yakutat Bay . ; ° ; : : : : : . ‘ 6 Yamethin ‘ k s : t x : : 5, 8, 53, 92, 111, 121 Yawnghwe . . - : ; . “ ; . 38, 43, 44, 111, 130 Yenangyat 64 Yenangyaung ; 65, 99 Yiinnan 1, 75, 98, 99, 100 Ywataung 61 Z Zayatgyi ‘ 44 Zawgyi river . 50, 95, 115 Zebingy1 . ° ° . ‘ : : : 108 ne fault : : a . 5 : : ‘ ; : 108 a 19, 83 Zigon (Mandalay) : . 4 ,. (Tharrawaddy) : a ‘ , . ; 4 : : 70 GEOLOGICAL SURVEY OF INDIA. Memoirs, Vol. XLII, PI. Photographs by J. Coggin Brown, G. S, I. Calcutta. VILLAGE MONASTERY OR ‘“‘ PONGYI KYAUNG” OF THE NORTHERN SHAN STATES. Showing how the framework is supported on wooden piles. GEOLOGICAL SURVEY OF INDIA. Memoirs, Vol. XLII, Pl. 2. Ga Sa thee Oa METHOD OF PAGODA IG OUST KRG C LEON, * To illustrate the instability of such structures during Earthquakes. i : Pas porn im P : % pole » - : a a > . 7 * Jie . - . .* Can . * * - F — feet a a b ‘ F] - % % ww > a “9 ~ * oan am, sf » ¥ Z * - ¢ oa 2 * & ao : . Py ~ * “ 7 ms GEOLOGICAL Bie eee oe Et OL. FIND LA Memoirs, Vol. XLII. Pl. 3. a aie 8 = isis] =f Ee ial Ss eee CG. S. ft. Cateutta. SECTION OF TYPICAL BUNGALOW. ee ke a aes te see ae w MOTVONNGA TVOIKGAL £0 NOILVARTTE aa PMV “fF “SS “9D LX] Sy ~~ LX . scm Jie] Be SY oi REY SIS > ld ‘UTX “OA ‘salomoy; III AR SE GED AAAAHDS TFOATPOTOAD GEOLOGICAL SURVEY OF INDIA. Memoirs, Vol. XLII, Pl. 5. WEST WALL EAST WALL COURT HOUSE EAST WALL €----- 13----> PARTITION WALL INNER WALL SOUTH WALL CLERKS RS. WEST WALL RECORD ROOM Q FOLLOWERS QRS. STONES FELL EAST INNER WALL SOUTH WALL CLERKS QUARTERS MENS BARRACKS SOUTH WALL NORTH WALL CLERKS QRS. WEST WALL EAST WALL CIVIL SURGEON'S QRS. WEST WALL MENS BARRACKS WEST INNER WALL EAST INNER WALL CLERKS QUARTERS A <--8--> <----13----> BATH ROOM WALL PARTITION WALL WEST WALL WEST WALL CLERKS QRS. M. |. STORES CLERKS QRS. Bet: Me, 15008, 14.2 — 200 SKETCHES SHOWING DAMAGE TO VARIOUS BUILDINGS IN TAUNGGYI. ee ee 2 -~ es aoe reaw ae. PRAWOLIDT Te UnBOOPrE AL SUR CET OF TVD ILA: memoirs, Vol. Xrie Pins. Ve, ¢: = Yusum Hsa \e) FAUETS OF THE NWORTBRERW: HAR See ee os Calter THe Di ba Tote Scale, 1 inch = 16 miles. QQ) Kyaukkyan fault (2) Chaung Magyi fault @ Sedan fault @ Zebingyi fault ©) Tonbo fault en ee bt MORK aks Sl, fiat wory me GEOLOGICAL SURVEY Of, (NDIA. Agen Dxong, es ; | \ . \ | tr , on i. \ VbubDrong Dewar Chéindoor \) j cs 2 i Pap. ee ; ‘ ‘a ; Nee ° (vale ! : 9 ; Chhi-shhl J \ P 2 —~astol 4 ied : BURMA mean Nething £4Ng-poR: Sango Chu Drdrg Dayu Gomba } WwANOK * ‘ eal ° | . Dron, RP Nain Tao pr L.Palts . po : /\ sents : wove | ° Tear ) { So . Boal (tsa ; oS Tan Tao() *Karkang \ “bage oe . \ Oo Pd Chang Th a 3 r 1s \ c ‘ Na THO \ 1 MIS } barn \ aN — i 0 \ . °\|Aalude ; ; pe’ } tate ~ a3 sai i, CRS ee ° rt Rina? ‘\ Ee of May 28rd. 1912. ata eee “hoina 12ASa ~ ay] , exam “Chat “, \ \ : : a5 oo? ree — 3 aa \fongea Ta wang f “iS Anaduphe ¢ ‘DRE 7: \ " bi: rang DI Gg Ibx ong + wae i, f SHOWING THE APPROXIMATE POSITIONS 13 OF THE Gis samc ISOSEISTS AND AXIAL EPICENTRE r é i Tralricx . Mics Sh, ° Taka Bong rene Leaning ihe Aa ee a aS ner —--| Bali Peat ws ot 5 t “pate rath _Sies e Siati 8% oR et ‘ Tezpu We T O N\G x Salin , > sai T oM6i vt 2 ut Mong Kuok: ‘“ "i, NG, RS ; NG Sid ugva Fen dy: Pee Taungsf ) _ Lf M. Sai M.Son ah Tekh - as. Aun ower Ming D = B l oi 3 5 Minbu. Yaméthin an . x Sp M. Sam\Nuak_ “M Nawk am : Pp i. Rend. Heer ong Ki M. Souen ¢ \ Vir binh : ae aN Ropeo Tah Seintdit 0 aia a Moingpun? Keng een jvm g ad te M. Hoa Mérg | 4 3am Tai oW\Ka ¢ ° 3 aad “) zit 7 Haine | A "Mcheghun \KenNiacs 5 ZFS ‘deepak Ni we Mte as eae A SiG ¥ ~ —— a “ M. Chayntay mf maRta *EAagLeey iy ‘ SS Sete oie Gf hae oD pein is . Kwang 5 s 3 8 B hiss elie ah: \ fo M. Cheng Rong : 2 MLam P Kw) Chu sale u ae Bhat Hoa Ps: am Nern Jueng Kvang ¥ seattle Thong ye Na gy Ba wlalse ¥ Ke a)” B/Ma Kem # Mat M Hom M mgnan Bortiean [Turakon ach \ Tinh M.Say Touny “a ee eek ae LR 3 om ecb yr” Sa > Khe ym he of Y a } 4 NI aa rate : Paki’ oe. t Shwegyin t Konak Y von! heat ‘ NY, { -, : 4 o4 4 ‘ 5 Ken Tai dy lgibanald M. Saniab 5 ly te Lui a Nong\lan M. Pahua 2° Bi 3 Noe ON y ce D ia x 5 M. oe ) \ n ad & 2 EPichat ) Kamuta ! a . ¢ “x gic 2 Suk M Sai Kou AN is i | : Sakon Lakon ER: 4 °M. Pitsa ak Kot. ca bn. n a ES | 2: ae | ie? | , Balwayvun 17 \P Mu i ~ ; \ ba Ronikee ° M. Barak Dahan ® Gule J) Moulmesn ay at \. Ml Bangkalan x Sons, | ye Eso ~ Amherst \ Mina , op ian Wag ‘Sty ichabon wad Renobot M. Kemmarety J ot , Tf oA iw Double I , Me Kalone pi Totactons 4 ray ‘ gq F J 3 lgquada Bar Rite of Peers \y Mies ta 9 Ur onk 3 | M Nakon § wen M. Pathaisung RP tes M. Kany) st oi. Poruhahirt . re M. ambaesa 8 re . Preparis North Channel late se ' ee es 8 } its * as : 'é a Pre or Nathyi ° fiw he Kwee ME - ri M. Det J Bassa. ; paris \ CO) a Abit OM Ne bake shoanaied \M, Kukean Q Fi \ van | wa tid $ M. Pa Kunchai Kantararom, ° “G Table is South Channel Northern Moxcos)s a _ MS Pan . 2 avaburh MM Sankea a .; tgs e 0 Braae Coos Middle Moscos, at ~ Kala burt #0 Pea foi G oM. Chantaktim Khong Coco Channel 2 - » \\Wfavey( yy ; “be ° se West Lo2Landtall J. se i dai es Badwey \ thud oy drranh ate M. Meluyprey uu 7 * ge post North |Andaman Narcondam I. “hig Mba és & Stanucp , n \) as > & Battam bang Intapview I. ff ag Lp oe? Prteha bur 3 ee its p re ANDAMIAN Middle Andaman : - P “ “\ se by Myng f) Outram 1. Ppphineone L., 9 coh ue Fs seasanigtwnag om: ISLANIp 8 _ Li iy oBarren I. “ ok M a \ Sl Fk enry Lawrence I, Rowa I. “Se wt Ss ; MERGUI oA op Kuwi Koh ChangS soa itl outh Andaman Havelock L ecllore 1. { North Sentinel \{ Port Blair Bentineie 1.) Oey ray ‘ A Domed I. elie L eiie Bank ARCHIPELAGO g : A ie pee Forbes 1.{} Little Andamlan ig *es9y Sullivan or bead ‘So Lampi I Pakchan o Loughborough Ld ; 7 T ane Wr. 15 BAS io] Ot Pegree Chani ec] © st uauhosi % ° fo) Chance I.) s Kar Nicobar Zz Pulo Panjang > Koh Phratong f) Memoirs, Vol. XLII Pie ——— re RS ROS _—————— ee ST ae —=———— eto. OG EC w BO Ruy Wey Oe Tee MOO tes, VV 6 te aes ae boos WW \: M, pony id see Bo Oey ya Daas Moms a 1 cae 2" 10 Revit aos es ee ee PID RTOS” TAINAN PRAIA AED YAY DAE PI DDL nn JY Pe ery. a see / | 2 1 9hrs O | Gs RE Ls ees a ee cia haa | i i i j i i a lok eal a ce 1 eseey Ary Beer oa | a1. 3 Ten 1 \ ' \ fb, ea Se Bese 806 5 eS alee es ae | : 110hrs O SiMLA “OORT SES MOG RAP DIREC PTLON -OF 0-0 @ E-AS OF AND |. WES et 2 1 hrs O I 1 I . ! SITMELA “OFF, Ri SEIS MOeOGeAS A i 1 | 1 i DLeRece 2 TOR OF BOD M NOR Ht -aND SOUTH — BURMA BB Ao Tope CA Cee Meee SOrd: 1.97 2. GCEOEOGO Ha oS eye (OF ID DIA. Memoirs Vou. XLII, PL. 9 OLA in. i Fenleg 8/, AAA Wire : ; : ‘ zn Rena Quche 29 Mag 697 -COLABA OBSERVATORY VERTICAL MOVEMENT SEISMOGRAPH ° m BURMA QUAKE 23*¢MAY 1912 \ 2 281 GMT d 22-22 35.3 ZERO LINE wee MILNE AND VERTICAL MOVEMENT SEISMOGRAPH. BURMA EARTHQUAKE, MAY 23rd, 1912. COLABA OBSERVATORY. Gt. Dae Oo. A Voie eet ea | VN "HAVUYDOWSIAS ANTIN AWOL V Bee pao CU BOE SV Sea fed a ek Cl Bs © fa be oy ertmr tr by J 7 netnted. Ated and | i a ‘HAVUYUDONWSIAS ANTIN AES, O dh Wee ae ST OdgdWOTOD ’ a i % , —————_—_—_———_—_——_—_———-" Yes ex Atw ib ih q°% NOHO ISD | a 4 ; Civ, | i ts * ‘twee © i fom Va ttt x OA stro mo SS aS LY A AY Ay A MnO) me 9 AED OY OE TO RY MER TS OD CROLL OGLCAL SURE IG.6 Foy, Meee Mae ee LTE CP. oLt. \ itt et Shift of Zero. Pen touching stop on the West. | bi ‘4 ‘i u lw v \ sa Wi, cea ‘ / / eran ee a | he Wy k " \ 4 ki \ i Wy W ry N N rv Mi My 4 ny y Wi i ¥ u l vi i N iy \ \ hi | Mi hi hi Mi Mi M » he W 4 i hy a W hi G. S. J. Calcutia Omori-Ewing Seismograph. BURMA EARTHQUAKE OF MAY 23rd. 1{912. COLABA OBSERVATORY, BOMBAY. CALCUTTA SUPERINTENDENT GOVERNMENT PRINTING, INDIA 8, HASTINGS STREET MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA VOLUME XLII, PART 2. COROT I APR 29 1918 LrpRar THE STRUCTURE OF THE HIMALAYAS, AND OF THE GANGETIC PLAIN, AS ELUCIDATED BY GEODETIC OBSERVATIONS IN INDIA. By R. D. OLDHAM, F.R.S. —_ Published, by order of the Government of India. CALCUTTA : . SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY OF INDIA, 27, CHOWRINGHEE ROAD. LONDON: MESSRS. KEGAN PAUL, TRENCH, TRUBNER & CO. 1917. Frice Three Rupecs ot 4. inthe GE MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA VOLUME XLII, PART 2. THE STRUCTURE OF THE HIMALAYAS, AND OF THE GANGETIC PLAIN, AS ELUCIDATED BY GEODETIG OBSERVATIONS IN INDIA. By R. D. OLDHAM, F.R.S. Published by order of the Government of India. CALCUTTA: SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY OF INDIA, 27, CHOWRINGHEE ROAD. LONDON : MESSRS. KEGAN PAUL, TRENCH, TRUBNER & CO. —_— 1917 CONTENTS. Paar CHapteR I.—INTRODUCTORY A a J % J z . 1 Crapter II.—The Nature and Interpretation of the Geodetic Evidence 10 CuapTerR I1I.—The Imaginary Range and Trough ‘ ‘ . 36 CuapteR IV.—The Underground Form of the Floor of the Gangetic Trough. - : : ; ‘ 2 65 CuapteR V.—The Support of the Hila ‘ ‘ . ‘ © 99 CuaprER VI.—Summary and Conclusions . ‘ > 4 ; ohio: INDEX TO GEODETIC STATIONS . : , d ; . _ . 143 GENERAL INDEX. : ; ‘ i ‘ . a m yt ae LIST OF PLATES. 12.—Map showing Geodetic Stations in the Alluvial Plains and Himalaya mountains, 13.—Map showing Geodetic Stations in and near the Dehra Dun. MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA. THE STRUCTURE OF THE HIMALAYAS, AND OF THE GAN- GETIC PLAIN, AS ELUCIDATED BY GEODETIC OBSER- VATIONS IN INDIA. By R. D. OLDHAM, F.R.S. CHAPTER I. INTRODUCTORY. The annual reports of the Great Trigonometrical Survey have contained occasional reference to certain peculiarities exhibited by geodetic observation near the outer edge of the Himalayas, and to a belt of lesser density as a reasonable explanation of them. These references had attracted little attention on the geological side, for those geologists who could understand them, and were also acquainted with the results of geological examination, knew that just such a belt of rock, of less than average density, did run along the foot of the hills, and though the form of the trough, in which it lies, differs from that suggested as an explanation of the geodetic peculiarities, it was clear that the effect of the known geological structure would be similar in kind to that revealed by geodetic observation, and there was no reason to suppose that it might not also be sufficient in amount. Matters might have remained in this state but for the publica- tion, in 1912, of a brief paper, by Sir S. G. Burrard, on the Origin of the Himalaya Mountains.1. The explanation offered would pro- bably have attracted little attention, and in due course have gone to join a respectable company in the limbo of forgotten theories, 1 Survey of India. Professional Paper No. 12. Calcutta, 1912. [ 49 ] x OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. had the paper not seemed to imply that the geodetic evidence necessitated the existence of a deep and comparatively narrow rift along the edge of the hills, filled with rock of lesser density than that on either side—with some suggestion of actual cavity—and at one place the figure of 20 miles was given for the depth of this rift.1 Such at least was the interpretation which the paper seemed to bear, and the figure, mentioned for the depth, implied a diaclasm so far transcending in magnitude anything which has been estab- lished from observation, in the Himalayas or elsewhere, that its acceptance would have necessitated the revision of what had been regarded as well founded deductions from geological evidence. Diaclasms of three miles in depth are well established, and even five miles is not impossible, and these are the figures which had been regarded as the probable, and the extreme possible, limit of the faults along the southern boundary of the Himalayas. The assertion that the geodetic evidence pointed to, if it did not necessitate, the existence of a diaclasm of four times the extreme magnitude of which we had any indication in geological observa- tion, naturally attracted attention, led to an examination of the grounds on which the assertion was based, and gave rise to a some- what extensive literature, which, being mainly controversial, was mostly unprofitable. I have no intention or desire to add to this literature ; his main rift has been placed further south, and the figure of 20 miles has been explained away,? thereby removing the contradiction which appeared to exist between the geodetic and _ geological observation, yet the original statement cannot be regretted for it has drawn attention to the geodetic work of the Trigonometrical Survey and led to an examination of the light thrown by it on some interesting and doubtful points of geological structure, which it had not been possible to elucidate by geological observations alone. In the course of this examination I shall have occasion to refer to theories which have been offered in explanation of the origin of the Himalayas, but only so far as to indicate the influence which they might have on geodetic observations, and so afford a guide to the directions in which these should be examined; for the object of this investigation is not advocacy, or attack, of any 1 Loc. cit p. 11. “ A rift in the sub-crust south of Mussooree and 20 miles deep would explain the large deflections in the interior of the Himalayas.” 2 Proc. Roy. Soc., Series A. XCI, 1915, p. 229. [ 150 ] INTRODUCTORY. 3 particular theory, but an attempt to add to the stock of funda- mental facts, on which alone a successful theory can be built. In the sequel it will be seen that, so far as the origin of the Himalayas is concerned, the observations help us but little on the way, though they do to some extent diminish our ignorance of the processes which have been at work, but in other directions they have very considerably added to our knowledge of the underground structure of the northern part of India, by converting ‘what were merely conjectural possibilities into well founded probabilities. The investigation has been limited to the region of the Himalayas and the alluvial plain to the south of them, though this does not cover the whole ground of possible cooperation between geodetic and geological observation. The curious band of excess of attrac- tion which crosses the northern part of the peninsula, for instance, may be found to assist in the interpretation of the geology of the country, but the data at present available do not admit of any definite conclusion being drawn, and its discussion has, conse- quently, been omitted, though it is not impossible that, when ob- servations are more numerous and complete, it may be found to help in the elucidation of the origin of the Himalayas. The completion of this work has been retarded by the call of other claims on my time, but the delay has enabled the attainment of more complete results. I have to acknowledge with gratitude the receipt of much assistance, in the communication of material, from Sir 8. G. Burrard, Surveyor-General, and Dr. H. H. Hayden, Director of the Geological Survey, also to Mr. D. B. Mair, for assist- ance in the mathematical part of the investigation. The actual calculations were done on a machine, in all but the simplest cases, and are sufficiently accurate for the purposes of this investigation, though they do not pretend to the refinement required in geodetic work. The first step to be taken in this investigation is a statement of the issues which are or may be affected by the new evidence, and from these all questions of stratigraphy or correlation must be excluded, as well as all those questions of structure which do not involve the distribution of large masses of rock of materially different densities. With this necessary restriction the following seem to be the conclusions which are well enough established to necessitate their acceptance in any discussion of the observations. [ 151 ] 4 QLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. (1) Firstly, there is the indubitable fact that the elevation of the Himalayas has been accompanied by the compression of the rocks of which it is composed. It is not meant that the whole of the disturbance of the Himalayan rocks has been the consequence, or the cause, of the elevation of the Himalayas; the contrary is indeed almost certain,! but the general distribution of the rocks, in the larger anticlines and synclines, along the general course of the range, and the fact that the prevailing strike is in the same direction, point to a connexion between the disturbance of the rocks and the elevation of the range. In the Siwalik region of the foot-hills the connexion is incontestable, for here we find that the rocks, which must have been deposited in practically horizontal beds at a time when the elevation of the Himalayas was already in progress, are now folded, disturbed, and compressed in a direction transverse to the general course of the range. (2) There is, along the outer edge of the Himalayas, a great fault, known as the main boundary fault, which separates the northern area of the rocks of the Himalayas from the southern aréa occupied by the Upper Tertiary Siwalik rocks of the Sub- Himalayas. This fault, as was originally shown by Mr. Medlicott, marks very closely the original limit of formation of the Siwaliks, and the boundary separating an area of elevation and denudation, to the north, from an area of subsidence and deposition, to the south. He also showed that the Siwaliks were formed under the same conditions as the marginal deposits of the Gangetic alluvium, that the material of which they were composed was derived from the Himalayan area,—in other words, that the Himalayan range had already been marked out as an area of special uplift in early pliocene times. Along the greater part of the length of the Hima- layas this fault brings the indurated older rocks of the Himalayas into direct contact with the soft sandstones and shales of the Upper Tertiary series, and throughout this region we have two groups of rocks of very markedly different densities separated by a nearly vertical plane of separation. A condition like this cannot but have a marked influence on the direction and amount of the force of gravity and, as will be seen in the sequel, a study of this effect enables us to form an approximate estimate of the vertical depth to which the contrast extends. Between the Jumna and _ the 1See Manual of the Geology of India, 2nd ed., p. 483 ; also Records, Geol. Surv., India XLIM, p. 149. [ 152 ] - INTRODUCTORY. 5 Sutle} rivers, older Tertiaries appear on the northern side of the main boundary fault and, beyond the Sutlej, the whole of the Tertiary system becomes involved in the mountain-forming dis- turbances. In this region the main boundary fault is no longer recognisable, having merged into one of a series of more or less parallel faults, of similar character, which traverse the area of Tertiary rocks in the outer Himalaya. (3) Mr. Medlicott also showed that the main boundary fault was not the only feature of its kind, for a series of similar faults is found within the Siwalik area, which were regarded as marking successive limits between an area of uplift and erosion to the north, and of deposition to the south of the fault line. This conclusion was more fully worked out by Mr. C. 8. Middlemiss! in the Sub- Himalayas of Kumaon and Garhwal, where he showed that not only was there a succession of faults within the Siwalik area, each of later date than the next one to the north and each in succession marking the limit of the region of Himalayan uplift, but that there was also a series of similar faults to the northwards, each in suc- cession earlier than the one to the south and, presumably, marking the successive limits of the Himalayan area; and a similar con- clusion is suggested by the geological structure of the Sikkim district.? From this it follows that, at any rate during the latter part of the period of elevation of the Himalayas, there has always been an abrupt limit of the region of compression and elevation, and that this boundary has progressively shifted southwards,* encroaching on an area of deposition and involving deposits of later date in the mountain-forming processes. (4) The clearly defined character of the southern margin of the hills towards the plains, running with a regular sweep along the foot of the hills, and the absence of detached outliers rising out of the alluvium, irresistibly suggests that the boundary is deter- mined by a structural feature similar to the main boundary and the faults in the Siwalik area, and though no direct measurement of the depth of the undisturbed alluvium is possible, the fact that it is identical with, and a continuation of, the Siwalik deposits 1 Memoirs, Vol. XXIV, pt. 2. ® Memoirs, Vol. XI, pt. 1. * This statement necessarily refers only to the position of the successive boundaries, relative to each other. There is no means of deciding whether there has, or has not, been any general movement of the Himalayas northwards or ‘southwards, whether in latitude or as regards distance frora the rocks of the peninsular area. [ 153 ] 6 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. affords a tolerably secure indication. The total thickness of the Siwaliks, in the Kumaon and Garhwal districts, was estimated by Mr. Middlemiss at an average of about 16,500 feet; Mr. Medlicott estimated the thickness of the Siwaliks north of Hardwar at 15,000 feet,? and the whole thickness is not exposed on this section. We may therefore take it that the depth of alluvial deposits, being the continuation of these Siwaliks, is not likely to be materially less than 15,000 to 16,000 feet at the northern limit of the plains, and we may safely say that the alluvium at the northern edge of the plains is very improbably much greater or less than about three miles in depth. (5) At the southern edge of the alluvial plain the thickness is small, the boundary is irregular, following the contour of the much denuded surface of the older rocks of the Peninsular area, which crop out, near the boundary, in numerous isolated patches and hills, rising from the surrounding spread of alluvium. All the features, in fact, suggest a gradual encroachment of the alluvium on an ‘old land surface of rock, and a gradual southward growth of the depression in which the Gangetic Alluvium has been deposited. Besides these well established conclusions, there are certain others of a more conjectural character, which need confirmation, or greater amplification, than the present state of geological know- ledge—or in some cases any conceivable advance in it—can afford. Of these the following seem capable of elucidation by the data to be dealt with: namely— (1) The question of whether the elevation of the Himalayan range was caused, or merely accompanied, by its compression. The natural conclusion would be that they were related to each other as cause and effect, but in which direction cannot be re- garded as proved. Were the elevation due to a simple process of tumefaction, or swelling up, of the material underlying the range, this would set up internal strains in the elevated mass and a ten- dency to spread, which might result in compression and folding. This hypothesis has in fact been proposed and experimentally illus- trated on the small scale,* but it has never been tested by actual 1 Memoirs, XXIV, p. 8 2 Memoirs, ILI, pt. 2, ea 118. 3 E. Rayer, Nature XLVI, p. 224 (1892), [ 154 ] INTRODUCTORY. 7 calculation of the relative magnitude of the stresses which would be set up, and of the resistance by which they would be opposed, nor does it seem that any such test could be satisfactorily applied, in view of the many unknown factors which would be involved. It will, however, be shown that the hypotheses, of elevation being due to compression or compression the result of elevation, each carry with them certain consequences in the underground distri- bution of matter, which would, in the case of the Himalayas, lead to results of recognisable magnitude. (2) No direct measurement of the throw of the main boundary fault can be made, and of the similar faults within the Siwalik area measurement has only been effected in one case. Mr. Middlemiss was able to show that one of the faults, in the Ramganga Valley, must have a vertical throw of 6,380 feet, or 11,880 feet measured along the hade of the fault,’ and as this is by no means the greatest of the faults we may take it that the throw at the main boundary must be at least as great, but beyond the fact that the throw of this fault must amount to several thousands of feet no more exact estimate is possible. (3) Closely bound up with the last, is the depth of the pre- Tertiary floor of the Siwalik deposits within the Siwalik region. It has been generally accepted that the level is higher than in the alluvial area to the south, and that the elevation of the Siwalik hills has carried with it an elevation of the floor on which they rest. This conclusion is illustrated in some of the sections drawn by Mr. Middlemiss and in the generalised and diagrammatic section given in the “ Manual” ?; it is supported by the mode of occur- rence of the inliers of older rock met with in the Tertiary area beyond the Sutlej, but it is by no means an inevitable conclusion in the region east of the Sutlej], where the main boundary becomes so well-marked a feature. If we consider the cross sections of the Siwalik area, those, for instance, which were reproduced in the “Manual,” we find a compression of from 30 to 100 per cent., on comparing the original with the present horizontal extent of the beds. Now a series of deposits 15,000 feet in vertical thickness, if compressed to one-third less than their original extent would be thickened by no less than 7,500 feet. Actually the mean ele- vation of the Siwalik area over the plains to the south is not over 1 Memoirs, XXIV, p. 87. 2 Manual of the Geology of India, 2nd edition, p. 473. [ 155 ] 8 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, PTC. a couple of thousand feet, and on most sections even less, so that, even allowing for the extensive removal of material, and lowering of the hills, by denudation, there is a possibility that the floor of the Siwaliks is not materially higher, and may even be lower, than that of the alluvial deposits immediately beyond them. (4) As has been stated, we have very good reason for supposing that the thickness of the alluvial deposits, along the southern edge of the hills, is not less than some 15,000 feet; we also know that the thickness near the southern edge is very small, but we have no direct knowledge of what takes place between these limits, whether the depth of alluvium is at its maximum near the northern edge and gradually diminishes to the southwards, or whether it increases to a maximum and then diminishes, or whether it con- tinues with a considerable depth to near the southern edge and then thins out rapidly. In other words, we are unable to draw a cross section of the Gangetic trough + with any degree of certainty. (5) Though the alluvial areas of the Gangetic and Indus drainage areas are continuous with each other, and the whole area is coloured uniformly on the geological map, it has been recognised that there is a considerable difference in the surface contour, in the arrange- ment of the river courses, and in the character of the deposits which form the surface of the two regions. From the Jumna eastwards to the junction with the Brahmaputra Valley is the great tract of the typical Gangetic alluvium, which bears all the characters of a plain of deposit and across which the rivers flow in courses determined by their own action and interaction. In the plains of the Punjab these features are largely absent, and the surface features suggest a much smaller thickness of alluvial deposit, a suggestion which is strengthened by the occurrence of inliers of older rocks, rising as hills in the centre of the alluvial plain. 1'The title of a paper by Sir S. G. Burrard, published in Proc. Roy. Soc., Series A , XCI, p. 221, ‘On the origin of the Indo-Gangetic Trough, commonly called the Hima- jayan Foredeep,’ is liable to convey a wrong impression. The basin filled by the Indo- Gangetic alluvium is certainly not commonly called the Himalayan Foredeep, and _ the use of the terms as synonymous is improper. The word “ foredeep ” occurs in Prof. Sollas’ translation of Das Anilitz der Erde as the English equivalent of the word Vortiefe, coined by Prof. Suess with the intention of conveying not only a description, but also a definite theory of origin. The word may be used without accepting this theory, but a term, which was invented to connote a definite theory of origin, cannot be used with propriety unless that theory is intended to be implied. I shall confine myself to the use of the word trough, which is purely descriptive and implies no theory of origin, and in using it shall refer only to the deep depression in the rock surface under the alluvial plain, not to the whole of the area which is mapped as alluvium, [ 156 ] INTRODUCTORY. 9 (6) At the other extremity of the Gangetic plain we find the alluvium extending southwards, across the gap between the Penin- sula proper and the plateau of the Assam range. The rocks of these two areas are similar in character and the Assam range must be regarded as, stratigraphically, part of the same geological area as the Peninsula. There is some geological suggestion that the stretch of alluvium, through which the Ganges and Brahmaputra reach the Bay of Bengal, forms no part of the depression, or trough, of the Gangetic plain of Upper India, and that the alluvium is a comparatively shallow covering over a rock barrier connecting the Rajmahal and Garo Hills.1 These are the geological problems in which elucidation may be helped by geodetic observations, they do not comprise the whole of those in which assistance from this line. of research may be looked for, but the necessary observations are wanting for dealing with the others, and especially with the very important one of what has taken place in the regions at either end of the Himalayan ranges, where they pass into the mountain systems of Indo-China on the one hand and of Afghan Turkestan on the other. 1 Manual, 2nd ed., p. 443. [ 157, ] 10 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. CHAPTER II. THE NATURE AND INTERPRETATION OF THE GEODETIC EVIDENCE. Before dealing with the observations it will be well to devote some space to a consideration of the nature of the evidence and the bearing of the observations, when converted from their original object, of measuring the dimensions and form of the earth, to that of elucidating the structure of the outer portion which is called, for convenience and brevity, its crust. Though the treatment may be regarded as elementary by a portion of those who will read these pages, it is none the less necessary for two reasons, firstly because many may be unfamiliar with the nature and the meaning of the observations, and secondly because, for those who may be familiar with this aspect of the geodetic results, it is important to have a clear understanding of the possibility, and more especi- ally of the limitations, of their application to the completion or checking of the results of geological observation, and it is this aspect of them which will alone be dealt with. The geodetic observations which have to be considered may be described as measures of the direction and intensity of the force of gravity, and are of two ¢classes. One deals with the deflection of the plumb-line from the direction which it would have on the surface of an ideal earth of perfectly regular form and uniform dis- tribution of density, the other measures the variations in the attrac- tion of gravity. Of these the first gives the horizontal and the latter the vertical component of the resultant of all the forces which produce a departure from the attraction which would be exerted by the ideal average globe. The position of two places on the surface of the earth, with regard to each other, may be expressed in two ways, either by a differ- ence in longitude and latitude, or by the length and direction of the shortest line connecting them. The determination of the first of these belongs to the methods of astronomy, the latter to those of trigonometrical survey, and the one could be converted into the other with equal accuracy if we knew with absolute accuracy [ 158 ] THE NATURE AND INTERPRETATION OF GEODETIO EVIDENCE. 1] the dimensions of the earth; but the principal problem of geodesy is the determination of these dimensions, on which depend the calculations by which the observations with the theodolite are con- verted into measures of distance and direction, and into differences of latitude and longitude. Were the earth a perfectly regular spheroid, and of uniform constitution throughout, the problem would be a simple one, and a few comparisons, of measured distances with observed differences of latitude, would suffice to determine the form and size of the spheroid. But these conditions are far from being met with in practice. The difference in the astronomical position of two stations is determined by observations of the sun and stars, and a measure- ment of their angular distance from the vertical, as shown by the plumb-line, or from the horizontal, as shown by a fluid surface ; the latter is that actually used, but the two are identical in result for the apparent horizontal plane and the apparent vertical line are always, and necessarily, at right angles to each other. Now the exact direction of the plumb-line, at any point, is determined not only by the attraction of the earth as a whole but by the attrac- tion of local masses, and may be affected either by variations in the density of the rocks at, or below, the surface, or by irre- cularities in the form of the surface near the station. A mountain range, or a mass of rock of greater than average density, to the northwards of a station would attract the plumb-bob and cause the liquid surface to be tilted in such a manner that the latitude, as determined by astronomical observation, would appear to be less than the true latitude of a station situated in the northern hemi- sphere, and a similar excess of attraction to the south would make the apparent latitude greater than the true. Differences in the density of unseen portions of the earth can, obviously, not be allowed for; they must be searched for and detected by the dis- crepancies between astronomical and geodetic measurements; but it might be thought easy to calculate, and allow for, the effect of the visible masses of mountain ranges and the visible hollows of the ocean basins, and so it would be were mountains mere ex- crescences formed of material added on to the surface of the spheroid, or the oceans merely hollows carved out of its surface. Such, it has been found, is not the case; mountain ranges do not attract the plummet to anything like the extent they should do, nor do ocean basins cause it to be attracted away from them, and the [ 159 ] 12 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, RTC. explanation of this phenomenon has introduced two allied, though distinct, concepts of compensation and isostasy. The word compensation we owe to Archdeacon J. H. Pratt,’ but the notion, though not the word, was suggested at an earlier date, by Sir G. B. Airy.2. Though the hypotheses regarding the constitution of the earth, used by these two investigators, differed radically from each other, the essence of the explanation was the same, that under every great protuberance of the earth’s surface, such as a mountain range, there was a mass of density less than the average at that depth, and that the plumb-line was not merely affected by the attraction of the visible mass of the mountain range, but also by the defect in mass in the underlying portion of the earth, which would cause an apparent repulsion of the plummet and so neutralise, or compensate, in part or in whole, the direct attraction of the mountain range. The most complete investigation of the effect of compensation, which has been published, is that carried out by Mr. J. F. Hayford, of the United States Coast and Geodetic Survey, in 1909.° Mr. Hayford adopted an hypothesis similar to that of Archdeacon Pratt, and assumed that compensation took the form of a defect of density, equal in amount to the excess of mass in the range and distributed uniformly through some definite depth which would be everywhere the same. The deflections which should be ex- pected from the relief of the country surrounding each station, up to a distance of 2,564 miles, were calculated, and compared with the observed deflections, the difference being regarded as an unexplained “ residual,” and it was found by a series of trials, that these residuals were lowest if the depth of the layer, through which the defect of mass was supposed to be uniformly distributed, or “ depth of compensation,” was 1137 km.; with a greater or less depth the “residuals”? were larger, and from this it was con- cluded that the depth of compensation in the United States was somewhere close to 113°7 km., or 70°67 miles. 1 J. H. Pratt, On the Deflection of the Plumb-line in India, caused by the Attraction of the Himalaya Mountains and of the elevated regions beyond ; and its modification by the Compensating effect of a Deficiency of Matter below the Mountain Mass. Phil. Trans., CXLIX, 745-778 (1859). ; 2. B. Airy. On the computation of the Effect of the Attraction of Mountain Masses as disturbing the Apparent Astronomical Latitude of Stations in Geodetic Surveys. Phil. Trans., CXLV, 101-104 (1855). ’Tho Figure of the Earth and Isostasy, from measurements in the United States, Washington, 1909. [ 160 ] THE NATURE AND INTERPRETATION OF GEODETIC EVIDENCE. 13 This, which he called the solution G, was afterwards modified ! on the inclusion of additional observations, and the depth of com- pensation increased to 122 km., but as the difference is trivial, and the earlier value has been used in the investigations published by the Great Trigonometrical Survey of India, and was used by Mr. Hayford himself in his investigation of the effect of compensa- tion on the vertical force of gravity, it may be accepted as a close approximation@to average conditions. The results of calculations based on it are so little different from those which would have been obtained from a slightly different depth of uniform compensation, that no useful purpose would be served by a revision of the calcula- tions.” It must not, however, be supposed that these depths of 113-7 or 122 km. have any real meaning; all that the calculations imply is that the effect of such compensation as actually exists is not materially different from that which would have resulted from a defect of mass equal to that of the material above sea level, if this were produced by a defect of density extending uniformly through a depth of 113-7 km. and everywhere proportionate to the excess of mass represented by the surface elevation above sea level. Any other form of distribution of density, which would bring about the same result would be equally in accord with ob- servation, and this conclusion is borne out by certain calculations made by Mr. Hayford. In addition to the hypothesis of uniform compensation he considered four others, namely— (1) A compensation uniformly distributed between the depths of 25 and 35 miles. ‘Supplementary Investigation in 1909 of the Figure of the Earth and Isostasy. Washington, 1910. 2In Mr. Hayford’s calculation, as in other treatments, it is assumed that compen- sation should be applied directly to the elevations above, or depressions below, sea level. The sea level is, however, an artificial datum for these purposes and the differences of level should, strictly, be measured from a datum representing the mean level of the solid earth, or the mean level as it would be if the oceans were supposed to be solidified and condensed to the mean density of the rock forming their floor. This datum would lie at about 3,000 ft. below sea level and its introduction would require an extensive re-caleulation of tables, which ought properly to be undertaken in a discussion of the effect of compensation, which included observations at stations near the sea coast. Where, as is the case in this investigation, the distances from the shore line are measured in hundreds of miles, and where, as will appear further on, the modification introduced by considering the effect of topography beyond a distance of one hundred miles 1s trivial, as compared with the differences indicated by observation, we may confine atten- tion to the difference of effect due to difference of elevation above an arbitrarily assumed datum, such as the mean sea level, the effect of the mass of the crust below this level, but above the mean level of the solid spheroid, and of its compensation, being the same in amount at all stations. [ 161 ] 14 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. (2) A compensation similarly distributed between the depths of 27 and 37 miles. (3) A compensation produced by a _ defect of density decreasing uniformly from double the average value to zero; for this the depth which gave the best results was found to be 175°4 km. (4) A compensation such as that suggested by Prof. Cham- barlin, at first imcreasing and then dgcreasing at a variable rate; for this the depth which gave the best result was found to be 287:4 km. Taking ten stations as typical of the different regions of the United States, and compaving the residuals with those resulting from the solution G, the mean differences were found to be °25, 22, -19, ‘09 seconds of are, for the four hypotheses respectively, and the maximum differences were 1°13, 1:04, ‘80, 38 respectively. As the mean of the residuals resulting from the solution G was 3:04” and the maximum 12°35”, it is evident that there are five different hypotheses of compensation, which vary widely in the assumed distribution of the compensation, but agree in giving it a mean depth of from 30 to 35 miles, and in giving almost identical results. This shows that the supposed depth, to which compensa- tion extends, has no real meaning, and that, although the effect of compensation, as it actually exists in the United States, is on the average very much the same as would result from a uniform defect of density extending to 113-7 or 122 km, according to whether the earlier or later solution of the problem is accepted, any other distribution of density might be equally in accord with observa- tions provided that the position of the centre of effect was not materially 4ifferent. In this way we are introduced to the concept of the locus of the centre of compensation. In any given mass, forming part of a visible protuberance on the earth’s surface, or of the underlying portion through which the compensation is distributed, there will be a point, so situated that, if the whole of the mass were concentrated at that point, the effect at the station of observation would be the same as that actually produced by the sum of the effects of all the separate particles of which the mass is composed. This point may be called the centre of effect, and in the case of the defect of density by which compensation is brought about the expression centre of compensa- {| 162 ] THE NATURE AND INTERPRETATION OF GRODETIC EVIDENCR. 15 tion is &@ convenient one. This centre of compensation must be clearly understood as something entirely different from the centre of gravity of the defect of mass by which compensation is pro- duced, the two are not coincident in position, and the divergence, which will not be great in the case of distant topography, may or may not become important in the vicinity of the station, according as the distribution of the defect of density is concen- trated in a layer of small, or distributed through one of great, thickness. The calculation of the depth of the centre of compensation does not, therefore, give iny direct information regarding the nature ~of the compensation, but an investigation of the effect of varying the assumed depth of the centre of compensation affords a ready means of seeing in what direction we may best look for an explana- tion of the departure of the observed from the calculated deflec- tion of the plumb-line. The general principle of this investigation can easily be deter- mined. In Fig. 1 let A represent the centre of attraction of an ele- Pee Fda t enna Det tm Om me mee me em ee Oe ee ee ee Fia. 1. vated mass, whose compensation is distributed in an unknown manner, so that the centre of compensation lies at the point C, then, if the divergence of the line AC from the vertical is { 163 ] 02 16 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. neglected, the effect of the compensation, at the station S, is re- presented by the formula m. D's je Sn 2 COS where D’ represents the deflection produced at 8, m, the mass whose effect is supposed to be concentrated at C, h, the depth of C below the level of 8, and a, the angle of depression of C at A. This expression has a limiting value of zero when a is 0° or 90° and attains a maximum when it has a value of about 50° 45’, or when the depth A is about 14 times the distance r. If this maximum effect, and the distance at which it is produced, are both expressed as 1:0, the proportion of this maximum effect which will be observed at other proportionate distances is given in Table 1." TABLE 1,—Relation between distance and effect of the attraction of an under-ground mass, Distance. Depression. Deflection, ‘1 86° 4’ “15 2 83° > 22” 30 3 8Q° = “44 “4 76> tau. ‘57 ‘5 Tao wae? -69 6 69° 44’ ‘79 ‘7 66° 10’ “88 “8 62° 30’ 95 Q 58° 42’ “98 1-0 54° 45’ 1-00 1-) 50°... 387 -98 1-2 46° 10’ “94 1:3 43° 23’ *85 1-4 poe: -70 1-5 AS ame +53 1-6 > Segara: Bs 31 1-7 7°. 38" 04 1 This table has a further utility in that it may be applied to the effect of any defect or excess of mass at any depth below the level of the station, where the distances involv- ed do not introduce the necessity of considering the curvature of the earth’s surface, and where the dimensions of the mass are such that it may be regarded as centrobaric at all the distances involved. In the case of more extended masses the effect is the sum of the effects of all the separate small masses of which it is composed, and this effect would usually diminish the ratio between the distance of maximum effect and the mean depth of the mass, but not reduce this below equality. It is unnecessary for the present purpose to treat this matter in further detail ; it is sufficient that the mean depth of the centre of such a mass will lie somewhere between 1°0 and 1:4 of the distances between the positions of maximum and zero effect. [ 164 } THE NATURE AND INTERPRETATION OF GEODETIO EVIDENCE. 17 While the effect of the compensation varies as indicated in Table 1, the effect of the attraction of the visible topography varies inversely with the square of the distance, and, for any particular distance from the station of observation, there is a definite ratio between the effect of the direct attraction of the visible topography and of its compensation, and this ratio is easy to determine. Re- ferring again to Fig. 1, the effect of the attraction of the elevated mass, if the divergence of A S from the horizontal is neglected, as it usually may be, is represented by the formula— where D represents the deflection produced at S— m, the mass of the elevated tract, r, the distance A S. Similarly the effect of compensation, expressed in terms of r, instead of h as in the formula on p. 16 will be— ~ m = 2 seo 2g 088 4 = = cos® a The ratio of the effect of attraction to that of compensation is, therefore, 1 : cos’a and the ratio to the net effect of attraction, and compensation, is, 1 : 1—- cosa, which represents the compensa- tion factor of Mr. Hayford, or the factor by which the calculated attraction must be multiplied to obtain the net effect, after allowing for compensation. This factor depends only on the angle a or, in other words, on the ratio between the distance from the station of observation and the depth of the centre of compensation, so long as the former of these is not large enough to necessitate the considera- tion of the effect of the curvature of the earth’s surface. As has already been pointed out, the centres of attraction and compensation, as the terms are here used, differ from the centres of gravity of the masses to which they refer; where the distance from the station is considerable, the two may be so nearly coinci- dent as to become practically identical, but at lesser distances they may be largely divergent. To take the assumption, used by Archdeacon Pratt and Mr. Hayford, of a uniform defect of density, extending through a definite depth, then the centre of compensa- tion would lie not far from one-half of that depth so long as the horizontal distance was such that the direct distance of the bottom [ 165 ] 18 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. of the column of rock from the station did not exceed that of the top by more than a small fraction of the whole. At lesser dis- tances the effect of the portions near the top outweighs those near the bottom, because not only are they much nearer, but also their effect is more nearly in the horizontal plane, and, consequently, the centre of compensation comes nearer and nearer to the surface till, at the limit when the distance becomes zero, the depth of the centre of compensation also becomes zero. It is obvious that if the compensation factor can be determined when the depth of the centre of compensation is known, the process can equally be reversed, and the corresponding depth of centre of compensation can be deduced from the factors. Taking the case of uniform compensation to a depth of 113°7 km., or 70°7 miles, we find that the depth of the centre of compensation at a distance of— : 1:2 miles, is 4:5 miles. yy: ae o=st 45° is mo Se It may be pointed out that the volume or mass of these three cones is in the proportion of 1 : 5: 90, while their effect is only in the proportion 1: 2: 3, and if the angle of the cone is taken at 90, that is, if the layer of rock is of infinite extent, and so of infinite mass, the effect is only increased to ‘0033 dyne, so small is the influence of the more distant masses as compared with those nearly underneath the station.’ Moreover these figures are not 1 It must again be noted that these statements and figures would only be true of a plane earth of infinite extent, and require modification when applied to a spherical or spheroidal earth, but within the distances and depths with which this investigation is concerned the effect of the curvature of the earth’s surface is inappreciable. [ -43 3] 26 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. only true of a simple layer of rock 100 feet in thickness, but are equally true of a proportionate excess or defect of density, distri- buted through a greater thickness in such a manner that the mass of any vertical column of rock, which wholly includes the cone, is in excess or defect by the equivalent of 100 feet of rock of average density. This formula, and the figures derived from it, will be useful in comparing the effect which should be expected on different hypotheses of the nature and distribution of compensation. The way in which these differences arise will be most readily explained by a reference to fig. 3, which represents the case of a station S on the surface of an elevated plateau; it will be affected by the eae Clee ae ee pe eg ae ee Ri Sg & ~ mw we - ; PALS; | $$$ $n ——D Fig. 3. downward pull of the mass of rock lying between the level of S and sea level, represented by D D, it will also be affected by a defect of downward pull, due to the diminution of density by which the weight of the plateau above D D is compensated. To simplify the consideration of the relative effects of these two forces we, will suppose that the variations of density are so dis- tributed that the centre of effect of any column of small area lies at the depth A A in the case of the plateau, and of C C in the case of the compensation; and that the line S M represents that along which any given mass will produce a greater effect at S than if it were situated at a greater or less depth on the same vertical line. Now take the case of a small column so situated that the centre of attraction of the plateau at A’ is on the line S M, and the centre of compensation vertically below it at C’; here the effect of the [ 1%4 | THE NATURE AND INTERPRETATION OF GEODETIO EVIDENCE. 27 attraction of the plateau is obviously larger in amount than that of the compensation, and the net effect will be a downward pull at S, which will increase the amount of the local measure of gravita- tion at that station. Conversely in the small column of rock situated so that the centre of compensation lies at C”’, on the line S M, and of the attraction of the plateau at A”, the effect of the com- pensation is obviously in excess of the attraction of the mass above sea level, and the net effect at S will be a diminution of the local measure of gravity. Somewhere between these two points must come a limiting distance, where the effect of the attraction of the mass above sea level is exactly balanced by that of the compensa- tion and the net effect at S reduced to zero; at lesser distances the effect of the elevated mass will exceed that of the compensation, and the net effect will be an increase in the local measure of gravity, but to a less extent than if there were no compensation, and at greater distances the effect will be reversed, and the net effect be a diminution of the force of gravity at S. The distance from the station at which this reversal takes place depends in part on the height of the station and the surrounding topography above sea level, and partly on the depth and nature of the compensation. For the particular hypothesis of compensa- tion used by Messrs. Hayford and Bowie the distance is about five or six miles ordinarily, but in the case of stations of great altitude may reach nearly twelve miles. An idea of the nature and amount of the effect of the direct attraction of an elevated mass and _ its compensation may be got from Table 3 (on next page), which shows the effect of the attraction of a circular plateau, of varying heights and dimensions, at a point in the centre of its upper surface, the values being expressed in dynes and calculated from the Hayford and Bowie tables. : Here we see that the effect of the mass of a circular plateau of 1,000 feet in height, contained within a radius of 14 miles, amounts to *031 dynes, and that no appreciable increase results from an enlarge- ment of the plateau to a radius of 100 miles, the more distant masses being so nearly on a level with the station that the vertical com- ponent of their attraction is negligible. If, however, we take the effect of compensation into consideration a reduction in the net effect becomes apparent beyond five miles from the station, For greater heights there is a continuous increase in the effect of the visible mass up to the limits considered in the table, but beyond a | ee ag 98 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. distance of 40 to 50 miles the further increase is very small, and may be ignored. The effect of the compensation on the other hand increases and the net effect, after reaching a maximum, goes on diminishing with an increase in the dimensions of the plateau. TABLE 3.—Altraction of a circular plateau, of varying radius and elevation, at a point centrally situated on its wpper surface, due to the visible topography, and to the same, compensated in accord- ance with the Hayford and Bowie tables, All values positive and expressed in dynes. © 1,000 ft. 5,000 ft. 10,000 ft. 15,000 ft. Radius in — S eee: I l : iid miles. | | | top comp. top. | comp. top | comp top. comp Se ee ae = eas | 14 | -O03L | 031 118 | -114 172 164 196 185 22 | -031 | -031 135 | +129 215 | +203 260 244 3-2 | -081 | -032 | 146 | -187 | -250 | -234 | Bat 207 5-2 | -031 | -031 154 | +141 | +282 | -258 383-345 7-5 031 | -030 159 141 301 266 422 “367 1-7-0381 028 | “163 | 137 315-264 | 452 | “378 17-9 031 | +025 | 165 127 325 249 | +473 | -359 365 | -031 | -020 168 | -101 335 202 | +494 295 61-4 O31 O15 170 | -075 338 155 902 | 226 103-3 | -031 | -009 | -170 | 050 341 108 | -508-| 159 | | From the figures in Table 3, it will be seen that in the case of a plateau extending for distances measured by hundreds of miles, it may well be that the effect-of compensation will completely neutralise that of the attraction of the visible mass, and the result- ing attraction of gravity be the same as if the whole of the elevated mass were non-existent. We may also find in these figures an explanation of the fact that the anomalies of gravitation above sea level tend to be positive if the effect of the visible topography is ionored, and negative if it is considered, for in the first case no regard is paid to the increase in the local attraction due to the mass above sea level, and in the second a greater effect is attributed to it than it actually exerts. Further, it is obvious, from a con- sideration of fig. 3, that an increase in the depth of compensation would enlarge the limits within which the effect of the visible mass predominates over that of its compensation, and so increase the [ 176 ] THE NATURE AND INTERPRETATION OF GEODETIC EVIDENCE. 29 force of gravity at the station, while a lesser depth of compen- sation would have the reverse effect. Taking all the considerations into account we may conclude that if, after allowing for the effect of the surrounding topography and its compensation, there is left a positive, or a negative, anomaly at any station, it may be due to one of three causes, and may indicate (1) that the compensation of the elevated masses is in- complete, or in excess ; (2) that the real compensation is such that its centre of effect lies at a greater, or a lesser, depth than that of the compensation assumed in the calculation; or (3) that there is a local excess, or defect, of density in the matter lying below the level of the stations, inde- pendent of the effect of the elevated masses and their compensation. The form in which the gravity observations of the Survey of India have been published has undergone greater changes than in the case of the deflection of the plumb-line. The older calcula- tions are based on Prof. Helmert’s 1884 formula for the theoretical variation of gravity with latitude, and on values of 5°6 and 2°8 for the mean densities of the earth, as a whole, and of surface rock, respectively. All the published anomalies, making allowance for the effect of height alone or of height and visible masses, were calculated on this basis, but, with the introduction of the considera- tion of the effect of compensation, different values for the density of the earth and of surface rock were adopted, namely 5°576 and 2°67 respectively, and Helmert’s 1901 formula replaced the earlier one of 1884. The result is that the anomalies allowing for compen- sation are not directly comparable with those in which it is not considered. The difference in the densities used has but a smal] effect, except in the case of the Himalayan stations, but the 1901 formula gives a larger value for the theoretical value of gravity and, consequently, a negative change in the value of the anomaly which amounts, in the stations dealt with, to from —-022 to —'027 dyne. ag There are, fortunately, a sufficient number of stations for which the Hayford anomalies have been calculated to serve most of the objects of this investigation, and these will be made use of, so far fait] D 30 OLDHAM: THR STRUCTURE OF THE HIMALAYAS, RTC. as possible, as they not only give a closer approximation to the absolute values of the anomalies but also to the differences between them. The other values of the anomaly of gravity, which are available for all stations, are comparable with each other, though not directly comparable with the Hayford anomaly, and afford an indication of the nature, and approximately of the amount, of the difference in the anomaly at any two stations and in this way will be utilised, as far as seems practicable. So far, attention has been confined to the fact of compensation and the effect of variation in the depth at which it takes place ; it will now be necessary to devote some space to a consideration of the manner in which compensation may be brought about, and to the cognate concept of isostasy. The word isostasy was introduced by Major C. E. Dutton,! and by etymology implies merely the statical condition that the mass —or, more correctly, weight— of matter under every considerable portion of the earth’s surface of equal area is the same, irrespective of the elevation of that area above or below sea level. The state- ment is not intended to apply to every small protuberance or de- pression in the surface of the land or bed of the sea, but to the general level, and involves, of necessity, a lesser density of the matter under an elevated region, such as a great mountain range, than under the plains at its foot, and a greater density under the depressed floor of the ocean. This leads to the same result as the concept of compensation, but the two are not synonymous, for the elevated regions of the dry land are continually suffering a loss of weight by denudation, while the material removed is deposited on the lowlands, and especially on the bed of the sea; in this way the load on one area is diminished, that on the other is increased and isostasy is destroyed, till the strain set up by this shift of load causes an underground flow of matter from the over- burdened to the lightened area and so isostasy is re-established. From this it will be seen that the two principles of isostasy and compensation are related to each other in as much as the former necessitates the latter, and further that, whereas compensation merely expresses a static fact, isostasy, in spite of its name, implies 1 Bull. Phil. Soc. Washington, XI, 'p. 53_(1889). [ 178 ] THE NATURE AND INTERPRETATION OF GEODETIC EVIDENCE. 31 a dynamic process,t which could only take place in a medium pos- sessing a considerable degree of plasticity under the stresses to which it is exposed. The various hypotheses which have been proposed, to account for the elevation of mountain ranges, excluding those which do not provide for compensation, may be divided into two categories, those which regard the elevations of the earth’s surface as being sup- ported by some form of tumefaction, and those which regard them as supported by some form of flotation. The earliest suggestion, that of Sir G. B. Airy,? was of the latter class; adopting the notion, still prevalent when he wrote, that the earth consisted of a comparatively thin solid crust floating on a fluid core, he showed that the crust would not be able to support the stresses set up by the weight of a great mountain range, which would break through the crust, and sink into the denser magma, till the buoyancy of this depressed portion was sufficient to support the weight of the range, and the difference in weight, between the depressed portion of the crust and the denser magma displaced by it, while support- ing the range, would also produce that compensation which the observations indicated. This hypothesis was afterwards adopted and developed by Rev. O. Fisher * who, taking the elevation of mountain ranges as due to compression, and consequent thickening, of the earth’s crust, recognised that the additional weight thereby imposed on the mountain region would cause a depression of the crust into the underlying denser magma and give rise to a protuberance on the underside of the crust corresponding to the mountains on the upper. Though both of these investigators based their explanation on the notion of a comparatively thin crust, floating on a fluid earth of greater density, it must be remarked that the latter condi- tion is by no means essential, for the whole of the processes concerned would take place within the outermost 60 miles from the surface of the earth, leaving the odd 3,900 miles of the radius unaffected, so that, provided there was a fluid or even plastic layer, of greater density than the overlying crust, in that region which lies above a depth of 60 miles from the surface, all the requirements of the hypothesis would be fulfilled, and the constitution of the more 1 Major Dutton recognised that the term was inappropriate, but the word which would have expressed his intention was preoccupied in a different sense. 2 Phil. Trans., CXLV, 101-104 (1855). 8 Physics of the Earth's Crust; Ist ed. 1881; 2nd ed, 1889. LCase, f D2 39 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETO. deeply seated portions would not enter into consideration. It must also be remarked that any hypothesis which regards the elevation of mountain ranges as a result of compression, seems necessarily to involve some form of isostasy by flotation, in order to account for compensation, for if the whole of the thickening took place in an upward direction the mountains would be an un- compensated excrescence of additional matter, but if the thicken- ing took place both upwards and downwards, and the outer crust consisted of less dense matter than that underlying it, there would be a defect of attraction which, at a sufficient distance, would neutralise the attraction of the mountain mass to a greater or less degree, according to the ratio of the excess and defect of matter. For complete compensation the two would have to be equal in mass, a condition which would imply complete isostasy and a support of the mountains by flotation. Much the same effect, and the same considerations will apply to any form of hypothesis which attributes the elevation of the surface to an intrusion of fluid matter below it. Here again, if the whole effect was the raising of the crust between the upper surface and the intrusive mass, the range would be a mere excres- cence of the surface and its attraction would be unmodified by com- pensation, unless we could assume that the intrusion was devoid of density, which is inconceivable, or that the displacement of the upper surface was accompanied by a downward displacement of the lower surface, leading to the replacement, under the upraised tract, of denser material by lighter. Any hypothesis of this kind, therefore, falls into the same great category as the supposition that the elevation of the range is due to a thickening of the crust by compression, in that it would imply an actual transfer of matter from a region outside, resulting in an increase of the mass of the outer crust underneath the upraised tract; and on any hypothesis involving this, it seems impossible to account for the accepted fact of compensation, without admitting that the upward pro- tuberance of the upper surface is accompanied by a downward protuberance of the under surface of the crust, the “root” of Mr. Fisher’s investigation, with the consequences of a displacement of the denser material under the crust by the lighter material of the crust itself, and an isostasy and support by flotation. An hypothesis of this kind opens up a further possibility of a considerable departure from locally complete isostasy and a dis- [ 180. ] THE NATURE AND INTERPRETATION OF GEODETIC EVIDENCE. 33 tribution of the load of the range, or of the flotation power of its root, over a considerable portion of the crust on either side of the range. This effect may work in one of two ways; if the growth of the upward protuberance exceeded that of the root there would be a local defect of support, which would be taken up by a depression of the crust on either side till the requisite support was attained. In this case the compensation of the range would be in defect, or in other words the mass of the range would be in excess of the defect of mass below it, while the tract on either side would be over compensated, so that the deep-seated defect of mass would exceed that of the visible elevation. This is a variation from a con- dition of the compensation of the range being complete, in the por- tion of the crust underlying it, which was actually investigated by Mr. Fisher; but it is also conceivable that the reverse might take place, and the development of the root be in excess of that of the range. In this case the surplus buoyancy would be taken up by a raising of the crust not only under the range but on either side of it, and the range would be over compensated while the tract on either side would show an excess of load over compensation. This modification of the hypothesis of support by flotation has not, so far as I know, been investigated as yet, but its possibility cannot be excluded, and, if supported by the geodetic observations, is in some ways an attractive one. It would give a ready explana- tion of some of the features in the geological history of the Hima- layas, such as the simple upward lift, of which there is evidence in the Deosai, north of Kashmir, in the plains of Hundes and else- where ; the peculiarities and origin of the great boundary fault would find an easy explanation, as also the tilting of the surface of the gravel slope along the foot of the Hills, which is noticeable in many parts, and the fact that the range seems still to be rising. An alternative group of hypotheses involves no addition to the material under the elevated tract, but regards the elevations of the visible surface as due to an actual swelling up of the matter under them, or, what comes to the same, a greater condensation under the more low-lying tracts of the surface. An hypothesis of this sort may be described as attributing the differences in level of different tracts of the earth’s surface to some form of tumefac- tion, and the effect has usually been attributed to differences of temperature. This explanation has the defect of being apparently insufficient, quantitatively, to account for the facts, and even if Fel J 34 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. it might suffice for the original formation of an elevated tract, with the accompaniments of compensation and a condition of isostasy, it would not provide for the maintenance, or re-establishment of the latter after disturbance by the removal of material by denuda- tion from the higher and its deposition on the lower levels. Recently an hypothesis of tumefaction has been proposed by Dr. L. L. Fermor,! which appears to be more competent to account for the facts met with in nature; starting with the fact that igneous rocks of the same chemical composition may present themselves in differ- ent forms of mineral constitution, and that these forms vary in specific gravity, he concludes that this variation is the result of the conditions of temperature and pressure under which the different forms of rock consolidated, and distinguishes between the plutonic and the infra-plutonic forms of rock, which may originate from the same magma according to the pressure under which it cooled down to crystallisation. From this concept the consequence follows that in appropriate conditions of temperature and pressure, there might be a passage from one mode of mineral aggregate to another, of different density, accompanied by a corresponding change in volume. As the difference in density of the extreme forms of mineral aggregate may amount to as much as 20 per cent., it seems that we might find in an action of this nature a sufficient explanation for the eleva- tion of even so lofty a range as the Himalayas and, in the opposite direction, for even the greatest depths of the sea, without having to invoke either too great a difference in density, or too large a bulk of material, to fall within limits which are justified by other observations. Dr. Fermor’s hypothesis would also account for the maintenance of a mountain tract against the action of denudation, for the change in the deeper layers of the crust might easily be a progressive one, and to some extent dependent on the decrease in load. We are not, however, here concerned with a discussion of hypotheses of mountain formation, but with the effect which an hypothesis of origin by tumefaction would have on the question of compensation. This, it will easily be seen, is provided for by the hypothesis, for the protuberance of the surface is the manifesta- tion of a corresponding decrease in density below, and in this way compensation is provided for. It is also obvious that the denuda- tion of the upraised tract and the deposition of the material removed 1 Geol. Mag. Decade VI, Vol. I, pp. 65-67 (1914) ; ef. also Rec. Geol. Surv. Ind,, Vol. XLII, pp. 41-47 (1913) and XLII, pp. 133-207 (1912). [ 182 ] THE NATURE AND INTERPRETATION OF GEODETIC EVIDENCE. 35 by denudation, on lower lying tracts may lead to departures from a condition of complete isostasy, but these will necessarily be in the direction of an excess of compensation in the hills and a defect in the plains; it is not conceivable that any hypothesis belonging to this class can account for the hills being under compensated or in other words showing an excess of load. In this way, then, we have a test which will distinguish between the two groups of hypotheses; so long as the geodetic observations indicate that the compensation of the hills is complete, or that the compensation is in excess of the visible mass of the range, we are free to choose between the hypotheses, but if they indicate an unmistakeable excess of mass in the hills, or a defect under the plains, after allowance has been made for compensation, the whole of one group is excluded. We are then restricted to the other, and can only choose between those hypotheses which involve an addition to the mass of the crust underlying the hills, whether this is brought about by the compression of the crust or by an underground migration of material from outside the limits of the range. [ ee | 3¢ OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. CHAPTER ITI. THE IMAGINARY RANGE AND TROUGH. Iu applying the general principles, outlined in the preceding chapter, and endeavouring to find the real meaning of the irregularities noticed in the geodetic data, two courses are open. The first is to take the whole of the stations, or a selected series of them, and calculate what the deflections should be at each, according to different forms of compensation, and then see which assumption gives the smallest average departure from observed results, or, more accurately, the least value for the sum of the squares of the differences between the observed and the calculated deflections. This is the method of geodesy, and is the only one admissible where minute numerical accuracy is essential, but it has the drawbacks of being extremely laborious, and of liability to degenerating into mere juggling with figures, unless great care is taken to keep in mind the exact signi- ficance of the calculations being gone through. Moreover, it is a method more suited to the final calculations of an investigation than to the preliminary stages, which may show that the more re- fined method would be no more than a vain attempt at a greater degree of precision than the nature of the data permits. For these reasons it is necessary to discover simpler means of dealing with the problem, and this is to be found in ignoring the complicated contour of the actual Himalayas, and substituting for them an Imaginary Range which shall not differ too largely from the actual range, while simplifying the calculations necessary for estimating the consequences of various hypotheses. It will then be an easy matter to compare these results with those of observation, and so determine which of the hypotheses must be rejected, and which, if any, can be profitably pursued in greater detail. It is not difficult to devise such an Imaginary Range as will render calculation easy, and at the same time be in agreement with the actual average contour of the Himalayas, that is with their average or generalised form, apart from the irregularities due to the erosion of the river valleys. Broadly speaking, the Himalayas proper, excluding for the present the foot-hills of the Siwalik area, rise abruptly on their southern margin to a height of about 5,000 [ 184 ] THE IMAGINARY RANGE AND TROUGH. 37 to 6,000 feet above the level of the sea; in the interior of the range is the great plateau of Tibet, which, presenting very considerable irregularities of contour, may, in view of the distance separating it from the stations of observation with which we will be concerned, be regarded as a plain of about 15,000 feet of elevation above the sea level. Along the southern edge of this plateau runs the great snowy range, including the highest peaks, and south of the snowy range comes the region of the lower Himalayas, where the summits do not rise to more than ten or twelve thousand feet above sea level. Though the distinction between these two regions, of the snowy range and the Lower Himalayas, is fairly well defined and somewhat abrupt, the average level of the ground shows a less abrupt change and in the Lower Himalayas themselves there is a gradual decrease in general altitude to about 5,000 feet at the southern margin of the hills, where the ground drops abruptly to the foot-hills, or Sub- Himalayas, of the Siwalik region. These may conveniently be represented in that portion of the range which will come into consideration, by a plateau of twenty miles in width, and fifteen hundred feet in elevation above the plains to the south. The generalised cross-section of the elevated mass of the Himalayas may therefore be represented as a plateau of 15,000 feet in eleva- tion, bordered by an inclined plane of 100 miles in width, sloping from 15,000 to 5,000 feet of elevation, and a plateau of 1,500 feet in height by 20 miles in width. For purposes of calculation, it will be simpler to substitute for this inclined plane a series of steps each ten miles broad and 1,000 feet lower than the next step to the north. The Imaginary Range would then have a _ cross-section like that shown in fig. 4 (page 38), where two actual cross-sections of the Himalayan Range are also given, for comparison. In the calculations regarding . this Imaginary Range, it will be assumed to have an east to west direction, with the elevated plateau on the north and the plains on the south. This is not only in general agreement with the Himalayas, but will allow of deflec- tions towards the range being expressed as northerly deflections, in accordance with the usual convention, by the minus sign, and 1 I have followed previous writers in accepting 15,000 ft. as the mean height of the central plateau ; actually the mean height would be more correctly 16,000 ft. or a little more, As the elevation of the land south of the Himalayas is ignored in the calculations, and only the height of the hills above the sea considered, the difference is partly eliminated, and in any case would have but a very small effect at the stations at which observations have been made. L 185 | OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETO. 38 "S}UOMIO}¥}S IvpNqe} OY} Ul posn sv ‘suO!7vIS 94} JO Stiequinu oy} poywoIpul st MOTeg “WOsted uO JO} ‘OTROS OTIBS 04} UO ‘pozuosoidol ore seALTEUMIA 9Yj} JO SUOT}OOS SsOIO Jenyor Omg f OSURY AIvUISeWT OY} JO UOTOOS SsSCIQ—"P ‘DLT a ekepewiyy | Nvo}ej}g UBT, ‘ UIt]g o1jeZuNDH 0 Caw SPA Ge eee Le 82) 6. Ol- Be air ere ri) ote Sk ! 4 } G+ + 4 } ! e+ 2 Ai= @- 6-0 ‘ : , . u pe) ae t\ oc me Rae ee tt Fn TR i en i a cn tr meen : - Shas Munn “th f e: ps Vv “Vr Awe PM; a . Se te He ee ef « ae oe ee ee oe a es " [ 186 | THE IMAGINARY RANGE AND TROUGH. 39 deflections away from the range as southerly, by the plus sign. A series of supposed stations, at intervals of ten miles apart, can conveniently be distinguished in the same manner, the station at the edge of the hills, which is here regarded as coincident with the main boundary fault, being 0, those to the north being successively —-1, --2, and so on, and to the south, in a similar manner as +1, +2, &c. The geodetic effect which should be looked for having been calculated for each of these stations, the results were plotted on squared paper and a curve drawn through the points, which will not be very widely different from the smoothed curve calculated for a set of stations similarly situated on the actual Himalayas. Having decided on the cross-section of the Imaginary Range, it is necessary to decide on how much of it is to be eonsidered in each calculation. The smaller the distance from the station which enters into the calculation, the simpler this will be, and there are three considerations which put a limit to the distance which can profitably be considered. The first of these is the fact that the attraction of any given mass of rock decreases with the square of the distance, so that its effect becomes negligible after a certain distance is exceeded. The second is the fact that the methods of geodetic observation can only give a differential, not an absolute, result. Im practice some one station is taken as a station of reference, and the observations at other stations are expressed as differences from that station. Now the nearer two stations are to each other, the smaller will be the proportionate difference in distance of any point remote from both, and, consequently, the smaller the difference in the effect of the attraction at each of the two stations; and so, for any pair of stations there is a certain distance beyond which all masses affect each in so nearly equal degree that their effect may be neglected, so far as the consideration of the difference in deflection at the two stations is concerned. For a distance of 10 miles between the stations this limit would be about 50 miles, for a distance of 25 miles between the stations the limit would be about 100 miles, and for a distance of 100 miles the differential effect of topography more than 400 miles away would be trifling, even if the effect of compensation is ignored. The third consideration, limiting the distance from the station which need enter into calculation, is the fact that when the effect of compensation is considered, the effect “of distant topography is almost or completely neutralised by its compensation, [ 187 ] 49 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, BIC. In my earlier investigation of the eflect of the Gangetic Alluvium on the Plumb-line,’ only those masses lying within 50 miles of each station were considered, but in this more extended investigation the limit has had to be enlarged and in each case a strip running transverse to the range and extending 100 miles on either side of the station, and so much of this strip as lies within 100 miles of it, has been taken into consideration. In other words each station successively has been conceived as lying in the centre of a 200-mile square, and everything outside this limit has been put out of con- sideration. It will be shown, further on, that the effect of this limitation, of the area considered, is so small, in proportion to the effect produced by the area actually considered, that it may be left out of consideration for the purpose of this investigation. We are now ready to take up the effect of different hypotheses of compensation as applied to the Imaginary Range and, as a starting point, the tabular statement No. 4 (page 41) gives the deflections which would be produced by the Range proper, excluding the eflect of the Siwalik Hills, at a series of stations 10 miles apart, the masses within a square of 200 miles a side being alone considered, and as they would result (1) from the uncompensated effect of the visible mass and (2) allowing for the effect of compensation according to Mr. Hayford’s factors for uniform compensation to 113°7 km. Before proceeding further it will be useful to consider what modification in these figures would result from including a larger area in the calculations and, as an extreme case far exceeding anything to be met with in nature, I have supposed the stations to be situated in the centre of a square of 2,400 miles on the side, and the plateau, slope, and plain of the Imaginary Range, to be extended over the whole of the area thus taken into consideration. In these circumstances the uncompensated deflection at the station 0, on the edge of the hills, would be increased by 78”; at station 10, or at a distance of 100 miles from the edge of the hills, in either direction, the deflection would be increased by 69”; the difference would, therefore, be increased by 9”. If, however, the effect of the Hayford compensation be taken into account, the increased de- flections would be reduced to just under 3” at the edge of the hills and just over 2” at 100 miles away, and the difference would be but 1 Proc. Roy. Soc., Series A, XC, pp. 32-41 (1914). [ 18 | THE IMAGINARY RANGE AND TROUGH. 41 TaBLE 4.—Deflections produced by the Imaginary Range due to the attraction of the visible masses; (I) uncompensated and (II) compensated by Hayford factors for depth 1137 km. | STATION | I II No. Uncompensated. Compensated. | | — 20 0 0 —19 0 | 0 —18 l | 0 =i? 1 0 — 16 z 0 — 15 3 1 —14 5 1 —13 4 2 —12 il 3 — ii 15 6 —10 23 ll — @Q 28 13 — 8 32 15 ee | 35 16 — 6 38 17 — 5 40 18 — 4 42 19 — 3 43 20 —— 2 45 21 — 1 48 24 0 76 53 + 1 34 15 + 2 23 } 9 1. | 17 5 + 4 12 3 4+ 5 9 2 + 6 6 1 + 7 4 0 + 8 | 2 . 0 + 9 1 0 + 10 0 0 0-7". It may be said that no reasonably admissible hypothesis of compensation could increase this difference by more than about 1”, and so the limitation of area, adopted for the purpose of sim- plifying calculation, is justified, for the effect of increasing the area would be much less in nature than in the artificial circumstances assumed for this calculation. The same conclusion is reached by a comparison of the deflec- tions, calculated as due to the Imaginary Range, with those of the actual topography of the Himalayas, and this can readily be done, since the necessary calculations have been made, for certain stations, {| 189 | 42 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. and published by Major H. L. Crosthwait.1 In Table No. 5 a list of these stations is given, together with their distances from the main boundary fault, and the deflections which were calculated for the actual station, as well as those at stations similarly situated on the Imaginary Range, allowance being made for the departure of the actual range from a due east and west direction. In each case the values are given (I) for the supposition that the visible masses are uncompensated and (II) for the supposition that the compensation is in accordance with Mr. Hayford’s tables for uniform compensation to a depth of 113°7 km. Finally there is given the difference between the value for the Imaginary Range, and for the actual topography on each supposition, or the amount of de- flection, northerly or southerly, which the latter gives as compared with the former. TaBLE 5.—Comparison of deflections due to the actual topography, with those due to the Imaginary Range, at stations similarly situated, allowing (1) for the effect of the visible masses and (IT) for the same as modified by the effect of Hayford compensation. | Deflections ; Difference | Distance due tothe | Deflections between the “ from main Imaginary calculated effect of Qa. : 5 A ose a boundary Range, in by Major actual and in miles, the meri- | Crosthwait. imaginary dian. topography. I I] I II I 1] LAE on 5 eee ee te Aa Ne dP dd |} YL, 88 4 8 Kurseong . : : ~t ers — 54 — 29 — 103 —23 —49 46 Mussooree . : 5 ‘ 4 —40 —19 |— 86 —17 —46 +2 Birond ’ ; : ee] Lets — 51 —20 |— 74—14 —23 +6 Dehra Dun . ; : ry 6 8. ae tS SO ie sebe “P ) Siliguri ; : ‘ : Less — 30 —13 84 —11 ; —54 +2 Jalpaiguri ¥ : ti ee ages fee 77 ee ~ St Oh oe Kaliana : j ; | 41 ,, /_— 6— 2|— 5 — 3 —52 +1 } It will be seen that the uncompensated deflections derived from Major Crosthwait’s calculations show a large northerly deflection, in 1 Investigation of the Theory of Isostasy in India: Survey of India, Professional Paper No. 13, Dehra Dun, 1912. In addition to the results published in this paper, I am indebted to the courtesy of Sir S. G. Burrard, Surveyor-General, for the details of the calculations from which they were obtained. [ 190 ] THE IMAGINARY RANGE AND TROUGH. 43 excess of those due to the Imaginary Range, but this is due to the fact that Major Crosthwait’s calculations include all topography within 2,564 miles of the station, and therefore the whole of the highlands of Central Asia, whereas those for the Imaginary Range only include topography within 100 miles distance. If we turn to the compensated deflections this great difference disappears and we find that Major Crosthwait’s calculations give rather smaller values for the northerly deflections. At the stations north of the boundary fault, that is to say within the Himalayan region proper, the difference varies from 6” to 2”, an irregularity which finds a natural explanation in the irregularity of the contour of the actual Himalayas and in the deep cut valleys which penetrate it. At stations ontside the Himalayas, where these irregularities have less effect, a greater uni- formity is observable and a closer agreement; the greater difference at Jalpaiguri is doubtless due to the inclusion in Major Crosthwait’s calculation of the southerly pull of the highlands of the Assam Range and the Peninsula. From this comparison two conclusions may be drawn. Firstly that the limitation, of the extent of topography considered, to that lying within 100 miles of the station is justified by the smallness of the effect of more distant topography, when the opposite effect of its compensation is taken into consideration; in none of the stations does the effect of the topography beyond 100 miles, and up to 2,564 miles, differ materially from about a couple of seconds of are, and in every one of them it is in the same, northerly direc- tion, so that no change is introduced in the difference between the calculated deflection for any pair of stations. Secondly it appears that the Imaginary Range will serve the purpose for which it was intended ; that the deflections calculated from it are, on the average of the same order of magnitude as those which would be deduced from the actual topography; and that the departures from the deflections calculated from Mr. Hayford’s tables which would result from a variation in the hypothesis of compensation will agree in character and order of magnitude with those which would result from the application of a similar hypothesis to the more complicated topography of a station, similarly situated, in the Himalayas, No more than this is, at present, required, so far as the range representing the Himalayas proper is concerned ; but for the greater part of its length the main range is bordered by a tract of lower Lae 44 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC, hills, which have to be included in making a comparison between the effect of actual and imaginary topography. These are absent in the Sikkim area; elsewhere they lie south of the main boundary, and belong properly to the region of the Gangetic trough, but must be considered as part of the topography so far as they affect the deflection of the plumb-line. They will be simplified into a plateau of 20 miles in width and 1,500 feet in height above the plains, dimensions which conveniently, and approximately, represent the actual topography ; and, as the mean density of the Siwalik rocks is about 2:2, and of the rocks of the main range about 2°7, the deflec- tions will be estimated at eight-tenths of those which would result from Mr. Hayford’s figures. In table No. 6 the deflections so obtained are given on the assumptions respectively, of no compensa- tion, and compensation according to Mr. Hayford’s tables; the difference does not in any case exceed one second of arc, and though there seems some reason, in this area, for not using the hypothesis of compensation, it will be safer to use the figures in the second column, which must be added to those obtained from other tables, when it is necessary to consider the attraction of the hills of the Sub-Himalayan region. Taste 6.—Deflections due to an Imaginary plateau, representing the Sub-Himalaya or Siwalik Hills, assumed 20 miles broad by 1,500 feet in height and of density *8 of average rock. STATION. * Uncompensated. Compensated. 4 anh | +1 0 — 4 + § 1 0 —3 +;1 + 1] <= 2 +°2 + ] —1 + 3 + 2 0 ays +13 = J 0 0 =e, == 14 —= 1% +3 — 3 amy} a4 —i 2 eae | +65 ae | a | +6 wer 0 ey — I 0 Andee 0 0 Having formed an estimate of what the effect of compensation would be, if it is given the average value determined by observa- [ 192 ] THER IMAGINARY RANGE AND TROUGH. 45 tions in the United States of America, which may be accepted as not widely different from the average effect elsewhere, the next stage in the investigation is to calculate the result of supposing a departure from these average conditions in one direction or another, The first of these, to be considered, is a variation of the depth of compensation, still supposed to be uniform throughout the depth to which it extends, and the depths taken for calculation will be those for which Mr. Hayford has given tables, namely 162°3 km. or about 100 miles and 79:8 km. or about 50 miles. In table No. 7, the result of calculation for these two depths is given, to the nearest whole second of arc, as well as the deflections resulting from Mr. Hayford’s factors for uniform compensation to a depth of 113:7 km., or about 71 miles, and the differences between these values. The meaning of these differences being that, if the calculation had been made according to the MHayford TaBLE 7.—Deflections which would be produced by the Imaginary Range on the supposition of uniform compensation to various depths. ~ 30s ASSUMED DerptTH OF COMPENSATION. STATION. | 162°3 km. Diff. 113:7 km. Diff. 79°8 km. ‘ eed ee a ion 10 se <2 | eal! aS ! — 9 ssi | hx FB es |; eat 23 | —10 era. | FS <6 | aD r3 — 12 oy ef] a4 Seay + 4 Betas be sn | ay | —4 —17 +4 — 13 em B > 2y ——4 — 18 +4 — 14 seg | 25 — 4 a [Y) +4 — 15 3 | ys sib | —= 20 +4 — 15 ey 26 =2e5 } ai +4 — 17 1 = AL eee) ae +4 = 20 0 rs a5 r= DS + § -— 48 + ] a |: — 4 was | 199 + 3 mie he <2 st see =o | ars a= ior cee oe an 9 —13 | —17 —4 | —14° —1 | —Ih 42 dis “8 —15 | —19 —4 | —16 —1) —13 +2 Za 4 =16. | —2 . =$'o1s 297 at —2 t=3. 2G Sei | =22 —5 | —19 —2 ai 15 a2 oe Shh ee BR ae BET OO ROE cd GE'S 8: | —19 | — 24 —65 — 21 —2 16 +3 sis == 20 SS ee ae ee a a | sah sos —21 | ,-27 +6 | —23 -—2 | —18 +3 xe Pa! | 2224 — 31 ee] —= 27 —3 = 22 +2 0 ig Ogee Ga pete RR a BS Se a ey se 18 mo9 tf mh peed. a2) 1B 48 + 2 — 9 = 12 —3 — 9 0 == 7 + 2 + 3 = § x 7 —2 5 5 0 ae 3 + 2 4 AZ = 4 —1 — 3 0 — 2 +1 = as g a0 2 a Sat i ae eae: ee OG Se 2a 2 a | ee | 0 = ] 0 i oder 0 — 1 = 1 0 0 0 0 + 8 0 — 1 0 0 0 0 0 > 9 0 0 0 0 0 0 0 -+ 10 0 0 0 0 0 0 THE IMAGINARY RANGE AND TROUGH. 47 The Hayford values for the effect of compensation depend, as has been pointed out, on a wholly empirical distribution of the variations in density, a distribution which would not accord with those theories of mountain formation, which, so far as they admit of compensation at all, demand a limitation of the effect to a cer- tain layer, or, at least, a concentration of the greatest effect within these limits. A calculation was, therefore, made of the effect of an assumption of a uniform depth of the centre of compensation at 25, 35, and 45 miles below sea level; the result is given in the table No. 8 (page 46), in which the result of the Hayford com- pensation is also included, for comparison. Here, again, we see that a greater depth of compensation results in an increased northerly deflection ; we also see that if the depth of the centre of compen- sation is as much as, or over, 35 miles the maximum difference is at the outer edge of the hills and decreases at stations further in, while a shallower depth gives an apparent southerly deflection, when compared with the result of the Hayford compensation. So far the compensation has been supposed to be uniform in character and depth ; we must now consider the effect of a variable compensation, such as would be introduced by an hypothesis in- volving the support of the range by flotation, and a thickening of the crust downwards into the denser matter below, as well as up- wards into the air. The most complete investigation of such an hypothesis, is that of Mr. O. Fisher, and it will be convenient to adopt his constants, and then investigate the effect of a variation in them. According to these, the mean thickness of the undis- turbed crust is 25 miles, and the difference in density between it and the subjacent magma is such that the general elevation above mean sea level would require a downward protuberance of 9°6 times as much to compensate, by its buoyancy, for the weight of the upward protuberance. On this supposition the bottom of the crust would lie at a depth of 25 miles under the plain, and under the first step of the Imaginary Range it would lie at 34:1 miles, under the second step at 35°9 miles and so on, and the whole of the compensation would be con- centrated in that part of the crust lying below 25 miles. The result of calculation from this supposition is given in table No. 9 (page 48), which shows that, as compared with the Hayford compensation, it not only gives mse to considerable northerly dif- ferences or “residuals”’ at stations within the hills, a result which f we'd E2 48 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. Taste 9.—Comparison of the Deflections produced by the Imaginary Range for wniform compensation to depth 113°7 km., with those which would be produced on the hypothesis of support by simple flotation, using Fishers constants, UNIFORM COMPENSATION | SIMPLE FLOTATION, : Tro 113°7 KM. STATION. | Deflection. Deflection. Difference. Oe eee ere ae ae: | af arth PATE — 10 aes id | =~ 14: a 3 — 9 =e AR TAD "4 aaa 8 15 a 19 — 4 —.7 =n =i) — 4 a~ § hy x | —4 a5 —18 aE WV, eerg — 4 —19 i 22; —3 ——r3 20) 28 oad a ===52,] 24 —3 ——— =) | | it ey 4 ) mag 53 = 66 AN + 1 vgs If =i are | + 2 tts rch 0 + 3 — 5 — 5 0 + 4 — 3 — 3 0 +6 =, gl? 0 + 6 =e | — |! 0 ary ee 1| teal | 0 «8 0 0 0 aes 0 0 | 0 st | 1) | 0 0 is the consequence of the greater average depth of the centre of compensation, but these differences are greater within the range than at its southern edge, and show a maximum at about 50 miles in. Moreover, the differences must be regarded as minimum values, since Mr. Fisher's constants, though arrived at by him on grounds independent of the particular hypothesis of mountain formation and support, represent a minimum value for the thickness of the crust and a maximum value for the difference in density between the crust and the underlying magma. If instead of 25 miles for the former a thickness of 30 miles is assumed, and instead of a difference of density such that for each 1,000 ft. of elevation re- presenting 1°8 miles it be taken to represent 3 miles of “ root,” values which are not beyond reasonable limits, then the “ residuals’ become -—7" at the station 0, —8” at station —5, and —6” at station —10. [ 196 ] THE IMAGINARY RANGE AND TROUGH. 49 Actually, on any reasonable hypothesis of support by flotation the differences would probably lie somewhere between these two extremes, but nearer the lower than the higher value. It has been pointed out that an hypothesis of support by flo- tation not only allows, but has a necessary consequence, of the likelihood that compensation would not be complete within the limits of the range, but might be partly distributed over the crust on either side. This want of balance may take place in two ways, and the one which will be considered first is a superelevation of a part of the range, accompanied by a bending down of the crust on either side. In table No. 10 the result of such a departure from com- Taste 10.—Correcttons to the deflections due to the hypothesis of support by simple flotation, on two separate swppositions of partial support, corrected by depression of the adjoining tracts, supposed to be confined (A) to the topography and (B) to the compensation. DEFLECTIONS RESULTING FROM HyYPporTHESIS Distance from —-— —- Se southern edge of . . superelevated tract No. I. No. IL. (in miles). ORS as Oe SS | (A) (B) (A) (B) 50 N. 0 0 0 0 40 | aw ee | ae 1} 30 ane oil¥ See | a3 20 ery | —3 —12 —65 10 HONG be =a —20 7 0 at 7 meet — 44 =i'§ 10 wr LY —i 4 49 am § 20 => 5$ — 12 ics 30 — 2 2 u.8 ano 40 | ) eve | — § —¢4 50 = ae | 0 a ant SS om 60 deg 0 a “J aie 70 1... +. 0 atin il 80 + 4 +1 + J 0 90 + 4 a | + 2 S| 10058. = ee +2 to 3 +2 plete local support by flotation is given on two separate suppoSi- tions, namely (1) that a tract 100 miles in width is superelevated by 1,500 ft. and that the defect in support is taken up by a depres- sion of the crust on either side, gradually dimirishing to nothing in 100 miles ; and (2) that the same tract is superelevated by 3,000 ft. [ 197 ] 50 OLDHAM: THR STRUCTURE OF THE HIMALAYAS, ETC. and the defect in support taken up by a depression of the crust on either side by the equivalent of 1,500 ft. gradually diminishing to nothing in 200 miles. In each case the figures given in table No. 10 must be added, algebraically, to those given in table No. 9 for the hypothesis of support by simple flotation, and so will increase or diminish the differences from the deflections due to the Hayford compensation, as the case may be. The effect of the opposite supposition, that the buoyancy of the downward protuberance is in excess, and the surplus power of flota- tion absorbed by an upward bending of the crust on either side, would be practically the same in amount, but with the opposite sign, as that shown in the table No. 10, the surplus buoyancy being supposed to be of equal amount and extent as the surplus load considered in that table. In considering the gravity observations a somewhat different course to that adopted in the case of the deflection of the plumb- line will be more convenient. The effect of the direct attraction of the visible masses is always determinable from the published observations, and different formule of calculation make very small differences in the amount to be allowed for this effect ; the anomalies, or more properly the difference of anomaly between two stations in the same region, may therefore be looked upon as representing local differences in the density of the matter under the station, of which the most important is that due to the effect of compensa- tion. It is, consequently, convenient to consider the effect of the compensation only, and the differences which would be introduced by varying the hypothesis. The first of these comparisons to be made is that of the Hayford compensation with an hypothesis of support by flotation. This is given in table No. 11 (page 51), and a few words of explanation will show the use of this and the other tables; taking station 0, at the edge of the hills, and calculating the gravity which should be found at it according to the Hayford factors, we would have to allow for the effect of the visible masses and a further correction of — ‘075 dyne for the effect of their compensation ; but if the support had in reality been, as considered in the second column, one of simple flotation its effect would have amounted to —-085 dyne, and the observed force of gravity would show a defect, or anomaly, of —-010 dyne. At stations more than 50 miles into the hills this would be reversed, and a calculation based on the Hayford tables would show a [ 198 ] THE IMAGINARY RANGE AND TROUGH. 51 TABLE 11.—Gravitation effect of the compensation only of the Ima- gary Range (1) according to the Hayford tables and (I1) on the hypothesis of support by flotation, using Fisher’s constants. All quantities negative and expressed in dynes. STATION. Hayford Compensation. | OR WN RK OR ND WP OL +++4+4 ~~ positive anomaly, increasing at stations further into the on the plateau, it rises to as much as + ‘040 dyne. 350 305 -200 Fisher Constants. | “310 *280 205 “185 -165 *140 “115 ‘O85 -060 -040 -025 “O15 “010 hills till, In the table No. 12 are given the gravitation effects of a com- pensation supposed to have a uniform depth of the centre of com- pensation of 25, 35, and 45 miles respectively, which shows the TABLE 12.—Grravitation effect of the compensation only of the Ima- ginary Range supposed to be centred at various depths. All quantities negative and expressed in dynes. DEPTH OF CENTRE OF COMPENSATION. STATION. 25 miles. | 35 miles. 45 miles. nabs it —| | DS 5 o: ~— 20 +380 *330 -300 — 10 345 ‘295 | +265 a, B | 235 | -200 180 gee & -210 | ‘180 160 Sh -180 “155 | -140 ee? -150 -130 | “115 eee | -120 105 -095 0 “085 | -080 | -O75 + 1 -060 *055 | *055 + 2 -040 -040 -040 4 3 025 | -025 -030 aie | O15 O15 | -020 se -010 -010 ‘015 [ 199 ] 52 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. extent to which the attraction of the visible masses is neutralised by a compensation whose centre of effect lies at these depths. And finally in table No. 13 are given the effect of the two modifica- TABLE 13.—Gravitation effect of two suppositions of departure from a condition of support by simple flotation. LT GRAVITATION EFFECT OF SUPPOSITION. Distance from southern edge of auperelevated tract. I Il 50 + :035 + -080 40 + +035 + 075 30 + +030 + -070 20 +. +025 + -060 10 + -015 + +045 0 | + +005 + +025 10 — 005 + -010 20 — -010 _. .005 30 — 015 — :015 40 — +020 — 020 50 a O90 — -025 60 — 020 — 025 70 —- 015 — 025 80 — -015 — -025 90 — -010 — -020 100 — ‘010 — 015 tions to the hypothesis of simple support by flotation which were dealt with in table No. 10. Here again a reversal of the supposi- tions and an assumption of over-compensation of the range, or part of it, balanced by a corresponding under-compensation elsewhere, would hardly affect the numerical value of the correction but would reverse its sign. In either case the values given in table No. 13 must be added, algebraically, to those given in table No. 11 for the hypothesis of simple flotation. The Gangetic trough will be treated in a manner similar to that adopted in the case of the range, and the effect calculated of an Ima- ginary Trough, or rather series of troughs of different forms and dimensions ; but before this can be done it is necessary to determine what value will be adopted as representing the mean density of the material with which they are filled, and this can be determined within narrow limits. The mean density of the superficial deposits [ 200 ] THE IMAGINARY RANGE AND TROUGH. 53 of the Gangetic plain is about 1:8, but the deeper layers have cer- tainly a greater density than this; at the same time they can hardly attain a greater density than that of the Siwaliks, which are com- posed of the same materials and have been subjected to the pressure of superincumbent deposits, as well as to the induration due to age and the compression to which they have been subjected in the course of the upheaval of the Sub-Himalayas. This fixes the upper limit of density at 2°2 and the probable mean density must lie somewhere between the two, though nearer the higher than the lower limit. In my earlier investigations a density of 2°1 was accepted, or a deficiency of two-ninths of the mean density of the rock forming the floor and sides of the trough ; later a slightly higher density was adopted, for convenience of calculation, and the defi- ciency put at two-tenths of the mean density of the rocky floor of the trough, representing a density of 2°16. Doubts have been expressed! as to the reality of so great a difference in density between the material forming the Himalayas and that which fills the Gangetic trough, and especially it has been urged that the material in the lower layers of the trough would be compacted, by the pressure of the superincumbent material and the percolation of water holding carbonate of lime in solution, till the difference in density between it and ordinary rock would be neg- ligible. These objections might be valid where depths of many miles are postulated, but, as will be seen further on, there is no need to suppose that the Gangetic trough is anywhere more than 20,000 ft. in depth, and as the Siwalik rocks, which have been subjected to the pressure of superincumbent deposits of about the same thick- ness, have an average density of only 2°2 or not much greater than the mean density assumed for the whole of the deposits in the Gan- getic trough, of which the Siwalik rocks are the most dense, it is evident that the deficiency of two-tenths, corresponding to a mean density of 2°16, does not err on the side of being too high. At first sight it might seem strange that there should be so great a difference between the density of the rocks forming the Himalayas and the material filling the Gangetic trough, seeing that the latter is the debris of the former, but all the denser minerals of the former have been decomposed, oxydised and hydrated, and the hard quartz- ites of the Himalayas broken up, to form the soft sandstones 18, G. Burrard, Prof. Paper, Surv. Ind., No. 12, p.4and T. H. Holland, B.A., Report 1914, p. 355. { 201 ] 54 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. and loose sands, silts and clays of the Siwaliks and Gangetic trough. Now the softer sandstones, such as the New Red, used for building purposes, have a density of 2°1 to 2°2, and river sand or clay both about 1°9, and as these types of rock represent the material of which the contents of the Gangetic trough is composed, the difference between its density and that of the Himalayas is about what would be expected from the difference in composition and state of aggre- gation. The effect of such a mass of lighter material, at stations outside the trough, is that the attraction towards one side is not counter- balanced by that towards the other, and the material filling the jangetic trough would exercise an apparent repulsion, causing a northerly deflection at stations to the north, and a southerly at stations to the south, of it. Within the limits of the trough the effect would depend on the position of the station and on whether, and to what extent, the effect of that portion lying on one side of the station exceeded that of the portion lying on the other. Tanne 14.—Deflections due to troughs, 50 miles broad, of various sections ; density *8 of average rock. STATION. | 15,000 to ete 4 0 to ea: ei 10,000 | 10,000 15,000 — ; feet. feet. feet. —10 0 § 354 Gi ada 0 | 0 i 0 a Ree a 0 0 ak: “8 ee | mete Peck Pf ae ER ed peor Ne | owe. im 5 ai a eee NERS, ee aes | eG vee. “Saree ae Be re eS saat aie ¥ eee eee ee as 9 sts nae oso, vim, Bee on} momatigs th any B sce aa Seg eG aso — 3 =e nD teat B tosh G BLY a3 Binh ee | nay § PA eee eee et Lae ar 0 2 19 HF — 24 as 36 — 21 ae | a Utiaman. é 80 — 140 + 8 + 9 as 2G Etora . . A ha 96 — 114 + 9 +10 Aa tj Parewa . F ; sry 96 — 114 + 9 +10 a Sora. j ; se 110— 96 +10 +10 4+ 12 Pariaon . i . ‘3 140— 48 +10 +10 + 10 Dewarsan 4 F eo 144— 80 +10 + 9 + 9 Kanakhera . : a 164— 40 +10 + 9 + 9 Pavia . ; 4 | 180 — 16 + 9+ 9 | 78 | Potenda : 5 , 408. +1 A + 6 Karara . . 5 é 76 ,, 0 0 | + 4 Amua . "i g ‘ 88 ,, 0 0 a Se “—° 5 Se a 66 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. A list of these stations is given in table No. 19 (page 65) with the addition of four stations, ranged along the northern fringe of the alluvium to the eastwards of the meridional series. It is in no case possible to measure the exact distance of any of these stations from the main boundary, as this runs through Nepal territory to the north of this section, but the distance from the outer edge of the hills can be determined with sufficient accuracy, and a comparison of the section at the western end of Nepal with that along the road to Khatmandu, shows that the width of the Siwalik tract is probably about 20 miles, so that the main boundary may be taken as lying at that distance from the outer edge of the hills and, where it needs to be taken into consideration, this must be added to the distance of each station from the outer edge of the hills as given in the table No. 19. In this table are also given the distances from the southern boundary of the alluvium, the figures in each case being approximate and measured to the boundaries of the alluvium as drawn on the general geological map of India on the seale of 32 miles to the inch. The deflection, actually observed at each station, is given, to the nearest whole second, in the last column of the table, and the first thing to be noticed is the presence of a considerable southerly deflection at the stations beyond the alluvium to the south. The distances of these stations from the boundary are too great for the deflections to be attributable to the effect of the alluvial trough, and we may look for their cause in the ‘“ hidden range” or belt of underground excess of density which has been found to exist in the northern part of the Peninsula. Turning to the stations on the alluvium, and comparing the observed values with the calculated deflections given in tables 14 to 16, we see that, so far as the southern half of the section is con- cerned, they indicate a trough deepening steadily from south to north at about 130 ft. to the mile, and that this slope is continuous for over 100 miles from the southern edge, so that in this way we reach an estimated depth of over 13,000 and probably about 15,000 feet. The northern part of the section gave more trouble, for here the effect of the Himalayas, which is negligible at the southern stations, becomes considerable. As it was impossible to calculate the effect of the actual topography at each station it seemed best to assume that the effect would not be very different from that of the Imaginary Range, allowing for Hayford compen- oe ae THE UNDERGROUND FORM OF FLOOR OF GANGETIC TROUGH. 67 sation, at a station situated at a corresponding distance, reckoned from the main boundary; at the stations nearest to the hills a small additional correction was included, for the effect of the attraction of the foot-hills of the Sub-Himalayan region. The figure allowed in this way, for the effect of the attraction of the Hima- layas, is a little less than the reality, but the difference would not exceed one second of arc, or at most a couple, at any of the first six stations, included in the table No. 19, and is negligible at the rest.! Allowing for this effect, a first attempt at calculation, on the supposition that the slope of the floor of the trough continued regularly up to the main boundary, showed that this would give too small northerly deflections at the northern stations, nor were matters much improved by supposing that the maximum depth was continued outwards from the main boundary for some con- siderable fraction of the width of the trough, before the upward slope commenced. It became evident, therefore, that the maxi- mum depth of the trough could not be at the northern edge, but must be somewhere out towards the centre, though nearer to the northern than the southern edge; a supposition was accordingly adopted, that the trough had a depth of 15,000 feet at the main boundary, increasing to 20,000 feet at 50 miles away and then decreasing to nothing in 150 miles. The result of this calculation is given in the column headed I, but at a later period, when the study of other sections had revealed a possibility that the trough attains its greatest depth close to the outer edge of the visible hills, another assumption was made, that the maximum depth was 25,000 feet at the outer edge of the hills, that the floor sloped re- gularly upwards from this to the southern edge of the plain, and on the north rose abruptly upwards to a depth of 20,000 feet diminishing to 15,000 feet at the main boundary. The result of this supposition is given in the column headed I. 1 We have a check on the correctness of method of arriving at the allowance to be made for the effect of the trough, and any other invisible influence, in Major Crosth- wait’s calculation of the residuals at Pathardi and Nimkar. On the same basis of reference as is here used in the text, the residuals, after allowing for the effect of visible topography and its compensation, are —12” and +4-5” respectively, the values derived by using the Imaginary Range were —9” and +4”. The use of the Bessel-Clarke spheroid would introduce a change of 1” in the values of the residuals, Evidently the Imaginary Range gives a larger deflection than the actual topography of this part of the actual range, but it must be remembered that the Hima- layas in Nepal territory are quite unsurveyed. jf 215 | 68 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. Comparing the calculated with the observed deflections, it will be noticed that either supposition gives results which are in very fair agreement with reality; only in the stations from Masi to Nimkar is there any considerable irregularity, but these stations are situated in the tract where northerly are passing into southerly deflections, and where a small variation in the assumed form of the trough would lead to considerable changes in the calculated deflections. Apart from this, the general course of the variation, as well as the actual values, of the calculated and the observed deflections are in very good agreement; at the northern stations the calculated deflections are in slight defect, and the same is true of the stations in the southern half of the section, but the former of these is easily accounted for by the probable excess of the northerly attraction of the Himalayas over that allowed for in the calculations, or both the deficiencies could be eliminated by assuming a rather greater depth of the trough, but no real benefit would accrue from any attempt at obtaining a closer agreement between calculation and observation. This study of one of the groups of latitude stations serves to illustrate at once the method which will be followed, and the limit- ations of any attempt to derive geological information from geo- detic observations. The method, though differing in form, is essentially the same as that adopted in geodetic work; a certain assumption is made, calculation is made on that basis and the results of calculation and observation compared, another assump- tion is then made and fresh calculations made until the average difference between the calculated and observed values of the deflection is reduced to the smallest amount. In geodetic work proper the closeness of agreement is tested by comparing the sum of the squares of the individual differences, and adopting the sup- position which gives the smallest value to this sum, as the one which most closely approaches the average conditions. This method is the only oneadmissible where a large number of observations, extending over a large area, have to be dealt with; it is not only unnecessary, but would give a wholly illusory appearance of pre- cision, if applied to a limited number of observations, and to the extraction of the information for which we are in quest. Here we must start with those conditions which represent a near approach to the average, and apply to them a correction for [ 216 ] THE UNDERGROUND FORM OF FLOOR OF GANGETIC TROUGH. 69 local departure from the average, in this case represented by the defect of density in the Gangetic trough, and it will be seen that either of the suppositions considered in table No. 19, if combined with the average conditions assumed in calculating the observed deflections, would largely reduce the differences between the cal- culated and observed values. They may therefore be regarded as approximations to the actual form of the trough, but it is not pos- sible to obtain a closer approximation, with any degree of certainty, owing to the uncertainty in which we are as to the density of the alluvium in the lower layers of the deposit, as to the nature and extent of the separate compensation of the trough, and as to the presence and character of any independent cause which would affect the direction of the plumb-line. The effect of the last two elements of uncertainty has been dealt with in the last chapter, and need not be enlarged on here. With regard to the possible increase in density of the lower layers of the alluvium, the depth, indicated by the observations, of 20,000 to 25,000 feet, even if allowance is made for the possible increase due to a separate com- pensation, is not so great as to necessitate or suggest a condensation of the sands and clays of which the alluvium is eomposed to a much greater density than the 2:16 which was assumed as the mean density of the deposit, and against this must be placed the fact that the upper layers have certainly a considerably lower density than that assumed as the mean of the whole deposit. Allowing for all these possible modifications of the conclusions come to if the whole of the deflections, so far as they are not accounted for by the visible topography, are due to the alluvial trough, the fact remains, that the published deflections agree so well with those which should result from a cross section and dimensions of the trough which are in accord with those suggested by a wholly independent line of research, as to render it probable that this is the preponderating, if not the sole, influence at work; and we reach the conclusion that the maximum depth of the trough lies at, or a little south of, the edge of the hills and need not exceed about 25,000 feet; it can hardly be less than 20,000 and is not likely to exceed 30,000 feet, so far as the indications of this group of latitude stations are concerned. The northern part of the section, which was not represented in the group just considered, is covered, further west, by a very [ 217 ] 4 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. complete group of stations in and around the Dehra Dun; it will, however, be best to defer the consideration of these observations and confine attention to the southerly continuation of the series, across the alluvial plain. This series forms a double line of sta- tions stretching across the alluvium and ranged on either side of the 78° meridian, which will be most conveniently treated as two separate series and are given in the table No. 20 in two columns, Taste 20.—Latitude Stations near 78° Longitude, | SraTION Distance from | Observed _ Deflections due 5 ‘ | Main Boundary. Deflections. | to the Range. SS Se Tene es ram _| oes Sarkara . | 32 —8 | — 6 Nojli 5 | 38 Se Vee, Sirsa f , | 56 | 5 _9 Kaliana . | 58 aaa. oe Bansgopal : ; . 76 | 2. j ae Datairi : : 5 | 92 te Bostan - | 104 en | | Sankrao . “ A ; 108 | 4. 4 Chandaos = % é 124 i Salimpur : ‘ : 124 | 44 Noh ot oe 144 be 8 Agra ~ A : 168 | =e | | Usira ; ‘ , 200 bene Gurmi . x“ ; represent the points at which there is a complete adjustment of the Altes Seeskn Ae “eum ~~, = Tse Sn ee ES STs (ye ET a. Sa See oO ae ——-;———- 0 ——— Fia. 8. Fic. 8.—To illustrate the adjustment between topography and compensa- tion in the Himalayas. In the central region, to the left of the diagram, the compensation is in excess of the load, producing an upward stress, as indicated by the arrows; in the outer region compensation is in defect, and there is a downward stress. The firm line represents the actual contour of the ground, the dotted line, that which it would have if the adjustment between topography and compensation, of load and support, were everywhere exact and complete. [ 263 ] 1146 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. compensation to the topography, not necessarily coincident with the zero points of the Hayford anomaly; to the left there is an ex- cess of compensation, resulting in a tendency of the range to rise as indicated by the arrows; between the two zero points the com- pensation is in defect and the excess of load resultsin a tendency for the hills to sink. The same conclusions may be otherwise depicted in the outline of the topography where the firm line re- presents the section of the range as it actually exists, and the dotted line that which it should be if the topography were everywhere adjusted to the compensation. One more conclusion may be drawn from the distribution of stresses indicated in the diagram. If the crust has sufficient strength to bear the load imposed on it by the superelevation of the outer hills, it is improbable that the adjustment would cease at the right hand zero point; the load on the tract between the two zero points would tend not only to hold down the central por- tion of the range trom rising but also to bear down the crust on the right into the plastic, denser, layer below, and so we might expect to find a defect of gravity outside the range, quite apart from that due to the defect in density of the alievium. It will be shown, further on, that there is some indirect evidence of the existence of such a depression of the under side of the crust, but there is no possibility of getting any direct confirmation of it from observations in the alluvial area, for the effect would be masked by that of the trough; and as our only estimate of the depth of the trough, except close to its margins, is derived from the geodetic evidence, any attempt, based on this evidence, to separate out the one effect from the other would be merely arguing in a circle. The local departures from a condition of equilibrium between topography and compensation, which have been found in the Hima- layas, indicate a degree of rigidity, and strength, of the crust greater than that which has sometimes been attributed to it, and this might lead to doubt as to the correctness of the inferences which have been drawn. On this point we have, fortunately, the recent elaborate investigation of the rigidity of the earth’s crust by Prof. J. Barrell,! in which, after dealing with geological and geodetic data in the United States and elsewhere, he concludes that the crust is strong enough to support a load of over 3,000 feet of rock, har- * Journal of Geology, Vols. XXII and XXIII passim, 1914-15. [ 264 ] THE SUPPORT OF THE HIMALAYAS. 117 monically distributed over a wave-length of nearly 400 miles,! a degree of strength which is much greater than is needed to allow of the local departures from equilibrium which are met with in the Himalayas. It will be of interest to find where the position of the right hand zero point of fig. 8 hes with regard to the outer edge of the Hima- layas. In this connexion we have a suggestion in the fact that the Hayford anomaly near the outer edge of the hills, after allowing for the effect of the Gangetic trough, seems to have a small positive value, of the order of -01 dyne, on both the Dehra Dun and the Sikkim sections. Too much weight must not be attached to this coincidence, as the actual compensation will not be identical with that adopted in the tables computed by Messrs. Hayford and Bowie, but it is suggestive of the conclusion that the zero point, where the uplift of the outer Himalayas comes to an end, hes beyond the edge of the hills, and under the northern part of the alluvial plain. This conclusion receives some support on the geological side. Everywhere along the foot of the hills there is a gravel slope, com- posed as a rule of much coarser material, and having a steeper surface gradient, than the alluvial plain beyond. This gravel slope known in part of Upper India as the bhabar, is the result of deposit of coarser material by the streams as they leave the hills, and the steeper surface gradient has generally been attributed to the steeper slope of deposit of this coarser material, as compared with the finer silt of the plain proper. On some sections, however, the increase of surface gradient towards the hills results in a slope too steep to be accounted for in this way, and almost everywhere we find the streams cutting their way through the old gravel deposits at a lower level, and on a lower gradient, than the general slope of the surface. ‘To some extent this may be due to climatic change, but this explanation does not seem adequate, and there remains a distinct suggestion, even where there is not a practical certainty, that there has been a general tilting of the surface and an uplift on the side towards the mountains. It is important to note that this surface tilt is too even and regular to be referred to any compression, folding, or similar process; it is not analogous 1Vol. XXIII, p. 30. Not, be it observed, in addition to the weight of the crust itself. This is supposed to be everywhere isostatically supported ; it is only the un- supported excess or defect which is borne by the strength of the crust. [ 265 ] 118 OLDHAM: THE STRUCTURE OF THI HIMALAYAS, ETC. to the disturbance which the strata have undergone in the Siwalik hills, but is a general tilt, which may reasonably be attributed to a general displacement of the crust, and to a continuation of the general uplift which is indicated in the outer hills, which, in this case, must extend beyond the limits of the hills into a region where its further progress can only be traced by inference from the geodetic data. It may also be poipted out that this interpreta- tion is in accordance with, and may in some respects be regarded as a confirmation of, the conclusions, independently reached, that the great boundary faults of the sub-Himalayan region are the result of tectonic processes in the outer part of the crust, and do not extend downwards to its lower limit. The conclusions which have been elaborated, as to the excess of support in the central part of the Himalayas, and the uplift which has thereby been superimposed on the mountain building processes in the outer hills, are of great importance in attaining an under- standing of what these processes are, and to what causes they may be attributed. In one respect the question of the origin of the mountains may be regarded as having. been put in a new light, for, hitherto, it has been usual to regard the visible range as the primary problem and the provision of support, or compensation, as a secondary one; but, in the light of the results of geodetic work in the Himalayas, the order must apparently be reversed, the primary phenomenon being the production of an excess of buoyancy under the range, in virtue of which the range is uplifted, and the range itself becomes but a secondary, though the most conspicuous, effect of the processes at work. [ 266 | SUMMARY AND CONCLUSIONS. 119 CHAPTER VI. SUMMARY AND CONCLUSIONS. The various groups of geodetic stations have now been con- sidered in detail, and the conclusions, which may be drawn from each, have been indicated, but it is still necessary to review these as a whole and to consider how far they help in the solution of the problems, still in doubt, which were indicated in the opening chapter as those in which the geodetic evidence might help. These questions will most conveniently be taken in the reverse order to that adopted in stating them, and it may be said that the geodetic observations fully support the two conjectures, that a rock barrier extends, at no great depth below the surface of the alluvium, from the peninsular rock area to that of the Assam Range to the east, and to the Salt Range to the west. We have also found complete confirmation of the geological deduction that the depth of the alluvium along the outer edge of the Himalayas is great, amounting to about 15,000 to 20,000 feet towards the northern boundary of the alluvial plain, figures which are in complete accord with those deduced from the geological examination of the Siwalik hulls. This agreement, between the results of two wholly imdependent and different lines of research, leaves little room for doubt that we have reached a correct interpretation of the underground form of the Gangetic trough from near its northern limit to the southern boundary, and that its maximum depth is about 15,000 to 20,000 feet, possibly more on some sections, probably less on others, but in most cases lying within the limits named. From this maximum depth, at a distance of from 10 to 30 miles from the northern edge of the plain, the floor slopes upwards, with a fairly uniform slope, to the southern limit, whether this is marked by the reappearance of solid rock, at the northern boundary of the Peninsular area, or by the hidden barriers under the alluvial plains, over which the drainage of the Ganges and Brahmaputra reaches the Bay of Bengal on the one hand, or the rivers of the Punjab flow down to the Indus and so into the Arabian Sea on the other. The underground form of the trough in its northern portion, along the edge of the Himalayas, is less clearly defined. On only [ 267 ] 120 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. one section, that of the Dehra Dun, do the observations extend across the Siwalik area to the Himalayas proper, and here they indicate that the maximum depth of the alluvium lies not far from the outer edge of the Siwalik hills, but whether actually at the boundary or at some distance from it is not established. Under the Siwalik area there is a distinct shallowing of the trough, pro- bably abrupt- and coincident with the outer edge of the hills, and, at the northern boundary of the Siwalik region, the floor of the trough rises abruptly along the main boundary fault, the throw of which is indicated as something less than 10,000 but probably over 7,000 feet. Another section, which traverses the whole width of the allu- vium near the 81° meridian, but stops short at the foot of the hills, indicates much the same conclusions, that the floor of the trough rises rapidly under the Siwalik area, though here the maximum depth may be 50 miles or more from the edge of the hills. A third section, near the eastern end of the trough, where the Siwalik zone is unrepresented, or covered by alluvium, indicates an increase in depth from south to north almost up to the outer edge of the hills, though a larger number of observations might put the maximum depth somewhat south of the station nearest the hills, at which the largest depth is indicated. The structure indicated on these sections may reasonably be extended to others, and in it we find a confirmation of the deduc- tion, which had been drawn from geological data, that the under- ground form of the trough near its northern limit, as well as the nature of the northern boundary, is radically different from what is to be found under the southern part of the trough. To the south of the present line of maximum depth the trough has been formed by simple subsidence and the alluvium deposited on an old land surface, preserved with little or no change in its original form. To the north, the rise is not only more rapid, but more irregular and determined mainly by tectonic processes, connected with the origin of the hills, which have profoundly altered the original form of the floor of deposition, and involved some of the originally un- disturbed deposits in the folding and faulting of the process of mountain formation. Incidentally we find-a confirmation of the interpretation which had been accepted, rather than demonstrated, that there is a rise in the floor of the trough under the Siwalik area, and indirectly [ 268 ] SUMMARY AND CONCLUSIONS. 121 ad of the deduction that the outer edge of the hills marks the posi- tion of a structure similar in character to the faults which traverse the Siwalik area, and form its northern boundary for a large portion of the length of the Himalayas.t There remains only the question of whether the compression, which the rocks of the Himalayas have unquestionably under- gone, is the cause, or merely the accompaniment, of the elevation of the range. The treatment of this question is impossible without considering that of the origin of the Himalayas and a discussion, which need not be detailed, of the explanations which have been offered, of the origin of the Himalayas, and of the closely con- nected problem of the origin of the Gangetic trough. It has already been shown that there is some suggestion of the boundary faults, and with them of the tectonic processes which have modified the underground form of the floor of the trough, being phenomena of the upper part of the crust alone, and inde- pendent of the more deep-seated changes in the distribution of density on which the compensation depends.’ This being so, it is obviously possible that the same conclusion might be extended to the whole of the trough, and its existence be regarded as due to processes which were confined to the upper part of the crust proper, with the result that there would be neither need nor reason to look for any more deep-seated cause of origin. The magnitude -and extent of the trough seem to make any such localised cause inappropriate, and the radical difference in the form and boundary of the southern part, as compared with the northern fringe, makes it probable that an entirely different set of processes have been at work, and that the trough as a whole may be due to deep-seated and widespread forces, involving the crust, as a whole, and the material which underlies it. In this case we cannot ascribe the trough to any deformation of a part of the crust, such as has pro- foundly modified the form, and defined the boundary, on the north, but rather to a general subsidence of the crust, increasing in amount from south to north. In searching for a cause, which could have produced this depres- sion, we must first of all reject the notion that it can be a direct downward pressure due to the weight of the alluvium, The notion 1 Supra p. 109. { 269 | 122 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. that the deposit of sediment on the surface of the earth must cause a subsidence, in consequence of the additional load, is one which has had some vogue; it is unnecessary here to discuss the justifica- tion of this idea, it is sufficient to point out that the cause is obvi- ously inapplicable in the case of the Gangetic trough. Not only is the surface of the alluvium at a lower level than that of the rock areas to the north and the south, but the density of the material is very considerably less than that of the rocks on either side ; consequently the load borne by the crust in the region of the Gangetic trough must be less than in the Himalayas to the north, or in the peninsular rock area to the south, as is proved by the result of gravity observa- tions in the alluvial plain. But though the weight of the sediment cannot have been the originating cause of the depression of the Gangetic trough, it may well have had considerable influence in determining the magnitude of its dimensions, for if there had been some other cause capable of forcing down the level of the crust to a given depth before the resistance to further movement became equal to the force, then the addition of a load of alluvium would enable the same force to lower the level to a greater extent than if the hollow had been left empty or only filled with water. The amount of this extra depression would depend on the balance between the force and the resistance; if both remained appreciably constant, within the limits of movement involved, the weight of the alluvium would enable this to be carried about five times further than would otherwise be the case, so that the Gangetic trough, taken as 15,000 feet deep, would only have had a depth of about 3,000 feet had it not been filled with alluvium as fast as it was formed. One such possible cause hasbeen indicated by Mr. Fisher. He pointed out that if material is removed by denudation from the surface of a range, and deposited by its side, the centre of gravity of that portion of the crust comprising the two regions would be shifted laterally, and, on the assumption of a crust supported by flotation, there would be a disturbance of the condition of equili- brium, so that the centres of gravity and of buoyancy would no longer lie on the same vertical line. As a result, a couple would be set up, tending to raise the range and depress the crust along- side it, till the loss of buoyancy under the range, and the gain under the plain, led to a re-establishment of a condition of equilibrium and, as a further result, a depression of the surface would be formed [ 270 ] SUMMARY AND CONCLUSIONS. 123 along the foot of the range, which would grow in depth, and in breadth, as the range increased in height. The reasoning is_per- fectly sound from a mechanical point of view ; given a crust of some degree of strength and rigidity, supported by flotation, the processes conceived will follow with logical necessity, and it is interesting to note that the results of this purely mathematical investigation agree remarkably with the deductions which result from geological examination as to the character of the southern margin of the alluvium, the history of its gradual extension to the south, and the radical contrast in character between the southern and northern margins of the trough. The only doubt is as to whether the cause invoked by Mr. Fisher would be quantitatively sufficient to pro- duce the results, and with regard to this it may be pointed out that the action, which he conceived, would be reinforced by the effect of an increase in the buoyancy under the range, such as has been indicated in the preceding chapter, so that it is possible for the combined effect of the two causes, working in the same direction, to have given rise to the depression of the Gangetic trough, though neither of them would, independently, have been sufficient. The only test which we can apply to this interpretation is to be derived from the geodetic data. It is, evident that a depres- sion of the lower surface of the crust, with the consequent displace- ment of denser by less dense material, would produce an effect on the plumb-line and the pendulum, it would cause a northerly deflec- tion to the north of the trough, and a southerly deflection to the south, and would give rise to a defect of gravity, greatest along the line of maximum depression and decreasing on either side. These effects, it will be noticed, are similar in kind to those produced by the alluvial trough, but, being much smaller in amount, are so effectively masked by those due to the alluvium itself that it is difficult to disentangle them. An attempt was made, by a com- parison of the results derived from the deflections and the oravity observations, to separate out the effect of a possible depression of the crust as a whole from that of its upper surface, the attempt led to an apparent confirmation of the hypothesis, but it involved too many considerations of very doubtful validity to justify the space necessary for its exposition. There are, however, within the area of the alluvium some observations, otherwise difficult to understand, which find an easy interpretation in this way, namely, [ 71 .j 124 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, RTC. the very considerable defect of gravity at Monghyr and the lesser defect at Sasaram, which cannot be attributed to the alluvium, but could find an explanation in a depression of the crust into the denser material below, though whether this explanation is valid cannot be established. It is outside the alluvial area that the test of the hypothesis must be looked for; the boundary of the alluvium would not neces- sarily coincide with that of the trough, for south of the alluvium the general level of the surface continues to rise, and in this region we may look for effects to be recognisable, which would be masked by others, of greater magnitude, in the alluvial plain. Now the investigation by Sir S. G. Burrard of the deflection of the plumb- line in India, published in 1901,! showed that along the northern edge of the peninsular area the deflections were all to the south- wards, and that further south comes a belt in which northerly deflections prevail. His investigation established the conclusion that these facts could only be explained by the ‘existence of a belt of excess of gravity, or as he expressed it a Hidden Range, traversing the Peninsula in a direction approximately parallel to the Himalayan Range, and having its crest directly under the station of Kalianpur. This conclusion has since been supported by the gravity observations, and by Major Crosthwait’s deter- mination of the residuals of unexplained deflection at a number of stations in India. The highest positive anomalies of gravity are at Kalianpur and Seoni; between these stations and the alluvial plain, positive anomalies prevail, but of lesser amount ; and the line of separation between those stations at which Major H. L. Crosthwait obtained a southerly, and those which show a northerly, residual, also runs through these two places and follows almost exactly the course of the ‘“‘ Hidden Range” as indicated » by Sir S. G. Burrard in 1901. In the diagrammatic representa- tion; reproduced in fig. 9, of this belt of greater density it is shown as comparatively narrow and steep-sided, and in this form the result would not accord very well with observation, a mass of the form indicated would produce effects distributed very much as shown by the figures in table No. 1, immediately over the crest there would be no deflection, then a gradual increase to a maximum and a gradual dying out again as the distance increased. Actual- ly, however, the observations suggest the existence of local 1 Survey of India, Prof.’Paper No, 5, Dehra Dun, 1901, [ 272 ] SUMMARY AND CONCLUSIONS. 125 irregularities of deflection superimposed on a general southerly deflection, which _. 23 remains fairly constant over a wide tract as of country ; this condition would be satis- | - 3 fied if we supposed the belt of greater 3 5 density to have the form indicated by the dotted lines in fig. 9, that is to say, instead of being narrow and steep-sided, to be broad with a gentle slope downwards on either side. If the excess of gravity along the crest of the range is taken as equi- valent to about ‘04 dyne, and the zero point at a distance of about 200 miles, the southerly deflection would be about 3”; and if the slope of the Hidden Range were continued into the depression under the Gangetic alluvium, in the manner which will be suggested immediately, this deflec- tion would continue in fairly constant amount up to and beyond the boundary of the alluvium. So far as I know, the only suggestion, Excessive Density ginal diagram ; the dotted line the modification gs ‘ Hidden Range’ of excessive density in the northern vations, which has yet been made, to account for ‘= * . - . . o the origin of this Hidden Range, is that ‘ 4 the excess of density is due to an intrusion, \ a \ 7) or series of intrusions, of dense basic or \ ultrabasic rocks.! To this the same objec- tion applies as to any ascription of the effect to a comparatively narrow belt of ; excessive density, and we must look else- , where for an explanation of the origin of this feature, which seems marked out, by its courses and position, as in some way ¥ connected with the origin of the Hima- layas. One such explanation follows, as a natural consequence from Mr. Fisher's interpretation of the origin of the Gangetic trough. Granted the existence of a floating Diagram representing the The firm line reproduce being in better accord with the obser 9, Fie. Peninsula. 1 T.gH. Holland. Presidential address to section C. British Aesociation Report 1914, p. 358, 126 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. crust, of sufficient strength to enable it to be forced downwards into the denser matter underlying it, in the manner which has been outlined, it is improbable that so large a depression would at once die out into a condition of equilibrium on the further side from the hills. The very strength of the crust which enabled the depres- sion to be formed would be likely to uplift the crust, on the further side, beyond the point of equilibrium, before it finally sank down into a normal condition, unaffected by the exceptional circum- stances connected with the Himalayan range. In this way the depression of the Gangetic trough would be bordered on the south by a tract where the crust was uplifted, as a whole, with the con- sequence of the rise of the denser matter from below into the hollow formed in the under surface of the crust, and so give rise to pre- cisely the phenomenon which Sir 8. G. Burrard found necessary to invoke, in order to account for the observed deflections of the plumb-line. The argument of the last paragraph may be made clearer by reference to fig. 10, where a cross-section is depicted, from the centre of the Himalayas to about the centre of the Peninsula, covering about 10° of latitude or a distance of some 700 miles. In this figure the actual relief of the surface is indicated on a some- what exaggerated vertical scale, in order to make it recognisable ; below is represented, on an equally reduced scale, the under surface of the crust, adopting Mr. Fisher’s constants of a thickness of 25 miles for the undisturbed crust, and a ratio of 96: 1 between the prominences on the under and upper surface of the crust, respec- tively. In this part of the figure there are two lines, one firm and the other dotted, of these the dotted line represents the under sur- face of the crust as it would be if there was at every point a complete compensation of the surface irregularity, the firm line represents the form of the under surface of the crust as it would have to be in accordance with the departures from exact com- pensation which have been established or inferred. The treatment is in fact the reverse of that adopted in fig. 8, in which the adjust- ment was made by an alteration of the surface level, and the hills supposed to be either held down or uplifted. 1 It is obvious that the dotted line, which represents what the under surface should be, were the inequalities in the surface and the Gangetic trough completely compensated under every point, may also be regarded as representing the proportionate amount of the compensation, irrespective of any theory of how it is brought about. | aa 127 SUMMARY AND CONCLUSIONS. ‘pary}-ouo ynoqge Aq poonper SOBJINS IOMO] OY} Jo Fey suo ynoqe Aq poyei0s3exo st sovjins soddn oy} jo o[vos feoMIea { sorter COL qnoqe Jo soueysIp @ syueseidel uoo0s 04} Jo YIZue] oyy, “preg jo ,.oduey usppryy ,, oy} wWu0y oy ‘TIL worder jo 4] premumop oy 4q peyyqdn sr ysnio oy} pur poyesuodutooun Ayivou Iv sy OY} o10YM UOdeL oy} SI AT {[] UOrBer Jo pvofreso oq 0} enp suyyy Aq posneo ysnio oy} jo uorssordep Jo uorBor oy} st TTT { E_ uorsor oy} Ul po] JO sse0x9 oY} 4&q aMop PIPy St yorym ‘7 uorser yo Aouvfonq snjdins oy3 Aq pozesojerodns st oovyjans oy} e1oym “q1oddns jo yoojJop jo uorser 94} TT {410ddns JO ssooxo JO UOIdel oY} SI [ 9X9} OY} UL pozeIOge[a uoNeyoId104UL 24} 0} Surproooe vovyins Topun oy} JO WAIOF [enjow oy} sjucsoader our WAY oy {4SN10 oY} UL AzISUOpP oBvIOAG WOIJ SeINjIedop [vooT OU pue ‘yoexe ereyMAIOAS O10 Jroddns pure peor GIeMJoq SOULTLG PY} FI OF P[NOA FI Sv ooBJINS JepUN oy} Jo WAIOF oY} SUoserdor OUT pe}40p OY} £4S8Nd0 peqangsrpun oY} Jo covjiNs JOMO, [VUISILO potunsse oy} Syucserder OUT] UoyoIq oY} ‘mOpeg = “yea 909 JO OINFVAIND JO 9[VOS [VIN}eU B UO YFNOI} ooDuey) OY} JO WOLoes SsOlO OY} pue pUNOIS oY} Jo ULIOF [eNZoe ay} po ~quosoidor St eAoqW “ensurueg 044 Jo yrzed pue yZnor} ooSuey ‘svAvpeunpy 24} fo UOM4O98 ssoInQ—'Ol ‘Oly [ 275 ] K2 128 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. Turning now to the interpretation of these two lines, we see on the extreme left of the figure, that the firm line is below the dotted one, representing the greater depth of “root”? required to produce the excess of compensation which exists in this region. To the right, but still within the region of the hills, this excess of com- pensation disappears and we enter a region where the crust is up- lifted, as a whole, by the excess of buoyancy to the left, the hills are still compensated to a large extent, but not completely, and the defect may reach a maximum of about the equivalent of 2,000 feet of rock, or one-sixth to one-fifth of the whole amount of what would be complete local compensation of this portion of the range. Further to the right, this uplift gradually dies out and a condition of equilibrium is reached, at a point somewhat beyond the outer limit of the visible hills, but not maintained, for the weight of the tract which has been uplifted by the excess of buoyancy in the central region bears down the crust on the side towards the plains, and causes the crust to be depressed below the level of equilibrium, giving rise to the depression of the Gangetic trough. This depres- sion reaches its maximum limit and then the buoyancy of the crust, further away from the hills, causes it to bend upwards, till a con- dition of equilibrium is again reached, at a point which seems to lie not far from the southern boundary of the alluvium, where it attains its greatest development and width, but to lie south of the boundary in the region of the Aravalli hills, and where the Raj- mahal hills project into the alluvial area west of the Gangetic delta, Further to the right the condition of equilibrium is, once more, not maintained, but the downward tilt of the crust to the left is continued as an upward tilt to the right, with a corresponding rise of the under surface of the crust, till the weight of the unsupported crust beyond puts an end to this uplift, and the crust bends downwards again into a condition where the influence of the Himalayan range is no longer felt. It will be seen that this development of the consequences which would result from the hypothesis of a floating crust, supported on a denser, plastic, but not necessarily liquid, substratum, is in close accordance with the larger features of the structure of the country south of the Himalayas. It provides for the trough, for the elevation of part of the earlier deposits formed from the waste of the hills on the north of this trough, and for a gradual extension, by progressive regular subsidence, to the southwards, as the range itself grew in magnitude; it provides also for that, belt of positive [ 276 |] SUMMARY AND CONCLUSIONS. 129 anomaly of gravity, traversing the Peninsula, with ‘its comcomit- ant effect on the plumb-line; and it may be added that the strength of the crust, required to produce these effects, is much the same as ,that deduced by Prof. Barrell from the geodetic work in North America.t This agreement, between the results of con- clusions drawn from observation and those obtained by deduction, lends considerable support to the hypothesis on which the deduc- tions were based, but it must be confessed that the Himalayas are the only range where anything like this agreement has been found, yet even this may rather strengthen than weaken the support, for it may well result from the magnitude of the range, which is not attained by any other mountains of the world. It is conceivable that only in the mountain system, of which the Himalayas form the culminating member, do the gravitational stresses set up by the processes of mountain formation reach a magnitude which enable them to dominate all other influences, and _ to preluce a simplicity and magnitude of structure, obscured in other cases by the action of other influences and resistances, which become more promi- nent with the decrease in the magnitude of the gravitational stresses.? We have seen that, the phenomena actually observed, in the region lying in and to the south of the hills, are in agreement with, and are easily explained by, the hypothesis of a solid and some- what rigid crust supported by flotation on a substratum of denser material; but when we come to consider more especially the range itself, difficulties arise in the acceptance of Mr. Fisher’s explana- tion of a simple thickening of the crust by compression. In_ his investigation the crust is supposed to be compressed as a whole and, recognising that the resistance of the lower part would be less than that of the upper, the neutral zone was put at two-fifths of the thickness from the upper surface, so that all above this would be thickened upwards and all below in a downward direction. In these circumstances the downward protuberance would be half as large again as the upward one, which would give an insufficient 1 Journal of Geology, XXIII, p. 30 (1915). 2 Too little is known of the Andes, the only other mountain system of comparable magnitude, to admit of comparison with the Himalayas. [Since this was written, some particulars of deflection of the plumb-line in the Andes have been published, indicating that it varies in much the same manner, and to about the same extent, in these two ranges, which are of very much the same magnitude, in the portions which have a redominating share in the effect on the plumb-line. Geog. Jour. XLVIT. 484-467, & STLVIIL 180-181, (1916) } pres 4 130 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. support by flotation, and the range would sink, carrying with it the crust on either side till a condition of equilibrium was attained. This explanation carries with it the necessity of a depression on both sides of the range; it renders the elevation _of the marginal deposits almost impossible, and is in contradiction to the excess of support which is actually found in the central Himalayas. The latter condition could, however, easily be met by putting the neutral zone at a higher level. If placed so that the amount of the crust below were ten times that above, which would correspond to a depth of about two and one-third of a mile in a crust of 25 miles in thickness, the downward protuberance would exceed the upward one in just about the proportion necessary to provide a small excess of flotation. In some respects a neutral zone so near the surface would be welcome, for some of the complicated structures, which have been revealed by geological survey of the more highly disturbed regions of the earth, certainly seem easier of explanation if we can consider the relief from compression as having taken place in a downward, rather than an upward, direction, and it is equally easier to accept these structures as having been brought upwards from a depth of a couple of miles than from five times that depth. On the other hand, a neutral zone so near the surface seems to give an inadequate cover for the production of a com- plicated folding of hard rocks, such as could only take place, without crushing and fracture, under a heavy superincumbent load of rock. A more important objection to this explanation is the fact that, though it would provide an adequate amount of support, it would not provide for the alternate defect and excess of compensation, which is revealed by observation, for, so long as the neutral zone is maintained at the same absolute level, preserving the same proportion between the thickness of crust above to that below it, the relative dimensions of the upward and downward protuberance would remain unchanged, and the hills would be uniformly over- or under-compensated, as the case might be. A relief from this difficulty may be obtained in several directions. In the first place if the neutral zone maintained a nearly constant depth from the surface, instead of the same fraction of the total thickness of the crust, the downward protuberance under the central range would be developed in greater proportion to the upward one, and the excess of buoyancy attained, The distri- [ 28 j SUMMARY AND CONCLUSIONS. 131 bution of resistance to compression, needed to bring this condition about, would be somewhat peculiar, but by no means impossible, yet it must remain merely a suggestion, in the absence of any means of testing it. Another possibility is that, in addition to the thicken- ing of the crust by compression, its density is actually reduced in some way or other, and here Dr. Fermor’s suggestion of the pass- age of rocks, belonging to the same norm, from a mode of greater density to one of lesser, affords a feasible explanation, but, like the previous one, it must remain a mere suggestion. Neither of these suppositions involves the implication of any fresh material, from outside the portion of the crust covered by the hills, in the process of mountain formation, but the excess of support under the main range might equally be accounted for by an invasion, of the tract under the hills, by material from out- side, whether by the injection of acid intrusions, or by a differen- tial movement of the lower and upper parts of the crust, such as could be described indifferently, according to the point cf view, as an over-thrust of the upper portion towards the south, or an under-thrust of the lower towards the north. It is in the last-named direction that the easiest relief occurs from the difficulties arising from a limitation of the cause to the area actually covered by the range. The attribution of part of the down- ward prominence to an invasion of material from outside the limits of the range, would enable the neutral zone to be brought down to a level which would remove any difficulty in explaining the production of complicated folding of the rocks, but it is important to note that any process of this sort can only be subsidiary to the effect of com- pression, and that we cannot, on the hypothesis under consideration, attribute the whole, or even the major part, of the elevation of the range, to the invasion of material from outside. The case can be put simply enough : using Mr. Fisher’s constants, the total thickness of the crust under the range would have to be just about twice as much as the normal thickness of the undisturbed crust, but these cons- tants, as has been pointed out,! represent what may be regarded as a minimum value for the thickening, which may amount to three times the normal thickness; the hypothesis, therefore, demands a compression of from one-half to two-thirds of the original horizontal extent of the crust. The actual amount of compres- sion, indicated by geological structure, cannot be estimated with 1 See p. 48. [ 279 ] 132 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. accuracy but, allowing for all possible over-estimates, it cannot be put lower than one-third, and is probably not much over one- half, of the original extent. It will be seen that the two estimates overlap, so that it is just possible to account for the support of the range, by compression limited to the area covered by the hills; on the other hand, if we take the highest estimate derived from the hypothesis and the lowest possible from observation, the downward prominence produced by compression would have to be reinforced by an equal bulk of material, of similar density, to pro- vide sufficient support for the visible range. These may be regarded as the extreme limits, and the most natural conclusion is that, although simple compression might account for the whole of the support, or might be unable to account for more than one-half, the conditions lie somewhere between these two limits, and probably nearer to the first than the second, so that we may take it that, on the hypothesis which is being considered, the greater part of the support of the range would be provided by the compression, which it has certainly undergone, though a small portion may be attributable to the invasion of material from outside. The specific question which had been put, of how far the ele- vation of the Himalayas is the direct result of the compression which they have undergone, seems to have been answered. An hypothesis has been found which is in accord with observation, not only within the limits of the range itself, but in the regions outside the range, where structures closely related to it in geograph- ical extent and, presumably, in origin, are met with. But before this hypothesis can be accepted as in any degree satisfactory, it is necessary to examine the other explanations which have been offered at various times, and it will be of interest to pursue the hypothesis which has been discussed somewhat further, to see whether a satisfactory explanation can be found of the compression which it makes mainly responsible for the elevation of the Himalayas. To take this last question first, it must be confessed that Mr. Fisher’s investigation gives no conclusive answer. He rejected the obvious suggestion that it was due to the contraction of the earth by cooling; the cause may be a real one, it provides a force very many times more than adequate to produce the effect required, but the possible range of motion is almost equally in defect of that necessary to account for the compression which has taken place. [ 280 | SUMMARY AND GONCLUSIONS. 133 He next investigated the possibility of an expansion of the crust by the injection of dykes; this process seems just about able to produce the amount of force required, but here again the range of motion is inadequate. He finally suggested the existence of con- vection currents, rising under the ocean beds, flowing outwards along the under surface of the crust towards the continents, and giving rise, by a drag on the under surface of the crust, to compres- sion in the continental areas. This cause, granted the existence of the currents, would produce an ample range of movement, but it is doubtful whether it could produce suflicient force to give rise to a yielding and compression of the crust. The drag exerted by such a current on the underside of the crust would be proportionate to three factors, the co-efficient of friction, the rate of flow, and the length of the tract along which the flow takes place; of these the first would be small, the second probably also small, but the third would be some hundreds of miles, and therefore large, so that the stress, accumulated along a length of the crust, might attain a magnitude sufficient to give rise to compression of the weaker portions of the crust.' It seems that, granted the existence of the currents postulated, the effect might be produced, but the con- clusion is by no means established, and the postulate has by no means been accepted, very largely on account of the nomenclature adopted. The notion of convection currents connotes, and was certainly intended to imply, a degree of fluidity which appears difficult to grant, but it is Important to observe that similar movements might take place in a material which exhibits none of the properties associated with a fluid, as it exists on the surface of the earth. A material having the properties of the asthenosphere of Prof. Barrell,? would have sufficient power of yielding, to long continued stresses, to permit of the existence of movements analogous to convection currents, and so provide the motive power required. Though possible, however, this explanation can hardly be regarded as probable, or even satisfactory, but it is at least a feasible one, and not more unsatisfactory than any other which has been offered as yet. Of these the first to be considered is that of Prof. Suess which, being incorporated and developed in his great work on the 1 Physics of the Earth's Crust, 2nd ed., 1889, p. 320. 2 Journal of Geology, XXII, 1914, p. 656. [eer 3 134 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. Face of the Earth, has attained a certain vogue, and a con- siderable amount of influence on geological thought and _ specu- lation. This explanation is based on the hypothesis of an originally highly heated solid globe gradually cooling by radiation from the surface, and the effects of surface deformation are attributed to the compression, to which the outer layers of the earth would be subjected, by the gradual contraction of such a globe. In ex- plaining the actual forms, assumed by the surface, great stress is laid on the supposed directions from which pressure was applied, and to which movement took place. In the case of the Hima- layas it is specially argued! that the form of the range, and of the associated ranges on the eastern and western frontiers of India, can only be explained if pressure was applied from outside towards the steady mass of the Peninsula, and is inconsistent with the supposition that the pressure and movement came from the south. On this view of the case the peninsular area naturally became a foreland, and the Gangetic trough a foredeep; but the whole of the reasoning, on which the conclusion is based, is permeated by two mechanical fallacies. The first is the possibility of a one-sided application of pressure ;. but pressure can only exist if there is some resistance, and the resistance necessarily gives rise to an equal and opposite pressure. If these opposing pressures exceed the resistance of the material, compression, .and consequent movement, will take place, but the direction and form, which this yielding will assume, is dependent solely on the nature of the resistances, and the amount of move- ment needful to relieve the pressure. The other fallacy is the possibility of absolute movement, and this will be most easily explained by reference to a diagram; in fig. 11 let A B be two es Ae *D <9 Fig. 11. points near the outer limit of the Himalayas, © a point well away to the northwards and D one well away to the southwards, and ? Das Antlitz der Erde, X11 (2), p. 707. English translation IV, p. 614. [ 282 ] SUMMARY AND CONCLUSIONS. 135 suppose the distance between C and D to be reduced. Then, in the first place, we can only determine the change in distance, and cannot say whether C has moved to the right or D to the left, except by reference to some more distant point, such as the north pole, which again can only be fixed by reference to some still more dis- tant points such as the sun or stars, which obviously have nothing to do with what goes on between C and D. Next, as regards this tract, we may suppose the tract to be uniformly compressed, in which case all the distances are proportionately reduced and the positions of A and B relative to each other are unchanged ; or we may suppose the distances from C to A and from D to B to remain unchanged, those from C to B and from D to A being shortened, and in this case the effect will have a different aspect according as it is viewed from C or D. From the side of C it will seem that A has been unmoved while B has been underthrust to the left, but from the side of D the reverse action will seem to have taken place, and A to have been overthrust to the right; so far, how- ever, as A and B are concerned it is only the relative movement which comes into consideration, and the result in either case is the same. From this we see that, as regards the processes which take place within the hills themselves, the question of whether the sur- face has been overthrust to the south or the lower layers under- thrust to the north, is meaningless ; the form of the range, and of the structures developed in the rocks of which it is composed, depends on the power of resistance, and the direction in which yield- ing takes place most easily, and not on the supposed direction from which pressure is applied. In other words the form of the range depends entirely on, the distribution of resistances within the hills themselves, and the answer to the question of the direction in which this relief has taken place, depends entirely on the point of view from which it is regarded. This matter has been dealt with as it seems important to clear it up, for the fallacies referred to are widespread and deep-seated and permeate a great deal of geological and other reasoning. The whole of the arguments based upon them are meaningless, so far as the origin of mountain ranges is concerned, but the fundamental objections to Prof. Suess’ theory are, that it fails to provide a sufficient range of movement, and is incompatible with the existence of compensation. The first of these objections can be put simply ; given a solid, heated globe, cooling into space, it is possible to [ 283 136 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. calculate the amount of contraction which it has undergone, if certain constants are known. ‘These are, the original temperature of solidi- fication, the co-efficient of contraction, the conductivity, and the temperature gradient; none of these are known exactly, but they are known to lie within certain possible limits, and calculation, based on these, shows that, on this hypothesis, the total decrease in the circumference of the globe, since it became solid, might be as small as a couple of miles and cannot be more than about ninety. In other words the whole of the contraction, which could have taken place throughout geological time, is not greater than the compression of the Himalayas alone, within the limit of the Tertiary epoch. The other objection is an even more important one; it was fore- seen by Prof. Suess, and anticipated by a denial of the existence of compensation. In the case of the Himalayas he must be credit- ed with a greater intuition than many of his successors and followers, for he recognised the fact that an alluvial trough, of the form which had been inferred from geological examination, would account for a large part of the facts on which the concept of the compensa- tion of the range had been based; from this it was not a long step forward to the suggestion that the whole of the facts might be ac- counted for in this manner, and the absence of any compensation of the range asserted! The position, though difficult, was still tenable at the time when he wrote, but in the light of subsequent observations, and of the investigation of the form and dimensions of the trough in chapter IV, must now be definitely abandoned. There can be no doubt, at the present time, that the Himalayas, as a whole, are compensated, though there are local departures in one direction or the other from exact equilibrium. This being so the only hypothesis of mountain formation which is consistent with a solid, rigid, globe is one of tumefaction, all hypotheses which refer the origin of mountains to compression, due to contraction, being excluded by the impossibility of providing for compensation. Another explanation of the origin of the Himalayas and _ the Gangetic trough, which has attracted some attention of late years, is that offered by Sir 8. G. Burrard.? Like that of Prof. Suess 1 Das Antlitz der Erde II (2), p. 707, English translation IV, p. 614. 2 On the Origin of the Himalaya Mountains. Survey of India, Prof. Paper, No. 12, Calcutta, 1912. [ 284 | SUMMARY AND CONCLUSIONS. 137 it is based on the hypothesis of a solid heated, cooling globe, but differs in recognising that this hypothesis necessitates the existence of a zone of tension underneath the outermost lavers of the crust. The fact that this consequence follows inevitably from the hypo- thesis, was first pointed out by Mr. Mellard Reade,' and once stated is so axiomatic that it immediately met with general acceptance. If we suppose a cooling globe, in which the cooling has only reached a certain distance down from the surface, we have an outer shell, which is contracting and so reducing its circumference, surrounding a central core; which remains unaltered in dimensions, and in these circumstances the outer shell must be thrown into a state of tension. Only in the outermost layers will the general reduction of the bulk of the globe, under the layers which, being already fully cooled, are incapable of further contraction, lead to the existence of com- pression, and it has been abundantly shown that the zone of tension must be of much larger dimensions than that of compression.” Sir Sidney Burrard, however, makes a somewhat different use of this deduction from his predecessors, and considers that the depression of the trough was produced by a withdrawal of material towards the Himalayas, and the range to have been produced by the invasion of the material so withdrawn. Such, eliminating the details of the mechanism invoked, is the essential character of the hypothesis; it seems to involve a greater tensile strength in the zone of extension than can easily be granted, greater cer- tainly than that of any known rocks, as met with near the surface of the earth; but so little is known, or can be known, of the physical properties of the material of the earth, when subjected to the tem- peratures and pressures which exist in its interior, that we cannot summarily reject the explanation, on this ground alone. In developing his explanation Sir 8. G. Burrard is as insistent on the direction of movement as Prof. Suess, though he insists on the exact opposite, and maintains that the Himalayas are due to an underthrust of the sub-crust from the southwards, instead of an over-thrust of the upper layers from the north. This matter has been dealt with already and it has been shown that the distine- tion is meaningless, so far as the processes which have taken place within the range itself are concerned; but it is not meaningless 1 Origin of Mountain Ranges. 1886, p. 123. 2 Of. O. Fisher, Physics of the Earth's Crust, 2nd ed., 1889, ch. VIII, for a discussion of this matter and references to earlier literature. [ 285 ] 138 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. as regards the region to the south of the range, now occupied by the Gangetic trough, and if this trough is really due to a withdrawal of material towards the hills, we have a process which is the converse of that suggested by Mr. Fisher. In the one case the crust is supposed to have been borne down, displacing a certain amount of denser material from beneath it, in the other the underlying material is supposed to have been withdrawn, leading to a settling down of the lighter material above, and as the form of the resulting trough, developed in Sir 8. G. Burrard’s latest exposition of his explanation,! is practically identical with that resulting from the present in- vestigation, the geodetic effects would be identical in either case, and we have no criterion for discrimination between the two inter- pretations. Nor do we get any help from the geological evidence. There is no indication that the region of the Gangetic trough is one of tension, as suggested by Sir 8. G. Burrard, but equally there is no certainty that it is not; within the region of the alluvium all evi- dence, one way or the other, has been obliterated, and only by con- sideration of the associated phenomena can a criterion be obtained. It has been shown that the view which regards the origin of the Gangetic trough as a consequence of the process of the elevation of the range, and the disturbance produced in the equilibrium of a floating crust, is in agreement with the geological and geodetic observations along the border of the alluvium and in the country beyond ; the same cannot be said of the alternative explanation. On the southern side it is not incompatible with the facts, and might give rise to the phenomenon of the Hidden Range of excess of gravity ; on the northern, in the region of the Himalayas, there are the same fundamental objections, which were pointed out in dealing with Prof. Suess’ explanation, that the hypothesis does not admit of a sufficient range of movement to account for the structure, and that it is inconsistent with the existence of com- pensation, ,and more especially of the alternate excess and defect of compensation, of the range. So far, however, as the explanation refers the origin of the Himalayas to an invasion of the region of the hills by the lower layers of the crust, independent of the de- formation which has taken place in the upper layers, it is in accord with the investigation which has been developed in this memoir ; for it has been shown that the facts, as they are known, seem 1 Proc. Roy. Soc., Series A, XCI, 1915, p. 233. [ 286 ] SUMMARY AND CONCLUSIONS. 139 incapable of complete explanation without invoking some such action, though the ultimate cause to which it is due has not been estab- lished, The same action is provided for by Mr, Bailey Willis, who attri- buted the origm of the mountain ranges of Asia to the greater density, and weight, of the crust under the Pacific and Indian Oceans, and to an underground transfer of material, from the oceanic to‘ the continental regions, in consequence of the pressure set up by this difference of weight. At a later date a similar explanation was adopted by Mr. J. F. Hayford, who puts the action as taking place within narrower horizontal limits.? So far as this undertow is supposed to occur at a depth below that in which the contortion of the rocks, now lying near the surface, took place, it is in effect similar to that of Mr. Fisher’s convection currents; but while these supply a continuous action, ample to provide for all the range of movement required, the alternative process only provides for a limited and insufficient range of move- ment, and in both cases it is questionable whether the pressure requisite to produce compression could be communicated to the upper layers of the crust. If, on the other hand, the compression is supposed to take place within the layer involved in the movement of the undertow, the range of motion might be sufficient, but the pressures developed, especially when supposed to be transmitted, through a long horizontal column of material, appear to be utterly inadequate. As has been pointed out before, we know too little of the conditions actually existing in the interior of the earth to reject this explanation as impossible, but, in view of the many difficulties in the way of acceptance, it cannot be regarded as a satisfactory and sufficient explanation of the facts revealed by observation. One more explanation of the origin of mountain ranges, which may be referred to, is the suggestion of Mr. Mellard Reade.*? He pointed out that if the average temperature of a tract of the earth’s crust was raised, it would expand, not merely in a vertical but also in a horizontal direction, and that the cubical expansion of the whole tract would most naturally find relief by yielding along a 1 Research in China, Vol. TI, Chap. VIII, 1907. 2 Science, new series, XX XIII, 1911, pp. 199-208 ; Journ. Geol., XX, 1912, 562-578, § The Origin of Mountain Ranges. London, 1886. [ 287 ] 140 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. line of weakness, where the rocks would be compressed, and thickening of the crust take place. If the temperature then sank, the material would not return to its original position, but the contraction be relieved by a general subsidence of the superincumbent rocks and a compressive extension of the lower layers. On an increase of temperature again taking place, relief would once more be found along the original lines, and the disturbance and thickening of the crust accentuated, till, by a repetition of the process, the largest mountain ranges might be formed. There can be no question that this cause is capable of producing much more than the pressure required, and a sufficient range of movement. It is a cause which might quite conceivably act, but, with the masses involved, the process would be slow, so slow in fact that even the vast periods, which have been deduced from the study of radioactive minerals, would seem insufficient for the pro- duction of the effect. fhe explanations which have been passed in review do not by any means complete the list of those which have been proposed, but they serve as types, and the difficulties which lie in the way of the acceptance of each of them apply equally to the variants of the type. The general result of the examination is that, while the general distribution of the excesses and defects of gravity agrees best with the supposition of a somewhat rigid crust, supported by flotation on a denser yielding layer, we can, neither on this nor any other hypothesis of support, find an explanation of the origin of the Himalayas, which can be regarded as complete and satisfactory ; nor does it seem possible to offer any alternative which can be accepted. In spite of this negative result the investigation has not been in vain; it was undertaken with no expectation of attaining a solution of the problem of the ultimate cause, to which the elevation, of the Himalayas is due, and it has not failed this want of expectation ; but it has yielded a fresh criterion, which must be met before any hypothesis can be regarded as acceptable. The con- clusions, however, must not, at present, be extended to other ranges of a different type of structure, without corroboration of indepen- dent observations, and even in the case of ranges of similar general geological structures, but very different magnitude, such as the Alps, it is not impossible that the difference of scale may seriously vitiate an application of the conclusions, drawn from a study of the greatest [ 288 | SUMMARY AND CONOLUSIONS. 14] range on the surface of the earth. If the conclusions, drawn from a study of the Himalayas, are corroborated by the study of other mountain ranges, an important step forward will have been made, and the problem will become one of accounting for the excess of support, of which the mountains themselves are but a secondary result and manifestation. BS ma — coe TA ince = err INDEX TO GEODETIO STATIONS. 145 INDEX TO GEODETIC STATIONS. In this list L signifies a latitude, G a gravity, station. Latitudes and longi- tudes are given to the nearest whole minute. There is some confusion in the longitudes, as the old and revised values of the longitude of the Madras Obser- vatory differ by nearly 3’. The published longitudes of gravity stations are all referred to the revised value ; those of the latitude stations usually, but not in every case, to the old values. The published longitudes are given without correction, except in those cases where the latitude and gravity stations are identical, or so close to each other that the use of a different reference for the longi- tude would lead to confusion. In these cases the longitude of the latitude stations has been revised to the new value ; in all others the published figure has been retained, as the small discrepancy is immaterial. Ele- | | Table. | Station. Latitude. | Longitude.| vation Page. (feet). ° / ° 4 Agra G. | 27 10 12-4 535 23 80 5 eee oe Se 73. 8 550 | 20 val Aligarh G4 21 64h 18. I 612 23 | Allahabad G. | 25 26 81 55 288 | 23 | Amritsar Dats She 74 55 770 24 ~—s- 84, 85 Amsot L. | 30 23 | 77 44 | 3,140 26 | Amua . Te be SO 2,113 | 19 Arrah . G.| 25 34 84 39 188 | 23 | 78,79 Asarori G.| 30 14 17 58 2,467 | 27,30, 92, 108 Bahak Ie 30 45 78 16 9,715 | 28, 29 101, 102 Bajamara L. 30 46 77 66 9,681 | 28, 29 | 101 Banog ibs 30 29 78 3 7,433 | 28, 29 | 101 Bansgopal L. | 28 33 78 34 677 20 | 70 Basadela L. | 27 24 82 17 366 19 Bihar . | Ape BG ee 85 31 391 21 | 73 Birond L. | 29 15 19 45 6,967 | 5, 28, 29 Bostan tel BS 47. 33 758 20 | 71,97 Bulbul Bot ES 84 26 3,352 21 73 Bullawala L DOr 7: FEE Ry 2,432 26 89 Buxar . G. 25 35 83 59 207 23 Calcutta L. 22 30 88 24 18 75 Chandaos L. 28 5 717 64 699 20 96 { 291 ] L2 144 el ! Station. Chanduria Charaldanga Chatra Chendwar Dadawra Darjeeling Datairi Dehra Dun . , Old 53 , New . 9 , E. Base Dewarsan Dubauli Etora . Fatehpur Ferozepore Garinda Gesupur Ghaus . Gogipatri Gorakhpur Gurmi Hardwar , Hathras Hatni . Hurilaong Inlia . lsanpur Jalapur Z Jalpaiguri. . 3 | Latitude. Ele- Longitude. vation (feet). ae eee 88 25 160 88 26 149 88 23 64 85 29 2,817 | 81 43 | 420) 88 16 6,966 ger Se ST, 78... S01 0h, OBO 78 3 | 2,289 78 38 | 2,240 | 78 1 | 1,958 80 21 | 439 85 20 189 80 42 429 717 44 | rae 74 37 | ~~ 647 | | | a 1,204 | 77 42 691 | 83 6 296 | 74 43 7,752 | 83 23 257 78 33 575 1 5 949 1s 3 587 77 62 3,096 84 24 1,378 S- 8 428 76 9 | 874 84. 23; 232 88 44 | 268 88 44 | 280 GLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. | Table. | Page. a 22 75, 95 22 74, 75 81 21 73 19 30 106 20 71, 97 27, 30 | 74, 78, 79, 90, 92, 107, 111 26 88 5, 26 88 26 87, 88 19 21 19 27, 30 91, 92 25 84, 96 24 23 96 19 113, 114 23 20 27, 30 | 92,108 23 96 26 87, 88 21 73 19 24 21 23 105 5, 22 76 INDEX TO GEODETIC STATIONS. 145 | Ele- | | Station. Jarura Jharipani Kaliana > Kalianpur 99 Kalka . Kalsi Kanakhera . Karara Kaulia Kesarbari Kesri . Khajnaur Khimuana Khurje . Kidarkanta . Kisnapur Kurseong 3°) . © Lachkua A Lambatach . Lohagara . Ludhiana Madhupur . Mahadeo Pokra Mahar Mahwari ‘ Majhar “ . Majhauli Raj Manichauk Mednipur Meerut ° Ee HOO POPP HOaHHHOaa Fae QOH HHOPP Pre ar Oe Latitude. | Longitude. 28 0 80 31 30 25 78 #5 29 31 77 39 29 31 77. 39 24 =«67 77 39 24. #7 77 39 30 50 76 56 30 31 77 +50 25 51 80 28 24 «56 81 18 27 49 85 17 26 8 88 31 25 47 77 438 30 16 717 «+53 30 22 75 3 28 14 17 54 ieee 78 13 25 2 88 28 26 53 88 17 26 52 88 15 30. 4 yi: Sea 31. 77° «+57 26 2 88 24 30 55 75 51 23 (57 88 32 27 42 85 34 24 45 85 10 23 26 84 54 26 «6 78 31 26 18 83 58 27 36 82 5 27 38 81 23 25 «5 84 22 29 0 77 42 31 32 74 23 vation | Table. | (feet). | 536 «19 810 | 5, 23 828 | 5, 20 1,763 1,765 2,202 | 30 1,684 | 17, 30 416 | 19 1,966 | 19 7,051 | 28, 29 204 | 23 1,487 | 20 2,576 | 26 731 | 24 649 | 23 12,509 | 28, 29 113 | 4,913 | 30 4,428 | 5, 22, 28, 29 2,674 | 26 10,474 | 5, 28, 29 205 | 22 835 25 92 22 7,095 | 28, 29 1,606 | 21 3,153 | 21 1,028 | 20 219 | 23 360 | 19 406 | 19 335 21 734 23 708 25 Page. 124 21, 97, 91, 92 87 84 101 81 106 103 89 101, 102, 104 84 146 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, BTC. | Ele- Station. Latitude. Longitude. vation , Table. a | (feet). | ° 77 ° / Moghalsarai . : et og ye TS BBO Se 257 23 Mohan : , ACs $0. 11 77 55 1,660 | 27, 30 | 92, 108 Monghyr : ; aoe re 95 23 86 28 154 81, 124 Montgomery . Fee 30 40 13. 6] 557 25 Moré . ; ; . GI 33° 16 77 54 | 15,427 30 | 110, 111 Murree ‘ ; . Fag? ge 78> 27 -1 104 Mussooree . : peice 30 28 78 5 | 6,924 30 107 a : : - Lf 96° BB 78 #4 6,937 | 5, 28, | 94, 101, 29 |102, 104 Muttra . ; - G+ 97 98 77 42 4 562 | 23 Muzaffarpur : 26 «7 85 25 | 179 23 Nimkar L. 97 21 80 32 | 486 | 19 67 Noh L. | 27 5 77 «41 710 20 Nojli G. | 29 53 77 40 | 879 | 23, 27 92 ie ew L. | 29 53 717 40 | 929 | 20, 26 Nuaon L. 25 35 84 14 | 251 21 Pahargarh L.| 24 56 | 77 44 1,641 | 20 Pahladpur L. 26 4 85 27 175 | 21 Parewa L. | 96-38. | 81°12 380 | 19 Pariaon L. 25 50 81 22 346 | 19 Pathankot G. 82= 17 Tbe 39 1,088 | 25 84, 85 Pathardi L.| 27 26 | 82 45 | 320] 19 Pavia . L.| 25 97 | 80 47 | 481 19 67 Phallut L. | 27 13 88 3 | 11,815 | 28, 29 | 102, 106 Poshkar L. ga 74 32 8,323 112, 113 Potenda . L. | 24 37 Si he OES 19 Rajpur: ‘ “ G 30 24 78 66 3,321 | 27,30] 90, 92, 107 . : L 30 24 78 6 | 3,500 | 26, 28, | 987, 88, 29 | 94, 101 Rakhi . : L 20° 17 %- 9-2 785 24 96 Ramchandpur G.| 25 41 88 33 132 23 95 Ram Thal L 28 30 Te S34 951 24 Ramuapur la Oe OF 4A SE OT. Oa 19 Ranjitgarh : 4 | 82 85 | 72 40 | 900 24 96 Roorkee « ‘ 3G 29 52 717 54 | 867 | 23, 27 92, 108 INDEX TO GEODETIC STATICNS. 147 | . | El Station, Latitude. | Longitude.| vation | Table. | (Page. (feet). | | ° , ° , | Salimpur. L.| 27 47 | 78 33 845 | 20 | Sandakphu . G. |: 97 621288 OF 1411,766 | 30 | 105 Sangatpur I, [2th oem oy. Se 84 Sankrao bi [8 sree Lao. 208 670 20 Sarkara L. | 29 16 78 35 761 | 20,°26 . 97 Sasaram G.| 24 67 83 59 340 | 23} 82, 124 Sawaipur L. | 29 39 : fie 697 | 24 | 83 Senchal L. | 26 59 88 20 | 8,600 | (28,129 | 102 Seoni . G. 4-22 &- | 79 88 2,032 | | 124 Shahpur T | 82 St 6 Sy BBO 24 84 Shorpur be 1-90} 18 77 58 | °2,916 | 26 Siliguri Gelb. 88 ap) 887 23 105 , | 26 42 88 25 401 | 5, 22! 75 SHI yas G.|-31 6 | 77 10 | 7,043 30 | 109 Sirsa Pees be | 78° 36. |: 739 20 | Sora. ee oi. aie Am Re) Sal be CC 19 Spur Point L. | 30 25 f (: Sager: aes amt cem™ 94 Sultanpur G.| 26 16 82 5 | 314} 23 | Tasing ae ats Ba Fe E | 2,050 24 Tones. * 5 eerie = PE Sa ee 10 740 | 21 72 Tonglu eB SE aS Laie 28, 29 | 102, 106 Usira : L. | 26 57 | 77 40 810 | 20 Utiaman 5 L. 7 aaa 81 12 386 | 19 te [ 295 ] nat a. a aS mee oh a igen ne _ oo ee Sy ~ Cee ay et er ne ee GENERAL INDEX. 149 GENERAL INDEX. ee SUBJECT. Page. ' ee ee SE EE Se : Airy, G. By. 5 5 F ; ; 3 < , : 12, 31 Alluvium, mean density of — . ; ‘ ; ; ‘ ¢ .| 53, 69 $s , Gangetic, depth of. ‘ : i A , » +: BSB, WS, 80, 82, 96, 119 % , Indo-Gangetic ; : ; x : ; = 8, 98 Anomaly of gravity ° : ‘ ‘ é ; ; : fe 22 ~ in India . ; : ; ‘ s ; a4 29 Aravalli hills . : % Z : . ; P , ‘ I 71, 82, 96, 128 5 » » continuation of, in Himalayas . ; . ‘ | 97 Assam Range A ~ : , 5 ge ets ; ; . | 76, 81, 86, 96, 98 Asthenosphere : : 3 - z : ; ‘ ‘ 2 133 Barak River . ‘ - ‘ x : : ‘ - , . 82 Barrell, J... . - 5 : : % ‘ : : -| 116, 129, 133 Basevi, J. P. , : 4 : P : ‘ : ‘: : 110 Bessel-Clarke spheroid . : j ; ; : : : ; 21 Bhabar . 117 Boundary faults of Himalayas ; : ‘ a, . | 4,7, 94,118 Bouguer correction to gravity | 23 Bowie, W. “ : : ; ‘ ; : ; : 2 Brahmaputra River ; ; : : ; . . ; : | 8, 76, 119 Burrard, 8. G. ; ‘ ‘ ‘ 4 ; ; , . . 1, 8, 53, 124, 126, 136 Compensation defined . d ‘ ‘ ; ; ; . | 12 a and Isostasy . ; ; 3 is z goer ong 30 3 , depth of , : < : , : ; oo 12 oe , centre of ; ; ; ; : , : aS 14 3 , limit of distance considered . ; : : ; 39, 43 3 , theories of - - : ; 3 . ; , 30 53 , test of theories of . ‘ ; ; x A ‘ 35 Convection currents ; ; . 4 ‘ ; P -| 133,139 [ 297 | 150 SUBJECT, Conyngham, G. P. Lenox Crosthwait, H. L. . Crust, rigidity of Deflection of the Plumb-line , in Himalayas ” ” > in Peninsula vi si , southerly, in alluvial plain Dehra Dun, district ? 99 , depth of eppsittics: at , distant topography , distribution of compensation at , Superelevation of Distant oe gravitation effect éf Dutton, C, E. ; ° Dyne, as a measure of seaviby Everest spheroid Fermor, L. L. Fisher, O Flotation, support by . . ” » compensation by , due to superficial cause x $5 , northerly, in outer Himalayas Foredeep : Free air correction to gravity Gangetic alluvium, density of . ve delta é i ; e e . e . ° . . ° e OLDHAM: THR STRUCTURE OF THE HIMALAYAS, ETO. Page. lll 42, 67, 70, 75, 76, 102, 103, 124 116 11 82 54, 99 113 54, 73, 75 108 78, 79, 108 30 22 21 34, 131 31, 47, 61, 62, 122, 123, 125, 126, 129, 131, 132, 139 31, 115, 129 47, 50 8, 134 23 69 9, 75, 81, 82 GENERAL INDEX. 151 a ee SUBJECT. Gangetic trough Garhwal » » depth of » » difference of northern and southern boundaries of . » » limits of » » origin of 9 99 Geodetic data, use of Gravity, anomaly of > 39 59 , in Ginaces tough 9 , in Himalayas » belt of excess, in Peninsula » 5 Variation of Hayford, J. F. Hayden, H. H. A » 3 Hidden Range of excessive rnetee Himalayas, compression of ” , origin of, by compression Fe » by invasion of ivkipots etonil % , still unexplained » Over-compensation of Central , Support of the , under-compensation of Outer: Holland, T. H. Imaginary Range Indo-Gangetic alluvium . Indus trough . Isostasy Jalpaiguri, easterly deflection at , connected with origin of Himalayas Page, 8, 52, 65 9, 73, 74, 75, 80, 82, 119 4, 5, 94, 76, 82, 95, 96 61, 98, 116, 121, 128, 137 98, 121 Pa ise 6 68 22 76, 84, 90 105 | 12, 23, 139 74 76 124, 138 4,7, 121, 129, 131 121, 129 131, 138 ; 140 > 1 198, 416G 112, 114, 126 . ° . ; 53, 125 152. OLDHAM: THE STRUCTURE OF TH! HIMALAYAS, BTC. ——— ees | SuBsEctT. Kalianpur, assumed deflection at Kashmir bed , depth of alluvium of Main Boundary faults Py eae > >» confined to outer crust * = » » throw of Mair, D. B. . Medlicott, H. B. Middlemiss, C. 8. Mountains, new aspect of origin of . 9 , Support of bs , test of theories of me , theories of origin of Movement, direction of Nepal Origin of mountains, new aspect of ” ” > theories of Pir Panjal Plumb-line, Ssdection ae Pratt, J. H. Punjab, depth of trough i in >» Observations in . z » » Shallow alluvium in Southern Rajmahal Hills Rangit River Reade, Mellard , “ Roots” of mountains . Sait Range Siwalik hills, density of rocks of 8 » » effect of, on plumb-line “ » » southern boundary of Son River : R : : | | 109, 121 7,93 3 4, 5, 93 5, 93 118 102 137, 139 32 76, 86, 96, 98, 105, 119 5, 102 GENERAL INDEX. 153 SUBJECT. Page. . Southerly deflections in Peninsula . ; : ‘ . : . | 54, 73, 75 Suess, E. . : ‘ F . ; ‘ ; : , h 8, 133 Tista River . ‘ ‘ ‘ ; 7. Pr : ‘4 ‘ 103 Undertow ‘ A é e ‘ : ; ; ‘ ‘ ; 139 Willis, Bailey : ‘ : - ; ‘ ; ; : ; 139 r 801 | é 2 + ys, athe & VoL. Vou. Vou. VoL. VoL. Vot. Vou. VoL. VoL. VoL. VoL. VoL. MOGs VoL. Vor. VoL. Vou. VoL. Vot. VoL. XXIV. XXV. XXXVI. XXVII. SXVITII. XXIX. XXX. XXXI. XXXII. XXXITI. XXXIV. XXXV. XXXVII. XXXVIII. MXXIX. we. Fe XLI. XLII. XLIII. XXXVI. Pt. 1, 1887 (out of print): Southern Coal-fields of Satpura Gondwana basin. Pt. 2, 1890 (out of print) : Geology of Sub-Himalaya of Garhwal and Kumaun. Pt. 3, 1890 (out of print) : Geology of South Malabar, between. Beypore and Ponnani Rivers. 1896 (out of print) : Geology of Bellary District, Madras Presidency. 1896 (out of print) : Geology of Hazara. Pt. 1, 1895 (out of print): Marine Fossils from Miocene of Upper Burma. Pt. 2, 1897 (owt of print) : Petroleam in Burma and its techni- cal exploitation. : Pt. 1, 1898 (out of print) : Geological Structure of Chitichun region.—- Allakbund in north-west of Rann of Kuchh.—Geology of parts of Myin- gyan, Magwe and Pakokku Districts, Burma.—Geology of Mikir Hills in Assam.—Geology of Tirah and Bazar Valley. 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STOLICZKA, except Vou. I, Pt. 1, by H. F. BLANFORD. Ser. I & I1I1.—Vol. I. The Cephalopoda (1861-65), pp. 216, pls. 94 (6 double). V.—Vou. II. The Gastropoda (1867-68), pp. xiii, 500, pls. 28. ViI.—Vot. III. The Pelecypoda (1870-71), pp. xxii, 537, pls. 50. Vill.—Vor. IV. The Brachiopoda, Ciliopoda, Echinodermata, Corals, etc, (1872- 75), pp. v, 202, pls. 29. (Ser. II, XI, XI.)}—THE FOSSIL FLORA OF THE GONDWANA SYSTEM, by O. FEISTMANTEL, except Vou. I, Pt. 1, by T. OLDHAM and J. MORRIS. Vou. &, pp. xviii, 233, pls. 72: 1863-79. Pt. 1; Rajmahal Group, Rajmahal Hills Pt. 2; The same (continued). Pt. 3; Plants from Golapili. Pt. 4; Outliers on the Madras Coast. Vor. II, pp. xli, 115, pls. 26. 1876-78. Pt. 1; Jurassic Flora of Kach. Pt. 2; Flora of the Jabalpur group. Vou. III, pp. xi, 64+149, pls. 80 (9 double) (I—XXXI-+IA—XLVITA). 1879-81. Pt. 1: The Flora of the Talchir-Karharbari beds. Pt. 2; The Flora of the Damuda and Panchet Divisions. Pt. 3; The same (concluded), Vou. LV, pp. xxvi, 25466, pls. 55 (2 double) (I—XAI+IA—XIVA). Pt. 1 (1882); Fossil Flora of the South Rewah Gondwana basin. Pt. 2 (1886); Fossil Flora of some of the coal-fields in Western Bengal. (Ser. IX.)—JURASSIC FAUNA OF KACH. Von. 1 (1873-76). The Cephalopoda, by W. WaaGEN, pp. i, 247, pls. 60 (6 double). Vou. II, pt. 1 (1893). The Echinoidea of Kach, by J. W. Grecory, pp. 12, pls. 2 (out : of print). Vou. II, pt. 2 (1900). The Corals, by J. W. Greaory, pp. 196, I—IX, pls. 26 (out of print), Vor. IIT, pt. 1 (1900). The Brachiopoda, by F. L. Krrcmt, pp. 87, pls. 15. Vou. III, pt. 2 (1903). Lamellibranchiata ; Genus Trigonia, by F. L. Kitoutn, pp. 122, pls. 10 (out of print), (Ser. IV.)}—INDIAN PRE-TERTIARY VERTEBRATA. V OL. I, pp. vi, 1387, pls. 26. "1865-85. Pt. 1 (1865); The Vertebrate Fossils from the Panchet rocks, by T. H. Huxtey. Pt, 2 (1878); The Vertebrate Fossils of the Kota-Maleri Group,~by Sir P. pp M. Grey Ecerton, L. C. MIALL, and W. T. BrAnrorp. Pt. 3 (1879); Reptilia and Batrachia, by R. LYDEKKER. Pt. 4 (1885); The Labyrinthodont from the Bijori group, by R. LyDEKKER (out of print). Pt. 5 (1885); The Reptilia and Am- phibia of the Maleri and Denwa groups, by R. LyprxKer (out of print). (Ser. X.}\—INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA, by R. LYDEKKER, eacept Von. I, Pt. I, by R. B. FOOTE. ; Vor I, pp. xxx, 500, pls. 50. 1874-80. Pt. 1; Rhinoceros deccanensis. Pt. 2; Molar teeth and other remains of Mammalia. Pt. 3; Crania of Ruminants. Pt. 4; Supplement to Pt. 3. Pt. 5;-Siwalik and Narbada Proboscidia. Vou. II, pp. xv, 363, pls. 45. 1881-84. Pt. 1; Siwalik Rhinocerotide. Pt. 2; Supple- ment to Siwalik and Narbada Proboscidia. Pt. 3; Siwalik and Narbada Equide. Pt. 4; Siwalik Camelopardalide. Pt. 5; Siwalik Selenodont Suina, etc. Pt. 6; Siwalik and Narbada Carnivora. Vou. III, pp. xxiv, 264, pls. 38. 1884-86. Pt. 1; Additional Siwalik Perissodactyla and Proboscidia. Pt. 2; Siwalik and Narbada Bunodont Suina. Pt. 3; Rodents and new Ruminants from the Siwaliks. Pt. 4; Siwalik Birds. Pt. 5; Mastodon Teeth from Perim Island. Pt. 6; Siwalik and Nar- bada Chelonia. Pt. 7; Siwalik .Crocodilia, Lacertilia and Ophidia. Pt. 8; Tertiary Fishes. Vor. LV, pt. 1, 1886. Siwalik Mammalia (Supplement 1); pp. 18, pls. 6. Vou. 1V, pt. 2, 1886. The Fauna of the Karnul caves (and addendum to pt. 1); pp. 40 (19—58), pls. 5 Share Von. IV, pt. 3, ey) Eocene Chelonia from the Salt-range; pp. 7 (59—65), pls. 2 (xii- xiii). (Ser. VIT, XIV.)—TERTIARY AND UPPER CRETACEOUS FAUNA OF WESTERN INDIA, by P. MARTIN DUNCAN and W. PERCY SLADEN, except Pt. 1, by F. STOLICZKA. : Vou. I, pp. 164+110+4+382491=599, pls. 54+284584+13—104. 1871—85. Pt. 1 : Portiary Crabs from Sind and Kach. Pt. 1 (new 2): Sind Fossil Corals and Alcyonaria; by P. Martin Duncan. Pt. 3: The Fossil Echinoidea of 4 Sind : Fas. 1, The Cardita beaumonti beds;.Fus. 2, The Ranikot Series in Western Sind; Yas. 3, The Khirthar Series; Mas. 4, The Nari (Oligocene) Series; Fas. 5, The Gaj (Miocene) Series; “as. 6, The Makran (Pliocene) Series; by Duncan and Sladen. Pt. 4; the Fossil Echinoidea of Kach and Kattywar; by Duncan, Sladen and Blanford. (Ser. XIII.)\—SALT-RANGE FOSSILS, by WILLIAM WAAGEN, Pu.D. Productus-Limestone Group : Vol. I, pt. 1 (1879), Pisces, Cephalopoda, pp. 72, pls. 6. ” ” ” », 2 (1880). Gastropoda and supplement to pt. 1, pp. 111 (73—183), pls. 10 (1 double) (vii— Xvi). ” ” 9 », & (1881). Pelecypoda, pp. 144 (185—328), pls. 8 (Xvli—xxiv). ” » 93 » 4 (1882-85). Brachiopoda, pp. 442 (329—770), pls. 62 (xxv—Ixxxvi). ” ” ” 3 © (1885). Bryozoa—Annélida—Echinodermata, 3 pp. 64 (771—814), pls. 10 (Ixxxvii—xcvi). »” ” ” » 6 (1886). Coelenterata, pp. 90 (835—924), pls. 20 (Xevil-cxvil).: = = » eee, rae Sat Coelenterata, Protozoa, pp. 74 (925— : Se 998), pls. 12 (cxvii—exxviii). silat from the Ceratite Formation : Vol. II, pt. 1 (1895), Pisces—Ammonoidea, pp. 324, pls. 40. : Geological Results : Vol. IV, pt. 1 (1889), pp. 1—88, pls. 4 (owt of print). ” ” » » 99 2 (1891), pp. 89—242, pls. 8 (out of print). (Ser. XV.)}—HIMALAYAN FOSSILS. Upper-triassic and liassic faune of the exotic blocks of Malla Johar in the Bhot Mahals of | Kumaon : Vol. I, pt. 1 (1908), pp. 100, pls. 16 (1 double), by Dr. C. Diener. ee Fossils of Kashmir and Spiti: Vol. 1, pt. 2 (1899), pp. 96, pls. 8, by Dr. C. iener. ° The Permocarboniferous Fauna of Chitichum No. I: Vol. I, pt. 3 (1897), pp. 105, pls. 13, Dr. C. Diener. : The Permian Fossils of the Productus Shales of Kumaon and Garhwal: Vol. I, pt. 4 (1897), pp. 54, pls. 5, by Dr. C. Diener. The Permian Fossils of the Central Himalayas: Vol. I, pt. 5 (1903), pp. 204, pls. 10, by Dr. C. Diener. The Pe ene Sse of the Lower Trias: Vol. II, pt. 1 (1897), pp. 182, pls. 23, by Dr. C. iener. The ee arene of the Muschelkalk : Vol. II, pt. 2 (1895), pp. 118, pls. 31, by Dr. C. iener. Upper Triassic Cephalopoda Faune of the Himalaya: Vol. III, pt. 1 (1899), pp. 157, pls. 22, by Dr. E. von Mojsisovics. Trias Brachiopoda and Lamellibranchiata ; Vol. III, pt. 2 (1899), pp. 76, pls. 12 (2 double), by Alexander Bittner. : The Fauna of the Spiti Shales : Cephalopoda : Vol. IV, Pt. 1, Fasc. 1 (1903), pp. 142, pls. 18; Fasc. 2 (1910), pp. 133—306, pls. 47 (2 double); Fasc. 3 (1910), pp. 307—395, pls. 38, by Dr. V. Uhlig; Lamellibranchiata and Gastropoda : Pt. IT, Fasc. 4 (1913), pp. 397— 456, pls. 7, by Dr. K. Holdhaus; Additional Notes on the Fauna of the Spiti Shales : Pt. II, Fasc. 5, by Miss Paula Steiger, Ph.D. (in the Press). The Fauna of the Tropites-Limestone of Byans: Vol. V, Memoir No. 1 (1906), pp. 201, pls. 17 (1 double), by Dr. C. Diener. The Fauna of the Himalayan Muschelkalk : Vol. V, Memoir No. 2 (1907), pp. 140, pls. 17 (2 double), by Dr. C. Diener. Ladinic, Carnie and Noric faune of Spiti: Vol. V, Memoir No. 3 (1908), pp. 157, pls. 24 (3 double), by Dr. C. Diener. 5 Lower Triassic Cephalopoda from Spiti, Malla, Johar and Byans : Vol. VI, Memoir No. 1 (1909}, pp. 186, pls. 31, by Drs. A. von Krafteand C. Diener. The Fauna of the Traumatocrinus Limestone of Painkhanda. Vol. VI, Memoir No. 2 (1909), pp. 39, pls. -5, by Dr. C. Diener. The etiiees: Fossils of Spiti: Vol. VII, Memoir No. 1 (1910), pp. 70, pls. 6, by F. R. C. eed. Ordovician and Silurian fossils from the Central Himalayas: Vol. VII, Memoir No. 2 (1912), pp. 168, pls. 20, by F. R. C. Reed. / (Ser. XVI.)—BALUCHISTAN FOSSILS, by FRITZ NOETLING, Px.D., F.G.S. The Fauna of the Kellaways of Mazdr Drik : Vol. I, pt. 1 (1895), pp. 22, pls. 13. The Fauna of the (Neocomian) Belemnite Beds: Vol. I, pt. 2 (1897), pp. 6, pls. 2. The Fauna of the Upper Cretaceous (Maéstrichtien) Beds of the Mari Hills: Vol. I, pt. 3 (1897), pp. 79, pls. 23. (NEW SERIES.) The Cambrian Fauna of the Eastern Salt-range : Vol. I, Memoir 1 (1899), pp. 14, pls. 1, by K. Redlich. é Notes on the Morphology of the Pelecypoda : Vol. I, Memoir 2 (1899), pp. 58, pls. 4, by Fritz Noetling. é : Fauna of the Miocene Beds of Burma: Vol. I, Memoir 3 (1901), pp. 378, pls. 25, by "Fritz Noetling (out of print). Observations sur quelques Plantes Fossiles des Lower Gondwanas: Vol. II, Memoir 1 (1902), pp. 39, pls. 7, hy R. Zeiller (out of print), 5 a ~ Permo-Carboniferous Plants and Vertebrates from Kashmir: Vol. II, Memoir No. 2 1905), pp. 13, pls. 2, by A. C. Seward and A. Smith Woodward. The ower Paleozoic Fossils of the Northern Shan States, Upper Burma: Vol. II, Memoir o. 3 (1906), pp. 154, pls. 8, by F. R. C. Reed. The Fauna of the Napeng Beds or the Rhetic Beds of Upper Burma: Vol. II, Memoir No. 4 (1908), pp. 88, pls. 9, by Miss M. Healey. ‘The Devonian Faunas of the Northern Shan States : Vol. Il, Memoir No. 5 (1908), pp. 183, pls. 20, by F. R. C. Reed. : ‘he Mollusca of the Ranikot Series : Vol. III, Part 1, Memoir No. 1 (1909), pp. xiv, 83 gis. 8, by M. Cossmann and G. Pissarro. Introduction by E. W. Vredenburg. On some Fish-remains from the Beds at Dongargaon Central Provinces : Vol. III, Memoir No. 3 (1908), pp. 6, pl. 1, by A. Smith Woodward. Anthracolithic Fossils of the Shan States: Vol. III, Memoir No. 4 (1911), pp. 74, pls. 7, by C. Diener. The Seat Giraffide of India: Vol. IV, Memoir No. 1 (1911), pp. 29, pls. 5, by Dr. G. E. ilgrim. . The Vertebrate Fauna of the Gaj Series in the Bugti Hills and the Punjab: Vol. IV, Memoir No. 2, 1912, Pp. 83, pls. 30, and 1 map, by G. E. Pilgrim. Lower Gondwana Plants from the Golabgarh Pass, Kashmir: Vol. 1V, Memoir No. 3 (1912), pp. 10, pls. 3, by A. 0. Seward. Mesozoic Plans from Afghanistan and Afghan-Turkistan : Vol. IV, Memoir No. 4 (1912), pp. 57, pls. 7,-by A. C. Seward. ; eae Faune of Kashmir: Vol. V, Memoir No. 1 (1913), pp. 133, pls. 13, by Dr. C. iener. ? The price fixed for these publications is four annas (4 pence) per single plate, with a minimum charge of Re. 1. RECOKDS OF THE GEOLOGICAL SURVEY OF INDIA. Vout. I, 1868. Part 1 (out of print).—Annual report for 1867. Coal-seams of Tawa valley. Coal in Garrow Hills. Copper in Bundelkund. Meteorites. . Part 2 (out of print).—Coal-seams of neighbourhood of Chanda. Coal near Nagpur. Geo- logical notes on Surat collectorate. Cephalopodous fauna of South Indian cretaceous deposits. Lead in Raipur district. Coal in Eastern Hemisphere. Meteorites. Part 3 (out of print).—Gastropodous fauna of South Indian cretaceous deposits. Notes on route from Poona to Nagpur vid Ahmednuggur, Jalna, Loonar, Yeotmahal, Mangali and Hingunghat. Agate-flake in pliocene (?) deposits of Upper Godavery. Boundary of Vindhyan series in Rajputana. Meteorites. Vor. II, 1869. Part 1 (out of print).—Valley of Poorna river, West Berar. Kuddapah and Kurnool formations. Geological sketch of Shillong plateau. Gold in Singhbhoom, etc. Wells at Hazareebagh. Meteorites. Part 2.—Annual report for 1868. Pangshura tecta and other species of Chelonia from newer tertiary deposits of Nerbudda valley. Metamorphic rocks of Bengal. ce Bey of Kuch, Western India. Geology and physical geography of Nicobar slands. Part 4 (out of print).—Beds containing silicified wood in Eastern Prome, British Burma. Mineralogical statistics of Kumaon division. Coal-field near Chanda. Lead in Raipur district. Meteorites. Vou. III, 1870. Part 1 (out of print).—Annual report for 1869. Geology of neighbourhood of Madras. Alluvial deposits of Irrawadi, contrasted with those of Ganges. Part 2 (out of print).—Geology of Gwalior and vicinity. Slates at Chiteli, -Kumaon. Lead vein near Chicholi, Raipur district. Wardha river coal-fields, Berar and Cen- tral Provinces. Coal at Karba in Bilaspur district. Part 3 (out of print).—Mohpani coal-field. Lead-ore at Slimanabad, Jabalpur district. Coal east of Chhattisgarh between Bilaspur and Ranchi. Petroleum in Burma. Petro- leum locality of Sudkal, near Futtijung, ‘west of Rawalpindi. Argentiferous galena and copper in Manbhum. Assays of iron ores. Part 4 (out of print).—Geology of Mount Tilla, Punjab. Copper deposits of Dalbhum and Singbhum : 1.—Copper mines of Singbhum ; 2.—Copper of Dalbhum and Sing- bhum. Meteorites. Vou. IV, 1871. Part 1.—Annual report for 1870. Alleged discovery of coal near Gooty, and of indications of coal in Cuddapah district. Mineral statistics of Kumaor division. Part 2.—Axial group in Western Prome. Geological structure of Southern Konkan. Supposed occurrence of native antimony in the Straits Settlements. Deposit in boilers of steam-engines at Raniganj. Plant-bearing sandstones of Godavari valley, on south- ern extensions of Kamthi group to neighbourhood of Ellore and Rajamandri, and on possible occurrence of coal in same direction. Part 3 (out of print).—Boring for coal in Godavari valley near Dumaguden and Bhadra- chalam. Narbada coal-basin. Geology of Central Provinces. Plant-bearing sand- stones of Godavari valley. Part 4 (out of print).—Ammonite fauna of Kutch. Raigur and Hengir (Gangpur) Coal- field. Sandstones in neighbourhood of first barrier on Godavari, and in country between Godavari and Ellore. f no Vou. V, 1872. Part 1.—Annual report for 1871. Relations of rocks near Murree (Mari), Punjab. Mineral- ogical notes on gneiss of South Mirzapur and adjoining country. Sandstones in neighbourhood of first barrier on Godavari, and in country between Godavari and Ellore. Part 2 (out of print).—Coasts of Baluchistan and Persia from Karachi to head of Persian Gulf, and some of Gulf Islands. Parts of Kummummet and Hanamconda districts in Nizam’s Dominions. Geology of Orissa. New coal-field in south-eastern Hyderabad -(Deccan) territory. area Part 3.—Maskat mg Massandim on east coast of Arabia. Example of local jointing. Axial group of Western Prome. Geology of Bombay Presidency. Part 4.—Coal in northern region of Satpura basin. Evidence afforded by raised oyster banks on coasts of India, in estimating amount of elevation indicated thereby. Possible field of coal-measures in Godavari district, Madras Presidency. Lameta or intratrappean formation of Central India. Petroleum localities in Pegu. Supposed eozoonal Timastotis of Yellam Bile. Vor. VI, 1873. Part 1.—Annual report for 1872. Geology of North-West Provinces. Part 2.—Bisrampur coal-field. Mineralogical notes on gneiss of south Mirzapur and ad. joining country. 7 Part 3 (out of print).—Celt in ossiferous deposits of Narbada valley (Pliocene of Falconer) : on age of deposits, and on associated shells. Barakars (coal-measures) in Beddadanole field, Godavari district. Geology of parts of Upper Punjab. Coal in India. Salt- springs of Pegu. Part 4 (out of print).—Iron deposits of Chanda (Central Provinces). Barren Islands and Narkondam. Metalliferous resources of British Burma. Vou. VII, 1874. Part 1 (out Z print).—Annual report for 1873. Hill ranges between Indus valley in Ladak and Shah-i-Dula on frontier of Yarkand territory. Iron ores of Kumaon. Raw materials for iron-smelting in Raniganj field. Elastic sandstone, or so-called Itaco- _ lumyte. Geological notes on part of Northern Hazaribagh. Part 2 (out of print).—Geological notes on route traversed by Yarkand Embassy from Shah-i-Dula to Yarkand and Kashgar. Jade in Karakas valley, Turkistan. Notes from Eastern Himalaya. Petroleum in Assam.* Coal in Garo Hills. Copper in Narbada valley. Potash-salt from East India. Geology of neighbourhood of Mari hill station in Punjab. Part 3 (out of print).—Geological observations made on a visit to Chaderkul, Thian Shan range. Former extension of glaciers within Kangra district. Building and orna- mental stones of India. Materials for iron manufacture in Raniganj coal-field. Manganese-ore in Wardha coal-field. Part 4 (out of print).—Auriferous rocks of Dhambal hills, Dharwar district. Antiquity of human race in India. Coal recently discovered in the country of Luni Pathans, south-east corner of Afghanistan. Progress of geological investigation in Godavari district, Madras Presidency. Subsidiary materials for artificial fuel. Von. VIII, 1875. Part 1 (out of print).—Annual report for 1874. The Altum-Artush considered from geo- _ logical point of view. Evidences of ‘ ground-ice’ in tropical India, during Talchir period. Trials of Raniganj fire-bricks. Part 2 (out of rint),— Part 3 (out of print).—Gold industry in Wynaad. Upper Gondwana series in Trichinopoly and Nellore-Kistna districts. Senarmontite from Sarawak.. Part 4.—Geological distribution of fossil organisms in India. Snbmerged forest on Bombay Island. < . 8 Vou. XII, 1879. Part 1.—Annual report for 1878. Geology of Kashmir (third notice). Siwalik mammalia. Siwalik birds. Tour through Hangrang and Spiti. Mud eruption in Ramri Island (Arakan). Braunite, with Rhodonite, from Nagpur, Central Provinces. Palwontologi- cal notes from Satpura coal-basin. Coal importations into India. Part 2.—Mohpani coal-field. Pyrolusite with Psilomelane at Gosalpur, Jabalpur district. Geological reconnaissance from Indus at Kushalgarh to Kurram at Thal on Afghan frontier. Geology of Upper Punjab. ° Part 3.—Geological features of northern Madura, Pudukota State, and southern parts of Tanjore and Trichinopoly districts included within limits of sheet 80 of Indian Atlas. Cretaceous fossils from Trichinopoly district, collected in 1877-78. Sphenophyllum and other Equisetacee with reference to Indian form Trizygia Speciosa, Royle (Spheno- phyllum Trizygia, Ung.). Mysorin and Atacamite from Nellore district. © Corundum from Khasi Hills. Joga neighbourhood and old mines on Nerbudda. Part 4.—‘ Attock Slates ’ and their probable geological position. Marginal bone of unde- scribed tortoise, from Upper Siwaliks, near Nila, in Potwar, Punjab. Geology of North Arcot district. Road section from Murree to Abbottabad. Vou. XIII, 1880. Part 1.—Annual report for 1879. Geology of Upper Godavari basin in neighbourhood of Sironcha. Geology of Ladak and neighbouring districts. ‘Teeth of fossil fishes from Ramri Island and Punjab. Fossil genera Noggerathia, Stbg., Néggeratliopsis, Fstm., and Rhiptozamites, Schmalh., in paleozoic and secondary rocks of Europe, Asia, and Australia. Fossil plants from’ Kattywar, Shekh Budin, and Sirgujah. Volcanic foci ' of eruption in Konkan. Part 2.—Geological notes. Palwontological notes on lower trias of Himalayas. Artesian wells at Pondicherry, and possibility of finding sources of water-supply at Madras. Part 3.—Kumaun lakes. Celt of paleolithic type in Punjab. Palwontological notes from Karharbari and South Rewa coal-fields. Correlation of Gondwana flora with other floras. Artesian wells at Pondicherry. Salt in Rajputana. Gas and mud eruptions on Arakan coast on 12th March 1879 and in June 1843. Part 4.—Pleistocene deposits of Northern Punjab, and evidence they afford of extreme climate during portion of that period. Usetul minerals of Arvali region. Correlation of Gondwana flora with that of Australian coal-bearing system. Reh or alkali soils =o ae well waters. Reh soils of Upper India. Naini Tal landslip, 18th Septem. er Vou. XIV, 1881. Part 1 (out of print).—Annual report for 1880. Geology of part of Dardistan, Baltistan, and neighbouring districts. Siwalik carnivora. Siwalik group of Sub-Himalayan region. South Rewah Gondwana basin. Ferruginous beds associated with basaltic rocks of north-eastern Ulster, in relation to Indian Jaterite. NRajmahal plants. Travelled blocks of the Punjab. Appendix to ‘ Paleontological notes on lower trias of Himalayas.” Mammalian fossils from Perim Island. Part 2.—Nahan-Siwalik unconformity in North-Western Himalaya. Gondwana _verte- brates. Ossiferous beds of Hundes in Tibet. Mining records ind mining record office _ of Great Britain; and Coal and Metalliferous Mines Acts of 1872 (England). Cobaltite and danaite from Khetri mines, Rajputana; with remarks on Jaipurite (Syepoorite). Zinc-ore (Smithsonite and Blende) with barytes in Karnul district, Madras. Mud eruption in island of Cheduba. Part 3.—Artesian borings in India. Oligoclase granite at Wangtu on Sutlej, North-West Himalayas. Fish-plate from Siwaliks. Paleontological notes from Hazaribagh and Lohardagga districts. Fossil carnivora from Siwalik hills. Part 4.—Unification of geological nomenclature and cartography. Geology of Arvalt region, central and eastern. Native antimony obtained at Pulo Obin, near Singapore. Turgite from Juggiapett, Kistnah district,-and_ zinc carbonate from iXarnul, Madras. Section from Dalhousie to Pangi, vid Sach Pass. South Rewah Gondwana basin. Submerged forest on Bombay Island. Vou. XV, 1882. Part 1 (out of print).—Annual report for 1881. Geology of North-West Kashmir and Khagan. Gondwana labyrinthodonts. Siwalik and Jamna mammals. Geology of Dalhousie, North-West Himalaya. Palm leaves from (tertiary) Mutree and Kasauli beds in India. Iridosmine from Noa-Dihing river, 6 ae Assam, and Platinum from Chutia Nagpur. On (1) copper mine near Yongri hill, Darjiling district ; (2) arsenical pyrites in same neighbourhood ; (3) kaolin at Darjiling. Analyses of coal and fire-clay from Makum coal-field, Upper Assam. Experiments on coal of Pind Dadun Khan, Salt-range, with reference to production of gas, made April 25th, 1881. Proceedings of International Congress of Bologna. Part 2 (out of print).—Geology of Travancore State. Warkilli beds and reported asso- ciated deposits at Quilon, in Travancore. Siwalik and Narbada fossils. Coal-bearing rocks. of 5 per Rer and Mand rivers in Western Chutia Nagpur. Pench river coal- field in Ohhmdrars district, Central Provinces. Borings for coal at Engsein, British Burma. Sapphires in North-Western Himalaya. Eruption of mud volcanoes in Cheduba. Part 8 (out of print).—Coal of Mach (Much) in Bolan Pass, and of Sharigh on Harnai route between Sibi and Quetta. Crystals of stilbite from Western Ghats, Bombay. Traps of Darang and Mandi in North-Western Himalayas. Connexion between Hazara and Kashmir series. Umaria coal-field (South Rewah Gondwana_basin). Daranggiri coal-field, Garo Hills, Assam. Coal in Myanoung division, He & district. 9 Part 4 (out of print).—Gold-fields of Mysore. Borings for coal at Beddadanol, Godavart district, in 1874. Supposed occurrence of coal on Kistna. Vou. XVI, 1883. Part 1.—Annual report for 1882. Richthofenia. Kays (Anomia Lawrenciana, Koninck). Geology of South Travancore. Geology of Chamba. Basalts of Bombay. Part 2 (out of print).—Synopsis of fossil vertebrata of India. Bijori iatiibttiod ant Skull of Hippotherium antilopinum. Iron ores, and subsidiary materials for manu- facture of iron, in north-eastern part of Jabalpur district. Laterite and other manga- nese-ore occurring at Gosulpore, Jabalpur district. Umaria coal-field. Part 8.—Microscopic structure of some Dalhousie rocks. Lavas of Aden. Probable occur- rence gf Siwalik strata in China and Japan. Mastodon angustidens in India. Traverse » between Almora and Mussooree. ' Cretaceous coal-measures at Borsora, in Khasia Hills, near Laour, in Sylhet. Part 4.—Paleontological notes from Daltonganj and Hutar coal-fields in Chota Nagpur. Altered basalts of Dalhousie region in North-Western Himalayas. Microscopic struc- ture of some Sub-Himalayan rocks of tertiary age. Geology of Jaunsar and Lower Himalayas. Traverse through Eastern Khasia, Jaintia, and North Cachar Hills. Native lead from Maulmain and chromite from the Andaman Islands. Fiery eruption from one of mud volcanoes of Cheduba Island, Arakan. Irrigation from wells in North-Western Provinces and Oudh. ; Vou. XVII, 1884. Part 1.—Annual report for 1883. Smooth-water anchorages or mud-banks of Narrakal and Alleppy on Travancore coast. Billa Surgam and other caves in Kurnool district. Geology of Chauari and Sihunta parganas of Chamba. Lyttonia, Waagen, in Kuling series of Kashmir. oe Part 2.—Earthquake of 3lst December 1881. Microscopic structure of some Himalayan granites and gneissose granites. Choi coal exploration. Re-discovery of fossils in Siwalik beds. Mineral resources of Andaman Islands in neighbourhood of Port Blair. Intertrappean beds in Deccan and Laramie group in Western North America. Part 3 (out of print).—Microscopic structure of some Arvyali rocks. Section along Indus from Peshawar Valley to Salt-range. Sites for boring in Raigarh-Hingir coal-field (first notice). Lignite near Rajpore, Central Provinces. Turquoise mines of NishApar, Khorassan. Fiery eruption from Minbyin mud Volcano of Cheduba Island, Arakan. Langrin coal-field, South-Western Khasia Hills. Umaria coal-field. Part 4.—Geology of part of Gangasulan pargana of British Garhwal. Slates and schists imbedded in gneissose granite of North-West Himalayas. Geology of Takht-i-Sulei- man. Smooth-water anchorages of Travancore coast. Auriferous sands of the Suban- siri river, Pondicherry lignite, and phosphatic rocks at Musuri. Billa Surgam caves. Vou. XVIII, 1885. Part 1 (out of print).—Annual report for 1884. Country between Singareni coal-field and Kistna river. Geological sketch of country between Singareni coal-field and Hydera- bad. Coal and limestone in Doigrung river near Golaghat, Assam. Homotaxis, as illustrated from Indian formations. Afghan field notes, Part 2.—¥ossiliferous series in Lower Himalaya, Garhwal. Age of Mandhali series in Lower Himalaya. Siwalik camel (Camelus Antiquus, nobis ex Fale. and Caut. MS.), Geology of Chamba. Probability of ge water by means of artesian wells in ee of Upper India. Artesian sources in plains of Upper India. Geology of. Aka ills. Alleged tendency of Arakan mud volcanoes to burst into eruption most , frequently during rains. Analyses of phosphatic nodules and rock from Mussooree. Part 3.—Geology of Andaman Islands, Third species of Merycopotamus. Percolation as affected by current. Pirthalla and Chandpur meteorites. Oil-wells and coal in> Thayetmyo district, British Burma. Antimony deposits in Maulmain district. Kash-~ mir earthquake of 30th May 1885. Bengal earthquake of 14th July 1885. Part 4.—Geological work in Chhattisgarh division of Central Provinces. Bengal earth- quake of 14th July 1885. Kashmir earthquake of 30th May 1888. Excavations in Billa Surgam caves. Nepaulite. Sabetmahet meteorite. Von. XIX, 1886. Part 1.—Annual report for 1885. International Geological Congress of Berlin. Paleozoic Fossils of Olive group of Salt-range. Correlation of Indian and Australian coal- bearing beds. Afghan and Persian Field-notes. Section from Simla to Wangtu, and petrological character of Amphibolites and Quartz Diorites of Sutlej valley. Part 2 (out of print).—Geology of parts of Bellary and Anantapur districts. Geology of Upper Dehing basin in Singpho Hills. Microscopic characters of eruptive rocks from Central Himalayas. Mammalia of Karnul Caves. Prospects of finding coal in Western Rajputana. Olive group of Salt-range. Boulder-bed of Salt-range. Gond- _ wana Homotaxis. Part 3 (out of print).—Geological sketch of Vizagapatam district, Madras. Geology of Northern Jesalmer. Microscopic structure of Matlani rocks of Arvali region. Malanj- khandi copper-ore in Balaghat district, C. P. Part 4 (out of print).—Petroleum in India. Petroleum exploration at Khaétan. Boring in Chhattisgarh coal-fields. Field-notes from Afghanistan: No. 3, Turkistan, Fiery eruption from one of mud voleanoés of Cheduba Island, Arakan. Nammianthal - erolite. Analysis of gold dust from Meza valley, Upper Burma. Von. XX, 1887. Part 1.—Annual report for 1886. Field-notes from Afghanistan : No. 4, from Turkistan to India. Physical geology of West British Garhwal; with notes on a route traversed 10 through Jaunsar-Bawar and Tiri-Garhwal. Geology of Garo Hills. Indian image- stones. Soundings recently taken off Barren Island and Narcondam. ‘Talchir boulder- beds. Analysis of Phosphatic Nodules from Salt-range, Punjab. Part 2.—Fossil vertebrata of India. Echinoidea of cretaceous series of Lower Narbada Valley. . Field-notes : No. 5—to accompany geological sketch map of Afghanistan and North-Eastern Khorassan. Microscopic structure of Rajmahal and Deccan traps. Dolerite of Chor. Identity of Olive series in east with speckled sandstone in west of. Salt-range in Punjab. Part 3.—Retirement of Mr. Medlicott, J. B. Mushketoff’s Geology of Russian Turkistan. Crystalline and metamorphic rocks of Lower Himalaya, Garhwal, and Kumaun, Sec- tion I. Geology of Simla and Jutogh. ‘ Lalitpur’ meteorite. Part 4 (out of Fade .—Points in Himalayan geology. Crystalline and metamorphic rocks of Lower Himalaya, Garhwal, and Kumaon, Section II. Iron industry of western portion of Raipur. Notes on Upper Burma. Boring exploration in Chattisgarh coal- fields. (Second notice). Pressure Metamorphism, with reference to foliation of Himalayan Gneissose Granite. Papers on Himalayan Geology and Microscopic Petrology. | Vout. XXI, 1888. e Part 1.—Annual report for 1887. Crystalline and metamorphic rocks of Lower Himalaya, Garhwal, and Kumaun, Section III. Birds’-nest of thechant Island, Mergui Archi- pelago. Exploration of Jessalmer, with a view to discovery of coal. Facetted pebble from boulder bed (‘ speckled sandstone’) of Mount Chel in Salt-range, Punjab. Nodular stones obtained off Colombo. Part 2?.—Award of Wollaston Gold Medal, Geological Society of London, 1888. Dharwar System in South India. Igneous rocks of Raipur and Balaghat, Central Provinces. Sangar Marg and Mohowgale coal-fields, Kashmir. : Part 3 (out of print).—Manganese Iron and Manganese Oves of Jabalpur. ‘ The Carboni- ferous Glacial Period.’ Pre-tertiary sedimentary formations of Simla region of Lower Himalayas. Part 4 (out of print).—Indian fossil vertebrates. Geology of North-West Himalayas. oe rock sculpture. Nummulites in Zanskar. Mica traps from Barakar and aniganj. Vor. XXII, 1889. Part 1 (out of print).—Annual report for 1888. Dharwar System in South India. Wajra Karur diamonds, and M. Chaper’s alleged discovery of diamonds in pegmatite. Generic position of so-called Plesiosaurus Parone Flexible sandstone or Itacolumite, its nature, mode of occurrence in India, and cause of its flexibility. Siwalik and Narbada Chelonia. Part 2 (out of print).—Indian Steatite. Distorted pebbles in Siwalik conglomerate. ‘** Carboniferous Glacial Period.’’ Notes on Dr. W. Waagen’s ‘‘ Carboniferous Glacial Period.” Oil-fields of Twingoung and Beme, Burma. Gypsum of Nehal Nadi, Kumaun. Materials for Lae in neighbourhood of Jabalpur and Umaria. Part 3 (out of print).—Coal outcrops in Sharigh Valley, Baluchistan. ‘Trilobites in Neobolus beds of Salt-range. Geological notes. Cherra Poonjee coal-field, in Khasis ‘Hills. Cobaltiferous Matt from Nepal. President of Geological Society of London on International Geological Congress of 1888. ee in Mergui district. Part 4 (out of print).—Land-tortoises of Siwaliks. Pelvis of a ruminant from Siwaliks. Assays from Sambhar Salt-Lake in Rajputana. Manganiferous iron and Manganese Ores of Jabalpur. Palagonite-bearing ae of Rajmahal hills and Deccan. Tin- smelting in Malay Peninsula. Provisional Index of Local Distribution of Important Msnerals; Miscellaneous Minerals, Gem Stones and Quarry Stones in Indian Empire. Part 1. Vou. XXIII, 1890. Part 7.—Annual report for 1889. Lakadong coal-fields, Jaintia Hills. Pectoral and pelvic irdles and skull of Indian Dicynodonts. Vertebrate remains from Nagpur district with description of fish-skull). Crystalline and metamorphic rocks of Lower Hima- layas. Garhwdél and Kumaon, Section IV. Bivalves of Oliye-group, Salt-range Mud- banks of Travancore coasts. Part 2 (out of print).—Petroleum explorations in Harnai district, Baluchistan. Sapphire: Mines of Kashmir. Supposed Matrix of Diamond at Wajra Karur, Madras. Sonapet Gold-field. Field notes from Shan Hills (Upper Burma). New species of Syring- ospheride. rs Part 3 (out of print).—Geology and Economic Resources of Country adjoining Sind-Pishin Railway between Sharigh and Spintangi, and of country between it and Khattan. Journey through India in 1888-89, by Dr. Johannes Walther. Coal-fields of Lairungao, Maosandram, and Mao-be-lar-kar, in the Khasi Hills. Indian Steatite. Provisional Index of Local Distribution of Important Minerals, Miscellaneous Minerals, Gem Stones, and Quarry Stones in Indian Empire. : Part 4 (out of print).—Geological sketch of Naini Tal; with remarks on natural conditions governing mountain slopes. Fossil Indian Bird Bones. Darjiling Coal between Lisu and Ramthi rivers. Basic Eruptive Rocks of Kadapah Area. Deep Boring at Luck- now. Coal Seam of Dore Ravine, Hazara. } Vor. XXIV, 1891. Part 1.—Annual report for 1890. Geology of Salt-range of Punjab, with re-considered theory of Origin and Age of Salt-Marl. Graphite in decomposed Gneiss (Laterite) im Ceylon. Glaciers of Kabru, Pandim, etc. Salts of Sambhar Lake in Rajputana, and _€ Reh.’ from Aligarh in North-Western Provinces. Analysis of Dolomite from Salt-- range, Punjab. 11 Part 2,—Oil near Moghal Kot, in Sherani country, Suleiman Hills. Mineral Oil from Suleiman Hills. Geology of Lushai Hills. Coal-fields in Northern Shan States. Reported Namséka Ruby-mines in Mainglén State. Tourmaline (Schorl) Mines in Mainglén State.—Salt-spring near Bawgyo, Thibaw State. Part 3 (out of print).—Boring in Daltongunj Coal-field, Palamow, Death of Dr. P. Martin Duncan. Pyroxenic varieties of Gneiss and Scapolite-bearing Rocks. Part 4.—Mammalian Bones from Mongolia. Darjiling Coal Exploration. Geology and Mineral Resources of Sikkim. Rocks from the Salt-range, Punjab. Vou. XXV, 1892. Part 1.—Annual report for 1891. Geology of Thal Chotiéli and part of Mari country. Petrological Notes on Boulder-bed of Salt-range, Punjab. Sub-recent and Recent Deposits of valley plains of Quetta, Pishin, and Dasht-i-Bedalot; with appendices on Chamans of Quetta; and Artesian water-supply of Quetta and Pishin. Part 2 (out of print).—Geology of Saféd Kéh. Jherria Coal-field. -Part 3.—Locality of Indian Tscheffkinite. Geological Sketch of country north of Bhamo. : Economic resources of Amber and Jade mines area in Upper Burma. Iron-ores and Iron Industries of Salem District. Riebeckite in India. Coal on Great Tenasserim River, Lower Burma. Part 4.—Oil Springs at Moghal Kot in Shirani Hills. Mineral Oil from Suleiman Hills. New Amber-like Resin in Burma. Triassic Deposits of Salt-range. Vor. XXVI, 1893. Part 1.—Annual report for 1892. Central Himalayas. Jadeite in Upper Burma. Bur- mnie, per Fossil Resin from Upper Burma. Prospecting Operations, Mergui District, 1891-92. : Part 2 (out of print).-Earthquake in Baluchistan of 20th December 1892. Burmite, new amber-like fossil resin from Upper Burma. Alluvial deposits and Subterranean water- supply of Rangoon. Part 3 (out of print).—Geology of Sherani Hills, Carboniferous Fossils from Tenasserim. Boring at Chandernagore. Granite in Tavoy and Mergui. Part peolart of country between Chappar Rift and Harnai in Baluchistan, Geology of part of Tenasserim Valley with special reference to Tendau-Kamauping Coal-field. Magnetite containing Manganese ana Alumina. Hislopite. Vout. XXVII, 1894. Part 1.—Annual report for 1893. Bhaganwala Coal-field, Salt-range, Punjab. Part 2.—Petroleum from Burma. Singareni Coal-field, Hyderabad (Decean). Gohna Landslip, Garhwal. Part 3.—Cambrian Formation of Eastern Salt-range.. Giridih (Karharbari) Coal-fields. Chipped (?) Flints in Upper Miocene of Burma. Velates Schmideliana, Chemn., and Provelates grandis, Sow. sp., in Tertiary Formation of India and Burma. Part 4.—Geology of Wuntho in Upper Burma. Echinoids from Upper Cretaceous System of Baluchistén. Highly Phosphatic Mica Peridotites intrusive in Lower Gondwana Rocks of Bengal. Mica-Hypersthene-Hornblende-Peridotite in Bengal. Vou. XXVIII, 1895. Part 1.—Annual report for 1894. Cretaceous Formation of Pondicherry. Early allusion’ to Barren Island. Bibliography of Barren Island and Narcondam from 1884 to 1894. Part 2.—Cretaceous Rocks of Southern India and geographical conditions during later cretaceous times. Experimental Boring for Petroleum at Sukkur from October 1893 to March 1895. Tertiary system in Burma. Part 3.—Jadeite and other rocks, from Tammaw in Upper Burma. Geology of Tochi Valley. Lower Gondwanas in Argentina. Part 4.—Igneous Rocks of Giridih (Kurhurbaree} Coal-field and their Contact Effects. Vindhyan system south of Sone and their relation to so-called Lower Vindhyans. Lower Vindhyan area of Sone Valley. Tertiary system in Burma. —* Vor. XXIX, 1896. Part_1.—Annual report for 1895. Acicular inclusions in Indian Garnets. Origin and Growth of Garnets and of their Micropegmatitic intergrowths in Pyroxenic rocks. Part 2 (out of print).—Ultra-basic rocks and derived minerals of Chalk (Magnesite) hills, and other localities near Salem, Madras. Corundum localities in Salem and Coimbatore districts, Madras. Corundum and Kyanite in Manbhum district, Bengal. Ancient _ Geography of ‘‘ Gondwanaland.’’ Notes. Part 3.—Igneous Rocks from the Tochi Valley. Notes. Part 4.—Steatite mines, Minbu district, Burma. Lower Vindhyan (Sub-Kaimur) area of Sone Valley, Rewah. Notes. . Vou. XXX, 1897. Part 1.—Annual report for 1896. Norite and associated Basic Dykes and Lava-flows in Southern India. Genus Vertebraria. On Glossopteris and Vertebraria, Part 2.—Cretaceous Deposits of Pondicherri. Notes. Part 3.—Flow structure in igneous dyke. Olivine-norite dykes at Coonoor. Excavations for corundum near Palakod, Salem District. Occurrence of coal at Palana in Bikanir. Geological specimens collected by Afghan-Baluch Boundary Commission of 1896. - . Part 4.—Nemalite from Afghanistan. Beare arien rock in Salem district, Madras Presidency. Worn femur of Hippopotamus irravadicus, Caut, and Falc., from Lower Pliocene of Burma. Supposed coal at Jaintia, Baxa Duars. Percussion Figures on micas. Notes. 12 Vor. XXXI1, 1904. Part 1 (out of print).—Prefatory Notice. Copper-ore near Komai, Darjeeling ‘district, Zewan beds in Vihi district, Kashmir. Coal deposits of Isa Khel, Mianwali district, Punjab. Um-Rileng coal-beds, Assam. Sapphirine-bearing rock from Vizagapatam district. Miscellaneous Notes. Assays. ‘ Part 2 (out of print).—Lt.-Genl. C. A. McMahon. Cyclobus Haydeni Diener. Auriferous Occurrences of Chota Nagpur, Bengal. On the feasibility of introducing modern methods of Coke-making at East Indian Railway Collieries, with supplementary note by Director, Geological Survey of India. Miscellaneous Notes. Part 3 (out of rint).—Upper Palxozoic formations of Eurasia. Glaciation and History of Sind Valley. Halorites in Trias of Baluchistan. Geology and Mineral Resources of Mayurbhanj. Miscellaneous Notes. Part 4 (out of print).—Geology of Upper Assam. Auriferous Occurrences of Assam. Sram occurrence of Scapolite from Madras Presidency. Miscellaneous Notes. ndex. Vou. XXXII, 1905. Part 1 (out of print).—Review of Mineral Production of India during 1898—1903. Part 2 (out a print).—General report, April 1903 to December 1904. Geology of Pro- vinces of I'sang and U in Tibet. Bauxite in India. Miscellaneous Notes. Part 3 (out of print).—Anthracolithic Fauna from Subansiri Gorge, Assam. Elephas Antiquus (Namadicus) in Godavari Alluvium. ‘Triassic Fauna of Tropites-Limestone of Byans. Amblygonite in Kashmir. Miscellaneous Notes. Part 4.—Obituary notices of H. B. Medlicott and W. T. Blanford. Kangra Earthquake of 4th April 1905. Index to Volume XXXII. Von. XXXII, 1906. Part 1 (out of RAS Sag Production of India during 1904. Pleistocene Movement in Indian Peninsula. Recent Changes in Course of Nam-tu River, Northern Shan States. Natural Bridge in Gokteik Gorge. Geology and Mineral Resources of Narnaul Dis- trict (Patiala State). Miscellaneous Notes. Part 2 (out of print)—General report for 1905. Lashio Coal-field, Northern Shan States. Namma,~Mansang and Man-se-le Coal-fields, Northern Shan States, Burma. Mis- cellaneous Notes. Part 3 (out of print).—Petrology and Manganese-ore Deposits of Sausar Tahsil, Chhind- wara district, Central Provinces. Geology of part of valley of Kanhan River in Nagpur and Chhindwara districts, Central Provinces. Manganite from Sandur Hills. Miscellaneous Notes. Part 4 (out of print).—Composition and Quality of Indian Coals. Classification of the Vindhyan System. Geology of State of Panna with reference to the Diamond- bearing Deposits. Index to Volume XXXIIT. Vou. XXXIV, 1906. : Part 1.—¥Fossils from Halorites Limestone of Bambanag Cliff, Kumaon. Upper Triassic Fauna from Pishin District, Baluchistan. Geology of portion of Bhutan. Coal Occurrences in Foot-hills of Bhutan. Dandi Coal-field : Coal outcrops in Kotli Tehsil of Jammu State. Miscellaneous Notes. : é ae Part 2 (out of print),—Mineral Production of India during 1905. Nummulites Douvillei, with reat on Zonal Distribution of Indian Nummulites. Auriferous Tracts in Southern India. Abandonment of Collieries at Warora, Central Provinces. Mis- cellaneous Notes. ; ee SO Part 3 (out of print).—Explosion Craters in Lower Chindwin district, Burma. Lavas of Pavagad Hill. Gibbsite with Manganese-ore from Talevadi, Belgaum district, and Gibbsite from Bhekowli, Satar District. Clasgification of Tertiary system in Sind with reference to Zonal distribution of Eocene Hchinoidea. Part 4 (out of print).—Jaipur and Nazira Coal-fields, Upper Assam. Makum Coal-fields between Tirap and Namdang Streams. Kabat Anticline, near Seiktein, Myingyan district, Upper Burma. Asymmetry of Yenangyat-Singu Anticline, Upper Burma. Northern part of Gwegyo Anticline, Myingyan District, Upper Burma, Breynia Multituberculata, from Nari of Baluchistan and Sind. Index to Volume XXXIV. Vor. XXXV, 1907. Part 1 (out of print).—General report for 1906. Orthophragmina and Lepidocyclina in Nanamalitee eiee: Meteoric Shower of 22nd October 1903 at Dokachi and neighbour- hood, Dacca district. Part 2.—Indian Aerolites. Brine-wells at Bawgyo, Northern Shan States. Gold-bearin Deposits of Loi Twang, Shan States. Physa Prinsepii in Maestrichtian strata o Baluchistan. Miscellaneous Notes. : ; Part 3.—Preliminary survey of certain Glaciers in North-West Himalaya. A.—Notes on certain Glaciers in North-West Kashmir. _ : Part 4.—Preliminary survey of certain Glaciers in North-West Himalaya. B.—Notes on certain Glaciers in Lahaul. C.—Notes on certain Glaciers in Kumaon. Index to Volume XXXV. Vor. XXXVI, 1907-08. rt 1.—Petrological Study of Rocks from hill tracts, Vizagapatam district, Madras # Spivcatdonty: oNahbstine- Syenites from hill tracts. Vizagapatam district, Madras Presidency. Stratigraphical, Position of Gangamopteris Beds of Kashmir. | Volcanic outburst of Late Tertiary Age in South Hsenwi, N. Shan States. New suide from Bugti Hills, Baluchistan. Permo-Carboniferous Plants from Kashmir. 13 Part 2 (out of print).—Mineral Production of India during 1906. Ammonites of Bagh Beds. Miscellaneous Notes. : ay Part 3 (out of print).—Marine fossils in Yenangyaung oil-field, Upper Burma. Fresh- water shells of genus Batissa in Yenangyaung oil-field, Upper Burma. New Species of Dendrophyllia from Upper Miocene of Burma. Structure and age of Taungtha hills, Myingyan district, Upper Burma. Fossils from Sedimentary rocks of Oman (Arabia). Rubies in Kachin hills, Upper Burma. Cretaceous Orbitoides of India. Two Calcutta Earthquakes of 1906. Miscellaneous Notes. : : Pari 4.—Pseudo-Fucoids from Pab sandstones at Fort Munro, and from Vindhyan series. Jadeite in Kachin Hills, Upper Burma. Wetchok-Yedwet Pegu outcrop, Magwe dis- trict, Upper Burma. Group of Manganates, comprising Hollandite, Psilomelane and Coronadite. Occurrence of Wolfram in Nagpur district, Central Provinces. Mis- cellaneous Notes. Index to Volume XXXVI. . : Vor. XXXVII, 1908-09. Part 1 (out of print).—General report for 1907. Mineral Production of India during: 1907. Occurrence of striated boulders in Blaini formation of Simla. Miscellaneous Notes. Part 2 (out of print).—Tertiary and Post-Tertiary Freshwater Deposits of Baluchistan and Sind. Geology and Mineral Resources of Rajpipla State. Suitability of sands in Rajmahal Hills for glass manufacture. Three new Manganese-bearing minerals :— Vredenburgite, Sitaparite and Juddite. Laterites from Central Provinces. Miscella- neous Notes. ; SS Part 3 (out of print).—Southern part of Gwegyo Hills, including Payagyigon-Ngashan- daung Oil-field. Silver-lead mines of Bawdin, Northern Shan States. Mud volcanoes of Arakan Coast, Burma. : Part 4 (out of print)—Gypsum Deposits in Hamirpur district, United Provinces. Gond- - wanas and related marine sedimentary system of Kashmir. Miscellaneous Notes. Index to Volume XX XVII. Von. XXXVIII, 1909-10. Part 1 (out of print).—General report for 1908. Mineral Production of India during 1908. Part 2.—Ostrea latimarginata in Burma. China-clay and Fire-clay of Rajmahal Hills. Coal at Gilhurria. Pegu Inlier at Ondwe. Salt Deposits of Rajputana. Miscellaneous Notes. Part 3.—Geology of Sarawan, Jhalawan and Las Bela. Hippurite limestone in Seistan, Afghan Fusulinide. Miscellaneous Notes. Part 4.—Western Prome,and Kama. Recorrelation of Pegu system. Pegu fossil fish- teeth. Yenangyat Oil-field. Iron-ores of Chanda. Geology of Aden Hinterland. -Petrography of Aden Hinterland. Fossils from Aden Hinterland. Miscellaneous Notes. Index to Volume XXXVIII. Vor. XXXIX, 1910. Quinquennial Review. of Mineral Production for 1904 to 1908. Index to Volume XXXIX. Vor. XL, 1910. Part 1.—Pre-Carboniferous Life-Provinces. Lakes of the Salt Range. Glaciers in Sikkim. New Tertiary mammals. Part 2.—General Report of 1909. Mineral Production of India during 1909. Part 3.—Tertiary Freshwater Deposits of India. Silurian-Trias sequence in Kashmir. Fenestella beds in Kashmir. Part 4.—Alum Shale and. Alum Manufacture, Kflabagh, Mianwali district, Punjab. Coal- fields in North-Kastern Assam. Sedimentary Deposition of Oil. Miscellaneous Notes. Index to Volume XL. ; Vor. XLI, 1911-12. Part 1.—Age and continuation in Depth of Manganese-ores of Nagpur-Balaghat Area, Central Provinces. Manganese-ore deposits of Gangpur State, Bengal, and Distribu- tion of Gondite Series in pnaie: Baluchistan Earthquake of 2ist October 1909. Iden- tity of Ostrea Promensis from Pegu System of Burma and Ostrea Digitalina Eich- wald from Miocene of Europe. Mr. T. R. Blyth. Miscellaneous Notes. Part 2.—General Report for 1910. Devonian Fossils from Chitral, Persia, etc. Sections in Pir Panjal shia and Sind Valley, Kashmir. Part 3.—Mineral Production of India during 1910. Samarskite and other minerals in Nellore District, Madras Presidency. Coal in Namchik Valley, Upper Assam. Mis- cellaneous Notes. Part_4.—Pegu-Eocene Succession in Minbu District near Ngape. Geology of Henzada District, Burma. Geology of Lonar Lake, with note on Lonar Soda Deposit. Inter- national Geological Congress, Stockholm. Miscellaneous Notes. Index to Volume Fe Vor. XLII, 1912. Part 1.—Survival of Miocene Oyster in Recent Seas. Silurian Fossils from Kashmir. _ Blodite from Salt Range. Gold-bearing Deposits of Mong Long, Hsipaw State, Northern Shan States, Burma. Steatite Deposits. Idar State. Miscellaneous Notes. Part 2.—General Report for 1911. Dicotyledonous Leaves from Coal Measures of Assam. Poting Glacier, Kumaon, Himalaya, June 1911. Miscellaneous Notes. Part 3.—Mineral Production of India during 1911. Kodurite Series. Part Sgt ea Reconnaissance through Dihong Valley, being Geological Results of Abor Expedition, 1911-12. Traverse Across the Naga Hills of Assam. Indian Aéro- _ lites. Miscellaneous Notes. 14 Vout. XLIII, 1913. Part 1.—General Report for 1912. Garnet as a Geological Barometer. Wolframite in Tavoy District, Lower Burma. Miscellaneous Notes. Part 2.—Mineral Production of India during 1912. Relationship of the Himalaya to the Indo-Gangetic Plain and the Indian Peninsula. Hambergite from Kashmir. Part 3.—Contributions to the Geology of the Province of Yiinan in Western China. I. The Bhamo-Téng-Yiieh Area. II. Petrology of the Volcanic Rocks of the Téng-Yieh District. The Kirana Hills. The Banswal Aerolite. Part 4.—Gold-bearing Alluvium of the Chindwin River and Tributaries. Correlation of the Siwaliks with Mammal Horizons of Europe. Contributions to the Geology of the Province of Yiinnan in Western China. III. Stratigraphy of the Ordovician and Silurian Beds of Western Yimnan, with Provisional Paleontological Determinations. Further Notes on the species ‘“‘ Camarocrinus Asiaticus ’’ from Burma. Vou. XLIV, 1914. Part 1.—General Report for 1913. Carbonaceous Aérolite from Rajputana. Nummulites as Zone Fossils. Part 2.—Contributions to the Geology of the Province of Yiinnan in Western China: IV. Country around Yiinnan Fu. Dyke of White trap from Pench Valley Coalfield, Chhindwara District. Statement of Mineral Concessions granted during 1913. 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Buy. ; Geologicat Museum, Library, and Office, Calcutta, GEOLOGICAL SURVEY OF INDIA Memoirs, Vol. XLII, Pi. 12 eos te . Lighten Lake , / (Freeh water! ee | rely Chorbat P \ i nb ial ; 16693 \."~ \ a Goma} AHanw « J8560 “ . 2090 Sirigh Jilganang Lake | (Salt -watenSf >; \ * Dongri Pass \ fl Tsaggar Lake (Salt Le AVY pts j Chang feng Fass e Drds / dp 18910 — waitiribad Ae fi s} ae ta 18030 Salt , = : ion L nh — | | : —/ ABROMTABA A ‘. Ne Hatian % Sete yess a [beacell s es 2 ss #66 * ap Al a es Liiatag | ~~ 7 | deenbang v M : 0 as b open ito Aba: t age ‘ I a) ana « ee “SS Surphrar / > Bdltal © “he Tee I a oa BE * 20610 sai ie 22310 To Huping L, oe a weter)\ | K ~ »i8E8O —— WUSOB 17860 * ; S oY Sy Pat as. Tank se “ Pe ‘o Shushot 0129 Oo - brang Be, ee oa (Salt | Gomo Lake | 15500 Scare Pass x ete Aru Lt. isis a WIS a 2007F Denjor\Fas oe Ke x ~ Ve 7 —™ WA : <2 ae ; ———) . S ee op ee \ Sees CS | / ee Fit viet sab i 29972 ~~) : i ers / a for Kenxe f ald LS 18930 a : : Aaa Senate \, | eet Gane ae | . | a NN es | SS FP, . 3 syna is Fort (Ruis Kp ; i Tai Lake |(Fresh water} Thandak Ni nal C “sd 3 3 te | : : 2 . ~~ 2 aurgo \, ," oe ae : Lanchutso <> Giaa ° L ae" 7 . Near LS\.\ Near: aye, ued _— *Tsoby pe 0 © XY thas 4 Breha “4 2040 Yh, \ Nupuk: Ce \ 17190_9— Lang one i (J solu fo 0 wi Tashi Bhup Lake 392 p ew Re, wh Oe . mba © . a. ee me teases 3 ; aa | LungdurLake — Kyang Dieu: Chupyile ° "2" ari | : : : aS. garsido ‘Khoi B ‘ , . ike | ° e y 2405 th : & | © 75200 hen Sag Nabipa Lake & Chukan : : oe Shale-ehals—| Sheen w® Golan’ Peake. Thok Dourakpa ala | Fh aah ERIN MRSC Ee : _ | : : 7 wher f lscriaee : ‘ FZ ~ wae a ‘ \ Cli mae ne aang Oe See Ship ane Ghugti Posed Taste Michelin by a oe i Gobring guy dla tu gs “Har hie ‘pur ye Ae ‘Mandi f, fr pers s ING Pag . ae e aah FP Dablind v Op | Camp “\Tra-pe Paas LAyt- I i fea Danglon gon surndo SF id ; es . Rage NE; 255 “gee i : 2 eines t ; oe ALA ~ sien \ “ ce f ‘Banja ner | oes Firnits- che Paine | ~ Bi 7 Gartok (Garyyar-sa) —- Nganglaring Lake Chaklam Pass" fe aa “ok 1 at : ‘) 5 «dee ee Wil. : ‘ 1S&E77 15840 F > eo ) | Ren tik 2 f ono \ 7 | ’ res . ae a, aie Sag. sy A ort Pf £ : : erent i Whe ned , : : o Kot » N uf SER J heat onastery dD - ase ( Ea) Tang wim Lake Gravity stations. Ad. {Neehoanda A—Dhig "9GOne bat on Pe ie \1a338%" OS : 16400 20280 vr ee A se ik ng [Pe oy D es Chakri 4 ai eee es — Mites he a ce : 4 a H 4 e anole ake : ee oe e 5 Ate Ato aes wh okie oy Berehe ( eehea \ a a h at Ay pd Oe, W } Gy af on Mi ‘eee Hi -chung gNa-ga ; 7 15180 Miadlistig: Mainsiesy * : Sa f D Ns as a> oar i y ~ , 7 a — me \ . ogee J - \ / D * D $e. fine L € lo ee = “HIND RE | m aot = bet 4 op ‘4 _ aati VA c ; f “Chir ittia. or Mana oe Dy fm - 2 ae be b Trot -pur-ri My Kailas >. nly |p oe $ a ‘.\ eaba Keg: 7 Yanga ee amdar punch ' nae Os = e -Esor (° iJRe 4 [> z a Rap ; Se ° ° se : ° e Tian “> alts 3! hg ~“Pharhsch oy ot ee torah? Bee GangStri | \ — € 10008 =| ae tajcha kong V7 $ The complete series of stations in the Dehra-Dun region is shown on Plate 13 ashe ee | o ‘Vf Solus ra anid oor) 4 en, tice ) ; . f Bap chen My j Se SS % \ i; Ves ce 5 a {¢ 42012 \ i Sake hy ee Se / ‘our-re Pp |S Zee . 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A/G ae : * Bawa : Thakam Sankar" #9440 Mt Everest Makalu. a a \ 4 . Lis xLingshi fase "18354 Hopub SS . SHAHJAHANPU Kheri ) a a| i 3 r _ iagkt a , c Bi alfred VGentlamba == ess Ki 5.8 : go : es Cazewgad a ee & : ho Lak hum gth ar OSI > Olaz. 2 tJ. it ve “Seg dr (2. Fucloann , + gett : ) Nh 5 (au ] l qber ara : Gumehho “é PI fp) ong oO é ? o. ° : -¥ ~ r % 'e 3 = af fra;#rt z= a € ; Baka hug Pe tdrol . , Dudh 14300 galaxkhangys : > ae De ee. aa Sar é ae | Darra P Patharkot . ; fap yy ; 21240 ig PY She ret ; Pre re : RAICH hav A —~—/ : —s | . — s Gainsari | Sankarpur \ fig » Nagges \ Yatun AN t iy Trbeni f 4 POX oe = Kapur te gil RA KH ee re ot Sea : ia | wn — RU ABA D 7 : V/s os Lhithib ® Sy a «sets BS 2 tia di > eos : LA. ms att Fagyvea wt F i = arori a f — WENT TE Sree ke pease. ¢ gar Bithurleots fo~ TO te fas sphiong Deong ss tea a \ >) a [ oe cco warlas® ~~.) _\BhilnalThoree ce > YQ Te tharpur \ Tarka tT Miehd aid 3 SS 8 Kot. eral dhulk Garhi - Le = = Sa =< =e 3 ‘aan wha \ a ey ¢ E Sule tikchola\, Fase im : ae SSE Kapcha: etd : : \ eS " ‘ x2 { ee Pe € : —— = a ék3 = oo = pak tas £! Sead rauta ee Pate ~ ee cee Re Oo ‘\ =: } Vaharcy joa wKha \ 23° Pam agar ma bas sinks ew ane CH fe os . Cate S emra y, ? zs: \\aet t = ‘ \ e Hardiant Gha dh : Rast = : i ARS i\ A © a Sadulldhne peur / ophivanoat a Shag aha Momo ctenr aes \ Batia AE Janihesary oe = = Shiileds pur ; ° Ros QUdaxpur oeBrr atcha|* : a [NBiraans Khudra Lon, \ = = DH anaha\ INS Gaxoul sy bec e, fe = Baht funS / @ LPeppegan) Pa dave "AUIS ‘ AN Lauri NS 4 — "| == Ee : S Patnidarry : dake? i : \ ( \ airy IY wot ~~a™ ‘SE = , wt ; Q ye Chatra BAK : = = } = ‘ VA Paes / Bargaot™ ~ Vn parks . \ wagers as Z7 ; AS y S = 9 —_— e Khalil bad \ a Hf PUR y / ye r} : : Mec run Aw 2 oP Z By Fe 1S an > SES ; f Paray, = : i UR : er { 2G lof, hss = S PBI naurt a) \ Sa é ° \ 3 n ibs ot Bé nhiawas , iN Ka hakh p u rN : “Hat: aS pur Kanchanp ur ae ed | ., faria . upon \s ss 2 Rudarpur och Aghh haura® hake reper’ 1H cos > ae yy Ajgain a =F Ses ‘t Bt, s, “ur . . a ~ : 3 fo ns \ | = ee i : : : S 13 : 2 : fas el Vitada SS. Bansgaoh 4 peor 2 = mee ea = p ——— [| Gopalgay ys | © “iD at Ri Birhanr\. § \l = — “e oO” \ ahise = AGQnNarc ‘io = Me = : re) OTs Phulparas’ Var tLe - === = — J I taneany Vas (a | i = ~ Fe —> Gol: ee’ 1, ~ Ha awa Of Mi O07 Madhu ban 3 = Bhai ue ¢ [SS Mhranyfharp urn? = Jalal ur" A P<, a x -3 ‘ernaullia Bar thal ua Bas feeds rae Mattpur = ah ection ee 7 \ ic => eq D “ : a cA [> Keds F ! 7 MEPL Vas tr ! \ fee Pury” == z: aoe = ne Po I ; + = AZAMC AT 2 ubar EA ——— j = nt = Ss SS SS Se Nizam bak? fe : Mu awn padahad, “iM Shahdany 4 " Oem nN tf a eee mea S254 i fopgeany é [] fat 7 eee ae. oo VOJBELAS 3 7 eee han bauli Ra a dre. <= : 4 4 “aN, 4 E . Xx partes, Okholi ‘. >< herp gore oa jim Mad 5 Siken wl Pay Lanyjitperee : om es Se Mau aC ‘4 Ratsand SS f = ? ? é 22. By - ==. ‘ Oo { ~ SN NS ~~ SA AS ” Rasva Se A A | : = Soephyg Revelgayy A e . 5) \y ahuirdbad > LIA \. x 1 . oF > ‘PBansdibts . : SSS ier Sou fers a \ , cae i — Sia Aauit ih el a au Fama dit poe’ 72 A he = Saidpu, PQ ae Hat’ i aN a 4 = aA ] yu Ae py / = = \ Coldl é hi \ oA == ai Ke GaLane ° \ PA DVAUL A te 3 fin Ye aS = = eee Sane id Madhippird. Budham Ghat aharsa —S Hathgaon NT SS Qa ; ~ = ; x a Atif Se, A HOS = a a hy ie faulAinatiin, e aap ps. S me at $ i —_ ae; BM yndhe Peres p Raf date : &)) (a. I ee ae 2 ee ‘ re Eeohani a Sher (iy Gow Te abhaurags* * == = s Z Jaga o Se: —— ghee a snighgeyY f re. <5 vg lela ERA PTR 2 in fr 2 x = Z Sheildhp Phidpur eS ie Ee ae Be pos : i *! o* ; ; = ’ : < #: se *. = OP 0 a Manipur : = 3 WS Sas Gandns A ; Cr “ — ae, if a 2 io Warbte een) Srl ; ww 5 i sebrihdewat Ga nhuria ro ‘ : Fj x ; = — * : aii == ¢5 f ez, | 1s es : \. Jhajha Z a. oban Py atte Birk oa | SF R igauk Fareiys Se = as = , es - — ZY ie a Bargaon 2 jf : at a = : S ot lo Katatiria ee, areGlia® $ibe gery : Z ue f S, ) Sinn als \ P sant | y AS q i NS S ‘ : Mi 4 ‘ i ae : N aa , a® ; bj Shihdaced = ; a7 Akbarpured ji hog \ LALEE Tiatps * ma Gaurpara o vakeur = — ie 3 Z , st Re S.azigat & ; \ Chil A 2 é ae i Hi; a : oe vee f Stha wal De “se s® tone niet / SAEs " 19814 Chakai ne h nefarapat ‘gis ¥) A . en = Zs 5 A i ol ay Ee 3 , . ° X Qnelot # a, 1" P } A Fis wil . a = Ly oR Doranda * Fl Kendwa ; os = 3 e a J Godagari PUR BOALIA i ff “ o = i Phe, : ~RAM \ =H onal : : / ‘/Mulammad¢ I. ° ap me é > O ~glered geri Dhanwér Rare : : - iw, ~ ; ({ thi Larprus > | itr ; ) aay, \ Ar h z } f vs ae if Parlabpur ° “Bian oc oe Pare asabad. 4 a Se gh fis geeky Sha PRs 2, tne un \ / ‘ of “ar IN / 4 ‘ ‘ 2 S ind fl ee Pachake wg ea wv arshida ; bad | 4 i aly 0 : % \e . a, ba | Lalbay tad ce Pare { oo. ae eae Pd 7» a tharbart Tope Girid ib Ps ais va tye j 0G mel. \ Patan , U a % fadvidi } N PORE ee Aindgiyy” Badanpur { el A ek Chichals farmkitar { . { 1 ae + Matin nee A is cha / o NL Apes RASS & ; a i : : jp be. as Awrwa uinpur "sade if i D TONGAN ! “Sum aria ~e 4 Pulganjo Nek a \ sth Re fi 3 . Pe eat MACS P___HAZARIBAGH Sh Smee NS —e Laperé. F 'Biaora? é "h A i EO SEG. SES RAS Ee, Ta eT 5. eee SR PALAMAU) wek no SS HON TI50 . ~S, ry * Fi fi " e, 7 ver +. “ALL 5 es bar dy: ; = . - 2 Dumurhi ft Apes sricith Seedi << bY a oo ge 4 Ly wey aX Sill co 83 A Be ; F = ~ i fuarha' i gai on dw a, ~Fomal 4 fk, ‘ae } Ms a\ . it M o Pro. ‘4 = . _ b _ ° ee PUR 8: ? i PNIeiwax “ay “. : Andhra. % bendwa: Vv ry Ss, ? walt (FO irvdp “ a) = r> > iS ae a < ats P 7 \ : my. =< 2 Rea. No.1 E.D. 0.1917 agate 3 , . 3 o Heliozincographed at the Survey of India Offices, Dehra Dun. 3 - oo BPP PLOGICAL SURVEY OF INDTA. | = Memoirs XLII, PLS. e————— oo aaron nnn . —————S TI ee Oh ig oot ~ Chab-rang- Dzong A , y ’ , c ; , A | er tip f wns ? “ , / ma { . H : be b s s et! ; fhe ll phi preted - ” - . = * > e~ - s = - oh FA IY 2 : . D : “A: Lg | Pit it Wag J ; .S 1 e r\ wee ’ : a” ~ i: 3 4 : y y >) if tage 3 SSS A> g6ag eS 1k B Wok: Ali — ~ LReprao Cam 7 s SOO < Le os QR dAe fF ; R : : Fy j ~ F # : a " X es ‘ — 4 rd y =, “ns i > | J Say’ oP/ = a hi 7 : : Fad lt, \ ve f iis : / fic 2 u : wen ‘ ; ol / j = . - f ‘ “ » oti Sie ee» Pi? ghee P b « i) P H _ aad %) OC) - q * S ? Les % Nc : . ( r a2 ‘ I ny \ Y, . . wt wy, - m < - . “ x s Fa | _ =e . 2 . 5 \ \ f \ \ ‘ 7 ‘ / : sr / \ f ew j oH sal \ ’ Fa ad o f { ‘ s q SOO ae & \ ’ } HY \ A DBhahhyw (NEE SS : ? 1 9 A S84 ZAI Nk ed Ss. . te “9 °. i \. o Sarodge a : \ ‘ H Se -Nawashahr ‘e * ae { * | eo = | | JULLUND | U ee oaadle | 209 ¢Réhon\ ,- fe = ales . ICANA TL 2eneve eee, N , “¢ f x . & ” — wie Bamrala. Kura. ' : ‘i Pg X Sees 15 = wWerinda_ “ Pea der. BO a Fe * : Sa nghol 3 7 >t € aA et Pee | Ps ot \ ir . Ch ah > — Chawea \ a & ee eet tnt hiner * oo tect rnanteecan ma : nner ~) ) BES ua (CC | pag ot NSS {i 4 55952 ; FL ANE X iat yA 2} SS a ek vod "Pees. ce Spay," we" { iH] sh a » { A\ . t =a y SS Amfoh¢ wy | seas : MN Vy \ ae ‘ f ; a \ "a6 e, wt B “: ee se age : | - c \ er 3 , . Kaprogarh ne Ys tide. aie REO SRajpura a f x, / Bs Ali f Viale " ? . “f . \ . . Bs : 7 "4 GEO. i fe eS ref - ~VQSambha P| > ie y) ee . \ eet eee ek Nery 5. 4 SS cerhinds (4 o- t = W i. Z > / J Se. ee Dholan ee = in aa ae Sarai Harlards< 7 Mee cae aaa is ea = i i y a : te ory. 4 , +. . : % j +, Bhadso Mi; \~ Chinarthal oY <4 OE ' aoe. A ~S Wied. € nis } thzad pur Fy a oa Mardanpur- “SS ee ee ww 4 g i ty : Z * E wd , qihei = —_ . { c J é aS = “ , ') : araingarh / i 9 e ioe H Wy ? lo: Q a i on r Fon mi va ad ¥ | BeloShahabid 187 a fe iB ™ | 5 : H | * { zi a JAS iP ra) eB " e* O- Poul , {7 f ete \ ALT pes Daulatpu fi 1 os Wa | V), / yee U ff Z i °Sultanphr,’ Anyang Va -~ « ' Lf * f Z o~ Go MA PS H O WIN G a Fike thala Rao 4 {GEODETIC STATIONS 7” / ura | x t HAR a \f oe gs - 2 Bhagednpis ee seg Chodi Sa 4 ; — . Ro ORKE OFLE%~- \ghoorkee \ he i; = : aN Awbahtar f. © eS Biang c. aed nade ? YNdgal || ' . F} Gangoh : Anibehta 4, Seburhera if in and near the . bon oo: i ioe es A. || nny fees ' “XS \ ay : il Ku ypura >: f Y Karinpur an hen eae aon me aoe \ Gore ae cme ‘ heopur ae \ cee 4, \d : ' } 44 { ae, “ 1 D ith H R A D U N e he -KARN a Fi "by we as ~ <" }} oil ce / f A ‘ : 3 Vf ; , : ~ 7 ; : € ‘ Ip . ; by y a a wr \ ps 4 fA - \ 4 db Ova “= ql _ f 3 eae 4 aa 5 : Jeoband ef es | " (tii oe go Rear * 6 ue Af HO WG ey SSS | 2500 ; } . j n er ; 1 ! FF . \ pk = at f MY : : ¥y : ij , reagd | oe es (* Keksur % y ‘SN } \ 'e) f ce@ eas S i | , a IS. \ y \ | Sabdlgarh Fort hits A\ | °Chausing*-y UN {4 / —~S Pindaurag Scale 7 Inch = 16 Miles. at t C~ oBPidauli - ‘ \ | | \ ee | 2 ae me Viernes Ps “ B hd pura pec | | del Charthawak. {JRN % ee ee o / Bhogpur § le | iow pBtirt_f_S_AMUZAFFARNAGY Lope ae : | i I N D ii xX : — pur ( Baghray. g. eee y Ree 2 “Mapduwar a saan, 2 * : . BAT Ka krauli A do ee Sambathera \. ye o oe Ferri y. zi é Mirdnpur Sisauli oe (A Ey h A S. ikarptr | : ‘ bi 4 e lk J i “=< = Inner boundary of theTertiary rocks. oy Snipes f ab x Bapoli ae ——.. Main Boundary Fault. (ies ale Git f . x ‘ . ASU a ae ee) cSurj nnagar mys dig 4 \ Pf sn me é \ ; The / \ Lor Phalau Wa °oBahsuma I wa &, aie t Z ‘ Hast aapur: I Chandpur 2 ae i} 7515p Lawar J -Mawana ae Ss \ t ; om -— LES | | ®ee0e ee scces Outer boundary of the Tertiary rocks. | amalkka \ x ene ——— 4 © s te x ; Nirpura, 2 — non oe == : 1 Ne’ Pe oats air he a : Khasgibh 0) : | | | | : \\7 @& oe OS Ai hth al A Bua: ss a i (rr { eee se i} | pelos N aN “ENE hn AF a + one he NES Sa Dilari Shoyrif er . \ yy 7: ee Nandgar ° 29 Lisspiiiaiiieiailaiias z CLE ILD BPS LRT N RRERUREMA rag pete Ot oe —— - mee one econo JSonepat 4 . 5 = - oe Se? et Mv , C andl. : Chuch a nT Da Be ve ye er i - di a : Rees y ; ‘ : a ae i c ‘alg / as - — 7 “~ 29 $ | | i] : | | | oF [EERUT oe | on , - e | re) bs ; 4a. os : © : : ; S) Qi) i H | } - } \ ee =) | | —— as i : Pee rae S : ; eer tan ae oe _ 3 Se J SO PE SDSS: SINE a a eee ea Ss SRG SB me a Nh Se SEAR ea re isk Sekai HELIOZINCOGRAPHED AT THE SURVEY OF INDIA OFFICES, CALCUTTA Rte. No. 3221. E 16 Scale 1,000,000 or 1-014 Inches to 16 Miles. ae . ie See ee ee a — | Boundaries - international demarcated, undemarcated...... — ianle 9: dhe sie aihesk Mis eek ie. ae ababee bh abet: 3 i } | ae uaK seins —-—— Mies r 3¢ a - Capital of Province, of Division, of District. ......... BOMBAY DELHI GAYA Miles 10. 5 0 10 20 50 40 Miles ; | | : | | . a ee | Do. Province or State demarcated, undemarcated «©. -.—.~ me K | _ Important Administrative Centres, Towns; Villages. . . . . Palamau Waltair Unhiatar | f ae | a. Harsco oe | | Railways-5'6”. Double, Single, Metre gauge, Other gauSes . . queues er ee ete” iy sats lesteeesicggtsa hoa ecceiestnhsalehcnteinind hadi ae ital aPC 7 IER e-2 <1 Rr wes See EER ot rte ge Le OAPI St Ae PR ee 4 aah a CR ea RT Pe ae SSE Re OLE ee a a, el et oe ae | Roads,-Metalied, Other roads and paths : Sa ee ERDSEN atin elie vieasiaeatana atelier cpr Seu seething Suse emanate aS kaidipmmtatonanbnien REFERENCES. MANGAL 8 BIJA 15 PATIALA 22 KALSIA DHAMI 9 KEONTHAL 16 SANGRI 23 KARNAL KUNIHAR 10 MADHAN 2-17 KANETHI 24 JIND MAILOG it Sor 18 DARKOTI 25 NABHA KUTHAR 12 THEOG DUJANA 26 LUDHIANA SIMLA 13 GHUND © 20 THAROCH 27 NAINI TAL BAGHAT 14 PUNNAR 21 AMBALA 28 MORADABAD IA oO fF © 8D Re KEONTHAL STATES ©