April 06
By THAN HTUN
(GEOSCIENCE MYANMAR)
Episode: 9
Lewis Leigh Fermor was born on 18th September 1880, the eldest of six children of Lewis Fermor and his wife Maria James. He was educated at Wilson’s Grammar School in Camberwell and studied metallurgy at the Royal School of Mines, where he took a BSc in 1907 and a DSc in 1909.
On the 13th of April 1930, Pascoe handed over the charge of the office of Director to L. L. Fermor and left India on long leave preparatory to retirement. The end of the decade was marked by a great business depression, and Fermor was still officiating when, early in 1932, the Government of India considered the financial position justified a general retrenchment in the cadre of all Civil Services and a ‘cut’ in all salaries. In consequence, when Pascoe’s retirement became effective on the 6th of April 1932, and Fermor became Director, the Geological Survey of India had lost the services of several valuable officers namely, Cotter, Brown, Jones, Banerji, Leicester, B. B. Gupta, and the experienced Chemist W. A. K. Christie. The harmful effects of this drastic retrenchment of the personnel of the survey were felt later at the time of the Second World War.
When Fermor became Director he had already established a secure place for himself in the mining and geological world through his outstanding work in connection with the description of the manganese-ore deposits of India and the discussion of their genesis and relationship to the Archaean rocks containing them. A petrologist of high order Fermor had discovered and described a number of new manganese minerals. After a service of 33 years, Fermor retired on the 7th of November, 1935.
In Burma, E. L. G. Clegg continued the mapping of the Mogok Stone Tract that had been commenced in pre-retrenchment days by Coggin Brown and A. K. Banerji. Clegg was joined at a later date by L. A. L. Iyer. Bradshaw assumed charge of the duties of the Resident Geologist and Official Member, Yenangyaung, and Singu Oilfield Advisory Boards at Yenangyaung. V. P. Sondhi continued his work in the Northern and M. R. Sahni in the Southern Shan States.
Publications
The series of publications on the correlation of the Archaean formations in various parts of India, which he wrote before and after his retirement, testified to Fermor’s profound knowledge of these rocks, inexhaustible patience, ceaseless energy, and a love of science which became his second nature.
Of papers in the Records, mention may be made of Coggin Brown and Sondhi’s Geological account of reconnaissance in the southern Shan States. There are two reports regarding Geological Reconnaissance in the Southern States; Taunggyi to Hopong and the Geology of the country between Kalaw and Taunggyi, Southern Shan States. The latter is a comprehensive report which included physical geology, a List of formations, Kalaw Red Beds, Coal measures, the Plateau Limestone, Lower Palaeozoic succession of the Pindaya inlier, Lower Palaeozoic succession of the Mawson-Mawnang regions, Lower Palaeozoic succession of the Pon-Taunggyi region, Structural geology, and Economic geology. The following is a concise account of the geology of Kalaw and Taunggyi.
The geology of the country between Kalaw and Taunggyi
The region described in this paper occupies an area of approximately 1,370 square miles lying between latitudes 20º30’and 21º 0’and longitudes 96º 27’30” and 97º12’30”. It is comprised of Survey of India, one-inch sheets Nos. 93 D/9-13, D/10-14 and 93 H/1. It includes very small portions of the Meiktila and Yamethin districts of Upper Burma, while the rest is occupied by numerous small Shan States, together comprising Myelat, and parts of the large states of Yawnghwe and Lawksawk, which lie to the east and north of Myelat respectively.
The area consists of an elevated tableland, for the most part, approximating 4,000 feet above the sea-level and lying beyond the outer hill ranges which divide it from the plains of Upper Burma further west; but it is itself traversed by parallel north and south ridges rising to over 5,000 feet and by inter-mountain valleys which, in the case of Yawnghwe valley, descend to 2,900 feet above sea level.
Within this region rocks of Ordovician, Silurian, Devonian, Permo-Carboniferous, Jurassic, Cretaceous, and Plio-Pleistocene ages occur and it forms indeed a key area to the study of the geology of the whole of Southern Shan States, while it’s known mineral deposits include ores of copper, silver and gold, lead, tungsten, and antimony, together with coal and lignite.
Previous Observers: During the field season of 1864-65 F. Fedden of G.S.I travelled through the Shan States from south to north. Entering the hills near Yamethin, 110 miles south of Mandalay, he crossed the Myelat on his way to Keshi Mansam and the Salween.
In 1887, E. J. Jones of G.S.I., visited various localities to investigate coal, lignite, and other mineral deposits. As the country was then only just recovering from widespread banditry and as the only map available was on the scale of 16 miles to 1 inch, Jones could make no attempt to survey geological boundaries and confined his attention strictly to the mineral occurrences.
In the season 1899-1900 C. S. Middlemiss made a geological reconnaissance in parts of the Southern Shan States and Karenni. This work is of fundamental importance in Shan geology and we, therefore, devote some attention to it here. He split up the geological fabric of the hills into a number of zones of distinctive character as regards composition and stratigraphy, as follows:-
1. Gneissic and metamorphic zone.
2. Great Limestone zone.
3. Purple Sandstone zone.
4. Sub-recent conglomerates, sands, and loams.
The gneissic and metamorphic zone is well exposed in sections along the motor road from Thazi to Kalaw between Hlaingdet (mile 9) and Pyinyaung (mile 31). The first rocks met with are well-foliated micaceous and hornblendic gneisses, intruded by veins of pink syenite, white pegmatite granite, and fine grey microgranite with biotite and muscovite. A little to the east of Pyinyaung the road enters the first of Middlemiss’s Great Limestone zones. The Purple Sandstones zone is very well seen in excellent exposures along the main road between a point four miles east of Pyinyaung and Kalaw. The purple rocks we now believe to be of probable Cretaceous age, as suggested first for similar strata in the Northern Shan States by C. L. Griesbach in 1901.
At the time Middlemiss was working here, T. H. D. La Touche was commencing his investigations into Northern Shan geology which culminated in the publication of his memoir and maps of the greater portion of the Northern Shan States.
Early in 1922, G. de P. Cotter spent a month on the Loi-an coalfield near Kalaw and produced a detailed report on that field and other associated coal occurrences. He proved that the Coal Measures contain a flora of the Middle Jurassic age and regarded the purple and red sandstones and conglomerates of the Kalaw neighbourhood as Upper Jurassic or Cretaceous.
Captain F. W. Walker worked with Dr Cotter and on the latter’s departure from the area, continued the systematic survey of sheets 93 D/10 and 14. He, like other geologists before and after his time, failed to realize that the rocks of the range separating the Heho and Yawnghwe valleys do not belong to the Plateau Limestones.
In June 1925, Clegg paid a visit to Mawson. He described the area as consisting of rocks of the Plateau Limestone formation.
C. S. Fox spent a few days at Kalaw in January 1929 and was fortunate to discover ammonites in the Red Beds there which, according to Dr Cotter, are of Cretaceous age, thus supporting the opinions originally advanced by Griesbach and by Cotter himself. In seasons 1930-31 he was joined by V. P. Sondhi who is responsible for the whole of sheet 93 H/1 and has completed parts of sheets 93 D/9, D/10, D/13, and D/14, including the different terrain west of the longitude of Kalaw.
Physical Geology
When the traveller to Kalaw by road reaches the crest of the final ascent just outside the town, he crosses the watershed of two great river systems, the Irrawaddy and Salween. By the railway route, it is traversed, together with the boundary line between Burma and the Shan States, at Myindaik, the first railway station below Kalaw. The western mountain ranges, Shan tableland and its ridges and old lake valleys, and drainage, are described in some detail.
The floating islands of Lake Inle: According to Dr N. Annandale, who was helped in the geological aspects of his investigation by Captain F. W. Walker, ‘Many different kinds of plants take part in island’s formation, but those of primary importance are certain large grasses and sedges that send out long floating runners from which new upright stems arise. Floating plants such as duckweed become entangled amongst these runners, and at the same time submerged weeds, especially a species of Ceratophyllum, grow up to the surface, where their upper parts are killed by the heat of the sun or the growth of algae. The mass of vegetation thus entangled is further agglutinated by the luxuriant growth of algae belonging to the family Rivulariacoae which forms large brownish masses. These elements of the island-in-the-making both decay and grow. Their decay forms a kind of fen-peat that is prevented from sinking by their floating and growing parts. A floating island covered with rich soil is thus formed, and plants of a great variety of species grow up upon it, forming dense entangled masses.
List of Formations
The formations met within the area were treated in the following order:-
Alluvial and travertine (Recent), Residual deposits and upland palms (Sub-Recent), High-level terraces (Pleistocene), Lacustrine deposits (Late Tertiary), Red Beds (Cretaceous), Coal Measures (Loi-an series) (Jurassic), Upper Plateau Limestone (Permo-Carboniferous), Lower Plateau Limestone (Devonian-Carboniferous), Silurian, and Ordovician rocks.
Kalaw Red Beds: Several very good sections of the different members of the Kalaw Red Beds are visible along the road in the Taungwindwin Valley and were originally described by Middlemiss. This stream has cut a well-defined deep course along the strike of these rocks. The conglomerates, which form perhaps the most remarkable feature as well as the greater bulk of the formation, are of varying texture, compactness, and composition and occur at different horizons. The narrow, sharp ridge along the valley on the east is formed by a coarse conglomerate band containing large boulders of hard, purple sandstone and smaller ones of limestone, embedded in a red, sandy calcareous matrix. And the high, rugged hill range flanking the valley on the west is built for the most of a coarse soft conglomerate remarkable for the large size and angularity of its sandstone boulders and the low proportion of its calcareous contents. Excellent exposures of the Kalaw Red Beds are to be seen about Kalaw itself, in the railway cuttings between Myindaik and Kalaw along the main road to Thazi for some miles. From the soft, friable, reddish-purple sandstones and shales, dipping westwards at about 25º in the small hillock, crowned with a pagoda, between the railway Station and the Kalaw Hotel, as noted above Dr Fox obtained ammonites of Cretaceous age and thus substantiated Griesbach’s opinion on the age of similar rocks in the Northern States.
The main ore body of the Bawzaing mine: leased by the Shan States Silver-Lead Corporation, Limited., this one occurs in a wide, nearly vertical, irregular fissure with ragged walls, trending approximately N. 20º W. obliquely across the strike of the country rocks. The fissure is filled with mineralized clay containing irregular limestone blocks of all sizes. Within this fissured zone there is an ore shoot with a decided pitch to the south and of very varying width, up to a maximum of 70 feet. The ore shoot was encountered in the Bawzaing shaft at about 75-80 feet from the surface, but in the Theingon shaft, 750 feet away, it was not met until a depth of over 124 was reached. It varies between 175-200 feet in height and, thinning out both above and below, displays a roughly lenticular section, as the main fissure pinches in at both the northern and southern ends of the ore shoot. The Bawzaing shaft is 400 feet in depth with levels of 120, 200, and 331 feet respectively. The Theingon shaft is 575 feet deep with five corresponding levels from it. The ore reserves estimated in April 1930, were 185,400 tons, averaging over seven per cent lead.
References: GSI (1934). Records of the Geological Survey of India, Vol. LXVII.
