224 Geological Society. 



PROCEEDINGS OF LEARNED SOCIETIES. 

 GEOLOGICAL SOCIETY. 



April 15th, 1908.— Dr. J. J. Harris Teall, M.A., F.R.S., 



Vice-President, in the Chair. 



The following communication was read : — 



' Notes on the Geology of Rurma.' 

 By Leonard V. Dalton, B.Sc, F.R.G.S. 



The object of this paper is to present the results of geological 



expeditions in the Irawadi Valleys carried out by the Author and 



Mr. \Y. II. Dalton between 1904 and 1000, and to correlate these 



observations with those made by previous writers, thus summarizing 



present knowledge of the geology of Rurma in general and of the 



Tertiary System in particular. The classification of rocks arrived 



at is shown in the following table : — 



Fr.r/r. 



Irawadi Series 2U,0U0(?) Pliocene. 



, , c, . f Pegu Group 7500 Miocene. 



ilrakan Series \ t> ■ rt onnn t? 



[ Bassein Group 8000 Eocene. 



{-Beds Cretaceous. 



Upper \ HalobiarlAmeBkone Triassic. 



[ Shales and grits (?) 



Lower. Flaggy shales and sandstones (?) 



The oldest rocks, not comprised in the above synopsis, include 

 representatives of the Silurian, Devonian, and Carboniferous 

 Systems, but little of their detailed geology is known. The 

 Cai-dita-I\eds may be correlated with the Cretaceous of India. 

 The ' Chin Shales' of Dr. Noetling seem to form part of the Bassein 

 Group, of Eocene age, which is of much greater thickness than 

 hitherto supposed, and the group rests presumably more or less 

 conformably on the beds below. The fauna is chiefly shallow 

 marine in facies. These rocks flank the Arakan Group on both 

 sides and in the south form the backbone of the range, where they 

 have been considerably metamorphosed. The Pegu Group probably 

 overlaps the preceding and is regarded as of Miocene age, although 

 the fauna has many relationships with that of the French Eocene. 

 J. a, ina globulosa is described as the first European Miocene species 

 recorded from Rurma. Estuarine conditions came on towards the 

 close of Miocene time, and, in the estuary of the Pliocene precursor 

 of the Irawadi. anticlinal islands of partly-consolidated Miocene 

 materials were formed. Around, and eventually over these islands 

 a great thickness of fluviatile deposits was laid down, corresponding 

 to the Siwalik Reds of the Indian Peninsula. Finally, post- Pliocene 

 denudation and upheaval revealed the Miocene islands as inliers, 

 while the Irawadi has left its gravels in patches throughout the 

 region. A Hst of fossils is given, and the species new to Rurma, 

 some of them new to science, are described. 



