Association for the Advancement of Science. 473 



age and dislocation. To this is due the sudden alteration in the 

 direction of the courses of the larger rivers, as noay be seen on 

 maps. Rocks similar to those situated in the Tenasserim provinces 

 extends northwaids up the course of the Salween River, and into 

 the adjoining districts of Burraah, to the north-east of Pegu. 

 And, again, close to the capital of Burmah, and stretching nearly 

 north and south, as far as examined, high ridges of metamorphic 

 rocks are again met w^ith, consisting of gneiss, micaceous schists, 

 and highly crystalline limestones, occasionally of a fine v*rhite co" 

 ^our, and largely used by the Burmese for sculpture. But the 

 great valley of the Irrawady is, throughout a very large extent o^ 

 its course, bounded on either side by a thick series of rocks, chiefly 

 sandstones, but with massive limestones also, which are locally 

 rich in fossils, and which, from this evidence, may be clearly re- 

 ferred to the eocene period. These stretch on both sides of the 

 river as far north as Pugahu, beyond which the higher grounds 

 recede from the river banks ; but they are in all probability con- 

 tinned thence into Munipoor, and so uuited with the nummulitic 

 rocks of the Khasi and Cachar Hills. These rocks have been con- 

 siderably disturbed and broken, but have a general and prevailing 

 strike nearly north and south, which strike, throughout many 

 miles, has determined the general course of th e River Irrawady 

 Their thickness is considerable, certainly exceeding 5000 feet. 

 Above these eocene rocks, and restinof upon them with slio-ht un- 

 conformity, is a series of beds of no very great thickness, charac- 

 terized by an abundance of gypsum disseminated in the layers 

 and veins, and in the lower beds of which occur the deposits of 

 clays and of vegetable matter, fiom which arc derived the larger 

 supplies of petroleum. These rocks are well seen at Senan Kyoung 

 (" stream of foetid water") and are traceable northwards to near 

 Amarapura. In the beds which appear to form the uppermost 

 part of this group, but which may possibly belong to another and 

 distinct series, are found some of the fossil bones of the larger ani- 

 mals which occur abundantly in this district. About forty miles 

 north of Amarapura we again meet with sandstones, shales, and 

 coal, resting uncomformably on the metamorphic rocks, and charac- 

 terized by remains of dicotyledonous trees similar to, if not iden- 

 tical with, those found in the coal-yielding group of the Tenasserim 

 provinces, and which are therefore referred to the same age (plio- 

 cene). This series, so far as examined, proved of no great extent 

 or thickness. We pass now to the Khasi Hills, which form a 



