GEOLonr. o 



THE CRETACEOUS GROUP. 



Beils of Cretaceous age are only certainly known on the west of tlio Arakan 

 range, in the southern borders of Arakan, near Maii in Sandoway. The detcrmina- 

 tiini of the ago of these bods, which have the appearance of being conformable to 

 the last, rests on a single specimen of Ammonites inflatns, a characteristic ' Ceno- 

 nianian' ceplialojiod, common in the ' Utatur ' liods of Southern India. No otlier 

 fo.ssils were found, and the country is very wild, and has not yet been brought 

 thoroughly under survey. There is, however, some probability that Cretaceous 

 rocks may exist in Tenasserim. On the Lenya River, in the e.\tromo south of the 

 province, a bed of coal occurs of very laminated structure, and containing numerous 

 small nodules of a resinous mineral like amber. This peculiar association of 

 mineral resin is characteristic of the Cretaceous coals of Assam ; and it is highly 

 probable the Lenya coal is of the same age. From Cape Negrais nortliward 

 stretches a considerable thickness of beds remarkable for the intense alteration 

 they have locally undergone. Their precise relations with the Cretaceous strata to 

 the north, or the Tertiary strata to the eastward, is not clear, and they may not 

 improbably embrace beds of both Mesozoic and Tertiary age. They are frequently 

 charged with silica, by infiltration, and in places display veins of fibrous white 

 quartz, associated with soapstone, chiefly along the western side of the Arakan 

 range, and nowhere can the intense alteration tlie rocks have locally undergone be 

 studied better than between tide-marks on the coast, where the liardened rocks 

 of this division stand out in the form of craggy ledges, boldly fretted by the 

 action of the waves and spray. 



THE NUMMULITIC GROUP. 



Rocks of Eocene age occur both east and west of the Arakau range. On the 

 east, at the froutier of Pegu, they are seventeen miles broad, in an east and west 

 direction ; but this breadth soon diminishes, though the group continues throughout 

 Pegu as far as Puriam Point, at the mouth of the Bassoin River. No precise 

 estimate of the thickness of this group can be made, but it not iuiprobably reaches 

 to 10,000 feet. The most conspicuous member of this group is a pale-coloured 

 limestone, charged with Nummulites and other fossils. Many of the shales, too, are 

 crammed witli similar organisms ; but well-preserved fossils are rare, and without 

 exception confined to the limestone or calcareous shales. In Thondoung (' liuie 

 hill '), near Thayet-myo, a bed of coal was formerly worked to a small extent, 

 but its development was too capricious and irregular to prove of value. It is in 

 this group, as will be explained further on, that the Burmese petroleum would 

 seem to originate. Although the age of the Tenasserim coal is not known, it may 

 not improbably be of early Tertiary age. Its quality is fine, the proportion of 

 volatile matter being large, whilst the amount of ash is small. Tlie beds containing 

 this coal are nowhere of great thickness, probably less than 1000 feet, and are 

 nowhere traceable over large areas, but form small basins along the Tenasserim 

 valley, their inaccessible position being a great bar to the profitable extraction of 

 the fuel they contain. At Thatay-khyoung, on the Great Tenasserim, a seam 

 occurs seven feet in thickness, including small partings of sand and clay ; whilst 

 at Heinlap, six miles distant, the seam is over seventeen feet thick. At Kaumapeying, 

 three-quarters of a mile north of Ileinlap, there is a seam eight feet thick, but which 

 contains much iron pyrites. A seam on the Little Tenasserim is only three feet 

 thick. The coal of the Lenya River has been alluded to as of probably Creta- 

 ceous age. 



THE SIWALIK GROUP. 



Above the Nummulitio group in Pegu and Arakan occurs a vast series of 

 sandstones and shales, the undoubted homologues of the Siwalik group of the sub- 



