An Outline of the Tertiary Geology of Burma. 489 



Little is known of the Eocene rocks ^ of Lower Burma (Henzada 

 and Prome Districts). They consist mainly of unfossiliferous shales 

 and sandstones much disturbed by faulting. The junction with 

 the pre-Tertiary rocks appears to be invariably faulted.^ 



2. Northern Region (Upper Burma). 



Here the Eocene rocks are of greater interest and have been 

 studied in some detail, especially with regard to the higher beds. 

 The succession is :— 



5. Yaw Stage (marine shales). 



4. Pondaung Sandstones. 



3. Tabyin Clays. 



2. Tilin Sandstone. 



1. Laungshe Shales with Paung-gyi Conglomerate at or near the base. 



Paung-gyi or Swelegyin Conglomerate. — A typical basal con- 

 glomerate from 2,000 to 4,000 feet thick. The contrast between the 

 folded but comparatively unaltered conglomerate and the under- 

 lying cleaved and folded shales or phyllites (Kanpetlet Schists, etc.) 

 has already been noted. The pebbles in the conglomerate seem to 

 consist very largely of fragments of these rocks together with a few 

 gneisses of more distant origin. 



Laungshe Shales. — Possibly from 9,000 to 12,000 feet in thickness. 

 The fauna of these beds has not yet been studied, but seems to include 

 several forms of late Cretaceous aspect, possibly survivals in the 

 early Eocene gulf. The most abundant fossil is a large Operculina. 



Tilin Sandstone. — It is probable that this arenaceous group, 

 marine in the south, becomes brackish or freshwater northwards. 

 It is certainly much thinner in the south, and cannot be traced as a 

 separate division to the south of latitude 20° 15'. This attenuation 

 from an, estimated thickness of up to 5,000 feet in the north to nothing 

 in the south probably accounts for the huge thickness claimed for the 

 Laungshe Shales in the south. 



Tabyin Clays. — A group of greenish, somewhat rubbly shales, up 

 to 5,000 feet in thickness. The most interesting fossil is Nwmyiulites 

 vredenhuryi Prever. In the south other nummulites, some of large 

 size, are found, a^^parently at this horizon or slightly higher (Minbu 

 district). A^orth of latitude 21° 45' the writer did not succeed in 

 finding any nummulites or other marine fossils, but numerous 

 thin seams of coal occur in the higher part. The coals of the Upper 

 Chindwin appear to belong to this and to the succeeding division. 



^ Roughly the " Nummulitics " of Theobald (op. cit.), but he mistook 

 certain limestone bands with Lepidocyclina which occur in the lower part of 

 the Pegu for Nummulitic Limestones, and so has drawn the upper limit of the 

 " Nummulitics" too high in several cases. Noetling {Pal. Ind., N.S., vol. i, 

 p. 6) intended to have substituted his own terms " Bassein " and " Chin " 

 Divisions for Theobald's " Nummulitics " and " Axials " respectively, but he 

 made serious errors in definition which invalidates his classification (see Pascoe, 

 Mem. G.S.I. , vol. xl, pt. i, 1912, p. 14). 



2 Theobald, op. cit., p. 102 (290) ; Stuart, Eec. G.S.I., vol. xli, pt. 4, 1912, 

 pp. 240-65, and pis. 22-4. 



