An O'lttline of the Tertiary Geology of Burma. 491 



Stage is marked by interesting bone-beds, whilst conglomeratic 

 bands with, fish remains occur throughout. With regard to the upper 

 limit, northwards from 21° 45' the series passes up gradually into 

 the overlying " Freshwater Pegu " ; whilst in the south it would 

 appear to be well defined by a bed which the writer prefers to regard 

 as the base of the Pegu. The latter bed, described below, has been 

 traced at intervals for 100 miles, though it should be mentioned in 

 fairness that general agreement as to the identity of the bed through- 

 out has not yet been reached. 



Post-Eocene {Pegu-Irrawadian) . 



As being the main petroliferous horizon the Pegu has been studied 

 in great detail, but it is only very recently that anything like a clear 

 conception of the deposits as a whole has been obtained, and much 

 remains to be done. In this respect Mr. E. Vredenburg's recent 

 work is extremely important in removing misconceptions caused by 

 previous writers.^ 



The Post-Eocene beds may be treated as a whole ; they are entirely 

 continental in the extreme north, and except for the very highest 

 beds, completely marine in the south. For the present the term 

 " Pegu System may be taken to correspond essentially with the 

 marine facies of the ]DOst-Eocene Tertiary. It ranges in age from 

 lowest Oligocene to Pontian or the lower part of the Pliocene". 

 The corresjjouding continental facies may be termed the Irrawadian. 

 However, until recently the Pegu and Irrawadian were believed to 



^ The following are the more important works dealing with the Pegu- 

 Irrawadian : — 



Palceontological. — Noetling, " Fauna of the Miocene Beds of Burma " : 

 Pal. Ind., N.S., vol. i, Mem. 3, 1901. Noetling's stratigraphical classification 

 and his " zones " should be entirely ignored and no attempt should be made to 

 use this memoir without reference to Vredenburg's " Results of a Revision of 

 some portions of Dr. Noetling's Second Monograph of the Tertiary Fauna of 

 Burma " : Rec. G.S.I. , vol. li, pt. iii, 1920, pp. 224-302. Other fossUs have 

 been described by Dalton (some Eocene), Q.J.G.S., vol. Ixiv, 1908, pp. 604-44, 

 but the stratigraphy of this paper is very unsound. Modern descriptions of 

 ■certain groups of Pegu fossils by Vredenburg have appeared and are appearing 

 in Rec. G.S.I. , vol. li, pt. iv (Terebridce) ; vol. iiii, pt. ii {Pleurotomidce, Conidce, 

 -etc.) (in progress). 



Stratigraphical. — The foundation of stratigraphical knowledge in Lower 

 Burma was well laid by Theobald, 3Iem. G.S.I., vol. x, 1874. A useful summary 

 of work done prior to 1911 is given by Pascoe, " The Oil Fields of Burma " : 

 Mem. G.S.I., vol. xli, pt. i, 1912. Foundation for later detailed work is found 

 in Cotter, " The Pegu-Eocene Succession in the Minbu District " : Rec. G.S.I., 

 vol. xli, pt. i, 1912, partly revised by Cotter and Porro in Rec. G.S.I., vol. xlv, 

 j)t. iv, 1915. The following papers are in need of revision as a result of later 

 work : Stuart, Rec. G.S.I., vol xli, pt. iv, 1912, pp. 240-65 (Henzada) ; Stuart, 

 Rec. G.S.I., vol. xxxviii, pt. iv, 1909-10, pp. 259-91 (Prome, etc.). Later 

 work of importance includes Vredenburg, op. jam. cit., Rec. G.S.I., vol. li, 

 pt. iii, 1920, pp. 224-302, also pp. 321-37 (some rather serious errors occur in 

 the correlation tables in the latter paper) ; Sethu Rama Rau and Vredenburg, 

 Rec. G.S.I. , vol. Iiii, pt. iv, 1921-2, pp. 321-42 (Singu) ; also pp. 359-69 

 {" Correlation of lower beds of Pegu "), and Cotter, Rec. G.S.I., vol. liv, pt. i, 

 1922 (in the press). 



