4 BURMA, ITS VEOPLE ASD PRODUCTIOXS. 



ITimalaj'an iTginn, ami representing the entire Middle and Upper Tertiary period 

 (Miocene and I'lioceno). Tlio bods, however, ditl'er from tlie corro.v[ionding 

 deposits of Northern India, in being distinctly marine, witli the solo exception of 

 the uppermost l)uds of the scries, ■which are probably of freshwater origin. A group 

 of shales at their base, 800 feet or so thick, has been Ke])arated under the name 

 ' Sitsyahn shales,' from a village on the right bank of the Irrawaddy above Promo, 

 where they are well seen ; and a great thickness of sandstones, often highly fossili- 

 ferous, which succeeds tiiem, and cannot be far less than 3000 feet thick, has been 

 named the Prome beds, from being largely developed near Prome ; but the countiy 

 occupied by these beds is not favourable for accurate estimates of thickness. Near 

 Kama, on the right bank of the Irrawadd^y, a blue clay of this group is richly 

 fossiliferous, being charged witli Foraminifera an<l well-preserved though small 

 shells. Many of these fossils fall to pieces im drying. The topmost beds of the 

 group are s;ajdstones abounding in parts in TurritcUie, (;i.]n\\8 of the genus Cladocci-n, 

 and many other shells and radiates, together with sharks' teeth of two or three 

 genera (Laiiina, Carcharodon. etc.). These marine beds pass up into clays and 

 sandstones in which no marine fossils have been detected, but wherein trunks 

 of silicitied trees abound ; and as these are untouched by boring mollusca, it is 

 presumed the water wherein they floated was fresh. The great bulk of this fossil 

 wood is exogenous, and not coniferous; but in the gravels of the Irrawaddy rolled 

 pieces of silicified endogenous wood occur, undoubtedly derived from the same beds. 

 These silicified wood beds are the highest Tertiary beds exposed in Pegu, and are 

 now much circumscribed in their area by denudation. They occur on the right bank 

 of the Irrawaddy, near Thayet-myo ; still more largely north of Prome, and along 

 the Pegu range, till they are covered up to the south, and concealed by the gravel 

 and surface detritus, to the formation of which tliey have so largely contributed. 

 Ou the east of the Pegu range, in Toung-ngoo, they are also met with ; and across 

 the Tsittoung, to the eastward, they are represented by a lateintic belt, often con- 

 glomeratic, fringing the hills east of the river. The most characteristic fossils from 

 these uppermost beds are Stegodon Cliftii, Mastodon lalidcns, M. Sivalensis, Eliiiwceras 

 irnvadicus, Aceroiherlnm i>erimcnse, Uexaproiodnn iravadicus, Blcri/copolfimns disnHia, 

 Vishiutherium iruvadinita, ColossocJwIys alias, besides other less characteristic forms, 

 clearly demonstrating the relationship of these beds with the Upper Siwaliks of 

 Northern India. These Tertiary beds have not been traced south of Pegu, 

 but range in full force into Arakan, though their divisions have not yet been 

 worked out. 



RECENT DEPOSITS. 



Alluvial deposits are roughly divisible into an older alluvium called Bhangar 

 in India, and a newer alluvium termed Khadir. The present river-valleys are 

 usually carved out of the former by wandering river action, whilst the Khadir is 

 the deposit of flood-waters, in the broad valleys excavated in the older deposit. 

 In Burma however, along the great river-valleys, as the Irrawaddy, Tsittoung, 

 etc., the alluvium of the country belongs to the former class, no large areas being 

 occupied by the newer deposits, which are restricted within the narrowest limits to 

 the immediate channel of the river. In this respect a striking contrast exists 

 between the delta of the Irrawaildy and that of the Ganges, the richest lam] of 

 Lower Bengal being composed of Khadir land, which is almost wanting in Pegu. 

 This difference in geolojjical structure is au index of the different conditions of 

 the two areas. Lower Bengal, being an ai'ea of subsidence, permits the accumu- 

 lation pari passu of Gangefic silt, whereby the balance of level is maintained, 

 whereas in Pegu, which is either sfjitionary or rising, the deposits of the Irrawaddy 

 in flood are swept out to sea, and no deposit of Khadir accordingly takes place 

 save in actual proximity to the river-banks. Another cause ojierates to limit and 

 reduce to a minimum the deposition of silt from the Irrawaddy in Pegu, 'i'hu 

 rains falling early, the flood- waters, depurated of their coarser particles, as thoy 



