80 
Records of the (Geological Serve// of India. 
[VOL. II. 
TOO square miles, of which not more than a, bare fifth or sixth is covered by the highest sandy 
bed with which the fossil trees are associated, and which from its incoherent character has 
everywhere suffered to the greatest extent from the action of denudation. There can be no 
doubt that the entire group formerly extended as an uninterrupted deposit far below the 
latitude of Rangoon, though the highest member of the group with its associated fossil- 
trunks docs not extend down now in force nearer than 130 miles or thereabouts to that town, 
or not south of the Tonnguyo nulla. The exact termination to the south, however, of this 
fossil-wood bed is rendered very obscure, by its merging, so to speak, in the debris which 
has resulted from the waste of the group, and beneath which it sinks and is lost si"-ht of. 
That it formerly extended much further south is rendered certain (and perhaps the occur¬ 
rence, in situ, of patches beneath the newer accumulations at the present time is also indicated) 
by the occurrence of large pieces scattered about within the area of the detrital beds above 
mentioned, of a size such a s to preclude the idea of transport from a distance ; as, for instance, 
between the Okhan and Thonsay streams, where a log of not less than four feet in length is 
embedded in a mass of confused detritus fully- 65 miles south of the spot I have assumed as 
the southerly limit of the group containing the fossil wood in situ. Smaller pieces of fossil 
wood are found much nearer Rangoon and in cuttings iu the neighbourhood. Those pieces 
on my first visit to Rangoon, and before I entertained any suspicion of the connexion of 
the beds at Rangoon and those containing the silicified wood, 1 was inclined to regard 
as brought to the spot by human agency, as the Burmese are fond of surrounding their reli¬ 
gious buildings with posts of this wood “ Engiu chouk," hut I am now convinced that 
such is net the case, but that the pieces in question are derived either from the wasted 
and missing Upper beds or from the lower ones of the group still remaining, which, as 
I shall show, contain the same fossil-wood, though sparingly and never in the same sized 
pieces as the upper or emphatically the fossil-wood bed of the province. Thus the fossil- 
wood in the Promo district occurs in two distinct formations and under very different 
conditions, viz., in tho form of entire tranks in situ or fragmentary pieces, but little rolled, 
and in well worn or polished pieces, some of large size, but more frequently as pebbles, which 
form a conspicuous ingredient iu the recent gravels. 
Below I give, in descending order, a table of the main divisions into which the miocene 
beds east of tho Irawadi may be divided, the upper three of which constitute the fossil- 
wood group of which I am now treating :— 
Miocene. 
(Descending). 
Fossil-wood grouty. 
(a). —Sand—in parts gravelly and conglomeratic—characterised by the profusion of 
concretions of peroxide of iron associated with it; fossils, trunks of silicified 
exogenous wood and locally mammalian bones. In the subordinate beds of 
conglomerate, rolled fragments of wood as above, silicified, (that is, mineralized 
subsequently to their entombment), mammalian and reptilian hones and teeth 
of cartilaginous fish. 
O ').—Pine silty clay with a few small pebbles mixed with sand in strings here and there 
the whole very fine and homogeneous aud devoid of fossils. 
(c) . —A mixed assemblage of shales, sand, and conglomerates, the last very subordinate, 
partaking much of the characters of beds a — b ; a little of the concretionary 
peroxide of iron. Fossils, rolled wood silicified; mammalian and reptilian 
hones and cartilaginous fish teeth. Towards the base, the beds contain marine 
shells, and pass into those of the next group. 
Pegu 6-routy. 
(d) . —An enormous succession of saudstones and shales of unknown thickness and not 
usually fossiliferous. Particular beds, however, contain fossils in profusion : 
(e. g., d- 1.—Hard sandstone with corals (Cladocera). 
d- 2.—Blue Kama clay, highly fossiliferous. 
d- 3.— Ci/therea Promensis bed or Prome sandstone, 
and numerous others which cannot be specified till their fossil 
contents have been more especially examined). 
