S72 
Becords of the Geological Survey of India. 
[voL. XI 
thought it necessary to regard the greater part of the crystalline rocks there 
occurring as metamorphosed younger deposits, hut it appears to me that after 
Mallet’s^ detailed survey, this view can no longer be entertained, although this 
observer appears to consider the whole crystalline series in Sikkim as younger 
than the trias. Coming from the plains one meets here also first of all the Si- 
■walik beds, which follow the edge of the mountains with but little interruption 
through the whole of Sikkim and Assam. After travei’sing a more or less narrow 
valley one comes upon not very tliick sandstone with coal, and here and there plant 
remains,^ and which should be regarded as a triassic sandstone. Over these 
sandstones coma azoic clayslates and crystalline schists of immense thickness, 
which are in their turn ovei-laid by gneissoid rocks. On the noiih side of Bri¬ 
tish Sikkim the succession of beds descends regularljA’rom the gneiss to the crys¬ 
talline schists, but no more sandstone appears. From this it is probable that the 
crystalline rocks were thrust over by lateral pressure, and that the sandstone ori¬ 
ginally deposited against them only underlies them in appearance ; similar occur¬ 
rences maj' be observed on a large scale in the Alps. It thus occurs that the coal- 
bearing sand.stone is overlaid regularly by Mallet’s Daling series in part, and'in 
part by his Buxa series. I can now leave the crystalline formations of the Hima¬ 
laya and turn again to more southerly regions. 
If the valley of the Brahmaputra be crossed, one meets again in the Khasi 
and Harrow hills, by which the valley is bounded on the south, with extensive 
crystalline areas,^ whose southern side only is covered by sedimentary deposits. 
More extensive surfaces are occupied by crystalline rocks in the mountains east 
of the Irawadi,'*' and the whole of the peninsula of “ Farther India” up to its 
extremity is composed of similar rocks. The Andaman Islands appear also to be 
built up entirely of crystalline formations.® Ceylon similarly is composed exclu¬ 
sively of crystalline rocks. 
It is not necessary for me to state here the more specific age of all the crys¬ 
talline rocks discussed above ; indeed, remarkably few preliminaiy studies bearing 
on that question have as yet been made, although Mallet has recently distinguish¬ 
ed a couple of formations within the older schistose series in the neighbau7'hood 
of Delhi. In one particular case, however, this more accurate determination of 
age is of less interest, as these formations are all devoid of organic remains. It 
is only with the Silurian rocks that an im^jortant series of foi-mations begins 
which demands closer consideration. 
If we consider the development of the jsaleeozoic formations in India in gene¬ 
ral, it wdll be seen clearly that they already show a development according to two 
different types, wliich I indicated in the introduction as the characteristic of the 
1 Mallet: Mem. Geol. Surv. of India, XI. 
2 MentioiK'd alivady by Hooker, Himalayan Journals, Vol. II, p. 24. 
^Oldbam; Mem. Geol.Surv. of India, I; Medlicott ; ibid, Vll. 
■* Theobald : Mem. Geol, Surv. of India, X. 
® S. Kurz: Report on the vegetation of the Andaman Islands quoted from memory, as my copy 
of the book in question has been mislaid. [The quotation is a mistake: only tertiary and eruptive 
rocks occur in the .\ndamaus.—H. B. M.]. 
