328 SCIENTIFIC RECORD FOR 1882. 



•which organic remains appear for the first time. These forms are Cam- 

 brian, and are compared with the Potsdam of North America. 



The late publications of its geological survey enable us to arrive at 

 some general views with regard to the Eozoic rocks of India. In the 

 peninsular region of that country we find, stretching from Ceylon to 

 the mouth of the Ganges, a broad area, almost unbroken, of granitoid 

 gneissic rocks, having the general lithological characters of the Lauren- 

 tian, and in many parts accompanied by crystalline limestones, whose 

 mineralogical resemblances to those of our older gneissic system are 

 well known. The Bundelkhand gneissic area, lying a little to the north- 

 west of the great belt, is conjectured by the Indian survey to be distinct 

 from and older than the latter. To these gneisses succeed a great un- 

 conformable series of what are described as transition or submetamor- 

 phic strata. These include quartzites, crystalline limestones, jasper-like 

 rocks, which, in some cases at least, have the composition of petrosilex 

 and are porphyritic ; beds of specular iron-ore, hornblendic and mica- 

 ceous schists, sometimes with garnet, staurolite, and andalusite. It is 

 probable, as supposed by the Indian geologists, Medlicott and Blanford, 

 that these transition rocks include two or more distinct groups. They 

 are of great but undetermined thickness. 



To these succeed what is called the Yindyhan series, which, though 

 generally unconformable, seems, in some parts of its wide distribution, 

 to exhibit such transitions from the series just described as to lead to 

 the conjecture that some of the strata included in the former are really 

 parts of the lower division of the Vindyhan series, to wiiich is assigned! 

 a minimum thickness of 2,000 feet. It includes limestones, quartzites, 

 argillites, and, in some parts, crystalline schists, recalling some of those 

 referred to the older transition series. It contains diamonds, of which 

 it has been conjectured to be the i)arent rock. The upper division of 

 the Vindyhan series is supposed to be unconformable to the lower, and 

 has a thickness of 20,000 feet, consisting of sandstones, limestones, and 

 argillites. No organic remains have as yet been observed anywhere in 

 this great series, which is consequently classed by the Indian survey 

 with Azoic rocks. It is well argued that such a great succession of 

 varied sediments would seem to offer the conditions for the preservation 

 of the remains of ordinary Paleozoic life, had such existed in the wide 

 Vindyhan area. This series suggests a comparison with the Sinisian 

 rocks in northern China, lying below the Cambrian (Potsdam) beds. 

 In peninsular India the Vindyhan is unconformably overlaid by the 

 Gondwana system, the base of which is upper Paleozoic. While these 

 ancient Vindyhan rocks of the peninsula are very little disturbed, we 

 find in northern or extra-peninsular India, to the north of the great 

 Indo Gangetic plain, a mountain-region in which even the Tertiary 

 strata bear evidence of the great disturbing forces that were displayed 

 in the elevation of the Himalayas. The gneissic rocks of this region 

 are distinguished from the reddish syenitic gneisses of the peninsula by 



