1868.] on Deep-sea Dredging s. 



193 



formation ; so that ive may be said to be still living in the Cretaceous 

 Epoch *. 



VIII. It can be scarcely necessary to point out in detail those various 

 important applications of the foregoing conclusions to Geological Science, 

 -which will at once occur to every Geologist who endeavours to interpret 

 the past history of our globe by the light of the changes it is at present 

 undergoing. But this Report would not be complete without some notice 

 of these. — In the first place, it may, I think, be considered as proved 

 that no valid inference can be drawn from either the absence or the scan- 

 tiness of Organic Remains in any unmetamorphosed sedimentary rock, 

 as to the depth at ivhich it ivas deposited. So far from the deepest 

 waters being azoic, it has been shown that they may be peculiarly rich 

 in Animal life. On the other hand, comparatively shallow waters may 

 be almost azoic, if their temperature be low or their currents be strong ; 

 and thus even littoral formations may show but few traces of the life that 

 might be abundant on a deeper bottom at no great distance. — ilgain, 

 it has been shown that two deposits may be taking place within a few 

 miles of each other, at the same depth and on the same geological horizon 

 (the area of one penetrating, so to speak, the area of the other), of 

 which the Mineral character and the Fauna are alike different, — that dif- 

 ference being due on the one hand to the direction of the current which 

 has furnished their materials, and on the other to the temperature of the 

 loater brought by that current. If our "cold area 5 ' were to be raised 

 above the surface, so that the deposit at present in progress upon its bot- 

 tom should become the subject of examination by some Geologist of the 

 future, he would find this to consist of a barren Sandstone, including frag- 

 ments of older rocks, the scanty Fauna of which would in great degree bear 

 a Boreal character (§ 11); whilst if a portion of our "warm area" 

 were elevated at the same time with the " cold area," the Geologist would 

 be perplexed by the stratigraphical continuity of a Cretaceous forma- 

 tion, including not only an extraordinary abundance of Sponges, but a 

 great variety of other Animal remains, several of them belonging to the 

 warmer Temperate region, with the barren Sandstone whose scanty Fauna 

 indicates a wddely different climatic condition, which he would naturally 

 suppose to have prevailed at a different period. And yet these two con- 

 ditions have been shown to exist simultaneously, at corresponding depths, 

 over wide contiguous areas of the sea-bottom ; in virtue solely of the fact 

 that one area is. traversed by an Equatorial and the other by a Polar cur- 

 rent f . Further, in the midst of the land formed by the elevation of the 



* I think it due to my valued Colleague to state that this hypothesis (which I myself 

 fully accept) entirely originated with him, having been foreshadowed in his first com- 

 munication to me on the subject (Appendix). 



t It may be said that the asserted existence of these Currents is a mere hypothesis, 

 until an actual movement of water in opposite directions has been substantiated. But, 

 as Prof. Buff has pointed out (p. 187, note), the existence of such deep currents is a 



