Prof. W. Thomson on the Depths of the Sea. 117 



extending southwards towards the Azores. The result of the 

 examination of the soundings was that the bottom in all cases 

 consisted of a fine calcareous mud, of countless myriads of the 

 shells of a Rhizopod, Glohigerina^ and of some very peculiar 

 bodies, which have been called Coccoliths and Coccospheres. 

 In the meantime, naturalists were examining the microscopic 

 structure of the white chalk ; and they found it to consist of 

 fine calcareous particles, Glohigerince and other Foraminifera, 

 and Coccoliths and Coccospheres. The structure of the chalk 

 was, in fact, identical with that of the chalk-mud of the At- 

 lantic. One might have thought that these deep-sea soundings 

 should have settled the question of the existence of life in the 

 depths of the ocean ; but they were all open to the objection 

 that the Glohigerince and other organisms could not be shown 

 to be absolutely living, and it was conceivable that they might 

 have lived nearer the surface, and have sunk to the bottom 

 after death. 



All over the "warm area," our dredge brought up little else 

 than the Globigefina-mud — not now, however, pure. The 

 dredge brought up about a hundredweight at a haul. On one 

 occasion, a little way to the south of the Faroes, it brought 

 up, mixed with the mud, about forty sponges, living, with the 

 delicate and exquisitely formed spicules suspended in the 

 transparent sarcode. Most of these sponges had long and 

 venerable beards of flint, spreading in all directions through 

 the chalk-mud. These beards brought up, entangled in them, 

 small clams, starfishes, and minute crustaceans ; and among 

 the mud were scattered the shells of the beautiful and well- 

 known Pteropods of the Gulf-stream. 



There can be no doubt whatever, indeed it is admitted by 

 all microscopists, that chalk is now being formed in the depths 

 of the Atlantic ; but an idea which suggested itself to us even 

 before we proposed our cruise has now ripened into a convic- 

 tion, that it is not only chalk which is being formed, but the 

 Chalk — the chalk of the Cretaceous period. There is one 

 abyss in the Atlantic in which the Himalaya Mountains might 

 lie with the waves rolling over them unbroken ; and there is 

 no direct evidence that oscillations have taken place in the 

 north of Europe or in North America since the deposition of 

 the earlier Tertiaries, beyond 1500 feet; in fact there is a 

 very strong presumption that the main features of the contour 

 of the crust of the earth have altered but little since the com- 

 mencement of the Mesozoic period, and that the great depres- 

 sions, the Atlantic, the Pacific, and the Antarctic Oceans, are 

 due to causes which acted even before that very remote epoch. 

 There have been constant minor oscillations ; but the beds 



