Geology by Submarine Researches. 321 



British Association, to which body I had the honour of pre- 

 senting a report on the subject, at the last meeting. 



When we examine the distribution and association of or- 

 ganic remains, in the upheaved beds of tertiary seas, we find 

 the zones of depth as evident as they are in the present ocean. 

 I have proved this to my own satisfaction, by a minute com- 

 parison of the newer Pliocene strata of Rhodes, where that 

 formation attains a great thickness, with the present state of 

 the neighbouring sea, and carrying on the comparison through 

 the more recent tertiaries with the more ancient, have found 

 indubitable evidences of the same phenomena. The strata 

 of the cretaceous system yield similar evidences, and doubt- 

 less, in all time, the element of depth exercised a most im- 

 portant influence in regulating the distribution of animal life 

 in the sea. If so, as our researches extend, we may hope 

 eventually to ascertain the probable depth, or, at any rate, 

 the region of depth, in which a given stratum containing or- 

 ganic remains was deposited. Every geologist will at once 

 admit, that such a result would contribute materially to the 

 history of sedimentary formations, and to the progress of 

 geological science. 



II. The number of species is much less in the lower zones 

 than in the upper. Vegetables disappear below a certain depth, 

 and the diminution in the number of animal species indicates 

 a zero not far distant. — This conclusion is founded on my 

 iEgean researches. Vegetables become fewer and fewer in 

 the lower zones ; and dwindle to a single species, — a nulli- 

 pora, at the depth of 100 fathoms. Although the lower 

 zones have a much greater vertical range than the higher, 

 the number of animal species is infinitely greater in the lat- 

 ter. The lowest region (the 8th) in the Mediterranean, ex- 

 ceeds in extent all the other regions together ; yet its fauna is 

 comparatively small, and at the lowest portion explored, the 

 number of species of testacea found was only eight. In the 

 littoral zone, there were above 150 species. We may fairly 

 infer, then, that as there is a zero of vegetable life, so is there 

 one of animal life. In the sea, the vertical range of animals 

 is greater than that of vegetables ; — on the land, the reverse 



