172 JOURNAL OF THE PLYMOUTH INSTITUTION. 
connecting the present with past geological ages, some of the 
animal contents of the dredges being described as “closely allied to, 
and apparently descended from the Fauna of the early Tertiaries.” 
Similarly we have an almost startling evidence of continuity in 
terrestrial formation afforded in Dr. Wyville Thomson’s interesting 
essay on “The Continuity of the Chalk formation,” wherein 
the author seems to have proved (against some objections of 
Murchison and Lyell) that “the chalk of the Cretaceous period and 
the chalk-mud of the modern Atlantic are substantially the same. 
There can be no doubt that we have forming at the bottom of the 
present Ocean a vast sheet of Rock which very closely resembles 
chalk ; and there can be as little doubt that the old chalk—the 
cretaceous formation which in some parts of England has been 
subjected to enormous denudation and which is overlaid by the 
beds of the tertiary series, was produced in the same manner, 
and under closely similar cireumstances—and not the Chalk only, 
but most likely all the great limestone formations. In almost the 
whole of these, the remains of FORAMINIFERA are abundant, some of 
them apparently specifically identical with living forms.”* Im- 
portant facts relating to Physical Geography have also been placed 
beyond doubt in these Deep-Sea Researches.t ‘ We found,” says 
Dr. Thomson, “that, in these two areas of the North Atlantic, 
(which freely communicate with each other, and are in immediate 
proximity,) two entirely different conditions of climate exist at all 
depths below the immediate surface, where, indeed, they differ but 
slightly. In the Faéroe Channel at a depth of 500 fathoms the 
bottom temperature averaged 1° centigrade, while at the same depth 
in the Atlantic the minimum index stood at 6° cent., a difference of 
7 degrees cent., nearly 13° Fahrenheit.” { Truly there is no finality 
* “Depths of the Sea,” page 470. + Ibid, page 307. 
{ Instances of glacial currents were adduced at the British Association 
meeting at Belfast. Dr. Carpenter exhibited a sectional map of the sea 
between Nova Scotia and Bermuda, showing isothermal lines. These lines 
were tilted up at the Western end, indicating the existence of a cold current 
between the American Coast and the Gulf Stream. This tilting up was 
interpreted by Dr. C. as due to the earth’s rotation, combined with the fact 
that this cold stream flows from North to South. A similar phenomenon 
was mentioned as found off the East Coast of Japan, where there exists a 
cold aqueous band between the Japan current and the land. On the Dogger 
Bank there is also a difference of 15° Fahrenheit in five fathoms. Mr. Gwin 
Jefferies thus explains why Arctic shells had been dredged on the Dogger 
Bank ! 
