146 
PROF. T. RUPERT JONES-ORIGIN AND 
sands, and shingle at the same time ; just as in that diagram- 
section of the North Atlantic we see a broad marginal plateau off 
the Irish coast, at first littoral and very shallow for about 60 
miles, then for nearly 200 miles with a varying depth down to 500 
fathoms; then a rather steep slope into the abyssal depths, which, 
varying from 1700 to 2400 fathoms, continue for about 1900 miles, 
when a gentle slope rises up for about 300 miles to the plateau, 
180 miles wide, with shallow water off Newfoundland. The 
marine life found at these several depths, and in many seas, both 
near land and in mid-ocean, is now fairly well known; and geolo¬ 
gists can compare oozes, silts, and sands, with marls, muds, and 
other “rocks,” and the fossils from different strata with the known 
creatures brought up by dredge, trawl, or sounding-line in various 
oceanic areas. The geological application of our knowledge of 
deep-sea forms is treated in a masterly manner by Professor 
Prestwich in his “Anniversary Address ” to the Geological Society 
in 1871.* 
The late Mr. R. A. C. Godwin-Austen was among the first to work 
out the geography and hydrography of the Cretaceous Period: his 
views as to the distribution of land and water at that distant time 
are given in a paper read before the Geological Society in 1855.f 
A gulf or relatively small sea, where now Southern Europe is, 
remained after the post-Jurassic changes, and this increased north¬ 
ward, with Purbeck-Wealden estuaries and lakes, until it was the 
Neocomian shallow sea; and the area still sank and the sea widened, 
overlapping and burying the remnants of its old shingle-banks and 
sand-shoals in new deposits time after time, until the thick Gault 
and its sandy equivalents and succeeding beds were formed, oscilla¬ 
tions of the land limiting the successive formations, as the relative 
level of land and sea was interfered with. Then a steady and 
long-continued subsidence of the region went on until neither tide 
nor storm could shift the sand and shingle of the shores into mid¬ 
ocean, where only wind borne volcanic dust, and fine mud and the 
finest sand could be carried by ocean-currents to mingle with the 
calcareous microzoa which mainly constituted the deep-sea deposit 
there. Thus was the Chalk-marl formed, with occasional chemical 
precipitations, perhaps, and certainly local developments of marine 
life, either as abundant Sponges or limited groups of Molluscs, to 
originate thin beds of different consistence and aspect (Totternhoe 
Stone and Chalk-rock). After a time—a long time—even the 
argillaceous material ceased to be brought to the inner expanse 
of the widening ocean; and Eoraminifera, sponge-spicules, and 
coccoliths supplied the chief material of the soft ooze of the sea-bed, 
on which the Echinoderms and Molluscs of the period existed. 
At this phase of its existence the Cretaceous Ocean, or great 
Chalk Sea, had an east-and-west extension, with islands and 
archipelagos here and there, whilst there was probably much land 
along its northern border, and a great east-and-west Continent in 
* 1 Quart. Journ. Geol. Soc.,’ vol. xxvii. t Ibid* vol. xii, p. 68, etc. 
