ance containing recent shells in
Chili, or anywhere on the western coast of South America, naturally led
Mr. Darwin to the conclusion that "where the bed of the sea is either
stationary or rising, circumstances are far less favorable than where
the level is sinking to the accumulation of conchiferous strata of
sufficient thickness and extension to resist the average vast amount of
denudation."[261] An examination of the superficial clay, sand, and
gravel of the most modern date in Norway and Sweden, where the land is
also rising, would incline us to admit a similar proposition. Yet in
these cases there has been a supply of sediment from the waste of the
coast and the interior, especially in Patagonia and Chili. Nevertheless
wherever the bottom of the sea has been continually elevated, the total
thickness of sedimentary matter accumulating at depths suited to the
habitation of most of the species of shells can never be great, nor can
the deposits be thickly covered by superincumbent matter, so as to be
consolidated by pressure. When they are upheaved, therefore, the waves
on the beach will bear down and disperse the loose materials; whereas if
the bed of the sea subsides slowly, a mass of strata containing
abundance of such species as live at moderate depths may increase in
thickness to any amount, and may extend over a broad area, as the water
gradually encroaches on the land. If, then, at particular periods, as in
the Miocene epoch, for example, both in Europe and North America,
contemporaneous shelly deposits have originated, and have been preserved
at very distant points, it may arise from the prevalence at that period
of simultaneous subsidence throughout very wide areas. The absence in
the same quarters of the globe of strata marking the ages which
immediately succeeded, may be accounted for by supposing that the level
of the bed of the sea and the adjoining land was stationary or was
undergoing slow upheaval.

How far some of the great violations of continuity which now exist in
the chronological table of fossiliferous rocks, will hereafter be
removed or lessened, must at present be mere matter of conjecture. The
hiatus which exists in Great Britain between the fossils of the Lias and
those of the Magnesian Limestone, is supplied in Germany by the rich
fauna and flora of the Muschelkalk, Keuper, and Bunter Sandstein, which
we know to be of a date precisely intermediate; those three formations
being interposed in G