Address to the Lincolnshive Naturalists’ Union. 265 
Keuper deposit, and at the same angle with it, appears a broad 
black band of rock, utterly different from the bed on which it lies. 
The Keuper marls are, as I have said, devoid of fossil 
remains, but this new deposit abounds, nay literally swarms, with 
them ; while, instead of marly deposits, the new strata consist of" 
fissile slaty shales, full of iron pyrites the token of exuberant life, 
and narrow bands of sand stone glittering with mica ; and, what 
adds to the wonder is, that, towards the base of this deposit, 
there lies a thin band of rock, not more than an inch in thickness, 
composed entirely of fish remains, bones, scales, teeth, and 
coprolites, pressed down into a hard solid mass; while a similar 
bed, scarcely as thick, occurs a little higher up. And how can 
all this have come about ? © 
To understand it we must know something of the world we 
live on. | 
Originally a vast nebulous mass, which gradually condensed, 
it is now (as generally accepted), a thin crust, some 25 miles 
thick at the most, resting on a molten fluid substratum, under 
which (as some think), lies a solid rigid core. Now a thin crust 
over a fluid cannot be stable, and the surface therefore of our 
globe is for ever changing, rising here and sinking there; rising 
in parts where denudation makes it thinner, and sinking in 
regions where, through volcanic action, or the pouring on of the 
débris of large rivers, and other similar causes, matter is being 
piled up and the strata thickened. 
And, in the region we are considering, action of this latter 
kind had taken place. The older strata had begun to sink, and, 
by degrees, the waters of a great ocean, coming up from the south 
over France, were let in upon them. ‘The inland lake became an 
arm of the Liassic sea, and the Rhcetic beds were formed. 
It must not .be supposed, however, that all this took place 
suddenly. It was the result of no convulsion of nature, no rending 
of the rocks and inrush of the sea, but it came about quietly and 
imperceptibly, occupying as much time, probably, as would be 
necessary for so great a change in our own days. First, as the 
