But only above the
chalk (as far as we yet know) do we begin to find species identical
with those living now.
This in itself would prove a vast lapse of time. We shall have a
further proof of that vast lapse when we examine the chalk itself.
It is composed--of this there is now no doubt--almost entirely of the
shells of minute animalcules; and animalcules (I use an unscientific
word for the sake of unscientific readers) like these, and in some
cases identical with them, are now forming a similar deposit of mud,
at vast depths, over the greater part of the Atlantic sea-floor.
This fact has been put out of doubt by recent deep-sea dredgings. A
whole literature has been written on it of late. Any reader who
wishes to know it, need only ask the first geologist he meets; and if
he has the wholesome instinct of wonder in him, fill his imagination
with true wonders, more grand and strange than he is like to find in
any fairy tale. All I have to do with the matter here is, to say
that, arguing from the known to the unknown, from the Atlantic deep-
sea ooze which we do know about, to the chalk which we do not know
about, the whole of the chalk must have been laid down at the bottom
of a deep and still ocean, far out of the reach of winds, tides, and
even currents, as a great part of the Atlantic sea-floor is at this
day.
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