tlantic Ocean, between Ireland and Newfoundland,
made in H.M.S. Cyclops. Published by order of the Lords
Commissioners of the Admiralty, 1858." They have since
formed the subject of an elaborate Memoir by Messrs. Parker
and Jones, published in the Philosophical Transactions for
1865.

The result of all these operations is, that we know the contours and the
nature of the surface-soil covered by the North Atlantic, for a distance
of seventeen hundred miles from east to west, as well as we know that of
any part of the dry land.

It is a prodigious plain--one of the widest and most even plains in the
world. If the sea were drained off, you might drive a wagon all the
way from Valentia, on the west coast of Ireland, to Trinity Bay, in
Newfoundland. And, except upon one sharp incline about two hundred miles
from Valentia, I am not quite sure that it would even be necessary to
put the skid on, so gentle are the ascents and descents upon that long
route. From Valentia the road would lie down-hill for about 200 miles
to the point at which the bottom is now covered by 1700 fathoms of
sea-water. Then would come the central plain, more than a thousand
miles wide, the inequalities of the surface of which would be hardly
perceptible, though the depth of water upon it now varies from 10,000
to 15,000 feet; and there are places in which Mont Blanc might be sunk
without showing its peak above water. Beyond this, the ascent on the
American side commences, and gradually leads, for about 300 miles, to
the Newfoundland shore.

Almost the whole of the bottom of this central plain (which extends for
many hundred miles in a north and south direction) is covered by a fine
mud, which, when brought to the surface, dries into a greyish-white
friable substance. You can write with this on a blackboard, if you are
so inclined; and, to the eye, it is quite like very soft, greyish chalk.
Examined chemically, it proves to be composed almost wholly of carbonate
of lime; and if you make a section of it, in the same way as that of the
piece of chalk was made, and view it with the microscope, it presents
innumerable Globigerinae embedded in a granular matrix.

Thus this deep-sea mud is substantially chalk. I say substantially,
because there are a good many minor differences; but as these have no
bearing on the question immediately before us,--which is the nature of
the Globigerinae of the chalk,--it is unnecessary to speak of th