on the other; seeing in the next place that any particular spots on
which accumulations have occurred, have been constantly moving up and
down, and sometimes out of the reach of a deposit, and at other times
its own deposit broken up and carried away, it follows that our record
must be in the highest degree imperfect, and we have hardly a trace left
of thick deposits, or any definite knowledge of the area that they
occupied, in a great many cases. And mark this! That supposing even that
the whole surface of the earth had been accessible to the
geologist,--that man had had access to every part of the earth, and had
made sections of the whole, and put them all together,--even then his
record must of necessity be imperfect.

But to how much has man really access? If you will look at this Map you
will see that it represents the proportion of the sea to the earth: this
coloured part indicates all the dry land, and this other portion is the
water. You will notice at once that the water covers three-fifths of the
whole surface of the globe, and has covered it in the same manner ever
since man has kept any record of his own observations, to say nothing of
the minute period during which he has cultivated geological inquiry. So
that three-fifths of the surface of the earth is shut out from us
because it is under the sea. Let us look at the other two-fifths, and
see what are the countries in which anything that may be termed
searching geological inquiry has been carried out: a good deal of
France, Germany, and Great Britain and Ireland, bits of Spain, of Italy,
and of Russia, have been examined, but of the whole great mass of
Africa, except parts of the southern extremity, we know next to nothing;
little bits of India, but of the greater part of the Asiatic continent
nothing; bits of the Northern American States and of Canada, but of the
greater part of the continent of North America, and in still larger
proportion, of South America, nothing!