birds, made when these rocks were in
the state of soft mud, and altogether several miles thick. He has a
great multitude of such facts before him, but they are all of this
character. Not one of them gives him the element of _time_. They
announce to him a succession of events, such as successive generations
of fishes and plants; but not one of them tells how long these
generations lived. The condition of the world was so utterly different
then, from what it is now, that no inference can be drawn from the
length of the lives of existing races, which are generally also of
different species. The utmost any man can say, in such a case, is, _I
suppose_, for there is no determinate element of time in the statement
of the problems, and so no certain time can appear in the solution.

Here is a problem exactly similar. A certain house is found to be built
with ten courses of hewn stone in the basement, forty courses of brick
in the first story, thirty-six courses in the second, thirty-two in the
third; with a roof of nine inch rafters covered with inch boards, and an
inch and a half layer of coal tar and gravel; how long was it in
building? Would not any school-boy laugh at the absurdity of attempting
such a problem? He would say, "How can I tell unless I know whence the
materials came, how they were conveyed, how many workmen were employed,
and how much each could do in a day? If the brick had to be made by
hand, the lumber all dressed with the hand-saw and jack-plane, the
materials all hauled fifty miles in an ox-cart, the brick carried up by
an Irishman in a hod, and the work done by an old, slow-going, jobbing
contractor, who could only afford to pay three or four men at a time,
they would not get through in a year. But if the building stone and sand
were found in excavating the cellar, if the brick were made by steam and
came by railroad, a good master builder, with steam saw and planing
mills, steam hoists, and a strong force of workmen, would run it up in
three weeks."

So our geologist ought to say; "I do not know either the source of the
materials of the earth's strata, nor the means by which they were
conveyed to their present positions; therefore I can not tell the time
required for their formation. If the crust of the earth was created
originally of solid granite, and the materials of the strata were ground
down by the slow action of frost and rain, and conveyed to the ocean by
the still slower agencies of rivers and