d extends southward to North Africa; while, eastward, it appears in
the Crimea and in Syria, and may be traced as far as the shores of the
Sea of Aral, in Central Asia.

If all the points at which true chalk occurs were circumscribed, they
would lie within an irregular oval about 3,000 miles in long
diameter--the area of which would be as great as that of Europe, and
would many times exceed that of the largest existing inland sea--the
Mediterranean.

Thus the chalk is no unimportant element in the masonry of the earth's
crust, and it impresses a peculiar stamp, varying with the conditions
to which it is exposed, on the scenery of the districts in which it
occurs. The undulating downs and rounded coombs, covered with
sweet-grassed turf, of our inland chalk country, have a peacefully
domestic and mutton-suggesting prettiness, but can hardly be called
either grand or beautiful. But, on our southern coasts, the wall-sided
cliffs, many hundred feet high, with vast needles and pinnacles standing
out in the sea, sharp and solitary enough to serve as perches for the
wary cormorant, confer a wonderful beauty and grandeur upon the chalk
headlands. And, in the East, chalk has its share in the formation of
some of the most venerable of mountain ranges, such as the Lebanon.

What is this wide-spread component of the surface of the earth? and
whence did it come?

You may think this no very hopeful inquiry. You may not unnaturally
suppose that the attempt to solve such problems as these can lead to no
result, save that of entangling the inquirer in vague speculations,
incapable of refutation and of verification.

If such were really the case, I should have selected some other subject
than a "piece of chalk" for my discourse. But, in truth, after much
deliberation, I have been unable to think of any topic which would so
well enable me to lead you to see how solid is the foundation upon which
some of the most startling conclusions of physical science rest.

A great chapter of the history of the world is written in the chalk. Few
passages in the history of man can be supported by such an overwhelming
mass of direct and indirect evidence as that which testifies to the
truth of the fragment of the history of the globe, which I hope to
enable you to read, with your own eyes, to-night.

Let me add, that few chapters of human history have a more profound
significance for ourselves. I weigh my words well when I assert, that
the man w