and stunted heath,
In broken volumes cast?
At sunrise, as by northern blast
The pillar'd smoke is roll'd away.
Fled all that cloud of Saxon war.
In headlong disarray."
* * *

CHAPTER XXI.

"He who, with pocket hammer, smites the edge
Of luckless rock or prominent stone, disguised
In weather stains, or crusted o'er by nature
With her first growths--detaching by the stroke
A chip or splinter, to resolve his doubts;
And, with that ready answer satisfied,
The substance classes by some barbarous name.
And hurries on."--WORDSWORTH.

In the course of my two visits to Miss Dunbar, I had several
opportunities of examining the sand-wastes of Culbin, and of registering
some of the peculiarities which distinguish the arenaceous sub-aerial
formation from the arenaceous sub-aqueous one. Of the present surface of
the earth, considerably more than six millions of square miles are
occupied in Africa and Asia alone by sandy deserts. With but the
interruption of the narrow valley of the Nile, an enormous zone of arid
sand, full nine hundred miles across, stretches from the eastern coast
of Africa to within a few days' journey of the Chinese frontier: it is a
belt that girdles nearly half the globe;--a vast "ocean," according to
the Moors, "without water." The sandy deserts of the rainless districts
of Chili are also of great extent: and there are few countries in even
the higher latitudes that have not their tracts of arenaceous waste.
These sandy tracts, so common in the present scene of things, could not,
I argued, be restricted to the recent geologic periods. They must have
existed, like all the commoner phenomena of nature, under every
succeeding system in which the sun shone, and the winds blew, and
ocean-beds were upheaved to the air and the light, and the waves threw
upon the shore, from arenaceous sea-bottoms, their accumulations of
light sand. And I was now employed in acquainting myself with the marks
by which I might be able to distinguish sub-aerial from sub-aqueous
formations, among the ever-recurring sandstone beds of the geologic
deposits. I have spent, when thus engaged, very delightful hours amid
the waste. In pursuing one's education, it is always very pleasant to
get into those _forms_ that are not yet introduced into any school.

One of the peculiarities of the sub-aerial formation which I at this
time detected