On the next page is the ground plan of the Temple of Isis, about
twenty-five hundred feet high. The first story is about a thousand
feet; the second, three hundred and fifty feet; the third, one
hundred and fifty feet; the fourth, five hundred feet; and the
fifth, five hundred feet. The finish at the top shows as a heavy
crumbling wall, probably one hundred feet or more high. How the mass
seems to be resisting the siege of time, throwing out its salients
here and there, and meeting the onset of the foes like a military
engineer.

The pyramidal form of these rock-masses is accounted for by the fact
that they were carved out from the top downward, and that each
successive story is vastly older than the one immediately beneath
it. The erosive forces have been working whole geologic ages longer
on the top layer of rock than on the bottom layer; hence the topmost
ones are entirely gone or else reduced to small dimensions. But what
feature or quality of the rock it is that lends itself so readily or
so inevitably to these architectural forms--the four square
foundations, the end pilasters and balustrades, and so on--is to me
not so clear. The peculiar rectangular jointings, the alternation of
soft and hard layers, the nearly horizontal strata, and other
things, no doubt, enter into the problem. Many of these features are
found in our older geology of the East, as in the Catskills
--horizontal strata, hard and soft layers alternating, but with the
vertical jointing less pronounced; hence the Catskills have few
canon-like valleys, though there are here and there huge gashes
through the mountains that give a canon effect, and there are
gigantic walls high up on the face of some of the mountains that
suggest one side of a mighty canon. In the climate of the Catskills