of that peculiar region.

Prof. J.E. Todd, State Geologist, in his "Preliminary Report on the
Geology of South Dakota," gives an interesting "Historical Sketch of
Explorations" in his state, beginning with the expedition of Captains
Lewis and Clark to the upper Missouri regions in 1804-6 to explore that
portion of the recent Louisiana Purchase for the government and notify
the Indians of the transfer; and including all other important
expeditions since that time down to his own official tour of the Black
Hills and Bad Lands in 1894. His own descriptions are so concise and
graphic as to invite quotation. Of the Hills he says:

"The Black Hills have an area of five-thousand square miles of a rudely
elliptical form with its major axis, approximately, north-northwest.
Most of this area lies within our state. The true limit of the Hills is
quite distinctly marked by a sharp ridge of sandstone, three hundred to
six hundred feet in relative height, which becomes broader and more
plateau-like towards the north and south ends. This ridge is separated
from the higher mass of hills within by a valley one to three miles in
breadth, which is known as the Red Valley, from its brick-red soil, or
the 'race course,' which name was given it by the Indians because of its
open and smooth character, affording easy and rapid passage around the
Hills. The junction of the outer base of the Hills with the surrounding
table lands has an altitude of three thousand, five hundred to four
thousand feet. Within this Red Valley one gradually ascends the outer
slope of the Hills and soon enters, at an altitude of four thousand five
hundred or five thousand feet, the woody portion of the region. This
outer slope varies greatly in width and is underlaid by older
sedimentary rocks, cut in almost every direction by narrow deep cañons.
This feature covers nearly the whole of the western half of the Hills