a aa ie 
gran 
Black Hill 
Falls, for important facilities in my 
F. V. Hayden on the Geology of Northeastern Dakota. 19 
elose grained and hard, that on breakin rock no trace o 
the fossil could be found. Iam secaeea however, that the 
rock is tilled with organic remains, but they. cannot now be sep- 
arated from the matrix so as to be identified. 
From Sioux Falls to the celebrated Pipestone quarry, the i 
tance is just 40 miles, measured with an odometer. Direc 
a little east of north. We passed over a similar andataaied 
prairie, with but one small tree along the route, and but one roc 
exposure, and that occurs about four miles south of the quarry. 
The rock is a very hard quartzite, composed largely of water- 
worn pebbles, quartz, jasper, small clay nodules, chalcedony ; 
some of the rock is a quartzose sandstone, other portions are 
fine grained siliceous rock. It lies in regular layers or beds, dip- 
ping “at an angle of about 5°, 30° S. of E* 
On reaching the source of the Pipestone creek, in the valley 
of which the Pipestone bed is located, I was surprised to see 
how inconspicuous a oa it is. Indeed, bad I not known of 
the existence of a rock in this locality so celebrated in this re- 
gion, I should aces passed it by almost unnoticed. A single 
glance at the red quartzites here, ussured me that these rocks 
were of the same age with those before soctiiaeie at James and 
Vermilion rivers, and at Sioux Falls. e layer of Pipestone 
is about the lowest rock that can be seen. It rests upon a gray 
quartzite, and there are about five feet of the same gray quart+ 
zite above it, which have to be removed with great labor be- 
fore the Pipestone can be secured. About 300 yards from the 
Pipestone exposure is an escarpment, or nearly vertical wall of 
variegated oe directly across the valley, Each 
end of the wall pas n view beneath the superficial cover- 
Sica of ae prairie. Tea is alte half a mile in length. About a 
this point is rome 50 feet. Note a treecan be seen; only a few 
we: ppishes growing among the rocks, There is a hittle stream 
of clear, pure water flowing from the rocks, with a perpendic- 
ular fall of about 30 feet, forming a beautiful cascade. The evi- 
dences of erosion were very marked, and the question arose— 
how could all the materials which must once have existed here 
joined on to these walls, have been removed, except by a stream 
much larger and more ‘powerful in its erosive action than the 
one at present flowing here? mee is a slight inclination of ac 
beds from 1° to 8°, about 15° 
About 200 yards oe of the quarry are five massive 
boulders, composed of a very coarse flesh-colored feldspathie 
ite, — much ike that which forms the nucleas of the 
 * Tam diy indebted to Col. Knox, commandant of Fort ” ee 
examinations, 
