IGNEOUS INTRUSIONS IN THE BLACK HILLS 33 
and discolored by weathering. At the base of the tower the 
columns in most instances, except at the southeast corner, curve 
abruptly outward, and, at the same time, increase somewhat in 
size. On the west side they become nearly horizontal and are 
soon lost to sight beneath accumulations of débris. Near the 
base of the tower, just above the treetops, as seen in Fig. B, 
Plate III., the rock loses its columnar structure, becomes massive 
and breaks with an irregular fracture. On the sides of the tower 
there are a few places where the lower portions of individual 
prisms have fallen away, leaving the upper two or three hundred 
feet still in place. In such instances one has a good view of a 
section of the prisms, which are seen to be four, five or six-sided. 
Owing to the abrupt outward curvature of the columns at the 
west base of the tower, the fragments that have fallen from above 
have been thrown farthest out on that side and now form an 
extremely rugged talus in which fragments of huge columns lie 
piled in endless confusion one on another, suggesting the ruins 
of some mighty temple. 
As shown in the accompanying illustrations, the sides of the 
tower are nearly perpendicular. This fact is still more impres- 
sive in nature, especially when one stands at the base of the 
great prisms, each of which is an uniform column over 500 feet 
high, and looks upward. The strongest and most experienced 
mountain climber must pause when he has scaled the rugged 
cliffs which form the immediate base of the tower and gains the 
point where the individual prisms make their abrupt curve and 
ascend perpendicularly. Beyond that point no man has ever 
reached, and, it is safe to say, never will, unaided by appliances 
to assist him in climbing. 
To gain a comprehensive view of Mato Teepee and of its 
relations to neighboring cliffs and plateaus, one should go about 
two miles west from the tower and ascend to the top of the table- 
land which has been cut away to form the valley of the Belle 
Fourche. Standing on the border of this table-land which rises 
more than 1000 feet above the silvery thread marking the course 
of the river in the valley below, one is a little lower than the 
