30 USIRAIGIL, Cy LLOSSIGILIL 
the dome, radiate from its center and, with one exception, are 
active only during wet weather. At the head of a deep, wooded 
gorge which leads northward from near the center of the uplift, 
there is a small spring from which flows a perennial rivulet. A 
view looking down this channel is shown in Fig. B, Plate I. The 
rock forming the cliffs is purple limestone and shows the char- 
acter of the zigzag escarpment that Newton compares with the 
torn edges of the paper through which a pencil has been forced. 
An examination of the bottoms of the drainage channels on 
the summit and sides of the Little Sun Dance dome, and of the 
débris with which they are partially filled, failed to reveal even 
a fragment of igneous rock.* 
The most interesting facts connected with the geology of the 
Little Sun Dance dome are, that the rocks were elevated by an 
extremely local force acting from below upward, and that the 
strata which suffered deformation were not fractured, or sensibly 
metamorphosed, during the process. The absence of fractures 
in the crown of the dome, as well as the vast amount of erosion 
which is known to have taken place in the region in which it is 
situated, show that the bending of the rocks must have taken 
place under a great weight of superincumbent strata. 
Sun Dance lill—vVhis hill is not only higher and larger than 
the one just described, but differs from it widely in its topo- 
graphic form. As seen from Little Sun Dance, it represents a 
bold scarp to the west and declines more gently and with many 
undulations in other directions. The western scarp (Fig. A, Plate 
{I) is composed of plutonic rock and has steep talus slopes at 
its base. The flanks of the hill, especially on the east, are com- 
posed of Red Beds, somewhat upturned. These strata extend 
entirely about the central core of intruded rock and slope away 
from it at low angles in all directions. 
A geologist on visiting Sun Dance hill, after examining its 
smaller neighbor, would say at once that the two uplifts are very 
similar in many ways. In Sun Dance hill the intruded rock was 
*This hill is marked as igneous on the map accompanying Newton’s report on the 
geology of the Black Hills. 
