202 GEOLOGY OF THE BLACK HILLS. 



rliombic section, but are sometimes triangular or hexagonal. With the 

 exception of an occasional fracture each column or crystal continues to the 

 very summit. The sides are of various dimensions, but average from two 

 to four feet at the base. Tliey diminish upward in the same ratio with the 

 total colunm. Careful examination at the base shows that the columnar 

 structure is not continuous below the portion of the peak exposed to view. 

 The columns differ somewhat in size and position from those characteristic 

 of basalt. The latter are commonly referred to contraction in cooling, 

 occasionally combined perhaps with a concretionary action ; and they are 

 always formed perpendicular to a surface of cooling. In a dike they are 

 perpendicular to the walls, and in an ovei-flow to the atmospheric surface. 

 They are rarely of any great length, and frequently they extend but a part 

 of the way through the bed, ending irregularly in a structureless mass. In 

 the Bear Lodge we have columns over six hundred feet in length rising per- 

 pendicularly from a seemingly massive base. It is exceedingly difficult to 

 account for this as a result of cooling by comparison with any known basaltic 

 phenomena; and, indeed, Bear Lodge, in its shape and structure, appears not 

 to have been repeated elsewhere by Nature, but stands alone, unique and 

 mysterious. 



The strata from which this igneous column springs are not in the least 

 disturbed at the nearest points where they could be examined, about 50 or 

 75 feet from the base, but the sandstones for some distance are converted 

 into a compact white quartzite. 



The Little Missouri Buttes stand on the plateau of Dakota sandstone 

 about four miles west of Bear Lodge and near the divide between the head- 

 waters of the Little Missouri River and the Belle Fourche. They ai-e three 

 in number, occupying three angles of a triangle, and are said to be called 

 by the Indians "the buttes which look at each other." Though prominent 

 landmarks, they rise only between four or five hundred feet above their 

 base. They are about one-half or three-fourths of a mile distant from one 

 another, but they are so thoroughly covered around their bases with debris 

 that their intimate structure and relation could not well be determined. 

 The Cretaceous sandstone forming the floor of the surrounding plain could 

 not be ascertained to exhibit any disturbance or change of structure due to 



