SQUARE BUTTE. 



401 



to the Colorado uroiip of tlie Cretaceous i)eri()(l. In the vicinity of tlie 

 hutte thi-s tal)lehin(l is deeply trenched l)y the Arrow river and its trihu- 

 tar^^ streams, and in consecjuence it forms locally a hroken country, 

 affording excellent geologic sections and typical '' hadlands " scenery. 

 At the hase of the hutte three intrusive sheets of tlie dark igneous rock 

 mentioned hy Lindgren occur in these sediments. 



Ahove this flat, trenched tahleland the hutte rises ahruptly to a height of 

 1,700 feet ahove its pediment. The slopes, at first gentle, change quickly 

 to steeper declivities and terminate at the toj), on all sides, by a precip- 

 itous wall several hundred feet high. Only in a few j)laces is this escarp- 

 ment cut hy very small, narrow gulches, which ])ermit difficult ascent to 

 the to}). The summit is a nearly level area, ellii)tic in outline and nearly 

 one mile across in its greatest length. It is largel}^ covered by a dense 

 growth of small i)ine, with occasional park-like glades and openings. 



FiGCKE 3. — View of Square Butte from the Slopes of Palisade Butte. 



Tile (piite symtnetric form of the l)utte is rather remarkable. It pre- 

 sents from nearly every i)oint the appearance of a very short section of 

 a liuge cylinder resting on a low, broad, truncated cone. This regular 

 arrangement is interru|)ted only on the southwest side, where a short 

 tongue-like protrusion of the mass occurs. The facts which have been 

 stilted are shown on the map accom[)anying tlie j)revious article (page 

 393), while they are presented in greater detail on a larger scale in figure 

 4 of the present paper. Figure 3 gives also a view of the butt(; from Tali- 

 aade butte and shows well tlu; tongue-like protrusion. 



/ rs L A (•(•(> ij Ti (J f) n I a i .v. 

 A careful examination of tin; butte shows that it is composed entirely 

 of igneous rock. Above the sandstones of the tableland no sedimentary 



