MOOK, STUDY OF THE MORRISON FORMATION IQl 



of the Lakota and passed through the following beds, probably all of 



which belong to the Morrison (Darton, 1904, 4) : 



Feet 



Pire clay, gray 3 



Sandstone, light gray, moderately hard 1% 



Pire clay 7V2 



Sandstone, gray, upper half very hard 4 



Shales, lead colored, soft at base 11 



Shale and fine sand 3 



Shale, bluish gray 18 



Sandstone, moderately hard 1 



Clay, bluish and purplish, hard below 20 



The Morrison formation in the Aladdin quadrangle has been described 

 by Darton and O'Harra (1905, 6). It is a thin but persistent deposit of 

 massive shale between the Sundance and Lakota formations. Its color 

 is generally a characteristic pale olive green, with 

 local bands of gray and maroon. In fresh ex- 

 posures some of the beds are darker and in some 

 localities portions of the deposit are black. "The 

 thickness is variable, owing to local unconformity 



mJj^J^ 



on its surface, and its measure is difficult to deter- pig. 63. — section nf the 



mine at most localities owing to talus and land- ^rm^hoic^ir^'or 'of 



slides along the base of cliffs of Lakota sandstone." coai mine at camin-ia, 



The shale includes thin beds of sandstone, most of T^yommy. 



T-i-^ . T TTiJ- 1 AT 11 Scale, 125 feet to 1 inch. 



which IS line-gramed and light m color. JNodules (Darton.) 



of hard clay occur in some of the beds. The for- 

 mation outcrops extensively along both slopes of the northern extension 

 of the Bear Lodge Mountains and outlying ridges; in the ridge between 

 Deer and Medicine creeks ; in the basins at the heads of Pine, Alum and 

 Hay creeks; in ridges north and south of Aladdin; and in the anticline 

 ea;St of The Forks. 



Darton and Smith (1904, 5) have described the Morrison formation 

 in the Edgemont quadrangle. In this quadrangle the Morrison consists 

 of massive shales and clays, partly light gray and partly red or maroon, 

 with occasional layers of fine-grained white sandstone. ^ West of Minne- 

 kahta the thickness is about 100 feet, but eastward, northwest of Cascade 

 Springs, the formation thins and dies out completely. Just west of 

 Cascade Springs the Lakota lies directly upon the Unkpapa sandstone. 

 The Morrison is exposed in the upper part of the slope at the base of 

 Lakota cliffs in the northern face of the hog-back westward. As the dip 

 is low and the formation is relatively thin, the outcrop is somewhat irregu- 

 lar. The formation is exposed in Hell and Falls canyons and in the 



