THE CARBONIFEROUS PLATEAU. 



11' 



are to be found in the deeper of the canons. On Inyan Kara Creek, and 

 especially on Redwater Creek and Heron Creek, they are readily 

 examined The accompanying- ideal section, running from the Red Valley 

 near Inyan Kara eastward across the pla- 

 teau to Custer Peak, a distance of thirty 

 miles, though only approximate in its de- 

 tails, will give a tolerably correct idea of wwdo^g 



2 2"^ 2 ° a 



Nearly the whole of the northern part ££lg ^«>3 



the structure of the mesa at this point 

 Nearly the whole of the northeri 

 of the plateau bears at the surface either the 

 silicious or the gray limestone (Nos. 2 and % 

 3 of the general section), and of the two the 

 gray limestone is more prominently ex- 

 posed. Crook Tower consists probably of 

 the gray limestone with a capping of the 

 silicious, and fragments brought from its 

 body are filled with Sjpirifera Rocky -montana. 

 Considerable portions of the limestones have 

 been removed by erosion from the surface 

 of the plateau and a greater amount at the 

 east than at the west. The silicious lime- 

 stone rarely appears in the cliff at the east, 



a fcdcd 



e o o -! 





1D o| 



- on w CD 



9 



3 



pi 



0) 



O 



a" 



o 



a 



=5. o e'a CD <J 



S. W 5 "-5 P n, CO 



H ^ ^ P C: ,_, 



p g p g g. hd 



and never with its full thickness, and there -^ §.<!«£ If 8. 



© t p £3 ? C* 



P 



5. _ .o 



£.83 



T 

 =<1 



&«=;? o 



83 „„ 



• &? 

 ® 2 



GO 



e 

 B 



9 



G> 

 pJ 



w 



are considerable areas covered by the gray 



limestone exclusively. Opportunities for the o-g^o 



full measurement of either member are rare 



and are confined to the deep canons — 



especially to the cailons of streams running 



eastward. The upper valleys of Inyan 



Kara and Redwater Creeks, running from 



south to north, are not of very great depth, 



and the edges of the bordering rocks are 



commonly in whole or part hidden in their sloping soil-covered sides. 



On 



the eastern side of the plateau, however, the northward flowing Spear- 



