420 N. H. DARTON STRATIGRAPHY OF THE BLACK HILLS, ETC 



of tints — gray, yellow, green, pink, and lilac — while gypsum and brown 

 earthy limestones are common. Gypsum occurs in small, lens-shaped 

 deposits, mainly in connection with limestones." 



The top of the upper Wyoming beds is marked by a sandstone 15 to 

 25 feet thick, varying from compact and massive to thin bedded and 

 friable, of which the lower 8 feet is usually brown, the middle 10 to 15 

 feet pink, and the upper 4 feet brown, all fine, delicately cross-bedded, 

 and ripple-marked. This stratum is very distinct, especially at its un- 

 conformable contact with the overlying Morrison, which " is somewhat 

 undulating." A typical section of the W}' , oming formations at Morri- 

 son, Colorado, is as follows : 



Upper Division 



Feet 



Sandstone, fine-grained, often massive, pink and brown ; persistent. . 15 to 25 

 Clays, bright-colored, gray, yellow, green, pink, and lilac ; gypsifer- 



ous and calcareous, especially at 40 feet below their summit 125 to 175 



Clays more arenaceous than above ; transitional in color, from grays 



above to prevailing brick reds below 150 to 200 



Sandstone and shale, alternating; brick red to pink; white dots; 



sandstones prominent 50 



Sandstones and shales. 60 



Shales, sandy and argillaceous, brick red, carrying narrow bands (3 



to 6 feet) of white crystalline limestone 75 



Lower Division 



" Creamy sandstone ; " quartzose; conglomeratic at base; two sandy 

 limestone bands in lower part; round ferruginous concretions near 

 top; forms prominent outcrop in valley between Archean and Da- 

 kota (average, 250 feet) 200 to 400 



Red beds ; conglomerates, sandstones, and shales, the last of minimum 

 development; color, red; outcrops, lofty spires and pinnacles and 

 towering masses of irregular shape 270 to 2,000 



I visited Morrison in 1901 in order to compare its section with those 

 which I had been studying in the Black hills and Bighorns. I found 

 the " creamy sandstone " series strongly suggestive of the Tensleep sand- 

 stone of the Bighorns and the top sandstones of the Minnelusa of the 

 Black hills. The overlying red shales begin abruptly and they are very 

 closely similar to the Opeche in aspect and relations. The limestone 

 bands have the character of the Minnekahta limestone, especially the 

 upper bed, which is 5 feet thick and lies, as stated by Eldridge, 70 feet 

 above the "creamy limestone," a position similar to that of the Minne- 

 kahta limestone in the northern part of the Laramie range, in eastern 

 Wyoming and elsewhere north and west. A careful search for fossils 

 yielded a few indistinct forms similar in appearance to the Bakewellia of 



