LANCE FLORA OF EASTERN WYOMING 91 



Fox Hills sandstone: Thickness 



Sandy shale full of Corbicula cytheriforinis? and Corbicula subelliptica var. 7no- *^/^" 



reauensis 0.5-1.0 



More or less carbonaceous shale 15.0 



Soft, massive gray sandstone with many brown concretions 25.0 



Gray sandstone and sandy shale with bands of sandstone containing Fox Hills 



fossils about 150.0 



Cross-bedded, ripple-marked, reddish-brown sandstone with irregular base 8.0-10.0 



Massive, soft, buff sandstone with many large and indurated masses and an abun- 



dant Fox Hills fauna 100.0 



Total Fox Hills about 300 



Pierre shale with only the top exposed 



Lance Formation 



As exposed in the Lance Creek area, v^^hich is its designated type locality, the 

 Lance formation consists of about 2600 feet of dull-gray sandy shales alternating 

 irregularly with lenticular, Hght-colored sandstones and thin Hgnite beds. Along 

 both Lance and Lightning creeks there are numerous good exposures which show 

 that individual units are very irregular, sandstones passing laterally into shales and 

 vice versa. Large, irregular concretions are prevalent at many horizons. The 

 massive sandstones are generally friable, though occasionally well cemented, and 

 are characteristically dull gray, weathering to light brown. The shaly beds are 

 generally dull gray or purplish gray, occasionally yellowish gray, and usually 

 weather to a somewhat lighter gray or pinkish gray. The lignite beds are thin, 

 discontinuous, and of poor quality. 



Although considerable time was spent in the field in search of a complete section 

 of the Lance to be measured, none of the sections examined was found suitable. 

 The following complete section was measured by Winchester and Barnett ^ in a 

 traverse which cuts across the northwest corner of the region shown in figure 2 and 

 ends at the mouth of Lance Creek: 



Section of Lance Formation Measured between East Cow Creek Butte, Sec. 32, T. 38 N., R. 67 W., 

 and the Mouih of Lance Creek, Sec. 11, T. 39 N., R. 62 W., Wyoming 



Thickness 



" Fort Union " formation [part] : «» feet 



Shale, carbonaceous, dark, sandy with a few thin beds of sandstone 200.0 



Shale, dark, carbonaceous 40.0 



Lance formation: 



Sandstone, yellowish, friable [may be "Fort Union"], with some light shale (bone 

 fragments at 90 feet below top; Triceratops skull at 180 feet below top; shells 



at 229 and 250 feet below top) 320.0 



Shale, sandy, with some hard brown, slightly carbonaceous bands and friable 



sandstone 147.0 



Sandstone, massive, friable; shells at base [identified by T. W. Stanton]: 

 Campeloma multilineata Meek and Hayden Unio sp. 



Sphserium sp. Viviparus? sp 47.0 



Tulotoma thompsoni White 



Sandstone, shaly, concretionary 3.0 



Sandstone, massive, yellowish brown, friable; Trachodon skeleton at base 30.0 



Shale, dark bluish gray, slightly carbonaceous 7.0 



Shale, sandy 5.5 



' Winchester, D. E., U. S. Geol. Surv. Bull. 471, 477, 1912. 



