MEDIAEVAL OR MESOZOIC TIMES. 



179 



their divisions on the whole appear to me the best possible. I have 

 changed the descriptions of Meek and Hayden slightly to make 

 them correspond more particularly with the geology of Nebraska. 



Divisions. 



Localities. 



to 



CO 



— . 

 CO ^ 



a* 



S 5 



Gray ferruginous and yellowish sand- 

 stone and arenaceous clays containing 

 massive molluscan, and reptilian fossils. 

 Maximum thickness, 500 feet. 



Fox Hills, near Long 

 Lake above Ft. Pierre 

 and along Big Horn 

 Mountains. Not in 

 Nebraska. 



P5 



CO 



« o 

 S ^ 



5 ° 



Dark grey and bluish plastic clays, also 

 containing massive fossils near the upper 

 part, also reptilian remains. Maximum 

 thickness, 700 feet. 



Middle nearly barren of fossils. Lower 

 Zone contains many massive chambered 

 shells. Dark bed of fine unctuous clay, 

 containing carbonaceous matter, with 

 veins and seams of gypsum, masses of 

 sulphuret of iron, small scales, fishes, 

 local, filling depressions in the bed below. 



Sage Creek. Chey- 

 enne and White River 

 above the Bad Lands. 

 Not in Nebraska. 



Fort Pierre out to 

 Bad Lands, down the 

 Missouri to Gr't Bend . 



Knox County on Ni. 

 obrara and on upper 

 Republican. 



