DISTRIBUTION AND GEOLOGIC SECTIONS 381 



To illustrate the lithological characters of these beds three sections 

 have been selected from widely separated localities. 



Sioux Fault Section 



The first one is the Sioux Fault section, which is the farthest east of 

 the eastern Jurassic exposures, with the exception of the Black hills : 



Cketaceous : 



Dakota conglomerate and sandstone. 



Jurassic : 



Feet 



1. Variegated marls and clays shading from yellow to dark maroon, 



with dinosaurian remains 38J 



2. Calcareous sandstone 2 



3. Bluish and yellowish marls, containing Brontasaurus at top and 



Morosaurus at base 22J 



4. Drab calcareous sandstone H 



5. Light colored clays and marls, with thin bands of sandstone 24 



6. Clays and marls varying from light gray to brown. 2'Sh 



7. Hard band of light gray clay 4£ 



8. Drab and greenish clays .... 22J 



9. Drab sandstone 2 



10. Yellow, greenish, and light brown marls shading into maroon in 



the upper portion 38j 



11. Gray sandstones 3 



1 2. Bluish gray clay 4 



13. Bluish and drab clays interstratified with yellowish bands 38| 



Total thickness of Freshwater beds 226 



14. Variegated clays and marls with bands of sandstone .' 43<] 



15. Yellowish sandstone 8-J 



16. Dark shale beds with remains of Baptanodon, Belemnites, Ostrea, 



Tancredia, Comtonectes, and a few Septeria 38J 



17. Yellowish sandstone 2\ 



18. Gray sandstone . . 5J 



19. Yellowish sandstone alternating with thin clay bands 6J 



20. Thin bedded gray sandstones with a few bands of clay h\ 



Total thickness of Marine series exposed 118 



Triassic not exposed. 



Freezeout Hills Section 

 Cretaceous : 



1. Dakota conglomerate. 

 Jurassic : 



Feet 



2. Drab marls and clays with a few thin bands of light colored sand- 



stone containing remains of Dinosaurs 55 



