CRETACEOUS AND TERTIARY FORMATIONS 



531 



Miles City, and it is known that these belong to the Lance for- 

 mation. The beds of No. 6 also contain the many brown, car- 

 bonaceous layers, so characteristic of the Lance formation in many 

 localities, as well as a number of coal beds, which are also found in 

 that formation in certain areas, as already shown. There would 

 seem to be seme ground, therefore, for including this member 

 with the underlying Lance beds rather than with the typical 



V '** 





Fig. 7. — The Fox Hills (A) and Lance (B) formations exposed on Hell Creek, 

 Montana. 



Fort Union, to which it bears little resemblance. If so included 

 the Lance formation in this region would have a thickness of about 

 400 feet. According to Brown there is an unconformity at its 

 base, which shows near the Cook ranch on Crooked Creek, and also 

 on Hell Creek. Neither of these points was visited by the writer, 

 and where the top of the Fox Hills was seen no evidence of a 

 long erosion interval was observed, though such may be present 

 in the localities above mentioned (Fig. 7). 



The Lance formation appears to grow thinner toward the north- 



