THE REGION U'.oi T GOLDEN. K7 



In tin- northern half these same peculiarities are again rael with, bul in 

 some particulars they are more strongly accented than in the southern. 

 The e are, the more sudden disappearance "I the hogback; the rapidity 

 with which the formation thins; and the marked crumpling, a hown in 

 their strikes, to which its beds have I >< -< ■ i j subjected withoul the overlying 

 strata being in the least affected. In dip the Dakota varies from 15 in its 

 more normal occurrence i>> vertical over the more disturbed, middle portion 

 of the field. 



Thi Ben — This formation completely disappears a shorl di tance north 



of Coon Gulch, and also ;it a poinl aboul opposite the middle "I the 

 first hogback north of Golden. The southern portion thins very gradually 



throughoul a distance of •">.', miles, while the disappearance of the "them 



member is completed in ;i little less than a mile. The Benton conform in 

 strike and dip to the Dakota, bul is overlain, after the disappearance of ih<; 

 Niobrara, l>\ successively higher strata of the Pierre aud Fox llill- forma- 

 tions as the center of the disturbed region is approached. 



The Niobrara. Tllis, Ylkl; 1 ] M • I '» 1 1 1 < >l I , I I i Ml | )| >< -;i I- <>lll\ IVulll ab0V6 ' I '» W 1 1 - 



ward, Inn it limits are found considerably t" the north and south <>i those 

 of the corresponding membi rs "I the older formations. In strike and * 1 1 1 > 

 it conforms with the Benton and Dakota, and, like them, in passing from 

 withoul inward, is overlain l>\ successive strata of the Pierre, though it. 

 is nowhere broughl in contacl with the higher member oi the Montana 

 group, 1 1 j * - Fox Hills. The disappearance of this formation i e pecially 

 well shown I >• it li in the north and south l>\ the physical character ol its 

 sediments: the upper, bright-yellow or Imtl, sandy measures, which often 

 form a well-marked outcrop, are firsl lost; then follows the destruction "I 

 the argillaceous middle pari of the series; and finally the prominenl ba al 

 limestones are themselves cut out. The disappearance occurs in the outh 

 only a shorl distance north "t Bear Creek, and in the north a quarter mile 

 north of Van Bibber < !reek. 



The Montana. — This group in strike conforms strictly with the overlying 

 Laramie, the basal sandstones of which afford a prominenl and reliable I ey 

 tn the relations "f these upper formations with the ones already considered. 

 The 'li|> of the component beds of the group, where all are present and in 

 normal occurrence, shows a gradual increase from l.Y to 90 as the distance 



