422 O. B. HOPKIXS STRUCTURAL FEATURES OF PLAINS OF ALBERTA 



The}' form a compact group of hills about one mile long by one-half 

 mile broad which rise a few hundred feet above the plains. Their su- 

 perior altitude has caused them to be eroded into typical bad-land topog- 

 raphy, exposing admirably the strata of which they are composed. 



The strata belong to the Pale Beds, the upper division of the Belly 

 Eiver formation, of Middle Montana age, and consist of a series of inter- 

 bedded sands, sandy clays, and lignitic clays with ironstone bands. 



The beds show a prevailing dip of about 30 degrees to the north-north- 

 east and a general strike varying from north 80 to 110 degrees east. At 

 many places the strike and dip is modified by slumping, which adds to 

 the apparent intensity of the deformation. 



Figure 3. — Sketch Map shoictug geologic Stnictiire of Jilitd Buttes 

 Sections 19 and 20, township 33 north, range 4 west of 4th meridian, Alberta. 



The same series of beds are repeated several times by the miniature 

 folds and thrust faults which run through the hills in a general east-west 

 direction. Sufficient work has not been done to map the details of the 

 structure accurately, and as figures 5-10 illustrate the intensity of the 

 faulting, folding, and crumpling I shall not attempt to describe it in 

 detail. That the same series of beds are duplicated is obvious from a 

 study of the outcrops and from the fact that only the upper division of 

 the Belly Eiver formation is involved, as stated above. 



A noteworthy feature of this supposed uplift is the general absence of 

 dips in any direction other than to the north. The fact that the hills 

 show only prevailing north dips caused them to be considered the north 

 limb of an uplift; but there are no complimentary east, south, or west 



