424 O. B. HOPKINS STRUCTURAL FEATURES OF PLAINS OF ALBERTA 



clips. This fact in itself makes the shape and extent of the supposed 

 uplift conjectural. 



Evidence of surficial N'ature of Disturbance 



There are many lines of evidence enumerated below, which lead to the 

 conclusion that the intense disturbance of the strata in this area is sur- 

 ficial in character; in fact, the only evidence of uplift is the presence, 

 locally, of steeply dipping, faulted, and folded strata. Such evidence is 

 conclusive so far as it does not run counter to all other evidence, as it 

 appears to do in this case. 



The supposed uplifts are located in every case on the outcrop of the 

 Belly Eiver formation, and in no case do they cause either narrowing or 

 mdening of the outcrop, nor do they bring to the surface strata older 

 than those normal to the area. Furthermore, several subdivisions of the 

 Belly River formation are recognized in this area and are found appar- 

 ently in their normal sequence, in a regular descending series eastward 

 and ascending series westward, thus indicating the absence of folds of 

 appreciable size, such as we should expect from the intensity of the 

 deformation displayed at Mud Buttes. If the observed dips were other 

 than surficial, certainly the normal distribution of formations would be 

 disturbed, as a 30 -degree dip has been observed over a distance of one- 

 half mile at Mud Buttes. If this dip should continue without duplica- 

 tion of strata for 1^ miles, the entire Cretaceous section would be ex- 

 posed, whereas only the upper division of the Belly River is found. 



Turning now to the structural information from well logs; the best 

 line of evidence is derived from four wells, which include the Muddy 

 Lake, Fusilier, West Regent, and Misty Hills wells. These are roughly 

 on a line from northeast to southwest, down the dip, and the last two are 

 in immediate proximity to Mud Buttes. 



The base of the Colorado Shale, which is the most reliable datum pres- 

 ent, shows a dip of 5 feet per mile from the Muddy Lake to the Fusilier 

 well, and 6^ feet per mile from the Fusilier to the Misty Hills well. 

 Thus the Misty Hills well, which is on one of the supposed uplifts, instead 

 of being structurally higher is in reality as low as would be expected from 

 the regional structure of the area. Furthermore, from the West Regent 

 well, which is on the north side of the supposed uplift, to the Misty Hills 

 well, a distance of 11 miles, there is a dip to the south of 7 feet per mile, 

 which is also normal for the area. The significance of this is obvious 

 from the fact that the Mud Buttes are half way between these wells. 



Thus, from the evidence available, we are led to the conclusion that 



