HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH IQl 



Coleman sums up the evidence for a Lower Huronian ice age as 

 follows : 



"A peculiar rock consisting of graywaclve or finer material showing little 

 or no stratification but containing pebbles or stones sometimes crowded but 

 more often scattered a few feet apart, is found from point to point over an 

 area 800 miles long by 250 miles broad. The stones are of all sizes up to 

 diameters of several feet and of all shapes from rounded to angular, many 

 being subangular with rounded corners. The stones are of several different 

 kinds, some fragments of immediately underlying rock, others having a distf>nt 

 source. 



"In the Cobalt region a few polished and striated stones have been broken 

 out of the matrix. They are closely like the Pleistocene boulder clay of the 

 same region except that they lack the Niagara limestones of the recent drift. 



"Hand specimens of matrix and enclosed pebbles are precisely like the 

 Dwyka tillite or conglomerate of South Africa which is undoubtedly of glacial 

 origin." 



It is obviously impossible to connect these deposits in eastern Canada 

 with those of the Cottonwood area in Wasatch Mountains, without some 

 surer means of correlation than lithological similarity. If, however, we 

 accept Coleman's evidence, the occurrence of glaciation is probable over 

 an area which is much too large to be attributed to local mountain gla- 

 ciers. The two Utah occurrences are 60 miles apart and were undoubtedly 

 of much wider distribution, having been removed by erosion previous to 

 the deposition of the Cambrian beds, as previously explained. It is highly 

 probable that these exceptional sediments are to be explained on the same 

 basis, and that suggested by Coleman deserves serious attention and may 

 be accepted at least for the present. An ice age of sufficient duration to 

 manifest itself over such a large area in eastern Canada might easily be 

 expected to register its effects in the western part of the same continent, 

 especially at approximately the same latitude and northward. 



Mr. E. L. Bruce, a member of the Canadian Geological Survey who has 

 seen the rocks as they occur in Canada and also the writer's material, says 

 that they are strikingly similar in almost every detail. The description 

 quoted above from Coleman's article applies equally well to the black rock 

 at the head of South Fork in Big Cottonwood Canyon. If we accept them 

 as glacial deposits, they are probably of the same age, and the quartzite- 

 slate series in the Wasatch and Uinta mountains is much older than has 

 been thought up to the present time. From the obvious scientific impor- 

 tance of establishing the existence of an ice age in that early period of the 

 earth's history, the question deserves further careful study. 



