^iLPINE STRUCTURES OF JASPER PARK. 



CHARLES KEYES. 

 (ABSTRACT.) 



To those of you who are especially interested in the mechanics 

 of mountain building-, and particularly to those of you who are 

 teaching the subject of geology I w^ish to present a few facts 

 concerning some very remarkable expressions of Alpine struc- 

 tures whi'Ch with diagrammatic clearness are displayed on this 

 side of the Atlantic. For fan-structures, closely appressed 

 flexures, and overturned folds it is customary to turu to dis- 

 tant Switzerland which cannot usually be visited by the student 

 until long after he has left college. The locality to which I 

 have reference is in the region of Jasper Park, in the northwest 

 part of Alberta. Until recently this district was one of the 

 m.ost inaccessible spots on all the North American continent. 

 Now two lines of railway reach it, traversing the deep valley of 

 the Frasier river and the canyons of the Athabasca river and 

 its chief headwater tributary, the ^Miette river, which together 

 cut completely across the Cordilleran area, exposing walls 2,000 

 feet in height. This superb natural cross-section is supple- 

 mented by numberless other expanses showing details, afforded 

 by cuttings on either side of the great gorge made by the Cana- 

 dian Northern and Grand Trunk Pacific railways in establish- 

 ing their grades. These observations were made mainly dur- 

 ing the past two summers. 



The Cordillera at Jasper Park as in other parts of the mighty 

 chain is characterized by great thrust planes, but unlike in 

 other portions of the uplift there is also sharp flexing on a large 

 scale (see Plate VIII from photograph by J). B. Dowling, of 

 the Canadian Geological Survey). The especially notable fea- 

 ture is the Appalachian or Alpine structure; and the relation- 

 ships of the various members are presented with far greater 

 perspicacity than anywhere else that I know of throughout the 

 entire extent of the Rocky Mountains, perhaps with greater 

 grap'hic distinctness than Appalachian structure is exhibited 

 anywhere in the whole world. 



Towards the middle line of the mountain system the general 

 uniformity of slant of the strata seems to indicate close-folding 

 of a moderate thickness of beds with consequent numerous repe- 

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