Identifier: bulletinofgeolo341923geol (find matches)
Title: Bulletin of the Geological Society of America
Year: 1890 (1890s)
Authors: Geological Society of America
Subjects: Geology
Publisher: (New York : The Society)
Contributing Library: Smithsonian Institution Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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ULTS OF THE NORTHERN ROCKIES 267 northwestern Montana.and has been tracednorthward into Canada. Near Philipsburg,Montana, a thrnst-zonecomprising two princi-pal and several minorfaults has been de-scribed by Calkins,^ivho considers it prob-able that this zone is asoutherly continuationof the Lewis overthrust.According to Calkins,this fault-zone is anearly tectonic feature,since the fault-planesliave been folded anddislocated by normalfaults to nearly thesame extent as the rockstrata. The Lomhard over-thrust, as described byHaynes, has a length•of about 13 miles and amaximum displacementalong the fault-plane ofabout 2 miles. The Beartooth fault,along the northeasternborder of the Beartooth ® W. H. Emmons and F. C. •Calkins : Geology and ore de-posits of the Philipsburgquadrangle, Montana. U. S.Geol. Survey Prof. Paper 78,1913, pp. 146-150. T W. P. Haynes : The Lom- bard overthrust and relatedgeological features. J o a r.Geol., vol. 24, 1916, pp. 269- .290. dominion of canadaunited
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Figure 1.—Distribution of the knoicn great OvertJirustsin the northern Rocky Mountains 268 G. R. MAXSFIELD STRUCTURE OF ROCKY MOUNTAINS Mountains, has a length of about 35 miles as mapped by Calvert.^ Itwas not at first considered as an overthrust, but its relationship to zonesof overthrusting farther southeast makes this interpretation highlyprobable. The Heart Mountain overthrust, first described by Dake^ and later byHewett, has a minimum horizontal displacement of 28 miles and shouldbe traceable over the entire eastern edge of the Absaroka Range perhapsfor 125 or 150 miles. The Darhy fault, as mapped by Schultz,^^ has a length of about 125miles and a horizontal displacement perhaps greater than 15 miles. The AhsaroJca fault, as mapped by Veatch^^ and Schultz,^^ has a knownlength of approximately 200 miles. Its zone of displacement may exceed25 miles in breadth and its throw.(stratigraphic?), like that of the Darbyfault, is said to exceed 20,000 feet. The Medicine Butte and Crawfo

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