ABSTRACTS OF PAPERS 91 



might be assumed for the part of a land area which sloped toward Appalachia, 

 and from which, by reason of continued elevation and erosion, a sufficient vol- 

 ume of detritus would be supplied to form the Appalachian sediments ; but in 

 that case an additional width of land should be imagined farther to the east 

 and sloping in that direction into the Atlantic. As to guiding restorations 

 of former land and water areas by the assumption that the volume of the 

 ocean has been constant since the beginning of Paleozoic time, that is prob- 

 ably the easiest assumption to make, but it does not seem to be the most prob- 

 able. In view of the enormous discharge of water from volcanoes, it is con- 

 ceivable that the volume of the oceans may have undergone a large increase 

 during the long continuation of volcanic activity, here and there, now and 

 then, over the earth ; if the contemporaneous hydration of newly exposed rocks 

 has not withdrawn water as fast as volcanic eruptions supplied it, the early 

 oceans may have been much smaller than the present oceans. In our present 

 ignorance on this subject, the assumption of a constant oceanic volume should 

 be regarded as only one of several permissible assumptions. 



Dr. Mather: The crumpling of the strata accumulated in DevoDian and 

 earlier Paleozoic time in the Andean geosyncline occurred at the close of the 

 Devonian period, from which time the eastern Andes have been in large meas- 

 ure a positive rather than a negative element of the continent — crumpled De- 

 vonian sediments overlain unconformably by Permian and younger terrestrial 

 strata. Evidence is lacking in central Bolivia of mountain-making movements 

 at the close of the Paleozoic era. 



Dr. Yaughan inquired if Professor Schuchert would rule the so-called Hima- 

 layan geosyncline out of the category of geosynclines. He replied that he 

 would. 



Professor Schuchert : Doctor Bucher is correct in saying that Haug wanted 

 to show, among other things, that the geosynclines are the most labile regions 

 of the earth's surface. Haug's paper is undoubtedly one of the classics in 

 stratigraphy and has stimulated further research as to the geologic work done 

 in geosynclines. On the other hand, his main studies are not based on a true 

 geosyncline — the Appalachian one is the typical geosyncline — but on a mediter- 

 ranean. The latter is a labile area, a long and narrow and very deep water- 

 way lying between two continents — Europe and Africa, for example — while a 

 true geosyncline is a labile, very shallow- water area within a continent. On 

 one side of the Appalachian geosyncline lies the unmoved Canadian shield or 

 neutral area of the North American continent, while its other and oceanward 

 side is the rising and inwardly moving geanticline, the Appalachian foreland. 

 The stratigraphy, petrology, and faunas, and especially the tectonic results, 

 are very different when the records of geosynclines are contrasted with those 

 of a mediterranean like the Roman one, or, better, Tethys. 



STRUCTURAL RELATION OF THE FURCELL RANGE TO THE CANADIAN 



ROCKIES 



BY FRANCIS P. SHEPARD x 



(Abstract) 



The Purcell Range of British Columbia is separated from the Canadian 

 Rockies by the deep, narrow Rocky Mountain trench. The structural geology 



1 Introduced by Rollin T. Chamberlin, 



