NEAV EVIDENCE ON THE TACONIC QUESTION 721 



the geology of the region summed up. Five subdivisions of the Stockbiidge 

 limestone around the north end of the Taconies were described and attention 

 was called to the extreme folding and metamorphism of the rocks. The slates 

 of the mountains are sharply outlined from the Stockbridge limestone and the 

 contact follows a rude semicircle around the end of the mountains. The char- 

 acters of this plane of separation were discussed and the conclusion was 

 reached that they could only be due to faulting. The bearing of this conclu- 

 sion was briefly considered. 



SOME FEATURES IN THE GRAND CANYON OF COLORADO RIVER 



BY N. H. DARTON 



(A'bstract) 



Several years ago the author measured sections at a number of points along 

 the Grand Canyon to determine the stratigraphy of the Arizona Plateau. 

 These sections were presented, and there was exhibited a colored preliminaiy 

 geologic map of the Vishnu, Bright Angel, and Shinumo quadrangles similar 

 to one now in the corridor of El Tovar Hotel at Grand Canyon. 



PRE-CAMBRIAN FORMATIONS IN SOUTH-CENTRAL BRITISH COLUMBIA 



BY REGINALD A. DALY 



(Al)stract) 



A reconnaissance along the Canadian Pacific Railway line has established 

 the following conclusions : 1. Dawson's "Nisconlith series" occurring in the 

 Selkirk Mountains is not Cambrian, but represents the northern continuation 

 of the "Beltian" (Belt terrane) rocks at the International Boundary. 2. 

 Dawson's "Nisconlith series" of the Shuswap Lakes area (west of the Selkirks) 

 is an entirely different pre-Cambrian and pre-Beltian group of sediments, 

 which unconformably underlie the "Nisconlith series" of the Selkirk section. 

 3. The Adams Lake volcanic series conformably overlies the thick limestones 

 of the "Nisconlith series" in the Shuswap Lakes area and is of pre-Beltian 

 age. 4. The "Shuswap series" of the Shuswap Lakes is not a distinct gneissic 

 'v^roup unconformably underlying the "Nisconlith series," but is the facies of 

 the "Nisconlith series" produced where that series was thermally metamor- 

 phosed by batholiths, 5. Though these pre-Cambrian rocks are typical crys- 

 talline schists, their metamorphism of the regional type was not due to dy- 

 namic action; it was "static" metamorphism (Belastungsmetamorphismus of 

 Milch). 6. The pre-Cambrian rooks are nnich less deformed (upturned) than 

 the overljing Carboniferous or Triassic rocks, illustrating the small depth of 

 the earth-shell which underwent strong folding in post-Cambrian time. 7. The 

 petrography of this pre-Cambrian and pre-Beltinn terrane strongly suggests 

 that it furnished the greater part of the elastic material of the Rocky Mountain 

 geosynclinal prism. (Beltian and Cambrian sediments.) 



COVEY HILL REVISITED 

 BY J. W. SPENCER 



Published as pages 471-476 of this volume. 



