FISH REMAINS IN BLACK HILLS ORDOVICIAN 567 



the southeast and east sides of the mouutaius. where some attained a length 

 of 10 to IS miles and a thickness of 500 to 1,000 feet. Glaciation is not ex- 

 tinct. A small cliff glacier occurs at the head of Big Timber canyon and an- 

 other in Sweetgrass, while a third is reported at the head of Rock creek. 

 Previous to glaciation the region had reached an early stage of peneplanation 

 and had been revived in two partial cycles of erosion. Glaciation did not con- 

 tinue long enough greatly to modify pre-existing topography, but did produce 

 broad, deep troughs in the weaker rocks and arretes in many of the sharp 

 divides. Later stream erosion has incised the glacial deposits and, in some 

 cases, the old trough floors. 



The papers were discussed by A. C. Lawson. 

 The following papers were read by title : 



SHALER MOUNTAINS, VNALASKA, A GRANITE CORE TO THE ALEUTIAN 



ISLANDS 



BY T. A. JAGGAK, JK. 



GROWTH AND DESTRUCTION OF METCALF CONE, BOGOSLOFF ISLAND, 1906-7 



BY T. A. JAGGAK, JK. 



Then was read 



8ANDIA MOUNTAINS 

 BY W. G. TIGHT 



The following papers were then read by title : 



GEOLOGY OF TEE ALASKA RA\GE 

 BY A. H. BBOOKS 



PALEOZOIC AND ASSOCIATED ROCKS OF THE UPPER YUKON BASIN 

 BY A. H. BROOKS AND E. M. KINDLE 



GEOLOGIC RECONNAISSANCE OF THE PORCUPINE VALLEY, ALASKA 



BY E. M. KINDLE 



The last two papers were published as pages 255-338 of this volume. 

 The following paper was read by title : 



DISCOVERY OF FISH REMAINS IN ORDOVICIAN OF THE BLACK HILLS, SOUTH 



DAKOTA 



BY N. H. DAKTON' 



[Abstract] 



Two years ago I announced to this Society the discovery of fish remains in 

 the Ordovician (Bighorn formation) of the Bighorn mountains, and gave a 

 resume of our knowledge of the Ordovician of the Northwest.^ During the 



1 Published by permission of the Directoi' of the U. S. Geological Survey. 



- Bulletin of the Geological Society of America, vol. 17. pp- 541-566, plates 73-79. 



