80 rROCEEDINGS OF THE CHICAGO MEETING 



the second set has a northeast trend ; but these A'ary more than the first set. 

 The small streams cascade over these escarpments and have not cut into the 

 margins materially. 



If the contour of stream profiles meaiis anytliing, there are still otlier steep 

 slopes wliicli seem to be faults of slightly older appearance, but still post- 

 glacial. The whole mountain group — north, east, soutli, and west — has streams 

 with broken profiles, and cliffs occur on every side, though more abundantly 

 on the west. Tliere are one or two hanging valleys which have been attributed 

 to glaciers forming in the group ; hut there do not seem to me to be any indi- 

 cations of ice-fields (cirques) or glacial valleys. Faulting explains all the 

 hanging valleys much more simply, especially when it is established that post- 

 glacial faulting occurred here on the scale of the fault that has just been de- 

 scribed as cutting the shoreline. 



In the Holyoke range and out among the Pelliam Hills there are several 

 sharp and clean-cut escarpments which have every appearance of being post- 

 glacial in age, since the glaciated surface is broken. While to date I have not 

 found others which cut a postglacial shoreline, I am convinced that there has 

 been considerable faulting in and about the Connecticut Valley some time since 

 ghicial times. 



Discussion 



I'rof. W. H. HoBBS : I think I can add evidence of similar sort from the 

 region of the Frivel River, Western Ontario. In a fortnight's canoe trip made 

 in 1919 within that region it was discovered that whereas the district is one 

 of almost no cover of unconsolidated materials and the hard pre-Cambrian 

 rocks are shaped, scored, and polished in the most striking fashion, yet for 

 long distances, sometimes a mile or more, escarpments run parallel to the river 

 courses, and on these escarpments no trace of glacial action is to be found. 

 Some of these escarpments were, by estimate, 100 feet or more in height. 



If I seem to be offering this proof of my thesis offered before in these ses- 

 sions, that the Atlantic region is in repose, by contrast with the Pacific, it is 

 really so only in appearance. The mobility of the earth's crust in the Pacific 

 area is yet vastly more mobile and the Atlantic region by contrast properly 

 described as nearly at rest. 



SIGNIFICANCE OF THE RELATION OF PROBOSCIDEAN REMAINS TO THE 



SURFACE OF NEBRA8KAN GUMBOTIL, NEAR OSCEOLA. 



CLARKE COUNTY, lOWA^ 



BY GEORGE F. KAY 



(Read before the Soeietij Decemher 30, 1920) 



CONTENTS 



Page 



Introduction }Sl 



History of the discovery 81 



The fossils and their relationships 81 



Significance of the relationships of the fossils 8ii 



Discussion 8o 



^ Manuscript received by the Secretary of the Society .January 10. 1921. 



