112 ABSTRACTS 



early part of its existence, as shown by the Hamline and Como pla- 

 teaus, was about 250 feet above the present river, or 930 to 940 feet 

 above the present sea level. A little later, when the plateau a mile 

 east of Lake Como was formed, the lake level had fallen apparently 

 five or ten feet. At the time of formation of the Summit Avenue 

 plateau, it had been further lowered several feet, having then appar- 

 ently an elevation of about 915 feet; and still later and smaller 

 plateaus show that this lake finally was reduced to 875 or 870 feet 

 above the present sea level. In one section it was observed that the 

 till, exposed to a depth of twenty to twenty-five feet, at an elevation 

 of about 875 to 900 feet above the sea, has throughout that thickness 

 an imperfect stratification. The author attributes this to the action of 

 the water of Lake Hamline, receiving the till from a previously engla- 

 cial and superglacial position in and upon the melting ice-sheet. It 

 is an observation almost exactly like that made by him a year earlier 

 in the drift section of the Lake Erie shore in Cleveland, Ohio; and 

 here, as there, he concludes that the volume of the englacial drift is 

 represented by the th „kness of the obscurely bedded or laminated 

 till. In another section a sheet of till ten to twelve feet thick, resting 

 on striated Trenton limestone, is shown, as the author thinks, to have 

 been wholly englacial, this being indicated by deflection of the glacial 

 striae. Many of the striae, intersecting the southward courses of ear- 

 lier glaciation, run N. 6o°-75° W., perpendicularly toward the neigh- 

 boring Lake Hamline and its long plateaus of water-deposited drift. 



(Abstracts to be continued.) 



