336 W. UPHAM — PREGLACIAL AND POSTGLACIAL VALLEYS. 



have caused the oxidation of tlie iron in the upper till and in tlie greater 

 part of the interglacial sand, giving to them a yellowish gray color, along 

 the east half of the section ; hut westward, where the upi)er till lies at a 

 greater depth, hoth that and the sand beneath have the dark bluish un- 

 weathered color, and there the yellowish oxidized condition reaches only 

 through the su])erficial sand. 



The thinness and uniformity of the sheet of upper till, having only 

 about a thousandth as much thickness as its length here exposed to view, 

 yet uninterrupted across the i)reglacial valley, lead me to refer it to en- 

 glacial drift of the temporarily re-advancing ice border. Probably a nearly 

 similar or greater thickness of the upper part of the lower till was also 

 englacial, being deposited by the ice during its first retreat. Lamination, 

 however, is not ver}^ noticeable in either till. 



The interglacial sand, which, like the two formations of till, seems 

 referable to deposition in the water of the glacial lake, was examined in 

 vain by Professor H. P. Gushing, of the Western Reserve University, and 

 by the present writer, in search of traces of organic remains. This sand 

 is doubtless modified drift that was su])i)lied from the receding ice. 



In the early history of military expeditions on lake Elrie the mouth o^ 

 the Rock}'- river and this neighboring drift cliff, with its sand and gravel 

 beach, were remarkable as the scenes of wreck and disaster. The former 

 locality, on November 7, 1763, witnessed the loss of nineteen bateaux, 

 several oflicers, and sixty-three privates of Major Wilkins' exi)edition to 

 the war against Pontiac and the French. Again, during the night of Oc- 

 tober 18 or 1\) in the next j^ear, 1764, a similar ex])edition, under Colonel 

 (afterward General) Bradstreet, sutTered great losses of V)ateaux, ])rovisions, 

 annnunition. and guns, by a sudden storm with high waves breaking u\H)n 

 them while encamped on McMahon's beach, at the foot of the drift cliff 

 whose section has been here described.* 



EAST SIDE OF THE CUYAHOGA VALLEY OV CLARK AVENUE. 



Under the guidance of Mr Thomas Pi wonka, of Cleveland, I examined 

 a very interesting section of the drift forming the east bluff of the Cuya- 

 hoga valley on P^ast Clark avenue and other sections of excavations to 

 obtain clay for brick-making situated within three-quarters of a mile 

 southward from that locality and within a half mile east of the immediate 

 Cuyahoga valley. These excavations are on the ui)land expanse of gla- 

 cial drift, mostly thinly covered by delta sand, upon which Cleveland is 

 built. 



A large main water pipe was laid during last summer across the valley 



♦Chaptei- by Dv J. P. Kirthuul in Wln'ttlesey's Early History of Cleveland, 18G7, pp. 97-129. 



