12 



NEW YORK STATE MUSEUM 



Between the terminal moraine and the present Lake Erie the 

 several recessional moraines are roughly parallel to the latter, or 

 have a general trend in the Erie basin northeast by southwest. 

 They decline or fall away to the westward and pass under the lake. 

 Of course they pass under the planes of glacial lakes Whittlesey and 

 Warren, which are more than 200 feet above Erie. This fact is 

 shown in the sketch map, which also shows that the ice front was 

 convex westward, in the direction of flow. 



Three factors combined to make the westward extensions of 

 these moraines weak and discontinuous. The glacial streams 

 flowing past the ice margins swept away more or less of the moraine 

 detritus within their reach, in some sections removing it entirely. 

 The portions of the moraines which were deposited under water were 

 spread out and subdued by the water action. Thirdly, the stretches 

 of moraine lying near the levels of the lakes were destroyed by wave 

 erosion and converted into beaches and water-laid drift. In 

 addition to these destructive effects during the glacial history are 

 those of weathering and rain and stream erosion during all subse- 

 quent time. 





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Fig. I Diagram of the Erian ice lobe. The concentric lines indicate ap- 

 proximately the successive forms and positions of the margins of the ice, 

 as shown by moraines. The Hnes are generalized and are not intended 

 to be exact. 



The Cleveland moraine, as named by Leverett, includes the irreg- 

 ular drift masses in the belt east and west of Chautauqua lake. 

 With this and the earlier moraines we have no special concern, as 



