Story of the Chautauqua Region 



evident that the agencies at work would have here formed a lake in 

 the same manner as they formed one in the Lake Erie basin, where 

 owing to lower levels and a more favorable situation they continued to 

 operate for a much longer time. 



As the glaciers did not withdraw from the basins with a slow and 

 uniform rate of retrogression, but evacuated only after long periods of 

 alternating advances and retreats, moraines were formed in many 

 places; and hence, when the ice disappeared, chains of small lakes 

 stretched all along the broad valleys north of the outlets. Periodical 

 freshets, bringing down the water accumulating from broad surfaces, 

 eventually cut channels through the moraine barriers. Thus, one after 

 another, many of these glacial lakes were drained, but their old outlines 

 may be traced in many places by the terraces and beaches which sur- 

 rounded them, and by the lacustrine deposits left in their beds. 



It is often remarked as a curious fact that nearly all our small lakes 

 lie on summits at the heads of streams. This should cause no surprise. 

 They remain there as lakes to-day, because they have always received 

 the drainage of but small areas, and have not been seriously affected by 

 annual freshets; consequently their outlets cut down very slowly, and 

 they have not yet had time to drain. There are evidences, however, in 

 nearly all of them, that the water once stood at a higher level than it 

 stands at present. 



Chautauqua Lake may be taken as an illustration of these changes. 

 It has cut down an outlet through about fifty feet of stratified rock. 

 This has, of course, reduced its surface level by that much. A higher 

 water-level than the present has been maintained in comparatively recent 

 times. Its level would not be nearly as large as it is, were its outlet 

 through drift instead of solid rock. The rock strata at the outlet of 

 Chautauqua Lake have saved it from rapid disappearance. 



The elevation of Chautauqua Lake is 1299 feet; maximum depth, 

 about one hundred feet. Its present outlet has cut a narrow channel 

 fifty feet deep through solid rock, between Jamestown and Dexterville. 

 There can be no doubt that this is a post-glacial excavation, and that 

 an ancient channel, deeper than the present lake-bed, exists to the north 

 of it. Chautauqua Lake, on the whole, is very shallow, and is partially 

 filled by stream deposits. The depth of the drift-filling is not known, 

 but, judging by the depth of the drift in other valleys in this section, 

 it must be great. While it cannot be considered established, there is 

 some topographic evidence in favor of the view that at least the northern 

 end of the Chautauqua Valley was in pre-glacial times tributary to the 

 Lake Erie Valley; the cause of the diversion being an extensive 

 morainic deposit across this valley. There is a constriction of the valley 

 near the middle of the lake, which suggests that this may have been the 



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