440 Karl M. Wiegand and Arthur J. Eames 



Following the last erosion period, just mentioned, the region was invaded at least 

 once, and very probably twice, by continental glaciers. The first glacial ice sheet 

 overrode the country completely, coming down from the north. The original north- 

 and-south valleys were dammed by the ice, and the water flowed over in many 

 places into the Susquehanna Basin at the south. Eventually the ice flowed also over 

 the divide, and by its erosive action it developed the through valleys which are a 

 characteristic feature of the present divide between the Finger Lakes and the Susque- 

 hanna Basin, and by its scouring action it also greatly broadened and deepened these 

 valleys. The scouring action of the ice was most extreme in the Cayuga Lake 

 Valley, where the entire valley depression was deepened to such an extent that the 

 bottom in the deepest part is now 16.5 meters (54 feet) below sea level. When the 

 ice had gone, hanging valleys were left along the hillsides of Cayuga and Seneca 

 Lakes due to the deepening and broadening of the north-and-south channels which 

 left the old preglacial tributary valleys high in the air where they joined the north- 

 and-south valley. Postglacial gorges were then cut by streams flowing down the 

 steep hillsides from these hanging valleys. After a long interval, during which the 

 climate seems to have been more genial than the present one, a second ice sheet 

 covered the region, continuing the work begun by the first ice sheet but evidently 

 doing little more than sharpen the effects produced by the first invasion. The 

 gorges cut during the interglacial period were filled with morainic and outwash 

 deposits, and, on the recession of the ice, new gorges began to form in new channels, 

 and this erosion is still in progress. These new gorges constitute the present exten- 

 sive system of ravines for which central New York is famous. As the ice retreated, 

 a glacial lake was formed between the ice front and the divide over which the water 

 drained to the southward. An overflow channel along which the water drained from 

 the glacial lake at the head of the Cayuga Basin into the Susquehanna Valley can be 

 readily seen at Spencer Lake, and another at Wilseyville. The occurrence of some 

 Ontario-plain and Coastal-Plain plants on the Spencer divide suggests a possible 

 relation to the fact that through this channel the water of the glacial lake occupy- 

 ing the southern part of the Ontario plain drained away. Could this drainage water 

 have affected the soils of the Ontario plain and the Spencer divide similarly? 



The level of the glacial lake in front of the ice mass was reduced at irregular 

 intervals, the lake standing at successively lower levels as new outlets were uncovered. 

 This is shown by the occurrence of terraces at various heights on the hillsides 

 bordering the Inlet Valley. These terraces are especially well marked near the 

 ravines, where material was deposited as deltas from the outflowing streams, as at 

 Coy, Buttermilk, and Enfield Glens, and they are also obscurely developed here and 

 there as old beach lines. 



The activity of the latest glacier as a transporting and erosive agency, and the 

 action of glacial outflow streams in connection with the presence of high-level 

 glacial lakes, have been the chief factors in the formation of the present soils through- 

 out the basin. More recently there have also been notable accumulations of collu- 

 vial, alluvial, and fluvial soil materials due to the activities of the modern drainage. 



SOILS OF THE CAYUGA LAKE BASIN, 

 AND THEIR RELATION TO THE PLANTS OF THE REGION 



The effect of the chemical and physical nature of the soil on the distribution of 

 plants, though long noticed in its rougher details, has not been worked out to a 

 condition approaching exactness. Such factors as texture, chemical composition, 

 water content, bacterial flora, and the quantity of organic matter present, are of 

 undoubted importance, but the exact values of these factors are at present only 

 imperfectly understood. It has been found, however, that few, if any, chemical 

 elements other than calcium, sodium, carbon, and nitrogen, produce an appreciable 

 effect on the distribution of plants. The flora of calcareous regions and that of 



