536 Professor FaircMld — Glacial Geology of W. New York. 



Channels of Glacial Drainage, 



A considerable number of the outlet channels of the larger local 

 glacial lakes have been studied and partly described in the papers 

 to which reference has been made. No outlet of the great pre- 

 Laurentian lakes lies within this area, the Iroquois outlet being to 

 the east. The area does contain, however, the channels which 

 drained the Warren waters down to the Iroquois level, a fall of 

 over 400 feet. These lay along the receding ice -front in the 

 Kochester-Syracuse region. Some were rock channels of considerable 

 duration, while others were shifting channels closely following the 

 glacier foot. These have been studied by Mr. Gilbert, but only 

 a brief notice published.^ 



Post-Glacial Stream Erosion. 



The great majority of streams on the low northern plain meander 

 in drift channels, rarely touching the rock, and have done little 

 work of corrasion. The heavier streams have in a few cases done 

 considerable rock-cutting. Of similar age and character to Niagara 

 gorge is the ravine of the Genesee at Kochester, but of less 

 dimensions. This cutting, with that of Oak Orchard Creek, Ironde- 

 quoit Creek, Seneca River, and all other minor ravines and falls on 

 the northward slopes, at an altitude less than 800 to 880 feet, are 

 subsequent to the time of Lake Warren. Those at an altitude of 

 less than about 400 feet are subsequent to Lake Iroquois. The 

 Genesee ravine at Eochester is mostly post-Iroquois. The fine 

 ravines at Mount Morris and Portage began much earlier, during 

 the Lake Warren episode, as outlets of moraiual lakes. 



DESCEIPTION OF THE MAP (PLATE XXI). 



Numerals. — The figures give elevations, in feet, above mean ocean-level. At 

 cities and towns, reference is to top of rail at the principal railway station. 



Divides, Water- Partings. — These are indicated by the heavy broken lines. 

 Cols which are known to have been outlets for glacial lakes are indicated by bars 

 placed transverse to the line of water-parting. The figures giving the elevation of 

 such cols are also placed transverse. 



Moraines. — The morainal belts have not been traced east of the Genesee river, 

 and cannot exist there in so good form as in the area west of the Genesee. 

 Throughout the region of the ' ' Finger Lakes ' ' the morainal drift is chiefly massed 

 in the deep north and south valleys, as indicated. North of those lakes the drift 

 was deposited in the presence of deep glacial waters, and morainal lines are scarcely 

 traceable. 



The terminal moraine, past the cities of Glean and Salamanca, is not as definite 

 a belt as the map would suggest. 



Kame Areas. — A few well-known areas of heavy water-laid drift are indicated 

 south of the two great bays in the south shore of Lake Ontario, but other areas exist, 

 notably in the Genesee valley, and associated with the larger moraines. South of 

 the great divide the valleys are deeply filled with the detrital overwash from the 

 glacial floods. 



Drumlins. — The areas of drumlins are only very roughly suggested. The 

 orientation of the drumlin axes is better indicated. 



Glacial Lake Shorelines. — Three shoreKnes are indicated : the lowest, 

 Iroquois, with an average elevation in the Finger Lake region of 440 feet ; the 



' G. K. Gilbert, " Old Tracks of Erian Drainage in Western New York" : Bull. 

 Geol. Soc. Amer., vol. viii, pp. 285-6. 



