69 



Escarpment." Eastvvardly, it is first observed in Monroe County, a 

 few miles west of Rochester. From thence it extends westerly 

 through the whole of Orleans and Niagara Counties, constituting 

 their highest elevations. In Orleans County, Oak Orchard Creek 

 and its tributaries, in their descent to Lake Ontario, flow over it in 

 various places. Niagara River has excavated through it its stupen- 

 dous chasm. In its westerly course, as well in New York as in 

 Canada, it constantly rises. At Lewiston it is 374 feet above Lake 

 Ontario, and at Ancaster, near Hamilton, it reaches the height of 

 510 feet. Almost from its very verge the surface of the ground, 

 probably because of the dip of the subjacent rock, slopes southerly. 

 North of the Mountain Ridge the surface descends rapidly, and an 

 interval of comparatively level land, varying in width from one to 

 fifteen miles, and lying at the average height of about 200 feet above 

 Lake Ontario, is soon reached. Its level below Lake Erie is about 

 141 feet. This territory, whether easterly or westerly of Niagara 

 River, may be properly called the Ontario District. 



The Catalogue presents the name of all the plants which have 

 been detected within a radius of fifty miles of Buffalo, and satisfac- 

 torily identified. The selection of such extended limits for a local 

 catalogue was controlled by the important considerations that a 

 smaller territory would not have brought within its cognizance the 

 extreme southeasterly portions of the Erie District, and would have 

 excluded several localities of great botanical interest, to the explora- 

 tion of which especial attention has been given : — among them the 

 rich and attractive region at Portage and the Falls of the Cenesee. 



The altitudes of many of the places named in the Catalogue have 

 been indicated upon the map which accompanies it. It is supposed 

 that these will prove of no little interest. The statement that in. 

 respect to the growth of plants a higher elevation is equivalent to a 

 higher latitude here meets with some note-worthy confirmations. 

 The proposition has been more definitely embodied in the formula, 

 (susceptible of easy mathematical demonstration), that, between lati- 

 tudes 35 and 60, an elevation of three hundred feet is equal to one 

 degree of north latitude. The higher portions of the Erie, Genesee 

 and Allegany Districts, lying been the parallels of 42 10' and 42 

 30' N. latitude, reach a height varying from 1500 to 2300 feet above 

 the sea. The temperature, then, of these places, should be equiva- 



