TOPOGRAPHY. 
15 
Again, this limestone is succeeded by soft marls and shales which have been levelled by 
the denuding agents, and present the second broad plateau. This is again limited on the 
south by a mass of limestone, sufficient to resist the power that wore down the others. Suc¬ 
ceeding this limestone, are in turn soft shales, forming for some miles a level country, and 
the next ascent is produced by the interstratification of harder layers of sandstone. These strata 
of sandstone being thin, prevented the entire levelling of the shale, but did not produce the 
well defined outline presented by the limestone; consequently we have the gently swelling 
hills, gradually receding, and the contour softened in the undulating curves which mark the 
windings of the streams. 
Such are the principal features of a portion of country, the rocks of which we are about to 
describe. 
Connected with, and dependent upon this character of the surface, are other circumstances 
to be noticed. The form of the country, determining the direction of the present water 
courses, is a matter of great importance. The highest portion of this district is occupied by 
the counties of Chemung, Steuben, Allegany, Cattaraugus and Chautauque, the mean eleva¬ 
tion of which is about two thousand feet above tide water. The northern portion of this range 
forms the dividing ridge of the principal streams flowing in opposite directions, which mingle 
their waters with the ocean at distant points. Those on the north find their way into the 
Atlantic by Lake Ontario and the St. Lawrence river; while on the south, some flow into 
the ocean by the Susquehannah, and others passing into the Allegany, find their way to the 
Gulf of Mexico by the Ohio and Mississippi. The Genesee is an exception to the general 
rule — a river which takes its rise beyond the borders of the State, and flows northerly through 
all these counties, and discharges its waters into Lake Ontario. A river of this magnitude 
passing through a great succession of strata, and descending in all its course nearly two 
thousand feet, has produced some grand exhibitions of the rocky strata. 
Valleys similar to that of the Genesee, cross the district in a north and south direction; 
the principal of these are occupied in part by lakes, as Cayuga, Seneca and Canandaigua; 
the valleys in all cases continuing to the north and south of the extremities of these lakes, but 
the direction of the water courses being opposite from the highest part of the valley which is 
south of the lakes. These ancient water courses, with the great lakes and the river dis¬ 
charging all the western waters through its narrow gorge, while they modify the topography, 
form some of the most striking features of the district, and are subjects of the highest interest 
both to the man of science and the utilitarian. 
To the same cause, to which we owe these prominent features and the hills of the southern 
counties, is also due the deep fertile soil prevailing throughout the greater part of the district. 
The materials excavated from these valleys in the form of fragments and masses have been 
transported and reduced to the condition of sand, clay and pebbles, which is distributed over 
the surface. By the same operation, also, the materials of the northern calcareous strata are 
mingled with the comminuted rocks of the south, and form the soil of unsurpassed fertility 
