450 Magara Falls. 
and we must take into the account new influences, which the pre- 
vious changes have called into operation. 
The great difference in elevation between Lake Ontario and 
Lake Erie, and the occurrence of the Cataract of Niagara, form 
one of the most striking features in the topography of Western 
New York. The difference in elevation of the upper o-reat lakes 
is comparatively small, they being nearly in the range of the strike 
of the strata, while the passage from Lake Erie to Lake Ontario 
is directly across the line of dip.* Lake Erie is three hundred 
and thirty-four feet above Lake Ontario, and the greater part of 
the descent from one to the other is overcome by the rapids and 
falls of the Niagara river in the space of one mile. 
JViagara Limestone. — Asilico argillaceous limestone forms the 
bed of passage from the soft shale below, to the purer limestone 
above. When freshly exposed it is often of a dark or bluish 
color, but soon changes to light gray or ashen; and though varia- 
ble in character, it is a constant accompaniment of the group as 
far as observed. It forms a good hydraulic cement, where it has 
been used for that purpose. 
In the eastern part of the district, these beds of passage are suc- 
ceeded by a dark bluish gray, subcrystalline limestone, of a rough 
fracture, and separated into thin courses by dark shaly matter. 
When not too much divided by seams, it forms a durable building 
material. This again is succeeded by a coarse-grained concre- 
tionary mass in irregular layers, exhibiting an appearance as if 
much disturbed while in a semi-fluid or yielding condition. The 
concretions often present cavities lined with crystals, or the re- 
mains of some fossil body. The upper strata are finer grained, 
with a resinous lustre; and on weathering the surface is harsh 
and sandy to the touch; this, however, seems due to the presence 
of magnesia rather than silex. 
Jigricultural Characters. — The two members of this group are 
marked, to a considerable degree, by a diflference in the soil. The 
destruction of the shale has given rise to a clay, which mingling 
with the more sandy productions of the Medina sandstone on the 
north, has produced a soil of unequalled fertility; and there is 
rarely, if ever, to be found a better wheat-growing soil, than the 
portion overlying this rock. In some places it has a greater 
amount of argillaceous matter than is desirable, and forms a stiff 
soil ; but where the slope of the surface is sufficient for effectual 
drainage, it produces no inconvenience. 
The soil covering the limestone, particularly where it is a little 
elevated above the country on the north, is of a loamy character, 
the argillaceous nature of the mass below having had little influ- 
*The geological positions of Lake Superior and Lake Ontario, the highest 
and the lowest of this chain of lakes correspond very nearly with each other. 
