^38 [Assembly 
Indurated marl and sandstone forms the limit on the north, succeed- 
ed by shales, argillaceous and compact limestones. The limestones, 
for the most part, occupy a position between the extreme northern 
boundary and the middle portions; these are succeeded by argillaceous 
limestones, or calcareous shales, occupying a considerable extent through 
the middle of the district. To these again, succeed a series of argilla- 
ceous shales and sandstones, which extend to the southern limit of the 
district. The calcareous shales of the middle portion lose their calca- 
reous matter on going southward, and become the dark shales of the 
Coal measures. Throughout the whole of this district, so far as exa- 
mined, we find no anticlinal or synclinal lines; the strata having an uni- 
form bearing, nearly east and west, and dipping to the southeast. Nei- 
ther are there any evidences of a disturbing force in the line of bear- 
ing; the outcrop and elevation is very uniform, exhibiting only a gen- 
tle undulation, operating over a great extent of country. Several of 
these rocky strata have their outcrop along the great limestone ridge or 
terrace, which extends from Rochester westward, far beyond the Nia- 
gara river. Along this line of bearing, we shall be able finally to pre- 
sent a very instructive section, shewing the increase and decrease in 
thickness of the strata above the sandstone; the thinning out of others 
and their commencement at a distant point; the change in lithological 
character of the same stratum at distant points, and the merging of two 
distinct strata into one. This line of outcrop, distinctly marked for 70 
or 80 miles, and less distinctly for thirty more, furnishes some of the 
most interesting phenomena, regarding lithological and paleontological 
changes. 
That portion of the district occupied by the limestones and calcare- 
ous shales, including nearly the whole of the two northern ranges of 
counties is one of unrivalled fertility. No other portion of the State of 
equal extent, possesses the same agricultural advantages. The soil is 
underlaid by calcareous rocks, constantly affording a supply of a most 
essential ingredient, the value and importance of which, if rightly ap- 
preciated, would even now, by judicious application, greatly increase 
its productiveness. To these we may add the facilities of transporta- 
tion and communication, limited on the north by Lake Ontario, and 
more southerly traversed by the Erie canal; still farther south by 
rail-roads, (completed and in progress,) affording along the line of 
each a market for the produce of the surrounding country. At many 
points we find durable and beautiful building stone; and along a line 
of twenty or thirty miles a stratum of rich iron ore. The southern 
part of the district, or that occupied by the slates and sandstones, is less 
