MONROE COUNTY. 
433 
little affected by the weather; but in most, it has been rapidly destroyed. The great objection 
to the stone, is the presence of a large proportion of argillaceous matter, absorbing water, 
which destroys it by the same process that the hydraulic cement is removed from the walls 
of locks. 
The limestone of Monroe county affords no marble or materials for decoration. The more 
siliceous portions of the Niagara limestone furnish a fine material for macadamizing roads, 
and it is much used near Rochester for that purpose. Paving stones are obtained from the 
drift. Flagging stone is not abundant, but is found among the siliceous strata of the Onon¬ 
daga salt group. 
The sandstone has been quarried near the outlet of Irondequoit creek, and used in the con¬ 
struction of piers at the mouth of the Genesee river. By the action of the waves and freezing 
water, it is very rapidly destroyed, and it becomes necessary to rebuild the piers almost 
annually. The stone from this quarry has recently been rejected for the construction of 
piers, and limestone substituted. An expense of several thousand dollars had been incurred 
in opening the quarry, before the stone was rejected. Had the proprietors submitted it to 
the examination of some competent person, or to the common tests, all this expense would 
have been saved. 
ORLEANS COUNTY.* 
The rocks of this county consist of the same as those on the east, with the exception of 
the Onondaga salt group, which has not been detected within its limits. The Niagara group 
rises in a terrace above the surrounding country, becoming more elevated in a westerly direc¬ 
tion. The Clinton group appears in much diminished thickness, but still highly fossiliferous. 
The Medina sandstone abounds in fossils at Medina, that being the principal locality where 
shells occur in this rock. The section from this place southward will give one a correct idea of 
the strata. The vicinity of Albion and Farwell’s mill, are also good localities for fossils in 
the Niagara group. The Medina sandstone occupies more than half the width of this county. 
Surface of the Country. 
The most prominent character of Orleans, when compared with the adjoining counties, is a 
remarkable evenness of surface. Indeed, the whole county, with the exception of its two 
* The details of investigation in this county, are principally extracted trom tho report of the late Dr. G. W. Boyd. (Annual 
Report of 1838.) 
Geol. 4th Dist. 
55 
