328 
[Assemble" 
the south . patt of Perrinton the surface is very irregular, the hills ris- 
ing from fifty to one hundred feet above the general level. These hills 
are composed of gravel and hardpan, and the general character of the 
soil is gravelly. Some of the hills are sandy, supporting a growth of 
shrub oaks and whortleberry; the soil, however, is said to be good when 
reclaimed. West of the Genesee few hills rise to a greater height than 
thirty or forty feet. All the hills in this part of the county rest upon 
the gypseous formation, and many ol them are formed by the destruc- 
tion of the upper portions of these strata. 
Most of the streams Tifford eligible mill seats, and it is to the water 
power furnished by the Genesee that Rochester owes much of her pros- 
perity. The great accumulation of water power at that place, depends 
on the geological structure of the country. Had all the strata been of 
equal hardness, the grand and beautiful succession of falls and rapids 
would not have been produced, but in place of them a uniform rapid 
current to the lake. 
The mountain ridge, or " limestone ridge," so called, becomes well 
defined a few miles west of Rochester. Here its elevation is only fif- 
teen or twenty feet, but it gradually rises towards the west, and at the 
western line of the county is forty or fifty feet above the level of the 
country on the north. This ridge or terrace does not pursue a direct 
line, but is tortuous and irregular in its course. 
The streams in this county, west of the Genesee, all flow in a north- 
easterly direction. I have not been able to find any cause for this in 
the structure or surface of the country. 
The general direction of the ridges or diluvial hills in the south part 
of the county is N. E. and S. W. To this course there are a few ex- 
ceptions. Along the river and the Irondequoit bay, the course of the 
ridges is more irregular, and we find them ranging in every direction. 
The highest of these hills in Monroe county is the " Pinnacle," about 
two miles southeast of Rochester. 
In many places we find swamps or marshes with large accumulations 
of partially decomposed vegetable matter, though none- of it has yet be- 
come peat. The substance is usually termed "muck," and is used in 
some places as manure. There are several of these swamps along the 
lake shore, where immense quantities of " muck" are deposited. Others 
on the south side of the ridge road, exhibit finely comminuted vegetable 
matter, with trunks of trees, deposited often to the depth of several feet. 
