MONROE COUNTY. 
429 
mile. The general thickness is about five feet, though often much greater. At its smallest 
dimensions, we shall find it 125,452,800 cubic feet, or 2,309,056 loads. 
Another extensive deposit of this material is found along the course of Mill creek, extend¬ 
ing from its source to Cady pond, and filling the marshes around the pond for the extent of 
many acres.* Its thickness is unknown, but in some places it exceeds three or four feet. 
Tufa forms in many places, in exposed situations, along this deposit. The soil above these 
deposits is usually a light, partially decomposed vegetable matter, allowing the water to pass 
through it, by which means it soon becomes parched, and the crops perish. By spreading 
on this soil a small quantity of clay or loam and the marl beneath, it could be made of the 
finest quality. The partially decomposed vegetable matter is also one of the best manures 
with marl or lime. 
In the town of Riga, on the land of Mr. Knowles, a deposit of this marl, of unknown 
depth, covers thirty or forty acres. It has been penetrated ten or fifteen feet, without finding 
its termination. The upper portions are very pure carbonate of lime, yielding lime of a very 
superior quality. It is cut out, while moist, in masses of the form and size of bricks, and 
laid in the kiln and burned. After penetrating this deposit about two feet, it becomes mixed 
with sand and other impurities, rendering it unfit for lime, but not for manure. By accident, 
several loads of this marl were deposited and remained for several years on a barren piece of 
ground ; afterwards this spot was ploughed, and has yielded large crops every year since, 
though before it produced almost nothing. Strange as it may seem, this change in the charac¬ 
ter of the soil was not attributed to the marl; consequently it has not been used on other parts 
of the farm. Numerous other localities have been noticed, but these are the most important. 
Those enumerated are upon the gypseous rocks, and similar deposits may be expected in the 
low grounds throughout the whole of this formation, the extent of which may be learned by 
referring to the Geological map. 
The decomposing gypseous rocks afford a marl, which is sometimes too clayey to be bene¬ 
ficial as a manure, but in other cases it is valuable, especially when mixed with shell marl. 
This marl approaches the surface in many places in the town of Pittsford, where it is of 
a character well adapted for use on sandy lands. The same marl is seen east of Pittsford, 
along the line of the canal, and at Fairport. Gypsum in small quantities has been found in 
the marl at these localities. On the west side of the river we find the gypseous marl in Riga, 
Chili and Wheatland, in some places approaching the surface, or appearing in the beds of 
small streams. The only place where this marl has been applied is in the town of Wheatland. 
Mr. Merry has used this and the shell marl, separately and mixed, and finds the results fully 
to realize his most sanguine expectations. Used on the light vegetable soil of the swamps in 
that neighborhood, this marl has produced astonishing results. A meadow of this kind, 
which produced little or nothing, was dressed with this marl, and sown with timothy 
* The source of this stream is aspring rising among the gypseous rocks. The spring in Caledonia, Livingston county, is the 
source of the stream from which most of the marl of the first named locality is deposited. 
