338 
[ASSEMBLT 
the course of Allen's creek in Wheatland. The eastern part of this 
deposit extends southward into Livingston county. Tufa forms the 
upper portion of this deposit in many places to the depth of three or 
four feetj and below it is the shell marl three or four feet thick. Some 
portions of the formation are nearly pure carbonate of lime, containing 
abundance of the shells mentioned: in other places it is impure from 
admixture of earthy matter. It extends, in length, about three miles, 
and in breadth from half a mile to one 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, extending 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. In low 
grounds here, where ditches had been dug, I observed the marMying on 
the surface as it was thrown out.^ The farmers generally do not appear 
to be aware of its importance. 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. 
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 pene- 
trated ten or fifteen feet without finding its termination. The upper 
portions are very pure carbonate of lime, yielding lime of a very supe- 
rior 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 depo- 
sit about two feet, it becomes mixed with sand and other impurities, 
rendering it unfit for lime, but not for manure. Ey 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 character of the 
soil was not attributed to the marl, consequently it has not been used 
on other parts of the farm. Numerous other locatities have been no- 
ticed, but these are the most important. Those enumerated are upon 
the gypseous rocks, and similar deposits may be expected in the low 
* The source of this stream is a spring rising among the gypseous rocks. The spring in Ca- 
ledonia, Livingston county, is the source of the stream from which most of the marl of the first 
named locality is deposited. 
