'44 Geological Reports on the State of New York. 



which we have heard assigned for the occasional rise of the 

 waters, is the increase of the tributaries, by abundant rains in 

 cold and wet seasons, when also there is little evaporation. Winds 

 make temporary accumulations which may occur at any time, 

 but we believe there is nothing to support the popular impression 

 of a regular or periodical rise of the waters of the lakes. 



Boulders of primary rocks are frequently mixed with those of 

 the vicinity. Feldspathic rocks abound, and there are rounded 

 masses of feldspar eigiit to ten feet in diameter, which are in 

 some places so abundant as to be broken up for building materials. 



Waters. — They are all hard, containing muriate of lime. 



Calcareous Tufa, is very abundant, and is often found involv- 

 ing great numbers of recent shells. Shell marl is found contain- 

 ing Cyclas, Lymnea, Planorbis, with other species of fresh-water 

 molluscs. There is in Livingston and Monroe counties, a de- 

 posit of this nature, three miles long, and half a mile to a 

 mile in breadth ; it is supposed to contain 125,452,800 cubic feet, 

 or 2,309,056 loads. 



Gypsum is found in various places in this region, and is very 

 beneficial on grass lands, as well as for wheat and Indian corn ; 

 one bushel to the acre is generally considered as a sufficient 

 quantity for grass. 



The usual remark, that vegetation is promoted by plaster, in 

 consequence of its attracting moisture from the air, appears to be 

 unfounded; it has very little affinity for water, and probably 

 precipitates the vapor only, as stony bodies generally do, and the 

 trifling quantity thus obtained, could hardly bring with it much car- 

 bonic acid for the food of plants. Ground plaster is sold for three 

 dollars a ton. 



Hydraulic Cement. — " Much of the cement now made is of very infe- 

 rior quality, and losses are constantly sustained from its use. This sub- 

 ject is one which requires strict and constant investigation, and the State 

 of New York would save large sums in the construction of her public 

 works by procuring a cement of good quality. 



" A cement required to withstand the action of freezing water, should 

 contain little argillaceous matter. Clay, in any form, absorbs water abun- 

 dantly, and if frozen while containing water, the cohesion of the parti- 

 cles is destroyed. By this process, every time it is frozen, a portion of 

 the surface at least is removed, and finally the whole mass. The chem- 

 ical composition of this rock is so variable in different localities, and 



