210 STATE AGRICULTURAL SOCIETY. 
works. The rock is of more even texture, and in thicker strata 
than elsewhere in this part of the State. It is free from 
injurious seams, and can be extracted in blocks and slabs of 
considerable size. The quarry in the Prisonlhird lies only three 
feet from the surface, and is covered with a light-colored clay. 
The rock is a subcrystalline bluish grey limestone, in layers 
from four to ten inches, fracture rough with occasional irregu¬ 
lar iron-stained cavities; weathers dirty buff. It is too 
cavernous to dress well, but works into walls readily. The 
entire town is underlined with these rocks, at a slight depth, 
so as to be reached in many of the cellars, even. These beds 
represent the Galena limestone of the lead mines, which has 
nearly thinned out here, but still contains some lead and the 
peculiar coral seen further south and west. Some of the 
quarries furnish stone which chips tolerably, and in one, the 
entire surface is polished as smoothly as a marble floor. From 
this quarry the fine slabs w r ere obtained which are seen in the 
Prison floor, and which have been used with their natural 
surface unchanged in constructing many of the cells of the 
convicts. All the quarries from Waupun south, along the 
valley of the Rock river, are in this rock, and no valuable 
stone is furnished till w r e reach Janesville. 
JANESVILLE QUARRIES. 
A very fine quarry has been opened in the 3ow r er bed of the 
Trenton limestone by Ira Miltimore, Esq., at Monterey, below 
Janesville. Just above the junction with the sandstone, occur 
some calcareous strata slightly mixed with clay and fine sand. 
The bedding is smooth and distinct, dividing it into strata from 
six to ten inches thick, which are crossed by clean, vertical 
seams, usually filled with the red clay of the lead mines. The 
stone taken from this quarry dresses well, and may be sawed 
and even polished. It is variegated with curious facoidal 
and concretionary markings, which give to the sawed or dressed 
slabs a very singular appearance. This stone is extensively 
used at Janesville and vicinity, and the Blind Asylum has 
been constructed of it. The quarry is w r ell located in the 
