354 [Assembly 
Clay, 
Blue, yellow, and variegated clays, occur at many points in Orleans 
county, and are employed in the manufacture of brick of a fair quality, 
as at Albion, where there are several kilns immediately in the village. 
A handsome blue clay was seen at Linden, a thriving village one mile 
south of Yates centre. Blue and yellow clays appear at several points 
along the lake shore, forming limited beds in the banks, but at present 
they are not explored. 
Boulders. 
A variety of primitive boulders were noticed along the Erie canal be- 
tween Hulberton and Holley; also a little north of Medina, between the 
canal and ridge, and on the lake shore, in Yates. In the northeast part 
of Barre, on the limestone range, one large boulder of granite was ob- 
served, with grayish quartz and opalescent feldspar. Also at the same 
place, one very large transported mass of sandstone. 
These erratic blocks are found scattered over the surface, but I think 
in less profusion than farther east. Near Jefferson lake are several large 
masses of granite, with dark blue feldspar^ resembling the rock which oc- 
curs in place in Essex county, where it forms whole mountains. These 
boulders are unlike any of the rocks of the western counties, and have 
travelled from the north. At Oak Orchard, on the east bank of the creek, 
one small boulder was noticed, consisting of dark limestone with fossils 
distinguished as belonging to the limestones which repose upon the sand- 
stone, as seen in the southern part of the county; but from its situation 
it was considered to have been brought down the stream by the high 
waters of the creek. 
Marl, 
A limited deposit of calcareous marl was noticed about one mile south 
of Holley, on the west side of Sandy creek. It is white, in a state of 
powder, and contains an abundance of shells, principally the Helix al- 
bolabris (white tipped snail.) It occurs on the side of a hill, resting on 
the red sandstone, and was exposed in digging a raceway. 
Calcareous marl also occurs in a swamp on the farm of David Hook- 
er, two and a half miles north of Medina. 
Calcareous tufa forms in large quantities at the falls of Oak Orchard 
creek at Shelby, from the decomposition of the calcareous shales. 
