No. 200.] 
295 
has been called "grayband," by Professor Eaton; it, however, appears 
to be only a gray stratum of the sandstone, generally more siliceous and 
indestructible than the rock below. In some localities, however, the 
grayband is an indurated marl, destitute of silex. 
The rock below the grayband is variegated to the depth of 20 or 30 
feet, with gray or greenish gray spots and seams. Although this 
formation has been called sandstone, much the largest proportion of it is 
an indurated marl, containing too little siliceous matter to entitle it to 
the name of sandstone. On the Niagara river, where there are more than 
five hundred feet in thickness developed, we find no more than forty 
feet of a siliceous character. The disintegration of this rock has pro- 
duced a soil corresponding to the varying constituents of the rock be- 
neath. The marl in the lower part of the formation is striped, vertical- 
ly and horizontally, with seams of green shale. 
Following the course of this rock westward, from the point of its 
greatest depression in Wayne county, it gradually rises, and at the Nia- 
gara river has attained an elevation of two hundred feet above the lake. 
In the eastern part of our district this rock is more siliceous than farther 
west; this character is observable in the soil and boulders on the surface 
as well as in the rock beneath. After passing the Genesee river, the 
great mass of this formation is an indurated marl, giving rise to loamy 
soils, except where strata of limited extent occur, possessing a siliceous 
character. 
The surface of this formation is undulating, as may be seen by tracing 
the canal in its course, the level of which first comes upon the sand- 
stone in Sweden, Monroe county. At Medina, farther west, the canal is 
excavated ten feet into the rock, and again at Lockport the top of the 
sandstone is twenty feet below the canal. Some allowance must be 
made for the deviating course of the canal which at some places is far- 
ther north or south than it is at others. Where the canal first comes 
upon the sandstone west of Rochester, it is at a point four miles farther 
north than at Rochester; this will account for the circumstance without 
supposing that the sandstone is more elevated than would be produced 
by the dip. 
At Medina, about forty feet from the top of this rock, we find a stra- 
tum, two feet thick, of siliceous sandstone of a greenish gray colour, con- 
taining Lingula Cyclostoma, Planorbis, Unio and Cytherina. Following 
this stratum, or bed, westward, we find it on the Niagara river twenty- 
