48 Geological Reports on the State of New York. 



that proves a force applied on the northern side, for a force in any other 

 direction could not produce the same result." 



The pebbles on the lake shore are faithful representatives of the 

 rocks of this region, and the siliceous limestone especially, con- 

 tains corallines, orthoeerae, bivalves, &c. 



Boulders are numerous all along the surface of the countries 

 contiguous to the lakes, but they are deposited in different pro- 

 portion in different places. 



" Boulders of granite, and other rocks, are scattered over the northern 

 part of the county, in some places the surface being literally covered with 

 them, while in the southern part they are almost entirely absent. In 

 this respect, Niagara county differs from Monroe, where, in the south- 

 ern part, boulders are very abundant and of large size. They are more 

 abundant in the eastern part of this county than towards the Niagara 

 river. These boulders appear to follow certain courses, and to extend 

 in great profusion over certain districts ; this distribution appears to have 

 been governed by some law, and we may yet arrive at data which will 

 enable us to describe the diluvial and its varying characters with as much, 

 or more precision, than we now do a stratum, or a series of strata, in an 

 older formation." 



Clay Stones. — "The gray loamy clay above the blue clay, in Niagara 

 county, sometimes attains the thickness of four or five feet, and in some 

 places occupies the place of the blue clay, where this has apparently been 

 removed. The gray, where it occurs, is entirely distinct from the blue, 

 and appears as if it might have been deposited at a subsequent period. 

 In this clay we find the calcareous concretions, called clay stones, or 

 'clay dogs;' these substances assume all imaginary forms, sometimes the 

 most fantastic. They are often in the shape of spheres, and sometimes 

 two or more of them attached together. They appear at regular inter- 

 vals in the strata, and commonly a line of them marks the junction of 

 the gray with the blue clay below. These substances are an earthy car- 

 bonate of lime, which is apparently deposited from the water percolating 

 from the surface. Fibres (apparently vegetable) extend from the surface 

 to the depth of three or four (sometimes twelve) feet, and around these 

 fibres, as a nucleus, the deposit is made. The gray loamy clay is per- 

 vious to water, while the blue clay is not. The fibres never extend into 

 the blue clay, but always terminate at its surface. We find the clay 

 stones surrounding the same fibre at different depths, and can often 

 trace the connexion of several. Sometimes there are merely rings of 

 calcareous matter, the internal part still being clay. Those formed di- 

 rectly around the fibre, are usually perforated, but others are often at- 

 tached on every side, which are entirely solid. It appears as if the 



