68 NEW YORK STATE MUSEUM 



varying in diameter up to 6 inches or a foot. The stratification is 

 rude, and shells are abundant. These are mostly fresh-water mus- 

 sels (Unio, Alasmodonta, etc.) and the valves are generally 

 found in conjunction, a fact which may indicate that these shells 

 lived here. Small gastropod and pelecypod shells are plentifully 

 mingled with the pebbles and sands. Below this are coarser- de- 

 posits where boulders up to several feet in diameter occur, and below 

 this occurs a bluish clay. In all of these beds shells have been 

 sparingly found. 



Several excavations have been made in Queen Victoria park, and 

 here shells are common. The Unionidae appear to be most abund- 

 ant, though small gastropods are not uncommon. All appear to 

 have been more or less waterworn. The mussel shells are gen- 

 erally decayed, ov/ing no doubt to percolating waters. Below Clif- 

 ton, the lower of two terraces is of a somewhat sandy character, 

 though many boulders occur in it. Shells of unios occur sparingly 

 in these deposits, and a few small gastropods were found in the 

 lowest terrace. Farther north several excavations in the lower ter- 

 races of the old river show loose gravels alternating with a sort of 

 till, a few Goniobasis and other gastropod shells being found 

 here. In some cases the gravels have become cemented into a con- 

 glomerate by a deposit of calcite between them, often of consider- 

 able thickness. Boulders of similarly cemented gravels are found 

 in the gorge below, at the whirlpool. 



It will thus be seen that, throughout the greater part of the young 

 Niagara, deposition was going on as well as erosion. The amount 

 of erosion of the river bed was probably very slight, that of the 

 banks being much more pronounced. The chief part in the 

 cutting of the gorge was enacted by the cataract, which cut 

 backward from Lewiston, the amount of dozvnward cutting by 

 the river being insignificant. The manner in which the cata- 

 ract performed its work of cutting may today be observed 

 in both the American and Canadian falls, as well as in water- 

 falls of other streams falling over strata, the arrangement of which 

 is similar to that obtaining at Niagara. The essentials are a re- 

 sistant stratum overlying a weak one, the latter being constantly 



