Agricultural Geology. 99 
View of the Upper Falls at Rochester — Fig. 5. 
At Rochester it forms nearly the whole height of the upper 
fall, and the banks on either side of the river for more than a mile 
below. This place offers a fine exhibition of the rock, and is one 
of the best localities in the State for a natural exposure. The 
constant undermining of the banks precipitates large masses to the 
bottom, and their fossil contents are thus made accessible. At 
this locality, its upper and lower limits are both plainly seen. 
Above it passes gradually into an impure limestone, which forms 
the beds of passage from the shale to the limestone above. The 
fossils mostly disappear at this point, and few are found in this 
part of the mass. Below it terminates abruptly, resting directly 
on the calcareous beds forming the upper member of the preced- 
ing group. There is never any gradual passage from the one 
to the other, and the peculiar fossils of the shale do not appear 
till we ascend some distance above the limestone. Nevertheless 
it is ti-ue that two or three of the common fossils of this shale 
have been found in the limestone below, and at the same time the 
greater number marking the Clinton group terminate below that 
rock. It may therefore remain a question, perhaps, whether these 
calcareous beds should be included in the Niagara group. Since, 
however, they bear a close analogy to the lower limestone of the 
Clinton group, and terminate above abruptly without offering any 
marks of gradual passage to the next higher group. I prefer for the 
present to include them in the lower, thus presenting a natural 
lithological assemblage. The presence of a few fossils common 
to the limestone and shale above would apply equally to all parts 
of the preceding group, a few forms being common to all parts of 
both. 
The precise arrangement at Rochester is as follows: — The ter- 
minating calcareous beds of the Clinton group consists of fifteen 
