82 
GEOLOGY OF THE FOURTH DISTRICT. 
The higher beds are well developed in the falls at Wolcott village, and the lower part of 
the formation can be examined by following down the ravine for a mile. This is the most 
eastern locality in the district where we find the rock exposed. West of this point, through¬ 
out the county, it is seen in all the small streams which flow into the lake. 
23. 
View of the Upper Falls at Rochester. 
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 preceding 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 true 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 terminating calcareous beds of 
the Clinton group consist of fifteen or twenty thin courses, each separated by a layer of shaff 
