CLINTON GROUP. 
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21 . 
1. Section of the strata one mile south of Medina. 
2. Section showing the Clinton group and associated 
strata at Lewiston, on the Niagara river. 
g. Niagara shale. 
f. Upper limestone of Clinton group. 
e. Place of the upper green shale ; no rock seen. 
d. Pentamerus, or Lower limestone of Clinton group. 
c. Lower green shale of Clinton group. 
b. Terminal grey mass of the Medina sandstone. 
a. Medina sandstone. 
e Niagara shale. 
d. Limestone, formed by the junction of the lower and 
upper limestones of the group, 
c. Lower green shale of Clinton group. 
b. Terminating grey portion of the Medina sandstone. 
a. Medina sandstone. 
Section 1 illustrates the order of succession one mile south of Medina, where the lower 
green shale of the group has diminished to three feet, and there is no evidence of the upper 
green shale, although the absolute contact of the limestones is not seen. The two limestones 
preserve nearly the same characters as at Rochester, though there is more hornstone in the 
lower mass, and its typical fossils are absent. 
The upper limestone contains pyrites, and is often iron-stained, presenting numerous irre¬ 
gular cavities, It also contains its peculiar fossil, Atrypa naviformis. The shale of the next 
group follows in the same order as at Rochester. 
Section 2 illustrates the order of succession among the strata at Lewiston, and along the 
Niagara riyer the same order is preserved. There is little change from Medina to this point, 
except that the two limestones of the group are here not only in contact, but apparently form 
a single mass, the lower part differing somewhat from the upper. 
