RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 253 
Trenton Falls, and zones 2 and 1 of the section below are to be under- 
stood to be exposed only in small part at Trenton Falls, but com- 
pletely at Rathbone Brook. The Utica is likewise not exposed directly 
at Trenton Chasm, but at several places in the immediate vicinity. 
Composite section (Raymond, 112). Zones 7 to 3 and upper part 
of 2 exposed at Trenton Falls. 
8. Thin-bedded black and brown carbonaceous shale with 
Triarthrus becki, Cryptolithus tessellatus, Pleurograptus 
linearis and many other graptolites. The contact with 
the limestone below is sharply defined and there are no 
transition beds. Utica shale (typical). Thickness 
about 300 feet. 
7. Light gray, coarse-grained lithified coquina in thick beds. 
Rafinesquina deltoidea, Hormotoma trentonensis and other Feet. 
fossils. 26 
6. Thin-bedded blue limestone with shaly partings. Ra- ‘ 
finesquina deltordea the common characteristic fossil. 92 
5. Thin-bedded blue limestone with thick shaly partings. 
Prasopora simulatrix and other common Trenton fossils 
abundant. 100 
4. Thin- and thick-bedded limestone, dark in color and 
fine-grained. Dziplograptus amplexicaulis a common 
fossil. 35 
3. Thin-bedded dark limestone with Triplecia extans and 
other fossils. | 20 
2. Thin-bedded dark limestone with some inter-bedded 
coarse-grained layers. Cryptolithus tessellatus the char- 
acteristic fossil. Trematis terminalis, Platystrophia - 
trentonensis, Calymene senaria and many other fossils 
present. 41 
1. Thin-bedded gray limestone with an abundance of Dal- 
manella rogata, and some other fossils. 32 
The Leray-Black River is beneath 1. I wish to call especial atten- 
tion to the fact that there are here two zones of Cryptolithus tessella- 
tus; one in the forty-one feet of limestone near the base of the section 
(this is the Glens Falls limestone) and one in the Utica shale. 
Cryptolithus tessellatus is not a facies fossil, as its occurrence in this 
section shows for it is in both dense fine-grained blue limestone and 
coarsely crystalline gray limestone (coquina rock) in the lower zone, 
and in the Utica it is in a very fine-grained carbonaceous shale. In 
northern New York at the eastern end of Lake Ontario, it is found in 
