Io. 
MANLIUS LIMESTONE OF HELDERBERG PLATEAU 49 
Cement beds which are compact, even 
bedded, and generally weathered back a foot or 
two, and sometimes several feet within the face 
of the cliff. This zone, as a rule, is conspicu- 
ously shown on the face of the escarpment. Its 
thickness is somewhat variable, ranging from 4 
feet, 9 inches, at the first spring east of the high- 
way to 3 feet in Harris’ section. It is given as 
44 feet by Hartnagel and on the Indian Ladder 
road it is 3 feet, 9 inches. In my former paper 
this zone formed the upper part of what was 
termed the transitional beds from the Tentacu- 
lite to the Pentamerus limestone; but it was 
included in the Tentaculite limestone. They 
were termed transitional because Tentaculites 
gyracanthus Eaton, the characteristic fossil of 
the Tentaculite limestone, was not found in 
them, while some of the other Tentaculite fossils 
were found well toward their top and the marked 
lithologic break at the top of the cement zone 
was thought to represent the line of division be- 
tween these two limestones as used by the older 
geologists. At the base of the cement rock is 
generally a shaly limestone, about 6 inches thick, 
which frequently shows ripple marks. The dis- 
tance from the top of this zone to the base of the 
Manlius limestone may be easily measured in 
the cliff near the first spring east of the Indian 
Ladder road. 
Massive rough limestone containing Strom- 
atopora in which Mr. Hartnagel reported Spirijer 
vanuxemt Hall and Leperditia alta (Con.) Hall. 
Thin-bedded limestone with Stromatopora 
layer at base. These two zones correspond to 
No. 6 of Harris’ section with the same thickness. 
Massive compact layer. 
Thin-bedded, dark-blue limestone which 
has a metallic ring. Many of the layers contain 
immense numbers of Tentaculites gyracanthus 
Eaton. 
Thick and thin layers of dark-blue lime- 
Thickness 
of Zone— 
Feet 
4it 
Total 
Thickness— 
Feet 
5 Ors 
