MANLIUS LIMESTONE OF HELDERBERG PLATEAU 47 
geologist of the Geological Survey of New York, also studied the 
Indian Ladder cliff and sent me a detailed section from the top of 
the ‘‘Hudson River” sandstone to the base of the Coeymans lime- 
stone, and recently the writer spent a day in a re-examination of that 
part of the section. The typical section near Manlius has also 
been examined and after this study it is apparent that the line of 
division between the Manlius and Coeymans limestones in the 
Indian Ladder section ought to be drawn higher than it was in the 
section published by the writer in his article of 1901. This probable 
change was indicated by the writer in a footnote on p. 290 of Pro- 
fessor Amadeus W. Grabau’s “‘Guide to the Geology and Paleon- 
tology of the Schoharie Valley in eastern New York.”! 
The following section is based to some extent on one furnished by 
Mr. Hartnagel, but it has all been remeasured and verified by the 
writer and on account of the importance of the Helderberg section 
in geological literature it is considered worthy of publication. 
Thickness Total 
No. of Zone— Thickness— 
Feet Feet 
eye Bluish-gray, coarser-grained limestone than 36+ 95+ 
the subjacent beds which is limited at the base 
by a rather marked bedding plane. In the 
lower 13 feet Mr. Hartnagel reported Stroph- 
onella punctulifera (Con.) Hall, Spirifer van- 
uxemi Hall, and Leperditia alta (Con.) Hall. 
Gypidula galeata (Dal.) H. and C. appears above 
the 1}-foot zone and within 5 feet becomes 
abundant. At the base is a coral resembling 
Cyathophyllum. ‘The lower 2 feet of this divi- 
sion Professor Harris called “‘ Transition layers,’’? 
and this name for the zone is quite appropriate 
since, lithologically, the rock is bluish-gray in 
color and coarser grained than the subjacent 
Manlius limestone; but on the other hand it con- 
tains Spirifer vanuxemi Hall and Leperditia alta 
(Con.) Hall, which are generaily considered as 
characteristic of the Manlius limestone, while 
t New Vork State Museum, Bull. 92, 1906, 386 pages, 225 figs., 24 pls., and 
“Geologic Map"of the Schoharie and Cobleskill Valleys.’”” This comprehensive hand- 
book on the geology of the Schoharie valley and northern Helderbergs will prove 
of inestimable value to students of this classic region. 
2 Bull. Am. Pal., No. 19, p. 25. 
