0161 7 T HtflAI 
The Ohio £A Naturalist , 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
libr^ 
NEW Y 
BOTANI 
QAROi 
Volume X. 
MARCH, 1910. 
No. . 
TABLE OF CONTENTS. 
Lamb— Pennsylvanian Limestones of Northwestern Ohio below the Lower 
Kittanning Coal 89 
Jennings— A Supplementary Description of Cerastium arvense Webbii Jennings . . . 136 
PENNSYLVANIAN LIMESTONES OF NORTHEASTERN OHIO 
BELOW THE LOWER KITTANNING COAL. 
G. F. Lamb. 
INTRODUCTION 
In the Lower Coal measures of Pennsylvania and Ohio there 
occur certain beds of Limestone whose outcrop is known to be 
more or less continuous around the northern, the northwestern, 
and the western border of the Appalachian coal basin. This is 
true more particularly of those limestones occurring below the 
horizon of the Lower Kittanning coal. This coal with its com- 
panion, the famous Middle Kittanning coal, constitutes a band 
which, for extent, continuity, importance, and distinctness, is 
perhaps second to none in the belt of the Lower Coal measures. 
This band divides the Lower Coal Measure limestones into two 
groups — those below the Kittanning Coals and those above them. 
The purpose of this paper is a discussion of the Limestones 
below these well known coals. Accordingly for definiteness and 
convenience of reference the line is drawn at the base of the Lower 
Kittanning coal. 
REVIEW OF LITERATURE. 
For our present knowledge of these limestones as they occur 
in the State of Pennsylvania, we are indebted chiefly to H. D. 
Rogers, H. Martyn Chance, I. C. White, and F. G. Clapp. Rogers 
in 1858 in his general section of the bituminous coal field of Penn- 
sylvania (the section beginning in Mercer and ending in Greene 
County) gives only two limestones below the Lower Kittanning 
Coal. The lower one of 2 feet thickness he names the Mercer 
Limestone. [Geol. Penn. Vol. II, Part I, p. 476.] On the next 
page of the same report he gives another limestone — Mahoning 
Limestone — as forming the top of the Tionesta Group. On 
another page he states as follows: 
89 
