RESEARCH· ·1970·

GE 1 0LOGICAL SURVEY RESEA·RCH 1970
HIGH-CALCIUM LIMESTONE DEPOSITS IN LANCASTER COUNTY,
SOUTHEASTERN PENNSYLVANIA_
By ALBERT E. BECHER and HAROLD MEISLER/
Harrisburg 1 Pa. 1 Trenton 1 N.J.
Work done in cooperation with, the Pennsylvania Geological Survey
Abstract.-Geologic mapping in the Lititz 7%-minute quadrangle,
Lancaster County, revealed the presence of the Annville
J..~imestone in the Piedmont province of southeastern Pennsylvania.
The Annville is a commercially valuable high-calcium
limestone that was reported previously only in the Great Valley
of the Valley and Ridge province. Chemical analyses of composite
samples from each of four stations in the Lititz quadrangle
indicate that the CaCOa content ranges from 94.2 to 96.5
percent, the l\fgCOo content ranges from 1.3 to 3.7 percent, and
the silica-alumina content is less than 2 percent. These analyses
indicate that the Annville Limestone is a potential source of
high-calcium limestone in the Lititz 7%-minute quadrangle.
During a hydrogeologic study in southeastern Pennsylvania
(:~1eisler and Becher, 1966, 1969), a li1nestone
unit was Inapped that semned to have an unusually
high calcite content. The unit was correlated with the
Annville Limestone of Ordovician age described by
Gray (1951) and Prouty (1959) in that part of the
Great Valley that lies in Dauphin, Lebanon, and Berks
Counties. In the Great Valley, the Annville is quarried
for high-calcium limestone. The areal extent of the
Lancaster County deposits (as indicated by surface
exposures of the Annville) and their apparent purity
suggested that they 1night be of commercial value.
Therefore, samples were collected and submitted for
chemical analysis.
Commercially valuable limestone used in the Inanufacture
of high-calcium prodt}cts should contain at
least 97 percent calcium carbonate and no n1ore than 3
percent silica and alumina (Swain, 1946). High-calcium
limestone is used 1nostly for 1netallurgical li1ne
and flux stone in the iron and steel industry, chemical
lime in the chemical industry and in the production
of paper, and for other uses in agriculture and construction.
GEOLOGIC SETTING
Exposures of the Annville Limestone in the Conestoga
Valley of the Piedmont physiographic province
occur in the northeastern part of the Lititz 71j 2 -minute
quadrangle in Lancaster .County (fig. 1). The Annville
Limestone, of ~1iddle Ordovician age, occurs near the
top of a thick stratigraphic sequence of carbonate rocks
·of Cambrian and Ordovician age described by ~1eisler
and Becher ( 1968). It lies between the older Ontelaunee
Formation, a dolomite unit, and the younger
~1yerstown Limestone. Outcrops of the Annville occur
on each flank of a large eastward-plunging anticline
that is overturned, past recumbency, to the north. The
northern outcrop of Annville (fig. 1), in the nor1nal
limb of the fold, strikes northeastward and dips
steeply northwestward, whereas the southern outcrop
of Annville, in the overturned limb of the fold, strikes
northwestward and dips gently to Inoderately northeastward.
The esti1nated Inaxi1nun1 stratigraphic thickness
of the Annville is about 200 feet.
DESCRIPTION OF SAMPLE STAnONS
Rock sainples were collected frmn all 1najor exposures
of the Annville Liinestone in the Lititz quadrangle.
The location of the sainple stations are shown
in figure 1. Stations 1885 and 1889 are small a bancloned
quarries in which about 60 feet and 20 feet,
respectively, of section is exposed. Limestone was :formerly
extracted frmn these quarries and burned by
local :farmers for agricultural lime. About 25 :feet o:f
the Annville Limestone section is exposed at station
B102
U.S. GEOL. SURVEY PROF. PAPER 700-B, PAGES Bl02-Bl0l