82 EDWARD STEIDTMANN 
hornblende with a little pyroxene and biotite. The constituents of 
the Losee gneiss are quartz, oligoclase, pyroxene, and some horn- 
blende and biotite. The Pochuck gneisses are mostly of unknown 
origin, but in part are igneous. They are dark-colored rocks com- 
posed of pyroxene, hornblende, oligoclase, and magnetite. The 
stratigraphic relations of the pre-Cambrian rocks have not been 
worked out. Their classification is lithological. They are believed 
to be related to the Grenville series of the Adirondacks and south- 
eastern Canada. 
Bayley* reports that the pre-Cambrian rocks of the highlands 
of New Jersey include a series of limestone, quartzites, conglomer- 
ates, slates, and micaceous schists whose stratigraphic succession 
is uncertain. They are surrounded by older and in part igneous 
gneisses. 
Bliss and Jonas? conclude that the Wissachickon mica gneiss of 
the Doe Run and Avondale region of southeastern Pennsylvania 
is of pre-Cambrian age and is separated by a thrust fault from 
Ordovician limestone. 
Cushing and Ruedemann} describe the Saratoga Springs area 
which lies in the eastern central portion of New York state. It 
includes portions of the Adirondack highlands, New England plateau 
and the Champlain downwarp. The pre-Cambrian rocks include 
Grenville sediments intruded by Laurentian granite. Later intru- 
sions of anorthosite, syenite, granite, and gabbro followed in the order 
named. The Grenville sediments consist chiefly of a variety of 
schists probably representing metamorphosed muds. Associated 
with them is a belt of quartzite with some limestone lenses. The 
schistosity and bedding of the sediments are inferred to be parallel. 
The schistosity strikes east and west and dips southward at a low 
angle rarely reaching 40°. 
*W. S. Bayley, “The Pre-Cambrian Sedimentary Rocks in the Highlands of New 
Jersey,” Congrés Geologique International. (XII Session Canada, 1914, pp. 325-34.) 
2Eleanora F. Bliss and Anna I. Jonas, ‘Relation of the Wissahickon Mica 
Gneiss to the Shenandoah Limestone and Octoraro Schist of the Doe Run and Avondale 
Region, Chester County, Pennsylvania,” U.S. Geol. Surv., Prof. Paper 98 (1916), 
PP: 9-34, 3 Pls., 3 figs. , 
3H. P. Cushing and H. Ruedemann, “Geology of Saratoga Springs and Vicinity,” 
New York State Museum, Bull. No. 169, 177 pp., 17 figs., 3 maps. 
