Ground Water in Northeastern Pennsylvania
Creators: name: Lohman, Stanley William
Publisher: name: California Institute of Technology
Year: 1938
Subjects: subject: ground water
subject: Susquehanna River
subject: Appalachian Plateaus
subject: Delaware River
subject: Geology
subject: FOS: Earth and related environmental sciences

description: This report describes the surface features, stratigraphy, and geologic structure and the sources and chemical character of the ground water in an area covering 7,087 square miles in northeastern Pennsylvania, including Carbon, Columbia, Lackawanna, Luzerne, Monroe, Montour, Northumberland, Pike, Schuylkill, Susquehanna, Wayne, and Wyoming Counties, the northern three-fifths of Dauphin County, and about 50 square miles of northern Lebanon County. The area is drained entirely by the Delaware and Susquehanna Rivers and their tributaries. It includes parts of two geomorphic provinces—the Appalachian Plateaus province and the Valley and Ridge province, both of which are subdivisions of the Appalachian Highlands.

The consolidated rocks of the area range from the post-Pottsville formations, of Pennsylvanian age (youngest), to the Juniata formation, of Upper Ordovician age (oldest). All the rocks are later than the Taconic disturbance, and the Juniata formation and the overlying Tuscarora sandstone (Silurian) rest unconformably on the Martinsburg shale (Ordovician), which is exposed south of the area. There are no pronounced stratigraphic breaks above the unconformity at the base of the Silurian except in Dauphin and Lebanon Counties, where all of the Lower Devonian and late Silurian are absent, owing either to a fault or to an unconformity. The youngest consolidated rocks, the post-Pottsville formations, contain the valuable anthracite beds, which are extensively mined in several large synclinal basins within the area. Anthracite is also obtained locally from the Pottsville formation and the Pocono sandstone.

More than half of the area is covered with glacial drift, mostly of Wisconsin age, although Illinoian and Jerseyan drift occurs south of the Wisconsin drift border which traverses the middle of the area. The recent alluvium along the larger streams that drain the coal basins contains considerable finely divided coal that is recovered by dredging at numerous points.

Within the densely populated and industrialized coal basins ground water is used only in a very few places, and municipal, industrial, and domestic needs are supplied almost exclusively by surface water. Within the coal basins the water level has been lowered by continual pumpage of mine water, and most of the little water that remains in reach of wells is unfit for ordinary use. The water thus obtained from the mines is largely utilized for washing coal, after which it is discharged into the streams.

Outside the coal basins the larger municipal supplies are obtained from surface water, but the domestic, industrial, and smaller municipal needs are supplied chiefly by ground water. In the rural regions domestic supplies are obtained largely from dug wells, but small springs and drilled wells are also used extensively. Industrial and municipal supplies are obtained chiefly from drilled wells and springs.

North of the Wisconsin drift border and for some distance south along the major drainage channels, glacial drift supplies all the dug wells and a few of the drilled wells. Large supplies of water can be obtained from glacial outwash in some places by means of properly constructed drilled wells using well screens, but very few attempts have been made to recover large quantities of water from any of the unconsolidated deposits.

Most of the drilled wells in the area obtain adequate supplies of water from sandstone, but a few obtain water from conglomerate, shale, or limestone. Most of the rock formations contain numerous beds of sandstone that can generally be reached by wells of moderate depth. The sandstones are in the main rather firmly cemented. and the water is contained chiefly in fractures, joints, and bedding planes. Shale yields small but generally reliable supplies. Limestone occurs only in a few places along the southern and western borders of the area and is of importance as a source of ground water only in parts of Columbia, Montour, and Northumberland Counties, where it yields large supplies of hard water to wells that encounter solution channels, but it may yield very little water where solution channels are not encountered.

Artesian conditions are related to the geologic structure. In the Appalachian Plateaus province, where the strata are nearly horizontal over large areas, flowing wells are not numerous but occur locally. In the Valley and Ridge province flowing wells are obtained in many places on the flanks of synclines or monoclines. A few flowing wells occur in glacial drift.

With few exceptions, the chemical character of the ground water is entirely satisfactory for most purposes. Water from glacial drift or light-colored sandstone or shale generally contains small amounts of dissolved mineral matter and is generally soft. Water from dark-colored shales or sandstone generally contains more dissolved mineral matter and in some places is noticeably hard. Water from limestone ranges from moderately hard to very hard.