USGS Science⌕ Search

Geology topics

Research about Pennsylvania

Source-linked reports with geographic coverage including Pennsylvania.

At least 775 records · Page 43Linked to original sources
USGS1953

Petrology of granophyre in diabase near Dillsburg, Pennsylvania

Small bodies of granophyre occur in the upper part of diabase bodies of Triassic age in southeastern Pennsylvania. One near Harrisburg was penetrated by a diamond-drill. Drill core specimens show a gradation from diabase to granophyre. New data include 10 chemical analyses, spectrographic determinations of trace elements, and the results of petrographic study of specimens from the drill core. The sequence, from diabase to granophyre, includes a chilled zone that represents an original magma of tholeiitic composition, normal diabase, pegmatitic facies of diabase, and granophyric diabase that is intermediate in composition and petrographic characteristics between diabase and granophyre, and finally granophyre. Alkalies and silica increase progressively from diabase to granophyre; iron increases to a maximum in transitional granophyric diabase, then decreases in the granophyre. It is concluded that crystal fractionation in a large sheetlike body of tholeiitic magma yielded a small amount of granophyre. Prior to complete solidification, a residual liquid rich in iron, alkalies, and silica accumulated locally in the upper part of the diabase sheet. In places volatile-rich iron-bearing solutions escaped into the overlying sedimentary rocks and deposited magnetite; the remaining liquid crystallized t o fine-grained granophyre.

Pennsylvania↗
USGS1953

Interpreting geologic maps for engineering purposes: Hollidaysburg quadrangle, Pennsylvania

This set of maps has been prepared to show the kinds of information, useful to engineers, that can be derived from ordinary geologic maps. A few additional bits of information, drawn from other sources, are mentioned below. Some of the uses of such maps are well known; they are indispensable tools in the modern search for oil or ore deposits; they are the first essential step in unraveling the story of the earth we live on. Less well known, perhaps, is the fact that topographic and geologic maps contain many of the basic data needed for planning any engineering construction job, big or little. Any structure built by man must fit into the topographic and geologic environment shown on such maps. Moreover, most if not all construction jobs must be based on knowledge of the soils and waters, which also are intimately related to this same environment. The topographic map shows the shape of the land the hills and valleys, the streams and swamps, the man-made features such as roads, railroads, and towns. The geologic map shows the kinds and shapes of the rock bodies that form the land surface and that lie beneath it. These are the facts around which the engineer must build.

Pennsylvania↗
USGS1953

Geology of anthracite in the western part of the Ashland quadrangle, Pennsylvania

The Western Middle anthracite field is one of four structural basins containing anthracite in eastern Pennsylvania. This report describes the geology of the part of the Western Middle field that lies in the western half of the Ashland quadrangle. (See index map, sheet 2.) The mapped area covers about 19 square miles in Columbia and Schuylkill Counties. The town of Centralia is in the northern part of the area, and the town of Ashland is in the southern part.

Pennsylvania↗
USGS1951

Water resources of southeastern Bucks County, Pennsylvania

This report has been prepared as a contribution to the development of southeastern Bucks County, Pa. It summarizes available information on the water resources of this 90-square mile area and evaluates current supplies. Future development of the area may change both the available quantity and the quality of the water supply. The effective development of the area demands a continuing knowledge of the water used and the potential quantity and quality of water available from both underground and surface sources. The area is strategically important to a great industrial section of the Bast. Its eastern boundary is a 26-mile segment of the Delaware River along the extreme southeastern border of Bucks County, Pa. (fig. 1). The present.population of the area is about 40,000, including 24,800 in Bristol Borough and Township and 6,770 in Morrisville. The area is traversed by both the Pennsylvania and the Reading Railroads and also by U.S. Highways 1 and 13. These are main transportation routes connecting the great market outlets of Philadelphia and New York. The Delaware River'is navigable from Morrisville to the sea. The area is only a short distance upstream from the Port of Philadelphia, which ranks second only to New York as the most important seaport in the United States. The area is mostly flat, open land 10 to 60 feet above mean sea level. It contains several large Industries, concentrated chiefly in the Bristol area (pi. 1). There are also scattered industries in the Morrisville, Langhorne, and Bensalem areas. However, Bucks County retains some of the characteristics of a farming region. Truck farming and gardening are still carried on to a considerable extent. Along Delaware River below Morrisville the mining of sand and gravel is an Important industry. The facts summarized in this report have been accumulated over a period of 25 years or more by Federal, State, and local agencies in connection with Investigations for other purposes. Most of the data used in this report have been obtained by the United States Geological Survey in cooperation with the Pennsylvania Department of Forests and Waters, the Pennsylvania Department of Internal Affairs, the Pennsylvania Department of Commerce, and State Planning Board, the City of Philadelphia, the Corps of Engineers, and the Interstate Commission on the Delaware River Basin. This report was prepared in the Water Resources Division of the U.S.Geological Survey by Jack B. Qraham, District Geologist; John W. Mangan, District Engineer; and Walter F. White, Jr., District Chemist, under the general direction of C. G. Paulsen, Chief Hydraulic Engineer.

Pennsylvania↗
USGS1951

Geology of anthracite in the east-central part of the Mount Carmel quadrangle, Pennsylvania

The Pennsylvania anthracite fields, the principal source of anthracite in North America, are in the eastern part of the Commonwealth of Pennsylvania. The coal occurs in four elongate areas - Northern, Western Middle, Eastern Middle, and Southern fields - that trend northeastward and lie in echelon arrangement. The fields range in length from 24 to 66 miles and in width from a fraction of a mile to 10 miles, and include about 484 square miles of coal-bearing land. The area covered by this report is in the Western Middle field.

Pennsylvania↗
USGS1951

Geology of anthracite in the southwestern part of the Mount Carmel quadrangle, Pennsylvania

This report is the second to be prepared as a result of a geologic investigation of the anthracite fields of Pennsylvania begun after consultation with the Bureau of Topographic and Geologic Surveys of the Commonwealth of Pennsylvania. This report and others in preparation will show (1) the location of coal outcrops, (2) the depth, pitch, and other structural features of representative coal beds, (3) the natural and artificial barriers between mines and the structural relationships between the various coal basins, and (4) the correlation of the beds, the stratigraphic intervals between them, and the thickness, continuity, and other physical characteristics of the coal. The reports will bring up to date and amplify the Grand Atlas of the Anthracite Fields published by the Second Geological Survey of Pennsylvania in 1884-1885, and the reports that supplemented that atlas. It is expected that the reports will aid operators who are mining either on the surface or underground, or who are formulating plans for control of mine water. It is hoped that these reports will also direct attention to overlooked or unutilized reserves of coal. A preceding report described the west-central part of the Mount Carmel quadrangle (Rothrock et al., 1950) and it is planned to publish similar reports on other unit areas as they are completed.

Pennsylvania↗
USGS1950

Ground-water problems in the Philadelphia area [Pennsylvania]

Large quantities of ground water are used by the Philadelphia Naval Base and many industries in south Philadelphia, as well as by municipalities near Philadelphia in both Pennsylvania and New Jersey. The areal contact between unconsolidated sand, gravel, and clay strata of the Atlantic Coastal Plain and consolidated rocks of the Piedmont province extends in a northeast-southwest line through central Philadelphia. This line of contact, the so-called Fall Line, sharply separates the area of highly productive sand and gravel aquifers of the Coastal Plain from the less productive bedrock aquifers of the Piedmont Plateau. The daily withdrawal of ground water from sand and gravel in the Philadelphia area, including Bristol, Pa., and Trenton, N. J., is approximately 110 million gallons. Wells around Philadelphia yield an additional 13 million gallons a day from consolidated rocks of the Piedmont province. The Raritan formation of Cretaceous age is the principal aquifer for wells in south Philadelphia and the adjacent Camden area. The large quantity of water pumped and the limited extent of this aquifer in the area provide a potentially serious interstate water problem. Ground-water levels in the strategically important Naval Base area have not declined seriously as yet, but increasing withdrawal planned in adjacent New Jersey is expected to lower water levels in south Philadelphia The Delaware and Schuylkill Rivers are believed to be the chief sources of recharge to the Raritan formation, even though heavy pumping on either side of the Delaware River may be expected to affect water levels on the other side. Recharge appears to be adequate generally for present rates of withdrawal, but further studies are needed for an evaluation of the safe maximum yield of the area. The chemical quality of ground water pumped from the Raritan formation is satisfactory for most purposes, but periodic analyses indicate that the concentration of dissolved solids is increasing. This deterioration of the chemical quality probably is due to the character of the water and bottom sediments of the Delaware and Schuylkill Rivers. Shallow aquifers in south Philadelphia contain large amounts of gases generated by the decay of river silts and city refuse occupying low areas. The States of Pennsylvania and New Jersey, together with the municipalities concerned, are coordinating their efforts for a practical solution to the ground-water problems of the Philadelphia area.

Pennsylvania↗
USGS1950

Memorandum on pumping test at Ambridge, Pennsylvania

By arrangment with Mr. J. Z. Columbia, Superintendent of the Ambridge Water Works, the United States Geological Survey conducted a "pumping test" in the Ambridge well field on November 10, 1949. As used in this report, "pumping test" means pumping a well at a fixed rate to determine the hydrologic properties of the water-bearing formation. By measuring the decline and recovery of water level in the pumped well and in other observation wells the necessary information is obtained for computing these properties. Such procedures are part of the field activities of the ground-water program in Pennsylvania being sponsored jointly by the Pennsylvania Topographic and Geologic Survey and the United States Geological Survey. The amount of water that can be pumped from an underground formation depends upon its ability to transmit water to a well and upon the amount of water that is released from storage when the water table or pressure head is lowered. The first is measured by the coefficient of transmissibility and the second by the coefficient of storage. These two characteristics are then used to determine the effect on water levels caused by changes in the location and rate of pumping from the aquifer.

Pennsylvania↗
USGS1949

Lower middle ordovician of south-central Pennsylvania

Broad paleostructural development in south-central Pennsylvania and Maryland was similar to that of central and eastern New York during the deposition of lower Middle Ordovician beds. Thick marine limestones of the easternmost belts of outcrop in the Cumberland Valley indicate the southward extension of the Champlain miogeosyncline. Thin and, in part, coarse-textured limestones in belts of outcrop just west of the Cumberland Valley indicate the extension of the Adirondack arch. Intermediate correlation shows the development of a relatively shallow platform east of the Adirondack arch and marginal to the Champlain miogeosyncline during part of the Bolarian (Kay, 1947) and Trentonian epochs. Detailed description, definition and correlation of the stratigraphic units are presented. The Pinesburg and Fannettsburg members (new) of the Shippensburg formation (redefined), the Housum and Kauffman members (new) of the Mercersburg formation (redefined), the Oranda formation (Cooper and Cooper, 1946) and the lower Martinsburg exhibit westward thinning by overlap or convergence or both from Champlain miogeosynclinal sections in eastern belts to sections on the Adirondack line in Path Valley. The Doylesburg member (new) of the Shippensburg is believed truncated to extinction southeastward from Path Valley by pre-Mercersburg regional unconformity. Argillaceous material in southeasternmost exposures of Oranda begins the Middle Ordovician transgressive clastic deposits resulting from the Vermontian disturbance. Correlations indicate Shippensburg is post-middle Chazyan to pre-Chaumont in age, Mercersburg is Rockland and Kirkfield, Oranda is Shoreham, and lower Martinsburg is Denmark.

Pennsylvania↗
USGS1949

The computation of second vertical derivatives of geomagnetic fields

Second vertical derivatives of magnetic fields, because of their high resolving power, are often very useful in interpreting magnetic anomalies. Formulas are developed which permit their ready numerical computation. Comparisons are made between the resulting approximate values and the rigorous values obtained for simple idealized fields. The similarity between maps of second vertical derivatives of fields and those of certain types of residual fields is discussed.

Pennsylvania↗
USGS1949

Petrology and habit of some diabase sheets in southeastern Pennsylvania

Small masses of granophyre occur in the upper part of diabase intrusions southeastern Pennsylvania. Diamond drill hole exploration of magnetite deposits near Dillsburg revealed a body of diabase beneath the sedimentary rocks in which the deposits occur. The drill core revealed a complete gradational sequence downward from a diabase chill zone through normal diabase, diabase pegmatite, transitional granophyric diabase into granophyre. New data include the results of petrographic study of a series of specimens from the drill core and 10 new chemical analyses. The sequence, diabase to granophyre, shows progressive increase in alkalies and silica; iron increases into the transitional granophric diabase stage, then decreases in the granophyre. The chemical variations are accompanied by changes in mineralogy which are described in detail. Field and petrographic studies of other granophyre masses were likewise made. Possible origins of granophyre from diabase are considered, and it is concluded that crystal differentiation in a large sheetlike intrusion most satisfactorily explains the genesis of granophyre in this region. Prior to complete solidification a residual liquid rich in iron, alkalies, silica, and volatiles collected locally in the upper part of the diabase sheet. In some places fractures released volatile-rich iron-bearing solutions which deposited magnetite in the overlying sedimentary rocks; the remaining liquid crystallized to fine grained granophyre. Elsewhere the volatiles were retained for a longer period; the resulting rock is coarse-grained with numerous miarolitic cavities. Ring-like outcrop patterns are characteristic of the diabase intrusions in southeastern Pennsylvania. Drill hole and geophysical data indicate that the diabase of these rings has the form of generally discordant curved sheets or basins. Pre-existing fractures or potential lines of weakness may have controlled the sheet-like form, or because of existing pressure conditions the diabase magma was forced to spread laterally rather than rise vertically.

Pennsylvania↗
USGS1947

The zinc content of plants on the Freidensville zinc slime ponds in relation to biogeochemical prospecting

The zinc content of thirty different kinds of plants growing on slime ponds containing on the average 12.5 per cent zinc were determined by the dithizone method. The zinc content ranged from 39 p.p.m. in the fruit of the false solomon's seal (Smilacina racemosa) to 5,400 in the horsetail (Equiseteum arvense}. This latter plant varied considerably in zinc at different places on the slime ponds. The zinc contents of the aspen (Populus grandidentata}, ragweed {Ambrosia artemisiifolia), and horsetail grown on normal soils are compared to those on the slime ponds and it is recommended that the poplar and ragweed be studied further as indicators of zinc ore bodies.

Pennsylvania↗