The Fredericksburg Complex, in part a migmatitic terrane in northeast Virginia, is subdivided on the basis of lithology, as well as aeromagnetic and aeroradiometric data, into two metamorphic suites. These suites are separated by the northeast-trending Spotsylvania lineament, a rectilinear geophysical feature that is probably the trace of an old fault zone. East of the lineament, the Po River Metamorphic Suite, of Proterozoic Z and (or) early Paleozoic age, consists dominantly of biotite gneiss, generally augen gneiss, and lesser amounts of hornblende gneiss and mica schist. West of the Spotsylvania lineament is the Ta River Metamorphic Suite, composed mostly of amphibolite and amphibole gneiss. However, to the southwest, along its strike belt, the Ta River contains abundant biotite gneiss and mica schist.

Spotsylvania County in east-central Virginia, including the independent city of Fredericksburg, has an area of 415 square miles. The combined population of the county and city was 27,458 in 1960. Farming and manufacturing are the principal occupations. The climate is humid and temperate with an average annual rainfall of 41.40 inches and an average annual temperature of 56.4 F.
The area lies within two physiographic provinces of the eastern United States the Piedmont province and the Atlantic Coastal Plain province. The Piedmont area consists of a gently undulating upland and the Coastal Plain is an almost featureless surface sloping gently to the southeast.

The Potomac strata occur in several apparently disconnected areas that for the most part lie in lines of prolongation of one another running nearly north and south. They form the most easterly of the Mesozoic tracts and rest upon the eastern margin of the pre-Oauibrian terrane, sinking to the east beneath the Tertiary. Unlike the older Mesozoic beds, they in no case occupy areas within the pre-Cambrian.

Several suites of plutonic rocks have been identified by geologic mapping in the polydeformed and metamorphosed (amphibolite-grade) Piedmont near Fredericksburg, Va. Two of these suites were dated by U/Pb (zircons) and Rb/Sr (whole-rock) methods. The oldest suite is the Falls Run Granite Gneiss, a coarse-grained, strongly foliated, and highly metamorphosed rock that ranges in composition from granite to monzonite.

A generalized introduction to geology (minerals, rocks, fossils, landforms, layered and deformed rock, economic and environmental geology, stratigraphy and geologic history of North America) with numerous examples from Virginia.

Pre-Ordovician, probable Early Cambrian metavolcanic and somewhat younger meta-intrusive rocks form a linear belt in the central Virginia Piedmont. On the basis of the geologic and geochemical features of these rocks in the Fredericksburg area, and insofar as this area is representative of the entire belt, it is concluded that this belt constitutes an ancient island-arc sequence.

This section of the terrane catalogue to accompany the Tectonic Map of Pre-Mesozoic Terranes in Circum-Atlantic Phanerozoic Orogens covers the central and southern Appalachian region of the United States, from New York City to central Florida.

This pocket-sized field guide describes how metamorphic rocks and rock masses may be observed, recorded and mapped in the field. Written at a level suitable for Earth Science undergraduate students, this book is an essential tool for any geologist -- student, professional or amateur -- faced with the task of making a general description of an area of metamorphic rocks. A clear, systematic framework, together with numerous colour diagrams, illustrations and checklists, enables readers with different backgrounds to produce useful descriptions, despite possible differences of background or specialist interest. Additional information is also provided to aid those who are undertaking field mapping courses or must compile field evidence into reports on the metamorphic evolution of a region. This book: Shows the reader how to observe metamorphic rocks in the field, from the outcrop to the hand specimen scale Is fully revised and updated to incorporate new developments in the field Offers a user-friendly and accessible writing style including a revised format with tabbed sections for easy navigation Covers key topics including classification and mapping of metamorphic rocks, understanding key textures and fabrics, and details on contacts and fault zones

This handy pocket-sized guide shows how to achieve successful fieldwork on sedimentary rocks, paying particular detail to the precision and accuracy of recording detail. Various sedimentary rock-types, textures and all the basic field techniques required are clearly described. Thoroughly revised to incorporate up-to-date information, this 3rd edition will be of use to all students and professionals with a geological background. Features include: New sections on safety in the field, the use of GPS in sedimentary studies, core description, fossils as depth indicators and facies models. Improved illustrations and a new updated layout.

Geology of the Eastern Piedmont in Virginia / J. Wright Horton, Jr., Brent E. Owens, Paul C. Hackley, William C. Burton, Paul E. Sacks, James P. Hibbard -- Early Mesozoic geology in Virginia / Joseph P. Smoot -- Geology of the Virginia Coastal Plain: new insights from continuous cores and geophysical surveys / David S. Powars, Lucy E. Edwards, Gerald H. Johnson, C. Rick Berquist -- Crustal structure and seismicity of Virginia / Samuel T. Peavy, John K. Costain, Cahit Çoruh -- Landscape evolution in Virginia / G. Richard Whittecar, Wayne L. Newell, L. Scott Eaton -- Soils of Virginia / W. Cullen Sherwood, Frederick M. Garst, L. Scott Eaton -- Hydrogeology of Virginia / David L. Nelms, George E. Harlow, Jr., T. Scott Bruce -- Atlantic Coast and inner shelf / David E. Krantz,

The field trips cover all of the major physiographic and geologic provinces of the central Appalachians in the Mid-Atlantic region. Trip 1 outlines the tectonic history of northern Virginia along an east-west transect from the Coastal Plain province to the Blue Ridge province, whereas the other field trips each focus on a specific province. From west to east, these excursions investigate the paleoclimate controls on the stratigraphy of the Paleozoic rocks of the Allegheny Plateau and Valley and Ridge province in West Virginia, Pennsylvania, and Maryland (Trip 3); Eocene volcanic rocks that intrude Paleozoic rocks in the westernmost Valley and Ridge province in Virginia and West Virginia (Trip 4); age, petrology, and structure of Mesoproterozoic gneisses and granitoids located in the Blue Ridge province within and near Shenandoah National Park, Virginia (Trip 2); the use of argon data to unravel the complex structural and thermal history of the metamorphic rocks of the eastern Piedmont province in Maryland and Virginia (Trip 5); the use of cosmogenic isotopes to understand the timing of bedrock incision and formation of terraces along the Potomac River in the eastern Piedmont province near Great Falls, Virginia and Maryland (Trip 6); the nature of the boundary between rocks of the Goochland and Chopawamsic terranes in the eastern Piedmont of Virginia

The field trip in the Fredericksburg area is intended to familiarize participants with the Stafford fault system.

Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 363. The Appalachians are one of the Earth's classical orogenic systems. These mountains gave rise to the concept of the geosyncline in the writings of James Hall (1859) and James Dwight Dana (1873). During the ensuing years the concept evolved quite differently in Europe and America, a story that has been recounted by Hsü (1973). The geosynclinal concept was never an adequate theory to explain orogenic processes, but as long as the architecture and correlation of the metamorphosed and deformed internal zones of orogens remained obscure, it provided a framework for categorizing observational data. The concept reached its zenith in 1951 when Marshall Kay classified North American geosynclines into eight subdivisions.

The name "Potomac Formation" was intended to cover only certain deposits in the states of Virginia and Maryland belonging to the Coastal Plain and lying upon the crystalline rocks of the Piedmont region.

Origin and Mineralogy of Clays, the first of two volumes, lays the groundwork for a thorough study of clays in the environment. The second volume will deal with environmental interaction. Going from soils to sediments to diagenesis and hydrothermal alteration, the book covers the whole spectrum of clays. The chapters on surface environments are of great relevance in regard to environmental problems in soils, rivers and lake-ocean situations, showing the greatest interaction between living species and the chemicals in their habitat. The book is of interest to scientists and students working on environmental issues.