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The New Jersey Highlands are underlain principally by Middle Proterozoic orthogneiss, paragneiss, and marble that were metamorphosed to upper amphibolite to hornblendegranulite facies and were intruded by granitoid rocks. The oldest rocks are dacitic, tonalitic, and trondhjemitic gneiss and granite of calc-alkaline affinity and metabasalt of the Losee Metamorphic Suite. They are associated spatially with quartz-rich and quartz-poor charnockitic rocks. Field relationships and geochemical data support a cogenetic interpretation for the dacitic, tonalitic, and trondhjemitic rocks and the charnockitic rocks. They are herein all included in the Losee Metamorphic Suite. The rocks of the Losee Metamorphic Suite form a basement assemblage that is unconformably overlain by a layered sequence of supracrustal rocks that consist of quartzofeldspathic gneiss of arkosic and (or) graywacke composition, metaquartzite, calc-silicate gneiss, and marble. Quartzofeldspathic gneiss and calc-silicate gneiss are ubiquitous, but marble occurs mainly in the western Highlands. Metaquartzite occurs as thin lenses and layers throughout the Highlands and provides an excellent marker. Amphibolite formed from different protoliths is widespread and is found in virtually all Middle Proterozoic rocks. Widespread synorogenic granitoids include the hornblende-and biotite-bearing rocks of the Byram Intrusive Suite, dated at between 1,116±41 Ma and 1,088±41 Ma, and the clinopyroxene-bearing rocks of the Lake Hopatcong Intrusive Suite, dated at 1,095±9 Ma. Both have similar major-and trace-element abundances and are interpreted as having fractionated from the same magma. They are included as suites in the Vernon Supersuite. The postorogenic Mount Eve Granite has been dated at 1,020±4 Ma and is confined to the extreme northern Highlands. Middle Proterozoic rocks are very locally unconformably overlain by weakly metamorphosed Late Proterozoic rocks of the Chestnut Hill Formation and are intruded by abundant diabase dikes of Late Proterozoic age. The Proterozoic rocks are unconformably overlain by the Lower Cambrian Hardyston Quartzite.

Cretaceous and Cenozoic sediments of the New Jersey Coastal Plain are underlain by basement rocks that may range in age from Middle Proterozoic to Mesozoic. Buried pre-Mesozoic crystalline rocks in New Jersey are important because they link rocks of the central and northern Appalachians. The peak metamorphic grade recorded in aluminous rocks from beneath the Coastal Plain is in the amphibolite facies.The inner Coastal Plain is underlain dominantly by pelitic and psammitic schist and minor amounts of mafic rock that are correlative with the Potomac terrane in Maryland, Delaware, Pennsylvania, and Virginia. Gravity and magnetic highs within this part of the Coastal Plain probably result from mafic rock in a rootless pluton or a thrust slice. The alignment of these inferred mafic rocks along the same structural trend suggests that they may be related. These bodies may be equivalent to rocks in the Wilmington terrane in Delaware or the Bel Air-Rising Sun terrane in Maryland. Wells drilled in the northern and central outer Coastal Plain returned graphitic, two-mica schist and marble along a trend that is coextensive with the Brompton-Cameron terrane in southern Connecticut. The southern Coastal Plain may be underlain by rocks equivalent to the Chopawamsic terrane (James Run Formation) and to the south, rocks of the Roanoke Rapids terrane (Eastern slate belt). Although drill-hole data are sparse in this part of New Jersey, wells to the west in northern Delaware penetrated chlorite schist, biotite schist, and quartzite. Pyroxenite from this part of the Delaware Coastal Plain may be correlative with the Bel Air-Rising Sun terrane, or more likely it is a separate fragment of ultramafic rock correlative with the Roanoke Rapids terrane (Eastern slate belt). Metagabbro from the southernmost part of New Jersey may be coextensive with gabbro and associated greenschist-facies rocks in the Chesapeake block (Eastern slate belt). Gravity and

The Accotink Schist, Lake Barcroft Metasandstone, and Popes Head Formation Keys to an understanding of the tectonic evolution of the northern Virginia Piedmont.

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geologic information. L.M Bybell and G.W. Andrews provided age information of subsurface units. Members of the USGS Water Resources Division in Trenton, N. J. also provided a large amount of support to the project, notably Otto Zapezca. This group supplied support in the drilling of some of the coreholes and provided most of the geophysical logs. An integral part of the map was to produce detailed subsurface framework. Most of the drilling was done by the personnel from the Branch of Eastern Regional Geology primarily Donald Queen and Eugene Cobbs.The text for the various plates were reviewed thoroughly and intensively by Gregory Gohn of the USGS and Richard Dalton of the New Jersey Geological Survey. These outstanding reviewers improved the style and to a degree the substance of these texts. DESCRIPTION OF MAP UNITS (Plate 1)Coastal Plain Sediments Cohansey Formation (middle Miocene, Serravallian)--Sand, loose, white to yellow in most outcrops, locally gravelly and less commonly clayey. Locally stained red or orange brown by iron oxides. In a few areas, the sands have been ce*nented into large blocks of ironstone.This formation is the major surface unit in the central New Jersey Coastal Plain. The maximum thickness in the map area is about 200 ft. The Cchansey has been extensively eroded and stripped from large areas of the New Jersey Coastal Plain, particularly in the north; detached Cohansey outliers are common. In spite of its widespread nature, the Cohansey is poorly exposed because of its loose sandy composition, which causes it to slump easily. Fortunately, because of this same sandy nature, the Cohansey has been widely mined, and man-made exposures are common in many areas. In general, the Cohansey sands are crossbedded, although the style of crossbedding varies significantly depending upon th^ environment of deposition. Most of the crossbedding is trough type, especially in the non-marine channel fill deposits (Owens and Sohl, 1969, fig. 14A an-1 C), and the scale of the crossbeds varies from small to large. In some areas, plarsr bedding is well developed in sections having abundant marine burrows (generally clay-lined Ophiomorpha nodosa). Such marine-influenced beds (largely foreshore deposits) occur west of Asbury Park (Asbury Park quadrangle), near Adelphia (Adelphia quadrangle), north of the Lakehurst Naval Air Station (Lakehurst quadrangle), and at Juliustown (Columbus quadrangle) (Owens and Sohl, 1969, fig. 14D). Rarely, as near West Berlin (Clementon quadrangle), shell ghosts have been observed (Newell and others, 1988).Sands in the Cohansey typically are medium grained although the rar

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