GRAVITY MAP OF GLENS FALLS QUADRANGLE, NY

A gravity map of the Glens Falls one degree by two degree quadrangle published by the United States Geological Survey and compiled by D.L. Daniels is used to correlate gravity anomalies with the general geology in the area. The major features on the map is a north-south trending gravity high that coincides with the axis of the Green Mountain anticlinorium and a gravity low over the Middlebury synclinorium. These two anomalies are separated by a north-south trending steep gravity gradient due to the density contrast between the Green Mountain Massif and the adjoining Taconic sequence in the west. East of the Green Mountain gravity high is a gravity low centered over the Connecticut Valley synclinorium.

The gravity map illustrates the excellent correlation between gravity anomalies and geology in the region. The gravity high over the Green Mountains is thought to be due to a deep-seated change in density in the lower crust. The Consortium for Continental Reflection Profiling (COCORP) results indicates the Green Mountains are allochthonous. The western section of the map reveals gravity highs over the Adirondack Region and a gravity low over the Anorthosite Massif in the northwest section of the map.

A gravity low occurs over the Taconic Klippe in eastern New York where COCORP studies indicate the crust is thicker. East of the Green Mountains geophysical data suggests a fundamental change in crustal character in the Connecticut Valley synclinorium. Smaller gravity highs in this region are associated with mafic and ultramafic rocks while gravity lows are due to low density felsic intrusives.