Description:Since the 1980s, the USGS has
mapped sand and gravel aquifers and confining units for Long Island, New York
at the 1:250,000 scale. To maximize the usefulness of the aquifer maps, GIS
datasets of the 1: 250,000-scale aquifer maps for Long
Island were developed. To further increase applicability of the
maps, consistent mapping units were developed, delineated, and presented in
relation to aquifer framework and hydrology. The result is consistent GIS
datasets of surficial geology and aquifer boundaries
from maps of selected unconsolidated aquifers in Long Island New York at the 1: 250,000 scale. This map
layer contains the surficial hydrogeology and hydrogeologic extent (portrayed as lines) for a hydrogeologic unit beneath Long Island in the state of New York, USA.
The map layer was developed as part of an effort to digitize surficial geology and aquifer boundaries occurring in
water-resources investigations reports published at 1:250,000. The published
maps contain base and cultural features not included in these data. Data
sources can be found via the report number (e.g. HA-709) referencing the
Supplemental Information section in this metadata document.
These shapefiles depict the upper surface altitude of seven of
the eight hydrogeologic units, which, in ascending
order are: consolidated bedrock, Lloyd aquifer, Raritan
confining unit, Magothy aquifer, Monmouth greensand, Jameco aquifer, and Gardiners Clay. The upper glacial
aquifer-the uppermost unit-is at land surface over most of Long
Island and is therefore not included.