State Geologic Maps
New York Geologic Map
US Geologic Maps
Other Country Geologic Maps:
Irish Historical Geological Maps
Long Island Index Maps
Long Island GIS Users’ Group
Long Island Sound Study GIS Data Resources
Long Island Sound Estuary GIS Data Catalog
GIS for the LI Breast Cancer Study Project
NYC Map
Social Explorer (has NYC historical time series maps, among others)
New York New Jersey Trail Conference – trail maps and hiking guides
The Cornell University Geospatial Information Repository - GIS data for New York State
American Geological Institute
Geological Society of America
United States Geological Society
British Geological Survey