To locate these maps, consult the following reference sources:
USGS maps are arranged by USGS series at the Science Library. They are filed in the USGS map cabinets in the Schwarz Map Room in numerical order within the particular series. To find the series and number of the map you need, consult the Guide to USGS Publications. Under the state name, maps are indexed by 7.5' quadrangle names. To determine the quadrangle name for your area of interest, consult the map indexes stored in the file cabinet in the Reference area.
Canadian maps, maps issued by state geologic surveys, Geological Society of America (GSA) maps and American Association of Petroleum Geologists (AAPG) maps are available. Indexes to some of these maps are listed in the "Index Maps and Reference Aids" section below.
Many geologic maps are included as plates in books. A subject search in the Barton catalog under "Geology--place name" will identify the books which cover your area of interest; choose the "Full display" option when viewing a record in Barton to find out whether maps are included in the book. Books which focus on a particular geographic area may be found in the stacks beginning at QE39.
For atlases, use a combined keyword search in Barton: sw=place name and w=atlas*.
Check the folio shelves for a geological atlas of your area.
There are folders for each U.S. state which contain various state and USGS map indexes and bibliographies.
The following publications may be helpful in determining which maps cover your area of interest.
Finally, a search in the GeoRef database may help you find maps covering your area of interest.