USGS Basics
The Library has USGS maps in several scales, listed below:
7.5 Minute Series: The most popular map type at Carleton. These maps line up with local quadrangles. Our collection is well organized, recent and close to complete. 7.5 minute maps are kept in the sliding cabinets starting at the eastern end of the map alcove and moving most of the way across. Maps are organized by state and alphabetically by quadrangle within each state. In the first drawer of maps for each state, there is an index map showing the quadrangles within the state and their names.
- Smallest scope, most current, most comprehensive, best indexed.
15 Minute Series: 15 minute maps cover an area four times as large as 7.5 minute maps. Because of this, they're slightly less detailed. Carleton's collection of 15 minute maps is older and contains many duplicate quadrangles. Because of this, it's easy to see how an area has changed over time. The 15 maps are kept in an older set of cabinets against the eastern wall of the map alcove. (to the right if you come in from the stairwell). These maps are theoretically indexed, but in many cases the indices are missing or incomplete, so it would be wise to find the name of the quadrangle you're searching for online.
- Slightly larger scope, older, many quadrangles missing, mostly unindexed.
30' by 60': The next size up from 15 minutes. These are kept in the same bank of sliding cabinets as the first of the gift maps. You can find what you're looking for by checking the paper index in the first drawer.
- Larger scope, slightly older, mostly complete, fairly well indexed.
1:250,000: Larger, regional maps. These come after the 7.5 minute maps in the sliding cabinets. Again, there is a paper index in the first drawer. Also note that 1:250,000 scale maps for Minnesota and Alaska are kept in separate drawers.
- Regional scope, fairly recent, comprehensive, well indexed.
USGS Links
The United States Geological Survey is the federal agency responsible for mapping the US and studying its natural resources and hazards. Accordingly, it publishes a lot of maps and reports of interest to students of many different disciplines at Carleton. Since 2006, these maps have been published online, and are accessible at one of the links below.
USGS maps generally depict standard quadrangles. These quadrangles are don't change, so you can compare a specific area over time. For more information about different kinds of quadrangles, check out this page from the USGS. If you're unsure what quadrangle a particular location falls in, you can look it up on the map at the USGS Store, or on one of Carleton's paper indices.
- USGS StoreDon't be fooled, you do not have to pay to shop at the USGS store. You can use it to find what quadrangle a location falls within, as well as to download PDFs of USGS maps.
- USGS MapsDescriptions of the various map series published by the USGS
- USGS TopoViewA new viewer for the USGS's topographic maps. Includes access to historic maps and maps of many sizes.
- EROS Data Center - USGS
This link opens in a new window
A gateway to a massive amount of USGS data, maps and satellite imagery
Sample USGS Maps
A 7.5 minute map of the Northfield Quadrangle, circa 2013. (USGS)
A 1:250,000 Scale Map of the St. Paul area, circa 1953. (USGS)
USGS Maps in GovDocs
A selection from a geologic quadrangle map.
The USGS issues many reports and many of these report are or contain maps. A lot of these maps are cataloged as GovDocs and can be searched using Catalyst. You'll know you've found one when you see a listing marked:
"CARLETON Government Documents Map in File Cabinets (2nd fl.)."
However, not all of these documents appear in the catalog. Geologic and Hydrologic Quadrangles, Miscellaneous and later Mineral Field (after number 856) maps are generally in the catalog. Land Use, Oil and Gas, International and earlier Mineral Field maps (before number 856) are generally not in the catalog.
SuDoc Numbers
The file cabinets on Second Libe are marked with their contents, but you can also tell which of these categories a USGS map or report falls into by its SuDoc number (for more on the SuDoc classification system, look at the Government Documents research guide). These numbers are usually printed on the folders the maps are stored in.
A SuDoc number looks like this: I 19.88:GQ-612.
The number printed on an envelope containing a map:
Notice that the letters and number after the colon are separated.
All USGS maps are going to have SuDoc numbers begining with I 19. The numbers that come after the colon are most important for us. The letters after the colon denote what kind of map you're looking at. The numbers after dash denote where the map can be found. Here are the letter codes that Carleton has maps corresponding to:
I-Miscellaneous
HA-Hydrologic Quadrangles
GQ-Geologic Quadrangles
MF-Mineral Field Investigations
OM-Oil and Gas Investigations
L-Land Use
MC-Geological Society of America
CP-International
Carleton does have indices of USGS maps of particular locations, however, they were printed in the 80's and might be dated.
A USGS geologic quadrangle map at Carleton
