Maps, Charts, and Photos - Frequently Asked Questions
- Q1. Can I view USGS topographic maps online?
- Q2. Where can I buy topo maps?
- Q3. What quadrangles cover my town or area of interest?
- Q4. Which USGS quadrangle covers the geographic feature I'm interested in?
- Q5. Where can I find out-of print 15-minute topo maps?
Reading Topographic Maps
- Q6. Where can I find an explanation of the symbols on USGS topographic maps?
- Q7. How do I read the scale on a map?
- Q8. How do I correct a magnetic compass heading to make it refer to true north? If magnetic north moves a different amount each year, how do I find the correction value in the future?
- Q9. Can I view aerial photos for Maine online?
- Q10. Does MGS have any air photos available to look at?
- Q11. Where can I buy aerial photos?
- Q13. I need to locate a satellite TV dish. What's the latitude and longitude of my house?
- Q14. Where can I find information about datums and coordinate systems?
A list of online map viewers is provided on the Maps, Charts, and Photos page.
The Maine Geological Survey sells U.S. Geological Survey topographic maps for Maine at scales of 1:24,000 (707 maps cover the state), 1:100,000 (35 maps cover the state), 1:250,000 (13 maps cover the state), and 1:500,000 (1 map covers the state). To order maps, go to our Maps, Publications, and Online Data site. Order maps for other states from the USGS store.
You can find out which quadrangles cover your area of interest by using the Maps and Publications Search. The Map-based Search is an interactive map that will allow you to zoom and/or pan to your region of interest and then click on the map to show the quadrangles available.
Use the USGS Geographic Names Information System to search for geographic locations by name. This site also provides direct links to online map viewers, centered on the geographic feature requested.
Reading Topographic Maps
Refer to the U.S. Geological Survey site: Topographic Map Symbols.
Refer to the U.S. Geological Survey site: Map Scales.
Q8. How do I correct a magnetic compass heading to make it refer to true north? If magnetic north moves a different amount each year, how do I find the correction value in the future? Back
You add or subtract the declination from the 360 degrees of the compass. Consult the following sites for more information:
- Geological Survey of Canada
- National Geophysical Data Center
- U.S. Geological Survey
The Maine Geological Survey has 38 sets of aerial photographs covering different parts of Maine. The photos were collected between 1940 and 1996 at scales from 1:6,000 to 1:80,000 and are available for use at the Maine Geological Survey during office hours. Use the Maine Aerial Photographs map to review photo coverage and availability.
A list of sources of aerial photograph for Maine is contained in Aerial photographs of Maine - Views from the sky.
The U.S. Geological Survey, in cooperation with the Association of American State Geologists, maintains the National Geologic Map Database. This site contains a geoscience map catalog, an image library, a geologic names lexicon, and a listing of new mapping.
You can determine your latitude and longitude coordinates online using the Maine Geological Survey wep map. Simply enter the name of your town and the state in the search box and move to the map of your town. Locate your house, and then use the Measure tool to click on the map. The latitude and longitude will appear in the box to the right of the map.
National Geodetic Survey - Frequently Asked Questions - provides information on datums, gps, and coordinate systems.
A variety of digital data layers are available for download. Statewide digital layers of sand and gravel aquifers, surficial materals, coastal bluff hazards, generalized bedrock geology, and generalized surficial geology are available through the Maine Office of GIS. Digital layers of detailed surficial geology quadrangles are available through the Maine Geological Survey website. Datasets may be downloaded free of charge over the internet.
Last updated on March 23, 2018