UPDATE 10/5/2014 – The National Atlas ceased to be updated as of 9/30/2014. A copy from 9/24/2014 lives on in the Internet Archive.
National Atlas Geology – https://wayback.archive-it.org/4416/20140919123233/http://nationalatlas.gov/geology.html
Representative Questions This Resource Can Answer:
- Is there more than one continental divide?
- Outside of Appalachia, where are America’s coal fields?
- Where are potentially active volcanoes in California?
The Geology section of the larger National Atlas is a mix of overview articles and of Map Maker samples. Click on on any of the samples in the upper right hand of your screen and then check out the map layers tab. My favorite layer is the “Impact Structures” map which shows the parts of the United States that appear to have been hit from outer space. Another fun layer is the Earthquakes 1568 – 2009 layer. It clearly shows that neither North Dakota nor Iowa has had an earthquake since 1568. If your story takes place there, you might need secret nuclear testing or Godzilla to justify an earthquake.
Other map layers of note include:
- Coal Fields
- Continental Divide
- Earthquakes 1568 – 2009
- Generalized Glacial Limits
- Metamorphic Areas
- Karst – Engineering Aspects
- Landslides – Costly Events
- Landslides – Costly Regional Events
- Landslide Incidence and Susceptibility
There are also maps of magnetic fields available, but I’m honestly not sure how to interpret them or how you might work them into a story.
In the overview articles, pay attention to Continental Divides in North Dakota and North America. This article notes that the “Great Divide” of the Rocky Mountains is only one of several continental divides. One of the continental divides is on very flat ground in North Dakota. For the explanation, see the article.
Sometimes you can successfully mix layers on Map Maker. Try viewing Landslide incidence and susceptibility, then coal fields and then put them together. Notice how the Appalachian coal fields overlap almost exactly with one of the highest risks of landslides in the country? That sounds like a hard life.