State Geologic Maps

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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Index Map

Gravity and Magnetic Maps of the States

Click on the desired state to view the map. Scale on all maps is one pixel = one kilometer

Southeast Alaska
Northeast Alaska
Northwest Alaska
West-Central Alaska
Southwest Alaska

Canada and the Caribbean

Geologic Map of Southern British Columbia
Geologic Map of Central British Columbia
Geologic Map of Northern British Columbia

Geologic Map of Southern Alberta
Geologic Map of Northern Alberta

Geologic Map of Southern Saskatchewan
Geologic Map of Northern Saskatchewan

Geologic Map of Southern Manitoba
Geologic Map of Northern Manitoba

Geologic Map of West-Central Ontario (north of Lake Superior)
Geologic Map of East-Central Ontario (north of Lake Huron)
Geologic Map of Northwest Ontario
Geologic Map of Ontario: James Bay
Geologic Map of Southern Ontario

Geologic Map of the Saint Lawrence Valley
Geologic Map of Maritime Provinces
Geologic Map of the Gulf of Saint Lawrence
Geologic Map of Newfoundland
Geologic Map of the Eastern Grenville Province
Geologic and Bouguer Gravity Map of the Grand Banks and Flemish Cap

Geologic Map of Cuba
Geologic Map of Hispaniola and Puerto Rico

About the Maps Washington Oregon

The maps were generated from U.S. Geological Survey Digital Data Series DDS-11, Release 2, 1998, by Paul G. Schruben, Raymond E. Arndt and Walter J. Bawiec. This is a CD containing a digitized version of the Geology of the Conterminous United States at 1:2,500,000 Scale, 1974, by P.B. King and H. M. Beikman. Maps of the individual states have been extracted and rectified with north up.

The CD contains a number of file types, including a color image viewable at one pixel = 500 meters. However, close comparison of the digitized map compared to the original paper map, as well as comparison to more detailed maps, shows that the map cannot be reliably used at such a scale. The viewing scale of one pixel per kilometer is probably the largest scale that can be reliably used, and caution should be used in applying the maps at kilometer scale.

Coloring has been maintained fairly similar to the paper USGS map with some exceptions. Within periods, colors mostly grade from dark at the bottom to light at the top. The middle color is used generically for undivided periods. For sedimentary units, coloring is as uniform as possible across the map, with a few ad-hoc variations for areas where extra subdivisions are required. The principal exception is that I insist granite is pink on a geologic map and other igneous rocks should be red or orange. Igneous and metamorphic rocks are colored using shades that contrast with other rock units, and vary in usage in the Appalachians (Paleozoic), Midcontinent (Precambrian) and far West (mostly Mesozoic and Cenozoic). Each map has its own color legend. 

How the Maps Were Made

The maps were generated using Global Mapper, then screen-captured and imported into Paint Shop Pro for final editing.


Marine refers to well-stratified rocks mostly (but not entirely) of marine origin. Eugeo refers to eugeosynclinal rocks, that is, deep-water sedimentary rocks of continental slope or trench origin. Other headings are self-explanatory.

There are about 160 lithologic units on the Geologic Map of the United States by King and Beekman, counting units with metamorphic overprint. The 256 colors on an 8-bit color palette are more than enough to show these, but many of the colors are very hard to distinguish by eye. Colors were chosen to minimize confusion as much as possible, but inevitably there will be adjacent colors that are hard to tell apart. To improve contrast, a few colors have been duplicated for units widely separated in space and time. For example, colors for early Paleozoic volcanic units (found only in the Appalachians) have also been used for some units in the far West.

Some periods are divided in some locations and undivided in others. Undivided periods generally use the middle color for the period. In practice this seems to result in little confusion. If adjacent units are other divisions of the period, the color represents a subdivision. If adjacent units are different periods, the unit is undivided.



Units of undivided age

Combinations of symbols refer to transitional or undivided units. For example DS refers to undivided Devonian and Silurian rocks.



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Created 23 July 2001, Last Update 07 January 2017

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