Geologic Map of Northwest Ontario

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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Offshore geology is shown separated by a white border. Most geologists think "Oh, yeah, there are some Paleozoic rocks around Hudson's Bay." It's only when you see a map at the same scale as other maps that you realize just how vast the Paleozoic cover rocks are.

Geology with One-Degree Grid

There are no roads in the map area.

Topography

Legend

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 Beikman, 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.

Symbols

Periods

Units of undivided age

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

Prefixes

Suffixes


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Created 23 July 2001, Last Update 02 May 2013

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