Talk:Geology of Minnesota

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Contents 1 Interesting Fact possibility for this article 2 Watersheds 3 Work in progress 4 Geology maps 5 A relevant USGS Site

[edit] Interesting Fact possibility for this article

The highest point in Minnesota is Eagle Mountain at 2301 feet, the lowest is Lake Superior at 602 feet. The 1699 feet elevation range between highest and lowest point is the 12th smallest of any U.S. state. ^[1] page 24 Gopher backer 02:58, 5 December 2006 (UTC)

Another interesting fact is that the high and low are only ~12 miles apart, which must be one of the shortest distances between high and low (Hawaii might be a short distace too.) Appraiser 03:14, 5 December 2006 (UTC)

The ref I have says 13, see Minnesota -Ravedave ^{(help name my baby)} 05:01, 5 December 2006 (UTC)

I'm a sucker for geotrivia like this. I think the winner may be Delaware, with about 4 or 5 miles from lowest to highest point, if I have it right. Pfly 06:04, 11 December 2006 (UTC)

I'm a sucker too, so I had to check. The high point in Delaware is at Ebright Azimuth, 448 ft. above sea level, 6.5 miles from Wilmington, Delaware. Wilmington is where the Delaware River meets the Delaware Bay, and is listed as 100 ft. above sea level (in the Wilmington article). Clearly, the low point in Delaware would be on the ocean-front in Sussex County at the south end of the state. Towns there include Lewes, Rehoboth, Bethany Beach, and Fenwick Island.

The highest point in Hawaii is at Mauna Kea, which appears to be about 17 miles southwest of the ocean using this map [1].

So, maybe Minnesota does have the record. Appraiser 14:54, 11 December 2006 (UTC)

Looks like the atlantic is the lowpoint in delaware. List_of_U.S._states_by_elevation -Ravedave ^{(help name my baby)} 15:49, 11 December 2006 (UTC)

Delaware Bay is at sea level, it is the ocean after all. Perhaps the 100 foot elevation is for someplace inland in Wilmington. In any case, I got my 4-5 miles simply by finding Elbright Azimuth Road in Google Earth and drawing a straight line to the closest sea coast. Pfly 16:58, 11 December 2006 (UTC)

Does the bay level in Wilmington change with the tides? I've been looking around some more and suspect the 100 ft. elevation stated is either wrong or is based on some assumption. It may be the elevation at city hall, or an average, or a high. The Washington, D.C. article has elevation = 0'-410'. I'm pretty sure the mean high tide level of the Potomac in the District is 10' or so higher than the mean high tide at the mouth of the Chesapeake Bay, so I don't think the 0' is correct. But it does point out that an elevation for a city is actually a range. I have Google Earth loaded on one of my other computers, so I'll use it to check some elevations when I get a chance. (It's really cool; you can find your exact house, click next to it, and it will give you long., lat., and elev. for that exact spot.) Appraiser 18:49, 11 December 2006 (UTC)

The USGS GNIS gives the elevation of Delaware Bay at a surprising -36 feet - http://geonames.usgs.gov/pls/gnispublic/f?p=151:3:13584473078477894291::NO::P3_FID:216373 .. but Google Earth shows the bay, even up near Wilmington, to be zero feet. The USGS GNIS also gives Wilmington's elevation at 100 feet, but you can see from where its point of reference is that it isn't on the coast but on a hilltop: http://www.topozone.com/map.asp?lat=39.74583&lon=-75.54694 .. ..anyway Delaware always wins these kind of superlative contests.. it's so small and flat! (even so, if Minnesota's highest and lowest points are that close, for a state that large, it is interesting (if a bit esoteric) geotrivia, even if its not the #1 state for such a thing. Personally I think there are too many superlative claims on wikipedia already. :-) Pfly 19:54, 11 December 2006 (UTC)

I agree - too much useless trivia on Wikipedia. The topic just piqued my curiosity. I'll accept that any shoreline on a body of water that is affected by tides and attached to an ocean is at zero elevation, even though I believe there are differences (like from the Potomac in DC to the open-ocean), but I think the -36' for the Delaware Bay is incorrect. GNIS shows the beach at Bethany Beach to be 0', and Delaware Bay is certainly not lower than that. So, I'd say Delaware does have the shortest distance between the high and the low. Hawaii certainly has the most dramatic change in elevation in a short distance. If Delaware is small and flat, Minnesota is large and flat. I heard one time that proportionately, Kansas is flatter than a thin-crusted pizza. I'm glad Minnesota has a hill here and there. Appraiser 21:31, 11 December 2006 (UTC)

Washington is pretty dramatic too, with Mount Rainier only about 40 miles from sea level at Puget Sound, about a 14,400 foot change. Definitely dramatic, I used to work in Tacoma. Adding to the pile of useless trivia, Pierce County gets to claim the largest elevation change within a county's borders, not counting Alaska. I hadn't heard the bit about the Potomac at DC being higher than sea level, now my curiosity is piqued. But we're in agreement that this is all quite trivial! Mmmm, pizza.. Pfly 23:32, 11 December 2006 (UTC)

[edit] Watersheds

Would this pic be useful for this article?-Ravedave 01:24, 25 June 2007 (UTC)

Possibly. The article needs an image of the regions. I was going to mark up the present image at the top but might use this one instead.Kablammo 03:04, 25 June 2007 (UTC)

I like the watersheds map, but I'm not sure that it is germane to "geology". Here, I'd rather see a map showing underlying limestone, granite, etc.--Appraiser 20:45, 25 June 2007 (UTC)

I'll revised the watershed map to lose the SD and IA parts, remove the freeways, and differentiate between the Des Moines River watershed and that of the Mississippi below St. Paul (which are colored the same in the version to the right). I'll put the revised version on Commons in the next day or so. I may add it to this article as a placeholder until we get a regional map. And we do need a bedrock map. There are several on line but I don't know of a free one. Kablammo 21:06, 25 June 2007 (UTC)

USGS should have at least some free online... [2] ? -Ravedave

Small ones can easily be made here: [3] (see license here) select some of the geological overlays. Larger maps could maybe be made by taking a bunch of screen shots and stitching them together. (automatically? )-Ravedave 22:28, 25 June 2007 (UTC)

I've rummaged through these before and can't find any US bedrock geology maps. Lots of other data, but none either of basement or first encountered bedrock. Kablammo 22:45, 25 June 2007 (UTC)

The map has been revised as discussed above, and colors changed to group basins within major watersheds together by variations of the a common base color for each major watershed. It could me modified to accommodate an outline of the geological regions, but that might get too busy. A blank map with significant glacial features (especially terminal moraines) would be better for the regions. I've posted this map at the map section of Portal:Minnesota for use elsewhere. Perhaps eventually there will be a Geography of Minnesota article. Kablammo 17:03, 27 June 2007 (UTC)

[edit] Work in progress

Other things I’m planning on doing:

• Geo history—

• add color image of bedrock geology to rock formation sections; if anyone knows of a free one, upload it and we'll see how legible it is Done, but map now added shows first encountered bedrock, rather than basement bedrock. Kablammo 21:46, 6 July 2007 (UTC)
• in glacial period—lose present image of polar projection of ice sheets, add state map showing principal terminal moraines and margins of Des Moines and other lobes. Possibly just a map with current glacial features-- leave history of their development to other articles Kablammo 21:46, 6 July 2007 (UTC)

• Regions—add oa map of regions, as mentioned above Done. Kablammo 21:46, 6 July 2007 (UTC)

• NE —add shaded relief topo image, with boundaries marked large map is sufficient
• NW — add shaded relief topo image, with boundaries marked
• SW —add boundaries to image; expand text to mention Morton gneiss and bedrock valley of R. Warren.
• SE —add boundaries to image, possibly mention calcareous fens in text
• Central —add shaded relief topo image, with boundaries marked; expand discussion of glacial landforms and lake formation
• E Central —add watercourses to image, mark regional boundary, mention sandstone

• References-- convert format to allow page citations for printed (or other paginated) sources Done. Kablammo 21:46, 6 July 2007 (UTC)

Once all maps are added we can determine how many scenic images the article will support. We should end up with an article of about 50+kb, well-cited, with adequate maps. Its principal emphasis will be current condition and recent geological events. Kablammo 03:04, 25 June 2007 (UTC)

[edit] Geology maps

MNDOT has simplified maps of bedrock and quaternary geology http://www.mrr.dot.state.mn.us/geotechnical/geology/bedrckweb.pdf http://www.mrr.dot.state.mn.us/geotechnical/geology/quaterweb.pdf

I am not sure of their copyright policy. Drillerguy 19:39, 25 June 2007 (UTC)

I am pretty sure MN state stuff is not under a public license, unfortunatly. -Ravedave 20:30, 25 June 2007 (UTC)

[edit] A relevant USGS Site

I could have sworn I saw a regional bedrock geology map associated with this website.

http://vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Places/volcanic_past_minnesota.html

Drillerguy 13:38, 29 June 2007 (UTC)