Strange Crater in Oregon

[MikeNTX]

I saw this last night and all day I have looked for information on it and cannot find a thing. This sure looks like a crater of some kind, an almost perfectly circular one that is 22mi (36km) across. As you can see it dwarfs nearby Crater Lake. I am wondering if it is a volcano or a impact crater and wonder if anyone has any idea of what it really is.

The plusses for it being a volcano is are: It is near the cascade mountains, A very active volcanic area. If it is a volcano it is obviously a supe volcano and they, like this crater are nearly always flat. A negative for this being a super volcano is that it is so perfectly circular. Of the ones I have read about they more irregular in shape.

The plusses for this being an impact crater is are: It is an almost perfect circle, just as other impact craters are. It has a low rim like larger impact craters have. Yes it is in an active volcanic area but the odds of having an impact there is the same as anywhere else. Plus if you look at the cascades very much you will see the main volcanoes form an almost perfect north to south line. This crater is just east of that line. Negatives for this being an impact crater are: It is in a very active volcanic region and any impact crater would soon disappear. Yes it is not in line with the rest of the main volcanoes of the Cascade line, but then neither is Mount St Helens.

So if anyone has any real ideas, please speak up.

[Flying High]

Thats an interedting find... I'm no geologist.. so can't help a'm afriad...

But.... I did notice from about 300 miles away... there are at least 5 lines which apear to radiate from the circle... when you look closer... they are streams / rivers...

Could these have been gouged out with an impact ?

[MikeNTX]

What lines were you talking about 300 miles away, can you point them out?

The more I look at this the more I want to say it is an impact crater. It is just so much bigger than anything in the Cascade range. You could put all of Mt Raineir inside of this thing.

[Lord SteveO]

Crater lake is actually just a collapsed volcano. It looks very much like an impact though.

I would imagine the bigger crater you see is something similar? Perhaps a massive supervolcano or something similar. It's huge anyway, at least 20km wide.

Alsi if you look to the northern side there are some much smaller crater that look like they could be older or minor vents from a volcano.

[Monkey boy]

This could well be a collapsed Super volcano as to the North East there are 2 depressions in the ground, one called Big Hole, the other called Hole-in-the-Ground. Both of these are extinct volvanoes.
The whole Cascade mountain range, spreading North is Volcanic & is still active. 50 miles North there are the Three Sisters Volcanoes, then going further afield you have Mt Hood, Mt St Helens, Mt Baker & Mt Rainier. All are designated Stratovolvanoes and have the potential of doing what Mt St.Helens did in 1980.

[BradG7]

It looks like nothing to me, just a circular formation of vegitation. :whoa:

[spydertl79]

I dont see anything spectacular there

[MikeNTX]

hi ... that feature is not a crater but is part of faulted area of Oregon's "Basin and Range" ...

Here's some info on the "Basin and Range"

"Within the Basin and Range Province, the Earth’s crust and upper mantle has been stretched up to 100% of its original width. The entire region has been subjected to extension that thinned and cracked the crust as it was pulled apart, creating large faults. Along these roughly north-south-trending faults mountains were uplifted and valleys down-dropped, producing the distinctive
alternating pattern of linear mountain ranges and valleys of the Basin and Range province."

The main ridge on the left and top of the circle is called "Walker Rim" ... it is a tilted fault block ("horst") similar to Abert Rim in southern Oregon which is much more well known ...West of Walker Rim is the Chemult Graben, approximately 6 miles wide ... Interstate 97 runs down it ... "horsts" (uplifts) and "grabens" (downdropping) go together ... the rest of the "circle" is small buttes and cones ...

Inclosed is a section of a map showing faults in that area -- the large grouping of yellow fault lines are Chemult Graben ... age of the faulting is less than 700,000 years ... the green fault lines in the middle of the "circle" are older fault lines, probably closer to 1,500,000 years ...


The entire map is here --- click on the "pdf/1:500000.pdf"

http://geopubs.wr.usgs.gov/open-file/of02-301/

in doing a Google Search on Walker Rim I found this webpage ...

http://130.166.124.2/or_panorama_atlas/page6/files/page6-1097-full.html

hope this helps ...
Lyn



Lyn Topinka, Computer Specialist and Webmaster,
Cascades Volcano Observatory
URL: http://vulcan.wr.usgs.gov/