<p>Most probably, he was referring to the Brunswick Magnetic Anomaly: <a href="http://www.geosociety.org/news/pr/2014/14-22.htm">http://www.geosociety.org/news/pr/2014/14-22.htm</a></p>

<p>This is an area of lower-than-normal magnetism present in North America in the Southwestern United States. Note that altough it COULD be a piece of Africa, it could also be caused by something else.</p>

CC BY-SA 3.0
2014-05-05T14:48:43.413Z
My lecturer made a point of it being upside down. I want to point out that lecturers have their opinion and do employ 'lecturers license'. I realize that this answer may be what he was referring to. But I cant be sure because of his assertion about it being upside down.
497362
CC BY-SA 3.0
2014-05-05T12:16:27.353Z
2014-05-05T12:16:27.353Z
Foo Barrigno
<p>When I studied earth science, a lecturer mentioned that one of the anomalies that earth science hasn’t been able to explain is a piece of crust in the USA.</p>

<p>This piece of crust appeared to match very well with the crust of another continent, if turned upside down, and didn’t match the surrounding crust in the USA.</p>

<p>I can't find any information about this and I can't forget about it. Is there any basis for this claim?</p>

CC BY-SA 3.0
2015-09-13T01:37:19.353Z
FWIW, Mt. Diablo in CA is a piece of the Pacific Plate that got scraped off of it and turned upside down. Not sure if that's what you're referring to.
BillDOe
CC BY-SA 3.0
2014-05-05T09:59:06.870Z
Did he mention in what part of the US.
tobias47n9e
CC BY-SA 3.0
2014-05-05T10:02:24.030Z
really sorry, cant remember, although i think he did mention it. i got the impression he was aware of only 1 such anomaly. Also I cant remember the location of the matching crust, MAYBE Africa but im really not sure.
497362
CC BY-SA 3.0
2014-05-05T10:19:01.957Z
Could be the remainder of a [nappe](https://en.wikipedia.org/wiki/Nappe). If the top part erodes only a piece of upside down crust could be left over, which seems to have no direct relation to the surrounding rock.
hugovdberg
CC BY-SA 3.0
2014-05-05T12:54:50.823Z
It could also be an ophiolite, although I don't think there are any examples of these being truly upside down although they might initially appear to be so due to a fold (eg. Troodos in Cyprus - where the higher elevations represent the upper mantle)
winwaed
<geologic-layers><tectonics>
Is there a piece of upside down foreign crust in the USA?
497362
# Is there a piece of upside down foreign crust in the USA?

(Asked by: username_0 on 2014-05-05)

When I studied earth science, a lecturer mentioned that one of the anomalies that earth science hasn’t been able to explain is a piece of crust in the USA.

This piece of crust appeared to match very well with the crust of another continent, if turned upside down, and didn’t match the surrounding crust in the USA.

I can't find any information about this and I can't forget about it. Is there any basis for this claim?

**Tags:** geologic-layers, tectonics

> **Comments:**
> **username_2**: Did he mention in what part of the US.  
> **username_0**: really sorry, cant remember, although i think he did mention it. i got the impression he was aware of only 1 such anomaly. Also I cant remember the location of the matching crust, MAYBE Africa but im really not sure.  
> **username_3**: Could be the remainder of a [nappe](https://en.wikipedia.org/wiki/Nappe). If the top part erodes only a piece of upside down crust could be left over, which seems to have no direct relation to the surrounding rock.  
> **username_4**: It could also be an ophiolite, although I don't think there are any examples of these being truly upside down although they might initially appear to be so due to a fold (eg. Troodos in Cyprus - where the higher elevations represent the upper mantle)  
> **username_1**: FWIW, Mt. Diablo in CA is a piece of the Pacific Plate that got scraped off of it and turned upside down. Not sure if that's what you're referring to.  

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## 1 answers

### Answer by username_5 on 2014-05-05. Score: 15

Most probably, he was referring to the Brunswick Magnetic Anomaly: <http://www.geosociety.org/news/pr/2014/14-22.htm>

This is an area of lower-than-normal magnetism present in North America in the Southwestern United States. Note that altough it COULD be a piece of Africa, it could also be caused by something else.

> **Comments:**
> **username_0**: My lecturer made a point of it being upside down. I want to point out that lecturers have their opinion and do employ 'lecturers license'. I realize that this answer may be what he was referring to. But I cant be sure because of his assertion about it being upside down.  

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