# Magnetic anomalies at ancient structures? **URL:** \ **Category:** Factual Questions\ **Created:** [August 8, 2016, 3:39am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110 "2016-08-08T03:39:42Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Diocletian](https://avatars.discourse-cdn.com/v4/letter/d/eb9ed0/32.png) [@Diocletian](https://boards.straightdope.com/u/Diocletian)\ **Post date:** [August 8, 2016, 3:39am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/1 "2016-08-08T03:39:42Z")
Hello everyone! So I was talking with an Ancient Aliens enthusiast, and someone said that the rocks at Pumapunku caused “magnetic anomalies.” I found the video that they were probably referencing here: [Puma Punku Bolivia: Ancient Cataclysm And Magnetic Anomalies](https://www.youtube.com/watch?v=LkfH_bMSD6M) Now a bunch of “Ancient Astronaut Theorists” seem to think that this is evidence of advanced technology, ancient cultures using electricity, or a host of other things. Now the guy in this video could just be lying, could be misled, or could just be misinterpreting the evidence. What do you guys think? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 8, 2016, 3:50am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/2 "2016-08-08T03:50:21Z")
> [@Diocletian](#): > > Now the guy in this video could just be lying, could be misled, or could just be misinterpreting the evidence. You are incorrect, he is definitely lying, misled, or misinterpreting the evidence. ---
**Author:** ![Diocletian](https://avatars.discourse-cdn.com/v4/letter/d/eb9ed0/32.png) [@Diocletian](https://boards.straightdope.com/u/Diocletian)\ **Post date:** [August 8, 2016, 3:58am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/3 "2016-08-08T03:58:01Z")
Yes, but I was only 99.99% sure it was one of those three, so I had to leave the .01% of doubt that maybe what he is saying is true. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [August 8, 2016, 4:18am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/4 "2016-08-08T04:18:44Z")
> [@Diocletian](#): > > Yes, but I was only 99.99% sure it was one of those three, so I had to leave the .01% of doubt that maybe what he is saying is true. It’s is almost certainly true. It’s almost certainly also misinterpreting the evidence. They aren’t mutually exclusive. The rocks may just contain some iron, which is the commonest cause of rocks causing “magnetic anomalies”. Rocks that cause magnetic anomalies cover [most of the planet](https://www.google.com/search?q=World+Digital+Magnetic+Anomaly+Map&biw=1536&bih=668&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjJquXb-bDOAhUDKZQKHe_oCrgQ_AUIBigB). Somebody built a church out them. Big freakin’ deal. It’s so spectacularly ordinary that it’s unlikely to be untrue. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [August 8, 2016, 4:21am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/5 "2016-08-08T04:21:50Z")
> [@Blake](#): > > It’s is almost certainly true. It’s almost certainly also misinterpreting the evidence. They aren’t mutually exclusive. > > The rocks may just contain some iron, which is the commonest cause of rocks causing “magnetic anomalies”. > > Rocks that cause magnetic anomalies cover [most of the planet](https://www.google.com/search?q=World+Digital+Magnetic+Anomaly+Map&biw=1536&bih=668&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjJquXb-bDOAhUDKZQKHe_oCrgQ_AUIBigB). Somebody built a church out them. Big freakin’ deal. > > **It’s so spectacularly ordinary that it’s unlikely to be untrue.** Then why are so many people attracted to this stuff and not repelled? ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [August 8, 2016, 4:25am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/6 "2016-08-08T04:25:45Z")
Three seconds on Wikipedia. “other stonework and facing of the Pumapunku consists of a mixture of andesite and red sandstone”. “The mineral assemblage [of Andesite] is typically dominated by plagioclase plus pyroxene or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals.” So the temple is made with a rock that commonly contains an appreciable amount of magnetite. And it causes magnetic anomalies. How totally mystifying. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [August 8, 2016, 4:36am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/7 "2016-08-08T04:36:09Z")
Lots of rocks have magnetic anomalies. Volcanic intrusions are a good start. If you want a really obvious anomaly, find a magnetic intrusion that was created before the last global field reversal. It will have a magnetic field that opposes the Earth’s existing field. Heck there is an entire branch of geophysics that spends its time mapping magnetic anomalies in order to work out what is in the Earth. Ore bodies that get developed into mines are discovered this way. Sometimes the anomalies can be ridiculously strong - basically because they contain lots of iron. The entire Earth has a magnetic field. This is not evidence that the Earth is itself an alien artefact. Magnets seems to remain something of a deep mystery for some people, and anything involving them evidence of advanced science. ---
**Author:** ![dreamregent](https://avatars.discourse-cdn.com/v4/letter/d/6f9a4e/32.png) [@dreamregent](https://boards.straightdope.com/u/dreamregent)\ **Post date:** [August 8, 2016, 5:51am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/8 "2016-08-08T05:51:02Z")
> [@Diocletian](#): > > Hello everyone! So I was talking with an Ancient Aliens enthusiast, and someone said that the rocks at Pumapunku caused “magnetic anomalies.” I found the video that they were probably referencing here: > [Puma Punku Bolivia: Ancient Cataclysm And Magnetic Anomalies](https://www.youtube.com/watch?v=LkfH_bMSD6M) > Now a bunch of “Ancient Astronaut Theorists” seem to think that this is evidence of advanced technology, ancient cultures using electricity, or a host of other things. Now the guy in this video could just be lying, could be misled, or could just be misinterpreting the evidence. What do you guys think? Begging the question, a form of circular reasoning. It’s not even necessary to watch the video. If the premise is that the mere presence of “magnetic anomalies” supports a conclusion that aliens were involved, the argument is logically fallacious because the conclusion entails an unstated & baseless presupposition (i.e. we must assume that aliens visited and conducted operations at this location before we can conclude this phenomena is a side-effect of alien operations). Indeed, how does one even know aliens would leave “magnetic anomalies” as a side effect of their activities? This could be dismissed as a number of other logical fallacies as well (e.g. non sequitur, burden of proof, etc.). ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 8, 2016, 12:22pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/9 "2016-08-08T12:22:52Z")
> [@Blake](#): > > Three seconds on Wikipedia. > > “other stonework and facing of the Pumapunku consists of a mixture of andesite and red sandstone”. > > “The mineral assemblage [of Andesite] is typically dominated by plagioclase plus pyroxene or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals.” > > So the temple is made with a rock that commonly contains an appreciable amount of magnetite. And it causes magnetic anomalies. > > How totally mystifying. You are using an anomalous definition of ‘anomaly’ if normal expected fluctuations in a magnetic field are considered anomalies. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [August 8, 2016, 2:25pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/10 "2016-08-08T14:25:58Z")
> [@TriPolar](#): > > You are using an anomalous definition of ‘anomaly’ if normal expected fluctuations in a magnetic field are considered anomalies. If you are a geophysicist or geologist that is exactly what they are. A normal expected fluctuation is still signal. “Normal and expected” just define the amplitude versus wavelength, not the content. It is all a matter of scale really. The Earth has its own magnetic field. There are variations of this field at all scales, anything from global scale (such as over the South Atlantic) to those found by someone sweeping the ground with a metal detector. You define your scale, thus your background, and any variation with a scale smaller is an anomaly. The South Atlantic Anomaly is larger than most countries. But against the Earth, it is an anomaly. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 8, 2016, 2:35pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/11 "2016-08-08T14:35:02Z")
> [@Francis\_Vaughan](#): > > If you are a geophysicist or geologist that is exactly what they are. A normal expected fluctuation is still signal. “Normal and expected” just define the amplitude versus wavelength, not the content. > > It is all a matter of scale really. The Earth has its own magnetic field. There are variations of this field at all scales, anything from global scale (such as over the South Atlantic) to those found by someone sweeping the ground with a metal detector. You define your scale, thus your background, and any variation with a scale smaller is an anomaly. The South Atlantic Anomaly is larger than most countries. But against the Earth, it is an anomaly. Ok, if that’s the usage in the field then I was ignorant. Sorry\*\* Blake\*\*. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [August 8, 2016, 3:04pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/12 "2016-08-08T15:04:42Z")
[Magnets.](http://cdn.memegenerator.net/instances/400x/9891990.jpg) ---
**Author:** ![davida03801](https://avatars.discourse-cdn.com/v4/letter/d/b5e925/32.png) [@davida03801](https://boards.straightdope.com/u/davida03801)\ **Post date:** [August 8, 2016, 3:09pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/13 "2016-08-08T15:09:34Z")
I used to like the History Channel, now with all this ancient alien idiotic babble that channel is on the click by list. ---
**Author:** ![dreamregent](https://avatars.discourse-cdn.com/v4/letter/d/6f9a4e/32.png) [@dreamregent](https://boards.straightdope.com/u/dreamregent)\ **Post date:** [August 8, 2016, 3:44pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/14 "2016-08-08T15:44:25Z")
> [@davida03801](#): > > I used to like the History Channel, now with all this ancient alien idiotic babble that channel is on the click by list. People who like to study primary sources generally don’t find much to like about the “history” channel. I liked it at one time…until I discovered the documentaries typically feed you a load of unsupported baloney or controversial one-sided views on the topic in question. ---
**Author:** ![Diocletian](https://avatars.discourse-cdn.com/v4/letter/d/eb9ed0/32.png) [@Diocletian](https://boards.straightdope.com/u/Diocletian)\ **Post date:** [August 8, 2016, 7:54pm UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/15 "2016-08-08T19:54:17Z")
> [@Blake](#): > > Three seconds on Wikipedia. > > “other stonework and facing of the Pumapunku consists of a mixture of andesite and red sandstone”. > > “The mineral assemblage [of Andesite] is typically dominated by plagioclase plus pyroxene or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals.” > > So the temple is made with a rock that commonly contains an appreciable amount of magnetite. And it causes magnetic anomalies. > > How totally mystifying. I honestly figured it was probably just properties of the minerals in the rocks, but since I have nearly zero experience with geology, I figured I’d ask here. Thanks! ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [August 9, 2016, 1:44am UTC](https://boards.straightdope.com/t/magnetic-anomalies-at-ancient-structures/762110/16 "2016-08-09T01:44:07Z")
[QUOTE=Francis Vaughan;1953751 The entire Earth has a magnetic field. This is not evidence that the Earth is itself an alien artefact. [/QUOTE] Saw it here first! I’d never thought of that possibility 🙂 I’m going to try it on my friends…