<p>The best way to know what's underneath the surface is to drill it:</p>
<p><a href="https://i.sstatic.net/MrOUrJpB.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/MrOUrJpB.jpg" alt="enter image description here" /></a></p>
<p>It's a very expensive method and you use it when you have a good reason to drill in that place (engineering projects, tunneling, exploration for resources, water wells, etc.). But nothing beats a good hole.</p>
<p>The global drilling industry is rather extensive, but somehow hidden from the public eye because most holes are drilled in places where people do not live.</p>

CC BY-SA 4.0
2024-09-19T12:25:54.217Z
2024-09-19T12:25:54.217Z
Gimelist
<p>A few things here to dissect and explain.</p>
<p>Let's forget the basalt for a minute and imagine a mountain made of limestone. Limestone is formed at the ocean/sea floor (a basin) and is turned into a mountain because of tectonic plates folding the limestone convexly into a mountain. Where the mountain finishes is where the fold turns concavely and other materials are deposited above the limestone, perhaps on a flat plain because that's where the river runs so sediment is deposited etc.</p>
<p>Now for erosion, this let's you see the layer beneath the limestone and tells you what other materials form the mountain. This doesn't have to be on the actual mountain but somewhere relatively close where you can see the same limestone and just beneath it a different material, therefore we can expect that in the interior of the mountain is that same material.</p>
<p>Back to basalt, basalt is different because it is can be much more localized (or not, Hawaii is pretty much all basalt and that's a big area) so it's really dependent of the area and context. However, basalt comes from the magma from below and intrudes though the existing rock layers spewing lava that turns into basalt.</p>
<p>So by mixing these two concepts and many other concepts, a geologist can map around the mountain to give a good idea of the whole thing.</p>
<p>Regarding &quot;dirt&quot;, well this is essentially a mixture of highly weathered and eroded rock with decomposed organic material. This is going to be a very small percentage of the whole mountain (not to be confused with soil).</p>
<p>As for the depth of the layers, the geologist could go to a nearby road cutting and see how thick the limestone is, and suppose that limestone is just as thick at the mountain. Basalt on the other hand might be a bit more difficult to know.</p>
<p>As for actually finding out yourself and hiring a geologist, well geologist have probably already done it to an extent probably. I know the UK and Spain have extensive geological maps already on this. For example this page from the british geological society: <a href="https://webapps.bgs.ac.uk/data/maps/maps.cfc?method=listResults&amp;MapName=&amp;series=E50k&amp;scale=&amp;getLatest=Y&amp;pageSize=100" rel="nofollow noreferrer">https://webapps.bgs.ac.uk/data/maps/maps.cfc?method=listResults&amp;MapName=&amp;series=E50k&amp;scale=&amp;getLatest=Y&amp;pageSize=100</a> you can find this map: <a href="https://largeimages.bgs.ac.uk/iip/mapsportal.html?id=1001507" rel="nofollow noreferrer">https://largeimages.bgs.ac.uk/iip/mapsportal.html?id=1001507</a></p>
<p>Many countries have maps like this.</p>
<p>The final method I'll quickly explain is to drill a hole in the ground (borehole) and then the geologist can log the soil/rock in detail, mainly used for civil engineering projects.</p>
<p>There are other methods but that's the idea.</p>

CC BY-SA 4.0
2024-05-25T22:23:06.757Z
If you're in the US, you might want to contact your state bureau of geology or geological survey and ask about what maps they have of the area.
Brian Borchers
CC BY-SA 4.0
2024-05-25T21:05:40.963Z
2024-05-25T21:05:40.963Z
Mr.inquisitive
<p>There is an idyllic verdant valley where I live, full of mountains and hills. Most mountains are covered by vegetation, but some have flat steppe-like tops where people have small farms and homesteads. There is this particular mountain that has a farm on top that is for sale; even though the foot of the mountain is full of trees and bushes, when I get closer to the edge on top I can see there are rocky parts which the current owner told me was basalt. I can also see random rocky spots engulfed by grass and flowers on top; actually such spots are scattered across the farm. I wonder if I could hire a geologist to inspect the internal part of the mountain. Can a geologist tell me how much of it is made of basalt and how much of it is just dirt? How about the depth of such layers? Does such an examination exist? If so, how does it work?</p>
<p>Thanks in advance.</p>

CC BY-SA 4.0
2023-12-24T06:58:40.280Z
https://en.wikipedia.org/wiki/Geological_survey
trond hansen
<geology><mountains>
How do geologists examine mountains and hills inwardly?
Kevin
# How do geologists examine mountains and hills inwardly?

(Asked by: username_0 on 2023-12-22)

There is an idyllic verdant valley where I live, full of mountains and hills. Most mountains are covered by vegetation, but some have flat steppe-like tops where people have small farms and homesteads. There is this particular mountain that has a farm on top that is for sale; even though the foot of the mountain is full of trees and bushes, when I get closer to the edge on top I can see there are rocky parts which the current owner told me was basalt. I can also see random rocky spots engulfed by grass and flowers on top; actually such spots are scattered across the farm. I wonder if I could hire a geologist to inspect the internal part of the mountain. Can a geologist tell me how much of it is made of basalt and how much of it is just dirt? How about the depth of such layers? Does such an examination exist? If so, how does it work?

Thanks in advance.

**Tags:** geology, mountains

> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Geological_survey  

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## 2 answers

### Answer by username_2 on 2024-09-19. Score: 1

The best way to know what's underneath the surface is to drill it:

[![enter image description here](https://i.sstatic.net/MrOUrJpB.jpg)](https://i.sstatic.net/MrOUrJpB.jpg)

It's a very expensive method and you use it when you have a good reason to drill in that place (engineering projects, tunneling, exploration for resources, water wells, etc.). But nothing beats a good hole.

The global drilling industry is rather extensive, but somehow hidden from the public eye because most holes are drilled in places where people do not live.


---

### Answer by username_3 on 2024-05-25. Score: 1

A few things here to dissect and explain.

Let's forget the basalt for a minute and imagine a mountain made of limestone. Limestone is formed at the ocean/sea floor (a basin) and is turned into a mountain because of tectonic plates folding the limestone convexly into a mountain. Where the mountain finishes is where the fold turns concavely and other materials are deposited above the limestone, perhaps on a flat plain because that's where the river runs so sediment is deposited etc.

Now for erosion, this let's you see the layer beneath the limestone and tells you what other materials form the mountain. This doesn't have to be on the actual mountain but somewhere relatively close where you can see the same limestone and just beneath it a different material, therefore we can expect that in the interior of the mountain is that same material.

Back to basalt, basalt is different because it is can be much more localized (or not, Hawaii is pretty much all basalt and that's a big area) so it's really dependent of the area and context. However, basalt comes from the magma from below and intrudes though the existing rock layers spewing lava that turns into basalt.

So by mixing these two concepts and many other concepts, a geologist can map around the mountain to give a good idea of the whole thing.

Regarding "dirt", well this is essentially a mixture of highly weathered and eroded rock with decomposed organic material. This is going to be a very small percentage of the whole mountain (not to be confused with soil).

As for the depth of the layers, the geologist could go to a nearby road cutting and see how thick the limestone is, and suppose that limestone is just as thick at the mountain. Basalt on the other hand might be a bit more difficult to know.

As for actually finding out yourself and hiring a geologist, well geologist have probably already done it to an extent probably. I know the UK and Spain have extensive geological maps already on this. For example this page from the british geological society: <https://webapps.bgs.ac.uk/data/maps/maps.cfc?method=listResults&MapName=&series=E50k&scale=&getLatest=Y&pageSize=100> you can find this map: <https://largeimages.bgs.ac.uk/iip/mapsportal.html?id=1001507>

Many countries have maps like this.

The final method I'll quickly explain is to drill a hole in the ground (borehole) and then the geologist can log the soil/rock in detail, mainly used for civil engineering projects.

There are other methods but that's the idea.

> **Comments:**
> **username_4**: If you're in the US, you might want to contact your state bureau of geology or geological survey and ask about what maps they have of the area.  

---

