<p>Tunnels have provided nothing more than what was learned from conventional geological drilling and surface mapping. Tunnels provide supplemental information. Very rarely do they provide "make or break" information that is pivotal to geological understanding on a large scale.</p>

<p>A tunnel is a lateral large diameter hole. Geological drilling produces small diameter holes, whose orientation can be lateral, vertical or anything in between. A sample of rock is take by both.</p>

<p>By using in-hole surveys and noting from where, within a hole, a sample was taken from it is possible to know where the rock sample came from. This is useful for creating geological maps of the region. It is even possible to place ground stress measuring devices in both drill holes and tunnels.</p>

<p>The mass of material taken from a hole, whether it be a geological drill hole or a tunnel is not particularly significant in expanding knowledge. More knowledge can be gained from multiple small samples taken over a large area.</p>

<p>Tunnels do give geologists the advantage of walking through a rock mass and seeing <em>some</em> structures like faults. But if the tunnel hasn't intersected a structure then the geologists may not know about it.</p>

<p>Your question is a bit like asking "what can be learn about a country by just walking along its roads". Additional information can be gained by walking off track, navigating rivers, flying over the country and talking to the inhabitants.</p>

<p>Tunnels provide <strong>some</strong> information. It is useful information, but multiple sources of information given us a better understanding.</p>

CC BY-SA 3.0
2018-03-07T15:25:42.437Z
Are their schematics of core samples from tunnels ?
WaterBearer
CC BY-SA 3.0
2018-03-07T02:00:12.203Z
2018-03-07T02:00:12.203Z
Fred
<p>Since tunnelling is like making a giant horizontal core sample, what did the analysis of the extracted rocks teach us? Is the inside homogeneous or layered, are there "deformations", etc?</p>

CC BY-SA 3.0
2018-03-07T07:27:40.167Z
I edited "carrot" to "[core sample](https://en.wikipedia.org/wiki/Core_sample)" in your question because I'm fairly sure that's what you meant. (In English "carrot" is only the vegetable).
Pont
CC BY-SA 3.0
2018-03-07T15:22:28.013Z
@Pont my translator mislead me, but who wouldn't dream of a giant tasty carrot ? https://youtu.be/WHEtmW1Ngqg
WaterBearer
<mountains><structural-geology><stratigraphy>
What did tunnel digging teach us about the formation of chains of mountains?
WaterBearer
# What did tunnel digging teach us about the formation of chains of mountains?

(Asked by: username_0 on 2018-03-07)

Since tunnelling is like making a giant horizontal core sample, what did the analysis of the extracted rocks teach us? Is the inside homogeneous or layered, are there "deformations", etc?

**Tags:** mountains, structural-geology, stratigraphy

> **Comments:**
> **username_1**: I edited "carrot" to "[core sample](https://en.wikipedia.org/wiki/Core_sample)" in your question because I'm fairly sure that's what you meant. (In English "carrot" is only the vegetable).  
> **username_0**: @username_1 my translator mislead me, but who wouldn't dream of a giant tasty carrot ? https://youtu.be/WHEtmW1Ngqg  

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## 1 answers

### Answer by username_2 on 2018-03-07. Score: 3

Tunnels have provided nothing more than what was learned from conventional geological drilling and surface mapping. Tunnels provide supplemental information. Very rarely do they provide "make or break" information that is pivotal to geological understanding on a large scale.

A tunnel is a lateral large diameter hole. Geological drilling produces small diameter holes, whose orientation can be lateral, vertical or anything in between. A sample of rock is take by both.

By using in-hole surveys and noting from where, within a hole, a sample was taken from it is possible to know where the rock sample came from. This is useful for creating geological maps of the region. It is even possible to place ground stress measuring devices in both drill holes and tunnels.

The mass of material taken from a hole, whether it be a geological drill hole or a tunnel is not particularly significant in expanding knowledge. More knowledge can be gained from multiple small samples taken over a large area.

Tunnels do give geologists the advantage of walking through a rock mass and seeing *some* structures like faults. But if the tunnel hasn't intersected a structure then the geologists may not know about it.

Your question is a bit like asking "what can be learn about a country by just walking along its roads". Additional information can be gained by walking off track, navigating rivers, flying over the country and talking to the inhabitants.

Tunnels provide **some** information. It is useful information, but multiple sources of information given us a better understanding.

> **Comments:**
> **username_0**: Are their schematics of core samples from tunnels ?  

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