<p><a href="https://i.sstatic.net/ffJ5X.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ffJ5X.jpg" alt="enter image description here" /></a>Hiking in a field of boulders along a river canyon in Alabama United states.  Sandstone boulders are 20'-30' (6 to 9 meters) tall.  There are perfectly round holes near the top.  I'm wondering what caused these.  I'm interested in the designs but mainly the perfectly round holes.</p>
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CC BY-SA 4.0
2023-04-04T21:51:25.930Z
Just to clarify (I have no idea, besides animals???), you mean these?  https://i.sstatic.net/MwjPv.jpg
JeopardyTempest
CC BY-SA 4.0
2023-04-05T07:29:40.170Z
The big one in the middle looks like tafoni: https://en.wikipedia.org/wiki/Tafoni
Jean-Marie Prival
CC BY-SA 4.0
2023-04-07T14:03:27.870Z
Mainly the perfectly round one in the upper right.
Mulli Deux
CC BY-SA 4.0
2023-04-07T14:04:43.063Z
thanks for the Tafoni information!  It answers several of my "how'd that happen" moments when out in a boulder field
Mulli Deux
CC BY-SA 4.0
2023-04-08T01:59:46.997Z
it could be chemical erosion, water erosion of even a trace fossil, from just a dark spot on a boulder anything definitive is difficult.
John
<geology>
How'd this hole get here?
Mulli Deux
# How'd this hole get here?

(Asked by: username_0 on 2023-04-04)

[![enter image description here](https://i.sstatic.net/ffJ5X.jpg)](https://i.sstatic.net/ffJ5X.jpg)Hiking in a field of boulders along a river canyon in Alabama United states. Sandstone boulders are 20'-30' (6 to 9 meters) tall. There are perfectly round holes near the top. I'm wondering what caused these. I'm interested in the designs but mainly the perfectly round holes.

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**Tags:** geology

> **Comments:**
> **username_1**: Just to clarify (I have no idea, besides animals???), you mean these?  https://i.sstatic.net/MwjPv.jpg  
> **username_2**: The big one in the middle looks like tafoni: https://en.wikipedia.org/wiki/Tafoni  
> **username_0**: Mainly the perfectly round one in the upper right.  
> **username_0**: thanks for the Tafoni information!  It answers several of my "how'd that happen" moments when out in a boulder field  
> **username_3**: it could be chemical erosion, water erosion of even a trace fossil, from just a dark spot on a boulder anything definitive is difficult.  

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## 0 answers

