<blockquote>
<p>it was simply an older stone smoothed by water that had fallen into sediment.</p>
</blockquote>
<p>This is exactly what happened. There's a name for that: a <a href="https://geology.com/rocks/conglomerate.shtml" rel="noreferrer">conglomerate</a>.</p>

CC BY-SA 4.0
2021-04-18T20:47:31.587Z
[Dropstone?](https://en.wikipedia.org/wiki/Dropstone)
Keith McClary
CC BY-SA 4.0
2021-04-18T23:40:50.263Z
@KeithMcClary the very rounded shape of the rock makes me feel like it was in a conglomerate, not a dropstone. But could be.
Gimelist
CC BY-SA 4.0
2021-04-18T04:14:02.913Z
2021-04-18T04:14:02.913Z
Gimelist
<p>My father, in his younger years, was a stone mason in Cincinnati Ohio. A couple of decades ago he was building a wall of some kind. He would fetch rock from a creek bed, haul it to the construction site, then shape it with what he calls a brick hammer.</p>
<p>After giving one rock a good whack, he found that it contained a smooth gray stone about the size of a child's fist. One side of the stone is a little darker than the other. When cracked open the stone appears fairly homogeneous.</p>
<p>How did this stone find its way inside the larger rock?</p>
<p>EDIT: Removed my speculation (cited by one answer) and other clutter. Added example of stone used for the wall.</p>
<p><a href="https://i.sstatic.net/xkrpX.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/xkrpXm.jpg" alt="Whole Rock" /></a></p>
<p><a href="https://i.sstatic.net/i1fds.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/i1fdsm.jpg" alt="Cracked Rock" /></a></p>
<p><a href="https://i.sstatic.net/e4CbB.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/e4CbB.jpg" alt="Wall Example" /></a></p>
<p>(click to enlarge)</p>

CC BY-SA 4.0
2021-04-17T17:30:11.260Z
Interesting question! I believe (I am not well versed in the field of geology) that you are correct. It seems pretty reasonable to me.
User123
CC BY-SA 4.0
2021-04-18T22:30:04.117Z
The author seems to already know the answer, "...led me to the belief that it was simply an older stone smoothed by water that had fallen into sediment." Yet the Author says, "But I don't trust my intuition when it comes to just about anything." This is why I didnt upvote this
Tardy
CC BY-SA 4.0
2021-05-03T18:02:17.323Z
Probably the stone did not go inside the other rock, but the other rock was built around the stone.  It is quite commonplace for sediments to build up around pre-existing rocks and then eventually become a surrounding rock.
Oscar Lanzi
<geology><rocks><petrology>
How did this stone become encased within different rock?
Kenny
# How did this stone become encased within different rock?

(Asked by: username_0 on 2021-04-17)

My father, in his younger years, was a stone mason in Cincinnati Ohio. A couple of decades ago he was building a wall of some kind. He would fetch rock from a creek bed, haul it to the construction site, then shape it with what he calls a brick hammer.

After giving one rock a good whack, he found that it contained a smooth gray stone about the size of a child's fist. One side of the stone is a little darker than the other. When cracked open the stone appears fairly homogeneous.

How did this stone find its way inside the larger rock?

EDIT: Removed my speculation (cited by one answer) and other clutter. Added example of stone used for the wall.

[![Whole Rock](https://i.sstatic.net/xkrpXm.jpg)](https://i.sstatic.net/xkrpX.jpg)

[![Cracked Rock](https://i.sstatic.net/i1fdsm.jpg)](https://i.sstatic.net/i1fds.jpg)

[![Wall Example](https://i.sstatic.net/e4CbB.jpg)](https://i.sstatic.net/e4CbB.jpg)

(click to enlarge)

**Tags:** geology, rocks, petrology

> **Comments:**
> **username_1**: Interesting question! I believe (I am not well versed in the field of geology) that you are correct. It seems pretty reasonable to me.  
> **username_2**: The author seems to already know the answer, "...led me to the belief that it was simply an older stone smoothed by water that had fallen into sediment." Yet the Author says, "But I don't trust my intuition when it comes to just about anything." This is why I didnt upvote this  
> **username_3**: Probably the stone did not go inside the other rock, but the other rock was built around the stone.  It is quite commonplace for sediments to build up around pre-existing rocks and then eventually become a surrounding rock.  

---

## 1 answers

### Answer by username_4 on 2021-04-18. Score: 5 | Accepted answer

> it was simply an older stone smoothed by water that had fallen into sediment.

This is exactly what happened. There's a name for that: a [conglomerate](https://geology.com/rocks/conglomerate.shtml).

> **Comments:**
> **username_5**: [Dropstone?](https://en.wikipedia.org/wiki/Dropstone)  
> **username_4**: @username_5 the very rounded shape of the rock makes me feel like it was in a conglomerate, not a dropstone. But could be.  

---

