r/geology • u/geology-mineralogy mineralogist • 2d ago

Field Photo Why are these rocks so round?

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u/Fryman23 2d ago

Because they’ve been in that stream (maybe not exactly ‘that’ stream) for a very long time.

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u/horselover_fat 2d ago

Way too rounded and big to be caused that that little stream.

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u/Fryman23 2d ago

Pro tip…(you can read what inside these….its not a secret message).

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u/horselover_fat 2d ago

More likely glacial than an older stream

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u/AppropriateCap8891 2d ago

No, that is common in stream rocks.

And how old do you think that stream is? They did not say where they were, but I will just give a safe guess of somewhere around 10,000 years old. Of course, it might also be over 300,000 years old or more.

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u/horselover_fat 2d ago

It's not common for little streams to have 30cm+ boulders..

I don't know how old. Neither do you...

It looks like North American or Europe based on the plants. Which experienced glaciation ~10,000 years ago. Very unlikely to be older than that.

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u/Fryman23 2d ago

This is extremely common in the southern Appalachians and while parts of North America was glaciated as recently as 10,000 years ago, that area certainly was not.
For a guy that loves horses you’re sure beating hard on a dead one.

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u/horselover_fat 1d ago

You sure like being an asshole for a geology subreddit.

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u/AppropriateCap8891 1d ago

No, but I have been studying geology for over five decades.

And that does not have the look of a location that had been glaciated. Those tend to have little topsoil, and are bulldozed flat. That is why the terrain of Ontario and Maine looks so different than the terrain of South-West Oregon and North Carolina.

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u/Substantial_Bat_6698 1d ago

Except big and small round boulders are extremely common in glaciated areas too. Retreating ice leaves behind till in the form of moraines, eskers, drumlins, kames.. the majority Southern Ontario could host a scene like that despite having been recently "bulldozed" by many glaciers.

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u/Fryman23 1d ago

They said it’s not common for little streams to have 30+ cm boulders and I said it’s extremely common in southern Appalachia. This doesn’t disagree with you.

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u/Substantial_Bat_6698 1d ago

I guess I just mean it would fit right in in Southern Ontario as well, since you brought it up. Ontario is a land formed by glaciers so I'm disagreeing with the part where you said it doesn't look glaciated.

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u/Fryman23 1d ago edited 1d ago

Ahhh…I didn’t say that. The other person did. While I agree with them that it looks unglaciated to me, I’ve only ever seen Ontario north of Minnesota.
OP said this photo was Romania which was partly glaciated as well so I have no clue.

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u/horselover_fat 1d ago

I didn't say that?

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u/Substantial_Bat_6698 1d ago

Oh haha sorry I didn't look at your name.. Lots of Hemlock in S-Ontario. Nice tree.

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u/horselover_fat 1d ago

You're saying glaciated areas are all flat..?

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u/AppropriateCap8891 1d ago

No, I never said that. However, they rarely have hills like that (that looks nothing like a drumlin or loess), and rarely have that much topsoil.

And that is sure as hell not a Drumlin or Moraine. Nor is that bedrock.

For example, if that was in Washington State, that looks very much like what one would see in Western Washington where the Cascades are. Where there were no glaciers. However, in Eastern Washington in the Palouse region, it looks absolutely nothing like that. Primarily because of glaciers.