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Impressions in Large Rocks + Coral and Imprint Fossils | New Member


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Hello all – Stumbled across this great site/forum after rekindling an interest in fossils and minerals from my youth.  I was able to visit a spot I spent a lot of time in summers as a child with my own children and looking to get them interested as well. 

Location: Southern Ontario on Lake Erie

After doing a little research, according to this map (https://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/M2544/M2544.pdf) from the Province of Ontario’s Ministry of Northern Development and Mines, the bedrock is Middle Devonian (from the Detroit River Gp.; Onondaga Fm. – I assume these are the formations?).  Though with the glacial activity I don’t know if the rocks below are consistent with that and how that impacts things.

1)  Does someone know what the spherical depressions/imprints in the large rocks are?  As a young child, I always pretended they were dinosaur egg impressions.  I understand now that isn’t the case but they still strike me as interesting I am curious if they are imprints or some sort of naturally occurring phenomenon in the rocks.  Given the size and location of some - it would seem they are not strictly erosion activity but no expert here :-)

2) Relatedly, I am curious what the black sections of the one rock might be (red arrows in the picture below) - just another type of rock that settled when the surrounding rock was forming?  To my recollection (and other pictures I have) these black "inserts" were not in other similar rocks nearby.  These are large rocks 2-3 ft wide x 2-3 ft long or larger – sorry but took them before learning the ways to try to provide scale on the forum and sorry there are not more/closer pictures - I didn't know a community like this existed when I took the picture. 

I have included some pictures of fossils found nearby.  I think they are fossilized corals and a horn coral.  The imprint fossil I think is a leaf?  I understand that this area was likely a tropical climate 400 million years ago so that would make sense I think.

Many thanks in advance!  While I don’t have much to share knowledge wise – I do have much to learn and appreciate the community!

Impression Rock w Black - arrows.jpg

Impression 3 - box.jpg

Impression 2 - box.jpg

Impression 1 - box.jpg

Coral 2.jpg


Horn Coral 1.jpg

Horn Coral 2.jpg

Imprint 2.jpg


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First coral looks something like Siphonodendron sp..

Second is a rugose, or "horn" coral.


Last item looks like mineral staining, to me.

While leaves would seem to make sense, they don't, really, as the area was underwater at the time. 

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Thanks Tim - the imprint "leaf" is noticeably depressed vis-a-vis the surrounding rock (probably hard to tell from the picture) but understand the staining suggestion.  Thanks again!

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