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Monday Morning Mystery photo

September 20, 2009

Found on the beach of Lake Michigan:

It’s about 3cm wide and 5mm thick at its thickest.  The hole is round with straight sides and about 5mm in diameter.  Any ideas?

Categories: Uncategorized
  1. September 20, 2009 at 23:19 | #1

    My theory : The stone originally condensed from mud around a branch. Later, when the branch rotted away a hole was left.
    The hole filled with softer material, which solidified similarly. This later got washed out first.

  2. September 21, 2009 at 08:16 | #2

    Eunoia’s explanation sounds more plausible than any that I attempt to come up with in the opposite direction, i.e., something non-human created a perfect hole in a pre-existing rock.

    Unless its the results of some person making a necklace a long time ago and discarding it. Don’t know.

    The thing that annoys me is that after too many years of working with the U.S. measurement system, I had to mentally convert your millimeter measurements to parts of inches to get an accurate picture of the size of this rock. It’s a beautiful image of what I consider a small rock.

  3. September 21, 2009 at 13:03 | #3

    It is obviously, patently, an alien artifact which, if analyzed and understood properly, can transport one to a far place regardless of the laws of physics as mankind currently understands them.

  4. September 21, 2009 at 13:21 | #4

    Gerry, that’d be a wormhole ;-)

  5. September 21, 2009 at 14:05 | #5

    I don’t quite see Euonia’s hypothesis … the conditions for the decay of the branch being lengthy enough too allow for formation of the rock around it would have to be pretty unique, I think.

    Large logs/trees can be submerged for a long, long time before decaying.  But how long does it take for mud to turn to stone, and under what conditions?

    The first step would be to have a precise analysis of the type of rock.  Someone should get on it before Geo is transported to that way cool beach with Jodie Foster.  Or maybe not … I’m thinking he may not mind that.  ;)

  6. September 21, 2009 at 14:19 | #6


    The fossil scenario : After a very long time—millions of years—both the mud and the plant or animal remains turn to stone. The bone, shell, or leaf has become a fossil.

    In my alternative scenario, the mud bakes into clay over weeks of scorching sunlight, then when the rainy season comes, the branch rots away, but the clay stays hard baked and -after many many years – becomes stone.

  7. September 21, 2009 at 15:50 | #7

    Someone should get on it before Geo is transported to that way cool beach with Jodie Foster.  Or maybe not … I’m thinking he may not mind that.

    What makes you think I’m not there now?  After the giant alien-designed transport thingie took me there, I had it blown up.  :coolsmirk: 

    Oh wait, reality.  Damn.

    My best guess, the rock is slate.

  8. September 22, 2009 at 06:42 | #8

    Eunoia—makes sense.

    DoF—damn, I need to learn to get to the launch site on time.

  9. September 22, 2009 at 06:53 | #9

    OK, I showed the rock around to other wedding revelers (there were some nerdy types there) and here were the prevalent hypotheses:

    1. Fossil.  That was the most popular one, followed by
    2. Necklace.

    Alas, nobody thought of alien artifact or Jodi Foster.  That had to wait until now for the Truth to be revealed.  Makes it a much better stone, I think.

    At least, I like that explanation a lot better than “fragment of slate roofing material discarded from a roofing project or blown off one of the mansions along the beach, and eroded by wave action”.  I had managed to come up with the most boring explanation.

  10. james old guy
    September 22, 2009 at 16:20 | #10

    It might be a ballast rock used in small boats.

  11. Neil
    September 22, 2009 at 21:44 | #11

    I’m definitely curious, but I have no ideas that haven’t already been offered.  The reason I’m so curious, is that I see rocks very similar to this one all the time.  I live near Pismo Beach, CA, on the central coast.  Along with long, sandy stretches, there are lots of rocky cliffs and tidepools.  If you walk a mile and pay attention, there are days when you can find several small to medium stones with holes that look like they were intentionally drilled.  It looks like a similar kind of beach stone to me, slate or something similar. 
      Hmmmm…now that I’m thinking about it(hey, that was the intention, wasn’t it?  You tricked me!) Some areas have large stretches of tidepool rocks, and on the big, more-or-less flat horizontal stretches, there are often pits on the top surface of the rock that also look too perfectly round to be natural.  The rock that forms the tidepools is often in fairly thin layers that are cracked and easily split apart.  Perhaps this rock was part of a larger plate where some kind of natural erosion made the hole, and was later separated from the whole.  Over time,  all the sides were weathered more or less equally, causing it to look as if the hole was either made after the stone was shaped, or was made while the stone was being made. 
      Is one of the flat sides flatter or sharper edged than the other?  Does the hole look equally rounded or beveled on both sides?  If there is a flatter or sharper or “less weathered” side, it could be the side that was attached to a larger structure while a pit was dug into the larger stone.
      Of course, all of this speculation still doesn’t answer the question of what made the hole in the first place.  I see similar holes on tidepools all the time, I always assumed they were made by repeated erosion(waves, wind, sand) hammering away at weak spots in the rock.  This still leaves the question of why so many “weak spots” would be perfectly round.  Perhaps once a chip is made in the rock by any means, water erosion takes over and smooths the edges while slowly digging deeper, leaving “round” as one of only a few shape options?

      That’s all I’ve got.  Even if I’m more or less correct, I’ve seen many beach rocks with round holes, made out of different types of stone, with different weathering patterns and shapes…some look too round or otherwise different to have all been made the same way, but then water erosion does kind of take the edge off of things…

  12. September 23, 2009 at 21:23 | #12

    Hmmm … there are tube worms that live deep in soft sea bottoms, near thermal vents.  Fossilized tube worms … or methane vents?


  13. Tamra Raiche-Skibsted
    October 2, 2009 at 23:43 | #13

    Water is my first guess, as in the tide pool option. Also the worm or other creature that bores holes into things for homes…

    Who knows, maybe God made it that way to get the atheists thinking… I guess it worked… sorry guys had to take a shot at that one.. hee hee…
    Cheers, Taz

  14. Dan
    November 12, 2009 at 22:08 | #14

    I have a palm sized rock, not flat, with a similar smooth round hole through it. I’ve been looking for anyting resembling mine and that’s how I happened upon the picture of yours.  Interesting that Neil says he sees rocks like yours frequently.

    I thought mine was an ancient tool, but maybe it is a result of natural phenomenon.  Mmmmm.

  15. November 12, 2009 at 23:15 | #15

    Dan – do you have a photo online?  Feel free to post a link.

    I have seen other stones like this that don’t seem like tools but I’ll be darned if I can figure out how such a perfect hole got drilled in them.

  16. December 30, 2009 at 23:35 | #16

    We live in the Monterey Bay area and just today I found several (6-10) stones with holes like these. I’ve been to that beach several times and I have never seen anything like them. Granted, the waves were actually quite calm today, to where the water was just lapping at your ankles, as opposed to threatening to take you under. I assume the rocks I found have been rolling around in the waves for a while. The ones I found are darker, and they are nice and “polished” by the sand. Some of the holes are in different directions on the same rock – for example, on one rock some of the holes will be from “top to bottom” and some will kind of go in at an angle. I too was very curious to find out how these came to be. I will probably make some kind of wind chime or wall hanging or something from them. They are quite beautiful.

  17. January 1, 2010 at 23:17 | #17

    My cousins came to visit for the New Year, and they informed me that little pebbles will sometimes get stuck in the rocks, and then as the waves beat the small pebbles into the rocks, they bore perfectly round holes into the rocks. This makes sense, as one of the rocks I found actually has a small pebble stuck in one of the holes. I wondered how on earth it got in there… now I know! And apparently, many of the rocks this happens to are actually just a clay/mud rock which will break apart when it dries. A few of mine broke apart when they dried out, but not all of them. I have pictures of my rocks on my blog.

  18. aye whole
    June 23, 2010 at 20:23 | #18

    hrmmm.,.. did anyone ever even think in there alien obsessed retarded brains that these rocks are simply weights for nets and fishing baskets made by NATIVE AMERICAN INDAINS ??!! DERRRR DERRRR ERRRR UMM MDERRRRRRRR!!! hahaha dumb asses ;)

  19. June 23, 2010 at 21:23 | #19

    Well you’ve certainly described yourself accurately, “aye whole”.  Too bad, because the messages you left afterwards, which were equally (pointlessly) insulting, gave actual reference links to support your point. 

    But I believe you are mistaken that these are fishing weights; the morphology is wrong for the examples you gave.

    Here are the links from your removed messages:

    Stone Weights.


    Oh, and one other link: the Comment Policy of this blog.

  20. Mindy
    July 21, 2010 at 13:29 | #20

    I found something similar with two large rocks on a beach in Ventura county off the Pacific Coast Highway.  Have a look:
    http://www.flickr.com/photos/froschy/4812123543/ .

    The beach was full of rock caves and tons of small and medium sized rocks being washed up on the shore.  I’m very curious about the apparent perfectly round hole as well.  :)

  21. July 21, 2010 at 16:39 | #21

    Wow… that’s an amazing picture Mindy!

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