[Rockhounds] glacial erratics (was Stonehenge geology resolved)

Tue Feb 3 12:07:20 PST 2009

Take a look at this picture...

http://static.panoramio.com/photos/original/234063.jpg

subtract the lichen covering from the left half which slants back 
(providing a growing surface)

Subtract the iron staining from the right half which leans forward 
(causing it to drain between the layers)

maybe?

Jeff

At 02:27 PM 2/3/2009, you wrote:
>I don't doubt your proposed possiblity Pete, just thinking numbers --
>I haven't seen a whole lot of rocks broken and sagging in the middle.
>Just threw that in as more ammunition as I expressed my pondering if
>it is a rock broken in two where it rests or several rocks that just
>happened to end up at the same spot. I can't imagine any reason why it
>couldn't be two separate rocks from the same "avalanche fall on to the
>ice" or otherwise plucked from the bedrock.
>
>Out of curiosity, I searched the web and looked at a lot of photos,
>none of which really helped. The Okotoks Erratic is quite a pile of
>rocks, hiding behind those two big pieces, with three main pieces and
>a lot of little ones. None of the photos were useful for lining up the
>layers to see if the two sides even matched in layers. As to the one
>side of those two largest pieces looking much more broken up and more
>rusty than the left piece, in some photos, they didn't look all that
>different.
>
>Nothing like computer-side geologizing.
>
>Regards,
>
>Lanny
>
>
>
>On Feb 2, 2009, at 9:52 AM, pmodreski at aol.com wrote:
>
>>Well, heck, Lanny, the explanation is all right there in the story
>>link that Kreigh sent, how the rock was split by the bats as they
>>were trying to save Napi, the supernatural trickster of the Blackfoot.
>>
>>Trying for the more scientific interpretations, perhaps, if the rock
>>had been carried to this spot as one more or less intact block by
>>the glacier, it could have been resting on stagnant glacial ice
>>after the ice sheet stopped moving, and melting away of support
>>underneath it might have undermined the rock and caused it break
>>apart if it couldn't support its own weight; or, it might even have
>>toppled off an ice cliff at the terminus of the glacier, perhaps
>>while the ice was still flowing.? Or, being weak in its center,
>>perhaps it was broken into several pieces while it was still being
>>carried along.
>>
>>lots of possibilities?
>>
>>
>>-----Original Message-----
>>From: Lanny R <lanny.r at roadrunner.com>
>>To: Rockhounds at drizzle.com: A mailing list for rock and gem
>>collectors <rockhounds at lists.drizzle.com>
>>Sent: Mon, 2 Feb 2009 10:13 am
>>Subject: Re: [Rockhounds] glacial erratics (was Stonehenge geology
>>resolved)
>>
>>
>>I have a doubt about the "Big Rock," this Okotoks Erratic really
>>being one rock broken into two pieces. First, I don't recall ever
>>seeing a large rock that I was sure had obviously broken into two
>>pieces where it had settled in the middle so that the two pieces
>>dipped inwards. Secondly, I can't see any match in the layers
>>between the two pieces. That might be just a problem of how it is
>>shown in the photograph, so that one can't really see them all that
>>well. Thirdly, the piece on the right is more broken up and has a
>>lot of rusty layers, very unlike the left piece.?
>>?
>>Any others care to express their opinion on this??
>>?
>>Regards,?
>>?
>>Lanny?
>>?
>>On Feb 2, 2009, at 8:48 AM, pmodreski at aol.com wrote:?
>>?
>>>Neat website about that big rock, Kreigh!?
>>>?
>>>?
>>>Some erratics are big. You might enjoy the size of the biggest one??
>>>??
>>>http://culture.alberta.ca/museums/historicsiteslisting/okotokserratic/default.aspx? 
>>>?
>>>??
>>>and the interesting legend of how it split in two.??
>>>??
>>>Kreigh??
>>>?
>>>?
>>>And, alas, I'm afraid your post was a great disillusionment to me,
>>> > because I couple of years ago I had visited, and was very
>>>impressed > by, the Madison, Carroll County, New Hampshire, glacial
>>>erratic, a > N.H. State "Wayside Monument" and locally known as
>>>"the largest > known glacial erratic".? It is,?
>>>?
>>>?
>>>"Madison Boulder is a huge granite rock measuring 83 feet (25 m) in
>>> > length, 23 feet (7.0 m) in height above the ground, and 37 feet
>>>(11 > m) in width. It weighs upwards of 5,000 tons."?
>>>?
>>>Your Okotoks Erratic "Big Rock" in Alberta has?clearly got it all >
>>>beat,?
>>>?
>>>"The Okotoks Erratic weighs 16,500 tons. It measures 9 metres high,
>>> > 41 metres long and 18 metres wide."?
>>>?
>>>and?evidently holds the world record, as is stated in the very good
>>> > Wikipedia article about glacial erratics,?
>>>?
>>>http://en.wikipedia.org/wiki/Glacial_erratic?
>>>?
>>>Next time I'm in Alberta (never been there, actually), I've got to
>>> > see it!?
>>>?
>>>Cheers, Pete?
>>>?
>>>?
>>>?
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