Frozen molehills and bizarre ice crystals
Andy Dingley
Any ideas on how this happens ?
Anne Burgess
news:fh605vgrurucdbtff...@4ax.com...
None at all - but congratulations on an excellent set of pics.
Anne
Nick
> http://www.jarkman.co.uk/album/molehill.htm
>
> Any ideas on how this happens ?
Mm, I saw this in Canada in '92 admittedly at about 10k feet in the Rockies !
My cousin who was walking with us told me that it's a regular thing, and it's
apparently to do with the way the ground freezes then thaws then freezes
again and it gets pushed up from the bottom......something like that anyway?!
I'll be scanning some of the pictures soon and updating my site....link to
follow....
By the way, as Anne said, excellent pictures :)
--
Nick in Northallerton
nrw7 on Yahoo! Messenger & nickw7coc on MSN Messenger too !
http://www.whelan.me.uk
Jonathan Stott
"Nick" <n_r...@no-go.ya_ho.o.aw_ay.con.invalid> wrote in message
news:apb15vs14nu8lij4u...@4ax.com...
> My cousin who was walking with us told me that it's a regular thing, and
it's
> apparently to do with the way the ground freezes then thaws then freezes
> again and it gets pushed up from the bottom......something like that
anyway?!
So the ice is being extruded through gaps in the soil by repeated
refreezing?
--
Jonathan
Canterbury, Kent - 40m asl - TR148598 - 51:17:47N 01:04:52E
.
Nick
>
> "Nick" <n_r...@no-go.ya_ho.o.aw_ay.con.invalid> wrote in message
> news:apb15vs14nu8lij4u...@4ax.com...
>
> > My cousin who was walking with us told me that it's a regular thing, and
> it's
> > apparently to do with the way the ground freezes then thaws then freezes
> > again and it gets pushed up from the bottom......something like that
> anyway?!
>
>
> So the ice is being extruded through gaps in the soil by repeated
> refreezing?
That was the impression I got, it was also something to do with the fact that
the ground was frozen so the ice had nowhere else to go but up...?!?!?
Sharon Curtis
Andy Dingley <din...@codesmiths.com> wrote:
>http://www.jarkman.co.uk/album/molehill.htm
>
>Any ideas on how this happens ?
No, but it doesn't just happen in molehills. Happened during this
winter in my garden (bare earth around during a re-landscaping).
Amazing to walk on. You sort of sink by several inches!
Sharon
Mike Tullett
news:<hds15vosqg0f48c0a...@4ax.com>:
>> So the ice is being extruded through gaps in the soil by repeated
>> refreezing?
> That was the impression I got, it was also something to do with the fact that
> the ground was frozen so the ice had nowhere else to go but up...?!?!?
This process is known as "frost heave". You'll find many references to it
if you do a Google search.
It can play havoc with soil thermometers, gradually lifting them after a
day of so of this effect - even breaking them in extreme circumstances.
--
Mike 17/02/2003 14:51:02 UTC
Coleraine
Tom Bennett
find many references to it
> if you do a Google search.
>
> It can play havoc with soil thermometers, gradually lifting them after a
> day of so of this effect - even breaking them in extreme circumstances.
In the winter of 1981/2 in the north-east, frost heave cracked my concrete
drive from end-to-end (about 6m ), lifted the foundations on my porch (they
went down again after the thaw, but left great cracks in the brickwork) and
lifted one of my brick gateposts, but not the other, such that the gates
were 3" out of horizontal alignment. The last effect never quite righted
itself
Pretty powerful forces are unleashed when water freezes into ice. Which
begs the question: Has anyone got a figure for it? And, does the speed at
which the ice forms affect this at all? - I can't see why it should do, but
it occurs to me that it might.
- Tom.
wafflycathcsdirtycatlitter
>
There was a similar thing in new Scientist a while ago - but my access to the
online archive is down... arggh - so I can't get to the article :( If it
resolves I'll post the details.
~~~~~~~~~~
Flush out that intestinal parasite and/or the waste product before sending a
reply!
Any speeliong mistake$ aR the resiult of my cats sitting on the keyboaRRRDdd
~~~~~~~~~~
Alastair McDonald
They look like mini-pingos to me! (In case you are worried about the
pronounciation, that rhymes with mini-tornados <grin>.) See;
http://www.aip.org/physnews/graphics/html/frost.htm
HTH,
Cheers, Alastair.
tadchem
The mechanism was recently reported in Science",(17 JAN 03) by M.A. Messler
and B.T. Werner:
http://www.sciencemag.org/content/vol299/issue5605/cover.shtml
The cover of the issue shows a field in Norway after repeated cycles of
freezing and thawing during the "thawed" part of the cycle. There are even
more interesting pictures in the text of the article.
Tom Davidson
Brighton, CO
Michael McNeil
They wanted money from me before I can see the article (I was directed
to the "send them lots of money" page from the free membership link.)
What I did see looked really interesting. Almost lunar.
(I never liked that theory about meteors striking the moon causing
those craters, they just didn't look right.) (Well they don't do
they?)
TudorHgh
>those craters, they just didn't look right.) (Well they don't do
>they?)
>
Maybe not, Michael. But it's a theory supported by everyone in the business.
Tudor Hughes, Warlingham, Surrey.
Jean-Michel Friedt
> to the "send them lots of money" page from the free membership link.)
> What I did see looked really interesting. Almost lunar.
Download http://mmyotte.free.fr/backup/380.pdf (681806 bytes)
Jean-Michel
Andy Dingley
<tadche...@earthlink.net> wrote:
>The mechanism was recently reported in Science",(17 JAN 03) by M.A. Messler
>and B.T. Werner:
>http://www.sciencemag.org/content/vol299/issue5605/cover.shtml
I don't think is quite the same underlying effect.
AIUI, the sorting effect is encountered in regions of poor soil
quality, with little humus (i.e. poor tensile and shear strength) and
they're fast-draining . It occurs when freezing under the soil heaves
up tussocks of soil that then shed their stones to the spaces between
them. Developing large features needs a flat plain left undisturbed
for a long period.
For the molehill photos,
http://www.jarkman.co.uk/album/molehill.htm
there is clearly an effect where ice is freezing an inch or two below
the surface, and the ice crystallisation has this unusual columnar
form. The soil lifting (in common with the stone sorting) is just the
frost heave we'd expect from this.
So why is the ice freezing in this narrow layer, and nowhere else ?
Why the unusual crystal shape ?
The site is in South Wales (Pontypool Park) and is a steep grassy
slope with a large mole population. It's regularly waterlogged, and we
often see springs at the lower molehills while the upper ones are
obviously the active tunnels.
Pegleg
Can't remember the term, but ask a geomorphologist for a definition.
Happens here (North Carolina, USA) all the time in winter.
Bob Strauss
Steve Jackson
<str...@wcu.edu> writes
>Can't remember the term, but ask a geomorphologist for a definition.
>Happens here (North Carolina, USA) all the time in winter.
Bob
I think you are talking about the formation of pingos in periglacial
regions.
--
Steve Jackson
Michael McNeil
Thanks. I had a bash at translating it in the geology group. There is
a list as long as your arm of dedications at the end of it. With all
those experts all eager to spend money on the subject, why couldn't
they have picked one to go to the moon with all those astanaughts?