On Thu, 22 Feb 2001 13:51:40 -0500, you wrote:
>Pål,
>Bob Shell from Shutterbug and
>the Contax
>discussion list had a question
>geological in nature. If your
>not too
>busy could you look at this link
>and
>tell if it could be a natural
>geologic
>formation. If you can't tell or
>don't
>have time I understand.
>
>Thanks Evan Hanson
>[EMAIL PROTECTED]
>
>
>http://www.viewzone.com/sender.html
>-
Wife and I call those Turtle Rocks because, in the small stream bed
versions we collect, the accumulated cells look like the back of a
tortoise.
My wife and I pick up similar cubed and layered rocks (on a much
smaller scale) down the local crick. We have a whole garden area
dedicated to Turtle rocks brought home one or two at a time.
Our biggest one weighs about fifty pounds, carefully transported home
a couple of miles balanced on the handlebars of my bicycle. I had to
walk the bike rather than ride, because the slightest jolt causes
Turtle rocks to break at a cell line, or even disintegrate into
individual cells.
Referring to the article, I believe those "cells" might be formed by
the action of dried clay mud, which creates cracked earth due to heat
and loss of moisture. Then a coarser-grained sediment with a higher
silica content accumulates in the cracks, eventually forming fairly
fragile "rock" in cubed layers. As the coarser sediment loses its
adhesion, it falls away, and the action of wind and water gives the
cracks between cells a beveled appearance.
During the drought two years ago, we could actually see new Turtle
rocks being formed. Just picking them up caused the cells to fall
apart.
An inner layer of a hardened Turtle rock is often yellow, looking like
a cheap crystal substance.
The authors of the article seem to be hoping the formation pictured is
man-made, but I believe it is a natural formation. Since all I know is
crick-bed geology, I can't say for sure what's in their picture,
though.
--
Happy Trails,
Texdance
http://members.fortunecity.com/texdance
http://members1.clubphoto.com/john8202
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