Can A Rock Bend? EarthCache
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FTF Congratulations to
Sauratown Smokey and Night-Hawk!!!
In addition to the unique features created by the Sauratown
Mountains and the Dan River, Stokes County, NC, conceals another
geologic oddity. In the Sauratown Range can be found deposits of
Itacolumite (it-a-COL-um-ite), commonly known as “limbergrit”,
bending rock, or flexible sandstone. This is one of the very few
deposits in the world, and believed to be the only deposit in the
United States.
Itacolumite is formed from interlocking quartz grains and mica
flakes. It readily splits into thin slabs. The sandstone will then
bend when in thin slabs. Some discussion has taken place regarding
the cause of the flexibility. At one time it was ascribed to the
presence of thin scales of mica which were believed to permit a
certain amount of motion between adjacent grains of quartz. More
probably, however, it is due to the porous character of the rock
together with the inter-locking junctions between the sand grains.
The porosity allows movement while the hinge-like joints by which
the particles are connected hold them together in spite of the
displacement. These features are dependent to some extent on
weathering, as the rocks contain perishable constituents which are
removed and leave open cavities in their place, while at the same
time additional silica may have been deposited on the quartz grains
fitting their irregular surfaces more 'perfectly together. Most of
the known flexible rocks are also fine-grained; in some cases they
are said to lose their flexibility after being dried for some time,
probably because of the hardening of some interstitial substance,
but many specimens kept in a dry atmosphere for years retain this
property in a high degree.
Itacolumite is a metamorphic rock. Metamorphic rocks are any of a
class of rocks that result from the alteration of preexisting rocks
in response to changing environmental conditions, such as
variations in temperature, pressure, and mechanical stress, and the
addition or subtraction of chemical components.
It is unlawful to remove anything from our State Parks. Please
observe all Park regulations.
Museum Hours: 9:00am - 4:45pm year round.
Park Hours: Vary by season. Please check the park’s website.
Thank you for your interest in this Earth Cache and I
hope you enjoy it!
Developed by a
Platinum EarthCache Master
To receive credit for this Earth Cache, you must visit the Park
Museum (no fee) within the Visitor’s Center of Hanging Rock State
Park and locate the Itacolumite display. Use the information at the
display to answer the following:
1. Describe the appearance (texture and color) of the itacolumite
sample.
2. Where else can itacolumite be found?
3. How is itacolumite formed?
4. If the sample was thicker, do you think it would still bend? And
why?
5. If the sample was shorter in length, so you think it would still
bend? And why?
6. Who provided the display?
Email me the answers. Please do not post answers in your log. All
logs with answers will be deleted immediately. Finally, you must
take a picture of you with your GPS while standing on the ‘back
deck’ of the Visitor’s Center with the view of the valley in the
background. Post the picture in your log. No picture, no
smiley.
The picture MUST be uploaded immediately after
posting your log AND the answers to the questions MUST be sent
within a reasonable amount of time on the same day as you claim
your smiley. All logs not complying will be deleted without notice.
As of 7-30-09, I will no longer send out emails asking for the
information.
Hope you enjoyed this Earth Cache and your visit to Hanging Rock
State Park!!
Additional Hints
(Decrypt)
[The posted coords are for the entrance gate of Hanging Rock State Park. You must drive up the mountain to the Visitor's Center located at 36 23.699 - 080 15.983]