Long Description
The best example of what you see here happens in Wyoming, USA. It is referred to as Devils Tower and it is an impressive example of columnar jointing. The Cariboo edition of this jointing is a little smaller in scale but it is also a perfect specimen. If you have visited the Lone Butte Earthcache then you are aware of some of the volcanic activity that has happened in this part of British Columbia. The butte is made of basalt and so are the columns in front of you. The big difference between the two geologic features is in the way they cooled after they were lava.
The columns cooled and crystallized from the outside first. Then the interior slowly hardened and caused the piece of lava flow to contract. Almost everything on Earth contracts upon cooling (except water in certain cases). As the core contracts it creates cracking on the outside of the flow. Once a crack has formed, it keeps spreading, up to 30 meters in some cases. The interesting thing about the cracks/joints is in their formation. They break and exhibit a uniform, symmetrical honeycomb pattern. The most common pattern is a hexagonal jointing structure but 4 and 5 sides also occur. The joints are created perpendicular to the flow of lava.
Other examples I have seen of columnar jointing are on Mount Boucherie in Westbank, BC and beside the highway going to Big White Ski Resort.
Please pull safely off the road and do not constrict traffic flow.
The classic honeycomb formation close up!
Sources
Dolfin61 :This Earthcache was fathered from the Cariboo Columns Earthcache. Do not log this one if you logged the CARIBOO COLUMNS EARTHCACHE.
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SEND E-MAIL TO QUESTIONS BELOW BEFORE YOU POST A LOG!!!
To log this Earthcache, fulfill the educational requirements by e-mailing me answer to the following:
1. Using the surrounding landscape contours and the fact that the columnar joints form perpendicular to the flow of lava, guestimate what general direction the lava was flowing.
ALSO,
2. (Optional) Post at least one picture of the columns and your GPS.
3. Indicate in your log the number of people in your group.
Hint- Use the contour lines (they are 457, 610, 762 and 914 meters).