Devil's Woodpile EarthCache
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
Located in spectacular Cathedral Provincial Park this unique geological structure is an impressive example of columnar jointed basalt. This formation has also been described as the ingredients for Satan's furnace!
Cathedral Park comprises an expanse of jagged mountain peaks, azure lakes and flower-dappled alpine meadows located between the dense, wet forests of the Cascade Mountains and the desert-like Okanagan Valley. The park contains some fascinating rock formations -- including a jumble of columnar-jointed basalt forms and massive, wind-eroded quartz monzonite towers -- making it an excellent spot for the experienced hiker. (i)
Stunning examples of columnar-jointing basalt can be found in this park. The Devil’s Woodpile was formed during rapid cooling of a thick lava flow in the region. Specifically, the Devil’s Woodpile lies in a section of the Cascade Mountians that was formed by three main geological forces. Nearby volcanoes such as Mt. Baker, Glacier Peak, Mt. Rainer, Mt. St. Helen, and Mt. Adams formed the basalt-laden mountain range. Basalt is a common extrusive volcanic rock, rich in magnesium and iron which is usually fine-grained due to rapid cooling of lava at the surface of a planet. Secondly, the Cascades were shaped by geological uplifting and folding due to plate collision in the Cretaceous period, lifting the ground and pushing it upward causing the mountain chain to form. Lastly glaciers played a large role in shaping the range into what can be seen today.
The unusual columnar formation is the result of interplay of these three forces. The shape of the columns attributed to specific tensional stress. If volcanic lava flow cools relatively rapidly, significant contraction forces build up. While a flow can shrink in the vertical dimension without fracturing, it cannot easily accommodate shrinking in the horizontal direction. This results in an extensive network of fractures (or joints) and in the formation of columns. The most common shape of the joints is hexagonal, but polygons with three to twelve or more sides can be observed. Note that the size of the columns depends loosely on the rate of cooling; very rapid cooling may result in very small columns, while slow cooling is more likely to produce large columns. (ii)
Another well-known example of columnar jointed basalt is the Devil’s Tower in Wyoming, which featured prominently in Steven Spielberg’s Close Encounters of the Third Kind. Additional notable columnar basalts include the Giant's Causeway in Ireland, Borgarvirki Fortress in Iceland, Samson’s Ribs in Scotland, Detunatele (Thunderstruck Rocks) in Romania and the Panska Skala in the Czech Republic. (iii)
1. To log this Earthcache, fulfill the educational requirements by e-mailing me answers to these questions;
a.) As columnar basalt formations can range in size from 1cm diametre to many metres in width, what is the estimated thickness of the individual ‘woodpiles’?
b.) This example of columnar joint basalt at The Devil’s Woodpile is quite unusual and rare, even amongst columnar jointing… What appears to be different at this geocache from most other columnar jointed basalt? (Hints available below).
ALSO,
2. Post at least one picture of the woodpile and your GPS – stay a safe distance away.
3. There is a wooden sign at these coordinates. Please email me the EXACT wording on it.
Please be extremely careful while observing this interesting geological feature.
REFERENCES:
(i) (visit link)
(ii) (visit link)
(iii) (visit link)
Additional Hints
(Decrypt)
Guvax bevragngvba… Pbzcner jvgu cvpgherf bs bgure snzbhf pbyhzane wbvag onfnyg sbezngvbaf, be fbyir nppbeqvat gb qrfpevcgvba nobir.
Treasures
You'll collect a digital Treasure from one of these collections when you find and log this geocache:
Loading Treasures