Welcome
Welcome to the Little Jerusalem EarthCache Series. This series was placed at the request of the Stae Park so it is important that you follow all rules to demonstrate how responsible geocachers are with the environment. Please stay on the trail and follow all rules as posted. At no point, should you touch, collect, or disturb the environment except where specifically directed. Please enjoy this series of EarthCaches responsibly. There is a $5 day fee to access this park.
Earth Science Lesson
At this overlook, beyond the fenceline, there is a very prominent and interesting geological formation (look directly north, you really can't miss it). Thousand years of erosion by wind and water have created this rock pillar but is it a hoodoo or a stack?
Hoodoos are tall skinny spires of rock that protrude from the bottom of arid basins and “broken” lands. Hoodoos are most commonly found in the High Plateaus region of the Colorado Plateau and in the Badlands regions of the Northern Great Plains. Hoodoos, which may range from 1.5 to 45 metres (4.9 to 147.6 ft), typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements often referred to as a cap. They generally form within sedimentary rock and volcanic rock formations.
Hoodoos are found mainly in the desert in dry, hot areas. In common usage, the difference between hoodoos and pinnacles (or spires) is that hoodoos have a variable thickness often described as having a “totem pole-shaped body”. A spire, on the other hand, has a smoother profile or uniform thickness that tapers from the ground upward.
A stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast. Stacks are formed when part of a headland is eroded, leaving a small island. They also form when a natural arch collapses due to sub-aerial processes and gravity. A stack may collapse or be eroded leaving a stump. Stacks form most commonly on chalk cliffs, because of the medium resistance to erosion. Cliffs with weaker rock, such as clay tend to slump and erode too quickly to form stacks, while harder rocks, such as granite erode in different ways.
Logging Tasks
- Are you able to observe a cap in this structure?
- Based on your observations and the information above, does this formation appear to be a hoodoo or a stack?
- Give at least one reason why you made your decision?
- Post a photo of yourself, or a proxy near GZ.
References
- Geologypage.com. (2016). Hoodoo: Waht is Hoodoo? How It Formed? Retrieved from http://www.geologypage.com/2016/07/what-is-hoodoo-how-it-formed.html
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Academickids.com (2005). Stack (geology) Retrieved from https://scienceviews.com/geology/mohs.html
