Dawson Park Hoodoos EarthCache
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Located in Dawson Park adjacent to a paved pedestrian trail. Parking is available at the Dawson Park trail head. It is an approximate 2 km (round trip) easy walk from the parking area. Cache can be logged without leaving the paved trail.
This earthcache takes you to an area of exposed bedrock and glacial sediment located near the east end of Dawson Park. When you reach the posted coordinates you will be able to see some incident hoodoos – or hoodoos that are just starting to form. The hoodoos are forming beneath resistant caps of iron-cemented sandstone. The resistant caps divert the surface runoff and protect the hoodoos from erosion.
The Cretaceous bedrock here is mainly sandstone. The caps of the hoodoos at this location divide layers of sandstone (top) and shale (bottom). The shale has a high bentonite concentration, which has the ability to expand to about ten times its dry volume with the application of water. As the shale dries, it shrinks and cracks, forming the characteristic “popcorn texture” on its surface. This feature is well illustrated in the shale at this location. Above the hoodoo caps, deep rills in the sandstone have formed as a result of water running over the exposed surface.
To log this cache:
1) You must post a picture with your log entry of yourself, your group, or your GPS receiver in front of the exposed bedrock with the hoodoos in the background. This picture can be taken from the paved path.
2) You must also send me an email indicating how high the caps of the hoodoos are above the pathway, and the approximate visible thickness of the sandstone and shale layers at this location.
Please stay on the path or vegetated areas to prevent damaging the formation.
Reference: "Edmonton Beneath Our Feet - A guide to the geology of the Edmonton region", Edmonton Geological Society, 1993.
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Treasures
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