Hole In The Wall Earthcache EarthCache
Hole In The Wall Earthcache
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The Hole in the Wall, is a large break in sandstone cliffs along the western shore of Valdes Island. Searching for this cache can be a significant undertaking but will reward you with incredible views and a unique education in the geology of the golf islands.
This geocache will take you along the Western side of Valdes Island, giving you the opportunity to view not only wildlife but the unique sandstone cliffs and formations along the way. I hope you have as much fun exploring the coastline as we did on our 4 day kayaking trip through the gulf islands that inspired us to place this earth cache. It is located in a break in 'The Wall' a large sandstone cliff extending for a good portion of the Western side of Valdes. It will also bring you to an unofficial campground for those of you, who like us, are on a multi day kayaking trip and in need of an isolated place to spend the night, if not you can continue on southwards to Blackberry point, another, much larger unofficial campground.
The Gulf Islands (including Valdes) were formed through a combination of tectonic plate movement, volcanism, erosion and glaciation, creating an incredible landscape allowing residents to enjoy some of British Columbia's favorite pastimes, including hiking, boating and camping. Of these tectonic processes are the primary force responsible for the formation of 'The Wall'.
About 100 million years ago, Wrangellia (a large piece of the earths crust) collided with the North American continent. Slow but tremendous forces caused some regions to fold and buckle into mountain ridges and others to crumble and erode.
42 to 55 million years ago, two smaller pieces of crust called the Pacific Rim and Crescent terranes collided with and joined onto Vancouver Island. The Crescent terrane is composed of marine volcanic rock and forms the land of Sooke, Metchosin and Colwood. The region that the rest of Greater Victoria is built upon is granite and gneiss (metamorphic rock) that is thought to have formed from magma deep within the layers of rock. It was exposed during the uplift and erosion associated with the collisions of the Pacific Rim and Crescent terranes.
On Valdes Island, as a result of these tectonic processes, fault lines have exposed the underlying sandstone to the elements. With the passing of time, the combined forces of salt, sun, rain and wind have carved an intricate design of hollows, crests and ledges in these west-facing cliffs. One of the more unique features that you sill see on your trip to the hole in the wall are small cave-like features that are networked together into a honeycomb-like pattern called Tafoni. They often occur in groups that can riddle a hillside, cliff, or other rock formation. The cause of their formation is not known but explanations for their formation include salt weathering, differential cementation, structural variation in permeability, wetting-drying, and freezing-thawing cycles, variability in lithology, case hardening and core softening, and/or micro-climate changes and variation (that is, moisture availability).
To log this earth cache, please answer the following questions and message them to me through my profile page:
1. While visiting the hole in the wall take a look at your surroundings and tell me what you think cause this hole to form?
2. There is a distinct band of rock extending most fo the length of the southernmost part of the wall, what color is this band and how wide do you think it is?
3. As you travel to the cache what is the average sixe of the tafoni's that you come across, also tell me what were the smallest and what were the largest tafoni that you saw?
4. Post a photo of yourself at 'The Wall' with your log (optional).
Sources:
http://nationalgeographic.org/encyclopedia/gorge/
https://en.wikipedia.org/wiki/Tafoni
https://www.crd.bc.ca/education/our-environment/geology-processes/geological-history-vi
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Treasures
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