Tower Beach - Sea Cliffs from the Ice Age EarthCache
Hidden : 4/7/2013
Difficulty:
2.5 out of 5
Terrain:
3 out of 5

Size: Size: other (other)

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Geocache Description:

The area where this earthcache is located is a clothing optional beach. The coordinates given are a suggestion for where to observe the cliffs, but naturally you can see them from many vantage points. Note: No dogs allowed on the beach between May 1 to September 30

27,000 years ago, the area where you are now standing was covered in glaciers. The glaciers started from the Georgia and Howe Sounds and eventually spread until they covered the whole lower mainland with about 2km of ice. This period was known as the Fraser Glaciation. The sea cliff itself that you observe is a fascinating look back to the Ice Age.
 
10,000 – 15,000 years ago the glaciers melted, leaving behind the deposited sediment that the glaciers brought. These fragile cliffs are comprised of a combination of sand and clay. However, the erosion has been caused by many other notable factors also. Some of the causes are unavoidable because of the position of the cliffs. Other causes, however are due to human activity and development of the area. Four main causes of erosion for the cliff have been identified:
  • Hydrogeological: water seeping through the cliffs is causing instability
  • Winter Freeze and Thaw: The annual freezing of the cliff causes the surface to expand and contract which also provides instability
  •  Wind and Rain: The cliff is  completely exposed to the elements, in a rainy climate
  • Human activity: There has been logging in the area and ongoing human construction
Before this area was a university, it was used for agriculture and recreation. During the Second World War, gun towers and barracks were built on the cliffs as part of defense installations in the area. And long before this time, the land was the home of the Musqueam peoples.
 
During the 1970s the Greater Vancouver Regional District as it was known, identified these causes of erosion and took several measures to slow down the erosion of the rapidly retreating cliff. It has been very successful however, there are still signs more work needs to be done. As recently as 2004, further damage has been observed of the cliffs above Wreck Beach, which suggest that further efforts need to be made to protect the fragile surface.
 
To log this Earthcache and claim a find, you must email (do not use message centre as I do not read those) to the cache owner the answers to the following questions. No other geocacher can do this for you. Please note that found logs without an accompanying email answering the questions must be deleted as per the Earthcache guidelines.
 
1. The cliff is composed of both clay and sand. Which do you see more of?
 
2. What can you observe that suggests it is eroding?
 
3. What work can you observe from this area has been done over the last 40 years to protect the cliff face from further erosion? Look high and look out into the water.
 
4. What is the difference in elevation between the spot on the beach where you are standing and the top of the trail at the trailhead above?
 
5. Completely optional: answer these questions while enjoying the beach au natural (no need for photos though!)


References:
"Vancouver, City on the Edge" by John Clague & Bob Turner ISBN 0-9697601-4-0
http://www.sfu.ca/geog312/readings/UBC.pdf
http://www.wreckbeach.org/erosion.html

Additional Hints (No hints available.)



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