Tsusiat Natural Sea Arch EarthCache EarthCache
Hidden : 9/24/2007
Difficulty:
1 out of 5
Terrain:
5 out of 5

Size: Size: other (other)

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Geocache Description:


** Warning**

The West Coast Trail is closed from October 1 to April 30 of every year. Anyone on the trail during this time will be charged under the National Parks Act.



You can visit Tsusiat Natural Sea Arch Earthcache by hiking the West Coast Trail starting in Bamfield (27km) or Port Renfrew (48 Km). The West Coast Trail is regularly named one of the best hikes in the world. A permit is required and there is a quota system in place. Do not hike the trail without the proper clearances required by Parks Canada. This EarthCache could also be done by boat without trespassing on the trail (as my picture shows) but remember to get the GPS.

Tsusiat Point is one of the many highlights that are encountered on the 75 kilometer trail. This area received its name from the Ditidaht tribe originally inhabiting the area. Tsusiat translates into ‘hole’. This explains why the area is also know as “Hole in the Wall”. The West Coast Trail was established from the many existing First Nations trading trails. These trails connected the various tribes to help with survival. Later, a telegraph line was built using the existing trails so that communications could be established along the west coast. The coastline was named the “Graveyard of the Pacific” by early sailors navigating the dangerous waters. After some horrific shipwrecks with high mortality rates the government was forced to make changes. The trail was opened so that it could become a life saving trail. Now the trail has been given a protected status by Parks Canada. This limits the footprint that humans leave on this fragile ecosystem.

Hole In The Wall is composed of rock and shaped by water. Waves have eroded the coastal rock for many years creating this arch. Rock is very solid and is very important in accomplishing this gravity defying feat. Rock hardness varies in differing rock types. The harder the rock, the longer it will resist erosion and weathering processes. Differing hardness and differential weathering creates layering of rock along a coastline. The coastline is composed of many alternating headlands and bays. Tsusiat Point is the very tip of the headland (C in Photo 1). The beach that you are approaching on is the bay (A in Photo 1). The formation of a headland and a bay are an integral first steps in sea arch formation. The rock hardness of the headlands is usually harder that the rock found in the bays.

Photo 1
Photo 1
Photo by Hippie Kidz.




Stand on the north flank of the headland and look for the cave. This cave is formed from the continual and constant power of wave action. The water has been diverted (D in Photo 1) around the headland (Tsusiat Point) and the wave action concentrates its power to the sides or flank of the headland. This cave is the beginning stages of a sea arch. Now, if the tides are below 7ft/2.1m, walk under “Hole in the Wall”. Stand under the arch and look at the waves that are incoming. They are moving in two directions, they are travelling at you from the north and from the south. Again, this is because the water is pushed around the headland and diverted to the flanks. The water meets in the middle. This will erode the rock where you are standing at a much faster rate. More rock material has been taken or eroded from this area than near the front of the headland due to the diversion. Originally both sides of the arch were formed by two separate caves that were positioned back to back. These caves were enlarged over time from the erosional power of wave action. Soon the two cave became so large that they touched. This formed the sea arch!

Photo 2
Diagram 1
Photo by Hippie Kidz.


What makes this an arch? According to Webster's Dictionary, an arch is defined as "a curved structural member spanning an opening and serving as a support." The curved structure must support the weight of itself and almost everything else over top the open space. This arch has been formed by natural causes. That further delineates this sea arch to be referred to as a natural sea arch. This arch will not survive for eternity. Eventually the supports will be to eroded and unable to support the keystone (B in Photo 1). The keystone will collapse (above E in Photo 2) leaving a sea stack or trombolo (F in Photo 3).




Photo 3
Diagram 1
Photo by Hippie Kidz.


Sources
Parks Canada West Coast Trail Map. 2007.
www.naturalarches.org
www.rgs.edu.sg/events/geotrip/stack.html

I am a proud

SEND E-MAIL TO QUESTIONS BELOW BEFORE YOU POST A LOG!!!
To log this Earthcache, fulfil the educational requirements by e-mailing me answers to these questions;

1 a.) Estimate how long the keystone is?
b.) What is another name for a sea stack?


ALSO,
(Optional) Post at least one picture of the arch and your GPS.
Indicate in your LOG the number of people in your group.

Additional Hints (No hints available.)



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