Sea Stacks near Saint's Bay EarthCache
Hidden : 7/26/2017
Difficulty:
2 out of 5
Terrain:
1.5 out of 5

Size: Size: other (other)

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Geocache Description:



Sea Stacks near Saint's Bay
 Saints Bay 1  Saints Bay 2
  

Saint's Bay is a beautiful spot on the southern coast of Guernsey, worth a visit. Visitors of this location will have the opportunity just nearby to observe interesting coastal erosion features, including some typical sea stacks.

Coastal erosion

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage or high winds. Waves, generated by storms, wind, or fast moving motor craft, can cause coastal erosion, which may take the form of long-term losses of sediments and rocks, or merely the temporary redistribution of coastal sediments. Erosion in one location may result in accretion nearby.

Coastal erosion results in dramatic or non-dramatic rock formations in areas where the coastline contains rock layers or fracture zones with varying resistance to erosion. Softer areas become eroded much faster than harder ones, which typically results in landforms such as tunnels, natural bridges, columns, and pillars. Also abrasion commonly happens in areas where there are strong winds, loose sand, and soft rocks. The definition of abrasion is grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles.

Sea stack

A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. Stacks are formed over time by wind and water, processes of coastal geomorphology. They are formed when a part of a headland is eroded by hydraulic action, which is force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island.
Stacks typically form in horizontally-bedded sedimentary or volcanic rocks. A more resistant layer may form a capstone.

Headland Erosion

The formation process usually begins when the sea attacks small cracks in a headland and opens them. The cracks then gradually get larger and turn into a small cave. When the cave wears through the headland, an arch forms. Further erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast - the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. This stump usually forms a small rock island, low enough for a high tide to submerge.


Your task to log this EarthCache as found:

Answer the following questions in your own words and send me the answers via message to my profile:
1.) When standing at the EarthCache (header) coordinates, take a look in the following direction: bearing 60 degrees, distance 570 meters. How many typical sea stacks can you observe? 

2.) Estimate the height of the highest of these sea stacks and, considering the tide times for the day of your visit (see link), tell me if there was high or low tide? 

3.) Give me a short description in your own words - how do you think these sea stacks have formed?

4.) Optional: If you like, you are warmly invited to add a picture of you / your GPS at the location to the log!
You can log immediately after you sent me the answers! There is no need to wait for a log permission! I'll contact you if there's something wrong.
Have fun and enjoy!

Sources:

britannica.com
Easterbrook, D. J. (1999): Surface Processes and Landforms.
thebritishgeographer.weebly.com
tides.digimap.gg
wikipedia.org


All pictures were taken by the author.

The most exciting way to learn about the Earth and its processes is to get into the outdoors and experience it first-hand. Visiting an Earthcache is a great outdoor activity the whole family can enjoy. An Earthcache is a special place that people can visit to learn about a unique geoscience feature or aspect of our Earth. Earthcaches include a set of educational notes and the details about where to find the location (latitude and longitude). Visitors to Earthcaches can see how our planet has been shaped by geological processes, how we manage the resources and how scientists gather evidence to learn about the Earth. To find out more click HERE.

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