Hole in the Wall EarthCache

Hole in the wall

Although only 137 km² in size, Grand Manan Island is a geological marvel. Three separate volcanic flows formed its western two thirds - including 100 metre high cliffs along the coast. The eastern third is composed of metamorphosed sedimentary rock, bearing semi-precious stones in areas. Waves and wind have sculpted its shoreline into unique formations such as "Hole-in-the- Wall".

Hole in the Wall. The Fish Head Formation is also thought to be Early Cambrian in age, possibly around 540 m.y. old. It is made of meta-gabbro, a plutonic rock that has been metamorphosed to a “greenstone” or fine-grained rock with green mica and epidote. East-west fractures in the have eroded on the western side of Fish Head to leave a wall of rock standing out into Whale Cove, and its lower section has also been eroded to produce a large hole. The result looks a bit like a flying buttress on the side of an old cathedral, or one of the natural bridges seen out west.

How a natural arch is formed

A natural arch, natural bridge, or (less commonly) rock arch is a natural rock formation where an arch has formed with an opening underneath. Natural arches commonly form where inland cliffs, coastal cliffs, fins or stacks are subject to erosion from the sea, rivers or weathering (sub-aerial processes).

Weathering and erosion can create caves, arches, stacks and stumps along a headland. Caves occur when waves force their way into cracks in the cliff face. If the cave is formed in a headland, it may eventually break through to the other side forming an arch.

A stack or sea stack is a geological land form consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island.

To log this Earthcache visit the viewing location. Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.

Questions:

1. Estimate the width and height of the hole?

2. What is the elevation where you are viewing?

3. Do you think the hole will erode more and why?

 4. Post a picture in your log with a personal item or hand in picture to prove you were there.

[REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the site.