Please note, this Earth Cache is only possible to do during low tide. The potholes won’t be visible during high water levels, so please plan your visit to this site accordingly
As you approach the posted co-ordinates , the ground will change from sandy beach to exposed bedrock. In the bedrock you will see some circular shaped depressions. Those depressions are commonly referred to as potholes.
These potholes were formed by a process known as “corrasion”. Corrasion is a term which means the mechanical erosion of bedrock by materials transported by running water, waves, glaciers, etc. Pebbles & other material carried by the river are swirled around and drill down onto the river bed, or as is the case here, in cracks in the bedrock during high water flows. The sand and other sized rock particles end up in the cracks in the rock, and with the swirling action of the water eventually erode the rock forming potholes.
The waves and tides keep the rock particles in motion, wearing away the sides of the cracks or depressions. These gradually become deeper and wider to become potholes, similar to what is observed here. Potholes generally range in size from a few centimeters to several metres in depth and diameter.
To log this earth cache you must answer a few questions that can be found by visiting the site. Please email me your answers. Do not post your answers with your log otherwise it will be deleted.
1) Estimate the average size (diameter & depth) of the potholes that you see.
2) Based on the size of the potholes and the size of the following grain sediments, which of the grain sediments do you think formed the potholes by corrasion? [Sand (0.5 to 2 mm diameter), gravel (2mm to 6 cm diameter), or cobble (6 cm to 25 cm diameter)]
3) Do you think the potholes are still being formed today? [Hint: are they empty or do they contain sediments?]