Erosion in the Maritime Carboniferousm Basin EarthCache
Erosion in the Maritime Carboniferousm Basin
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Prince Edward Island's west coast is a very good example to explore the local erosion. The island forms part of the Maritime Carboniferousm Basin. Beginning some 220-300 million years ago, and continuing for more than seventy-five million years, this lowland region or plain received massive accumlations of eroded material. Let's discover it together.
MARITIME CARBONIFEROUSM BASIN
The Maritimes Basin is a Mid-Devonian to Early Permian sedimentary basin that underlies parts of the northeastern United States and Atlantic Canada. It is a composite basin, meaning that it consists of many sub-basins, such as the Windsor-Kennetcook Basin of Nova Scotia. Some of these basins host important natural resources, including coal, petroleum, and minerals such as sylvite, halite, and barite. The Maritimes Basin was deposited and tectonically-modified during the final assembly of Pangea.
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EROSION
In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust, then transport it away to another location. The particulate breakdown of rock or soil into clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by its dissolving into a solvent (typically water), followed by the flow away of that solution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Natural rates of erosion are controlled by the action of geomorphic drivers, such as rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. Shoreline erosion, which occurs on both exposed and sheltered coasts, primarily occurs through the action of currents and waves but sea level (tidal) change can also play a role.
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EROSION - PRINCE EDWARD ISLAND
PEI’s landmass is of relatively recent origin in geological terms. An enormous sedimentary basin underlying the present Gulf of St Lawrence was created by freshwater streams that drained ancient highlands. The ice ages left an imprint on the land, especially during the late Pleistocene period between 75,000 and 10,000 years ago. When the last glaciers receded, uncovering what is now PEI, glacial debris and the marks of glacial scouring were left on the exposed land, which began gradually to assume its present character. Because of lower ocean beds and land depressed by the glaciers' weight, the Island was connected to the mainland by a low plain covering much of the present Northumberland Strait. As ocean levels rose with the melting of the glaciers, and as the land rebounded, the crescent shape of the Island emerged about 5,000 years ago.
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Today, a mantle of loose material known as glacial till, laid down 10,000 to 15,000 years ago, covers much of the island. The underlying sedimentary bedrock consists of red sandstone intermixed with shale. Rock exposures are predominately sandstone with lesser amounts of siltstone, claystone and congloomerate also present.
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At the earth cache location you see a good example of erosion on Price Edward Island. The red sandstone which PEI mainly consists of is open on the beach and is permanently eroded by the present natural forces. That is how the beach got its red color. The special geologic caracteristic of sandstone even accelerates the erosion: it is soft.
To log this earth cache, please answer the following questions:
1) In the earth cache listing you find several types of erosion. Please state the types which apply at this location.
2) Have a look around you on the beach. You do not only find red sandstone, but also other stones. Please describe the difference between the sandstone and a different stone you found: size, color and hardness. Try to squeeze the two stones. What do you discover?
3) Most parts of Prince Edward Island are not more than 50 meters above sea level. Try to find out which elevation the highest point on PEI has. Why is the island relatively flat?
4) Optional: Take a picture of you or your GPS close to the eroded sandstone and upload it.
You do not need to wait for my answer. You can log after sending the answers. If the answers are not correct, I will contact you.
Happy exploring PEI's geology!
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