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Chapter 18 - Formation of the Southwest Coast

The average tectonic plate on the Earth moves at about 4.28 cm/yr (derived by averaging the absolute velocities as stated here), which works out to be about 1 mile every 37.57 thousand years.

If I assume that both plates are average, and therefore moving at the average speed, and run the collision backwards in 12 million-years-ago (Ma) increments, the collision looks something like this:

Initial Theory of the Formation of the Southwest
Initial Theory of the Formation of the Southwest

This solution lacks an explanation for the peninsula Hartre and Southpoint are located on, however, and it also doesn't provide any reason for the bay around the mouth of the Elbow River.

A more speculative theory can explain both, however. If I slow down the northward creep of the southern oceanic plate enough, the oceanic plate's initial point of impact becomes the peninsula.

In this theory, the impact builds up the peninsula, and also arrests the eastward motion of the plate along the point of impact. The inexorable pull of the plate eastward, however, eventually rips the plate, forming a northward rift that allows the northern and eastern parts of the plate to continue to move eastward, while the southwest is essentially left behind. This rift forms the bay around the Elbow River (which may run along this rift), and also causes a fracture that separates Elde Island from the mainland (and helps explain such descriptive names as Ridgly and Cliffside, as well as the rocky eastern coast of Elde).

Formation of the Southwest
Formation of the Southwest

I would expect that the area around Ridgly is hilly--if not outright mountainous--due to the intense compression that occurred as this portion of the continental plate separated and was simultaneously forced northward. Also, the east and west coasts of the bay around the mouth of the Elbow River are probably clifflike in many respects, since this bay is actually a rift valley.


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Copyright © 2011 Bryan Newell, unless otherwise noted.