Sunday, July 24, 2016

Mr. Spock explains the Gold Rush

We were able to begins today's drive with an early stop at the Five Finger Rapids Recreation Site on the Yukon River.

It was called Five Finger Rapids by early miners for the five channels, or fingers, formed by the rock pillars. Just wait, there'll be a better picture down below, but this one give a nice overview from the road.

Stairs (219 steps) and a 1-km trail lead down to a closer view of the rapids. 

This is basically the same picture as above but this one has Frederick in it!

At the end of the trail was a viewing platform and I think you might be able to make out at least a few of the 5 fingers, and rock pillars.

Next we drove to a nice overlook of the Yukon River. Also at the stop was an interpretive sign about Beringia.

Beringia is the land mass stretching from Eastern Siberia through Alaska to the Yukon. During periods of glaciation, the water level of the oceans receded and a landmass formed that allowed species of plants and animals, including man, to cross from Asia to North America. The sign says
 that.... "if you could stand here 15,000 years ago near the end of the last glaciation, the vista would be of a dusty, treeless steppe at the edge of the ice sheet."

On the other side of the road the mountains are nicely rounded.

At last!!! Mr. Spock was able to get out of the car, at the Tintina Trench, which extends hundreds of miles across Yukon and Alaska and is the largest fault in North America.

Beneath the Tintina Trench is a fault line along which the bedrock has shifted a minimum of 280 miles laterally. Mr. Spock explained that some 65 million years ago, the rocks presently beneath Dawson City were adjacent to those of Ross River! About 8 million years ago the earth's crust separated along the fault, creating a wide valley or trench.

Mr. Spock then told us about finding gold. Mineral deposits are a by-product of the plate tectonic forces which shape the continents. When two tectonic plates come together, one is often pushed beneath the other where it melts deep within the earth. Some of the melted rock floats to the surface as lava, while more of it cools within the crust to form granites.

A modern example of this activity is the tectonic plate under the Pacific Ocean which is sliding beneath Alaska. Some of it reappears as Aleutian Island volcanoes. Volcanic rocks and granites are common in the Yukon. Many of them carried gold and other minerals out of the earth. Erosion eventually uncovered the gold-bearing rocks. The gold was washed into the Tintina Trench and buried in river sediments. Tectonic movements, volcanism, glaciation, erosion and sedimentation have combined to bring these gravels and their gold within human reach. It was just a matter of time before they were discovered.

It's simple when Mr. Spock explains it!

Tonight we are in Dawson City RV Park & Campground.

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