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Brownsville geology– a bedrock mystery

March 18, 2014

This area has interesting geological features. Previous posts have mentioned the bogs and the fossils found along the highway. These were features observed and utilized by early residents.

Brownsville    boulderThere are many large boulders on the hillside, but the location of bedrock is a mystery.

Geologist WA Johnston wrote in 1923 that there is “only one rock outcrop—at South Westminster—being known.”

He describes the uplands back of the river as “highland drift.”

  Diagram from 1921 shows surface deposits on the uplands, including the South Port Mann bog and the bedrock outcrop on the hill at Brownsville.

The bog was located at 104 Ave and King George Blvd.

  uplands surface deposits -  Fraser River delta

There is a piece of rock at the railway crossing on Old Yale Road at the base of the hill that appears different than the others, to a layman’s eye. and this could be the outcrop Johnston refers to. It is very close to the railway and the road, so if it were a boulder it would likely have been removed long ago.It is very much overgrown.

Old Yale road - rock outcrop -  BCER2Old Yale road -rock outcrop -  BCER1









Below a  makeshift tent, a boulder and a second massive boulder looming at right.

Brownsville campsite boulder

surface deposits - Fraser River delta

Diagram showing the distribution of surface deposits, Fraser River delta, BC – WA Johnston, 1921

surface deposits legend - Fraser River delta

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