Rocks and a flume

Yesterday I went to a 200 level lab for the Depositional Envrionments and Stratigraphy (GEOL243) course. I had been to a lecture on Wednesday as was surprised to find that I actually understood what they were talking about. It turns out that a knowledge of the physics of waves was quite useful.

The lab started with looking at a variety of different rocks and they had to decide what processes had caused the sediment layers to look the way they did. They also had to decide if you could tell which way was up. A lot of this seemed like common sense to me, for example if a layer was eroded away and had another layer deposited in it then of course you could tell which was was up as erosion like that will always go downwards… yay for gravity. You can see an example of this in the second picture.

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The third picture shows a rock where the layers have been disturbed by something burrowing through it.

Some of the rocks contained trace fossils. These were also useful in helping decide which way was up.

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The second part of the lab was going to the flume to see sediment patterns being formed. When ripples are created in a current the sediment is picked up from the upstream side and deposited on the downstream side creating patterns.

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You can see the ripples created by the flow of the water.

IMG_2506The flume with the water flowing. Up close you could see the sediment being picked up and deposited further down.

This reminded me of being at the beach as a kid and looking at the ripples forming in the shallow water and watching the sand get picked up each time a wave went over. It was quite fascinating.


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