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Yesterday @phaneritic and family and I hiked to Emma Lake in the lovely Sierra Nevada Mtns.
Here’s a little geology thread about the day.
Here’s a little geology thread about the day.
Emma Lake is a tarn- a Lake that sites in an alpine valley scooped out by a glacier. As the glacier flowed downhill it picked up the rocks in the mountain and carried them along. Where the glacier melted the rocks were dropped out into piles called moraines.
The arrow shows the path the glacier took downhill when it flowed. (Pardon the simplicity- I am working from a cell phone 
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The purple lines mark the location of several recessional moraines. These formed as the glacier melted and shrank uphill. This doesn’t happen smoothly- the glacier’s toe,or end, would remain in one place for a while. As it did, rocks would pile up creating the moraine.
Here you can see one ( the gray rocks) from below. This is where @phaneritic took his video of the creek yesterday.
You can also see the next one immediately above it as the lighter rocks.
You can also see the next one immediately above it as the lighter rocks.
On top of the gray moraine we get a view up canyon of the next moraines.
Looking closely you can see there are two- one with a few small trees and the next above it with a section of reddish rock on the right side.
Looking closely you can see there are two- one with a few small trees and the next above it with a section of reddish rock on the right side.
The slopes of broken rock on the left are eroding from the cliffs above. The steep piles they create are scree piles and are unstable. We witnessed 2 rock falls as we hiked up to the lake.
Look for the dust kicked up as the rocks fell.
Look for the dust kicked up as the rocks fell.
I witnessed a second rockfall near the lake. I think the strong winds were the trigger for knocking down the rocks that had liked been looser by freeze-thaw action throughout the year.
If you look closely you can see a rock roll downhill ahead of the dust.
If you look closely you can see a rock roll downhill ahead of the dust.
Here is Emma Lake. Behold the beautiful moraines, scree and cliffs! A geologist paradise!
We are off on another adventure so I’ll tweet about the lithology later.
We are off on another adventure so I’ll tweet about the lithology later.
