Another loose boulder on the north side of Sunset Bay State Park This one shows a very nice cut-and-fill structure. Flow concentrated in a restricted area gouged out a small channel, which was later refilled with sediment. This is another structure that allows determination of stratigraphic "up." First, when a sequence is cut, the sequence is older than the feature doing the cutting- so in this case, the set of beds being cut into by the channel is older than the channel doing the cutting. Second, in a stack of sedimentary layers, the layer on top is younger. Combining those two principles makes it clear that from the perspective we're viewing it, the rock above is upside-down in a stratigraphic sense.
As it happened, we were at Sunset Bay as sunset approached; the low angle and warmer quality of of the light is apparent in this photo.
Photo unmodified. March 8, 2012.
FlashEarth location.
It's kind of amazing to see this place I have been to so many times dissected geologically.
ReplyDeleteI do have to admit that I had noticed some strange geological formations there over the years but I had no idea just how active that place has been in the past.
It's pretty cool to see this from your viewpoint, things I had only glancingly noticed more fully explained and things I did not know at all that have been there staring me in the face for my fifty odd years.
Thanks for pointing them out.
My pleasure, literally! I've been having a great time with this series... and just think: 318 days to go yet.
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