Thursday, January 21, 2010

Torres del Paine, day 6, part I

You will recall that the first photo I showed you from Patagonia was this one:
sunrise_Dec_27

That's from just outside the Paine Grande Lodge, where we stayed for our fifth night in the park. I rose at dawn and was fortunate to have the camera handy for a few minutes of good low-angle pink/orange light. By the time the coffee was finished, the sun had risen higher, and the "golden hour" had finished. The mountain now looked like this:
cuernos_08

We began the day's hike, headed east along the southern face of the Paine Massif, aiming for the legendary Cuernos ("Horns") del Paine:
cuernos_12

A last look back at aquamarine Lago Pehoe, with a Nothofagus tree in the foreground:
cuernos_11

I saw a nice example of plumose structure in this boulder (fingertip for scale, far lower left):
cuernos_13

After not seeing any conglomerate since the first day of hiking, we started encountering it again, meaning that we had hiked back sufficiently to the east to re-enter the Cerro Toro formation. The conglomerate was varied, and so in one ravine, I took the opportunity to photograph its many guises...
cuernos_14

cuernos_23

cuernos_16

cuernos_17

cuernos_15

cuernos_27

Nice mudstone rip-up clasts in this one:
cuernos_18

One final sedimentary shot for this post: another graded bed, as viewed in cross-section:
cuernos_28
I love graded beds. They're a key part of the geologic saga at my favorite DC-area locale (the Billy Goat Trail), and the ones in Torres del Paine were just classic: light-colored sand transitioning gradually into darker-colored mud, with a crisp boundary between each graded bed and its neighbors above and below. As noted before, these primary sedimentary structures are formed when a cascading turbidity current slows down and starts dumping its particles. The heaviest drop out first, the lightest in weight drop out last. Each graded bed = 1 turbidity current.

I've got a lot of other shots from Day 6, but I think I'll save them for a second post.

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