December 25, 2011

After a day spent canyoning in the Narrows, we opted to hike the iconic trail of Zion National Park leading to Angels Landing.

The morning dawned cold and clear.  A banana mistakenly left overnight in the car turned black, frozen solid from the 20 ˚F temperatures.

We crossed the Virgin River and headed up into the bright red cliffs.

Until we reached the sunlight, the trail was unbelievably cold in the shadows.  When the first shafts of sunlight shone on us as we emerged from the chilly depths of the canyon, it was suddenly warm enough to strip off all baselayers and continue up the path.

Stopping for water at a hairpin turn, we greeted various groups of hikers trudging up the paved path.  Most were young couples, but my mother and I noticed a father-son duo making their way up the trail.  I greeted them, they asked where we were from, we answered and inquired back.  Turns out the son was from Boston, and he looked awfully familiar.  “Robin?  You were president of East Campus at MIT, right?”  He looked at me.  “You were from… Tetazoo?”  Euphoric to have a similarly young hiking buddy, Robin and I squirted ahead, while my mother and his father took a more sustainable pace behind us.

Evident on every canyon wall was evidence of cross-bedding; thousands of feet of an inland dune sea compressed into cliffs of various red hues.

Hoofprints marked the paved path.  Did donkeys help cart material to create this route?

The only downward looking image I took.

The geology here is fascinating: blood red cliffs are topped with bleached-out white rock.  Initially these formations were all red, ruddy with the iron mineral hematite, Fe2O3.  Hematite, which we also see in deposits on Mars, forms when igneous rocks containing iron, such as granite, are weathered down and form sandstone, with the hematite coating individual grains of sand as this process proceeds.

These sand grains eventually deposited themselves into a dune sea.  Watch out for banthas, Jawas, and Tusken Raiders.

After the dune sea turned into sandstone, water began permeating the rock formation, dissolving iron pigment and bleaching the cliffs white.  However, the extent of bleaching in these cliffs show that it wasn’t just water causing this chemical process to occur: the Navajo sandstone formation must have been submerged in hydrocarbons.  Petroleum solutions are reducing in nature, which contributes to the bleaching out the cliffs by dissolving the hematite.  Once the reducing liquids carrying dissolved iron meet oxygen, the former oxidizes out to form iron concretions, large chunks of iron that look like they came from space, when instead they formed from a mix of water, oil, and air.  More in a PDF here.

We ascended up a bit of trail known as “Walters Wiggles”, a zig-zagging path bravely constructed by a former park superintendent and named after him.  The switchbacks were incredible, hewn into an abrupt face of rock as this image by by Rick Crowle shows.

The trail came to a rest at an area called Scouts Lookout.  We pressed on, following something that very generously could be called a trail, which was more of a chain sunk into the rocks so you could pull yourself along the edge past dropoffs of about 1,500 feet on either side.

The rocks were layered, red and tan.  Fascinating formations.

We made it all the way to the top, basking in views of the entire valley.

The “trail”.

In some places, the chain’s movement had aggressively worn away at the sandstone.

Group portraits!

The funny thing about the Angels Landing hike?  I took no photos of the view directly down the cliff from the top of Angels Landing.  We spent our time looking upward; Robin got perhaps one shot of the view downward.  His photos follow.