January 20, 2010

Sonoran Desert Rains...The Day After at "Wind Cave"

Last night, storm number two rolled past dropping a good inch of hard rain on the desert floor. For a time, there was standing water on the ground, but by morning it has slowly seeped back into the rocky soil. With a 12 hour window before the 3rd and most powerful storm arrives, we decided to take advantage of the sunshine and head up Pass Mountain to the "wind cave". They are expecting that the next storm will drop as much as 3" of rain to the desert and perhaps 4 feet of snow in Flagstaff.

Here is the sunset with the clouds moving in before the rains hit.

The large lateral roots of this saguaro have been exposed.
Notice the runoff channel on the trail from the rains the night before.

Hard to tell in this photo, but the lichens on the cliff walls were irredescent green after soaking up the rains last night. Pass Mountain is of volcanic origin. It is mostly weak granite with huge crystals, which indicates the magma cooled very slowly deep underground. In the middle there is a thick layer of volcanic tuff, which is compacted volcanic ash from the massive Superstition eruptions about 35 million years ago.

Again, the lichens were much more prominent in real life, but you can see that grayish-green on the rocks. The Wind Cave was just a carved out feature in the soft tuff, not an actual cave. Because the tuff layer soaks up the moisture better than granite, it is both softer and slippery when wet and a better substrate for lichens and moss to grow.

Notice this little friend out to get a drink? It was less than 1" long

A view across the Valley of the Sun. Downtown Phoenix is way off in the distance. Those white specks are the campground we are staying at.

View from the Summit of Pass Mountain. That saddle and zigzagging trail below is the Pass Mountain Loop that was featured earlier.

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