I had spent the previous day wandering around Indio, California. I had perused the kitschy gift shop of one of the many date farms in the area, watched their 1950s film on the romance and sex life of a date, and devoured probably 15,000 calories worth of the yummiest date shake I have ever had the pleasure of devouring. I then proceeded to empty my wallet on groceries in an overpriced food emporium. I figured I might as well attend the presentation to make up for my total lack of pecuniary and caloric self–control. California is a serious chunk of real estate to drive around in, and the extra gas money would come in handy. I knew full well, though, that an 18–minute film about the sex life of a date would be a hard act to follow.
|Who counted Forty Nine Palms at this oasis?|
During the shortened daylight of the winter solstice, sunset in sunny SoCal comes early, around 4:30pm. By the time I staggered out of the time–share offices and into the December sunshine, it was nearly noon and I needed to get hiking in a bad way. After a fair bit of waffling about where to go, I finally hit upon Forty Nine Palms Canyon. The upside of this mildly strenuous hike was its distance and its draw – a mile and a half one–way to one of the Park’s distinctive fan palm oases. Perfect! The downside of this plan, though, was that the canyon is on the other side of the park from Indio. It would take me over an hour to get there and I would undoubtedly be driving back to the condo in the dark. On the upside, perhaps an owl or two might swoop across my headlights…
|At the start of Forty Nine Palms trail|
|Plutonic rocks a-plenty!|
Over the eons, groundwater slowly percolated down into the fractures. With this water moving through, some rock crystals along its path altered to clay while other more resistant crystals were loosened and ultimately carried away by the water. Rectangular shapes became more rounded, even though the rocks were still underground. As the climate changed from wetter to drier, eventually this protective ground cover vanished, exposing these rocks to the ongoing surface weathering and erosion that we see today.
|Trail steps rise past an intrusion within an intrusion|
It was impossible not to notice the size of the crystals along the trail. They were huge! These lighter–colored feldspar crystals can be up to several inches to a side and nearly perfect rectangles. Enclosed in a matrix of smaller grains, clearly they are not called megacrysts for nothing. It is always fun to come upon them and ponder their origin (although I did not have much time for pondering this afternoon, what with sunset due to overcome the daylight very soon). These larger crystals formed due to their being below ground for a long time, but then something happened, Perhaps the entire plutonic mass moved closer to the surface (but did not erupt as a volcano) and smaller, more fine–grained crystals were able to cool faster. Perhaps the chemical reactions that formed the crystals at different temperatures in the magma went to completion and the necessary elements (the potassium, the sodium, and the calcium, among others) were used up. Perhaps both processes occurred.
|megacrystic feldspars in a finer-grained matrix|
|The sun is dropping behind the mountains at Forty Nine Palms oasis|
|Fan palms thrive in this canyon due to the spring|
|Forty Nine Palms oasis|
|Forty Nine Palms? Who counted them?|
|Schist happens in Forty Nine Palms canyon|
I never did see that owl fly by in the dark.
My main resources:Trent, D.D. and Hazlett, R.W., 2002, Joshua Tree National Park Geology