The granitic rock formations in the photograph began life underground as molten magma. Eventually horizontal and vertical cracks developed, groundwater weathered the edges of the granite blocks and eventually eroded much of the surface soil, leaving formations like these for people like me to gawk at.
The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Insects, weather, meteorites, climate, birds and/or flowers. All are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us. |
Palm Desert, CA
Geologic wonders are commonplace in the Santa Rosa and San Jacinto Mountains of California, where the photograph above was taken. I fell in love with these mountains many years ago, they became my retreat when life in Los Angeles was just too stressful. Just a fifteen or twenty minute drive from Palm Desert and you could achieve complete tranquility.
My knowledge of geology is limited, so I will just give a brief overview of this fascinating part of the world. I’m hoping that some of the gaps will be filled by the Bucket’s far more knowledgeable commenters.
The Santa Rosa and San Jacinto Mountains are part of a major mountain system nearly 900 miles long, called the Peninsular Ranges. The Peninsular Mountain Ranges run north-south while southern California’s other major mountains the Transverse Mountain Ranges (Santa Monica, San Gabriel and San Bernardino Mountains) run east-west. Tom chester writes:
The San Jacinto Mountains and Santa Rosa Mountains are in many ways a single geographic entity, bounded by the San Andreas Fault on the north and northeast, and the San Jacinto Fault on the southwest.
The house where I used to stay was about 11 miles above Palm Desert. To reach it, you take the scenic Pines to Palms Highway which traverses a lot of the area’s truly fascinating geology.
Here, State Highway 74 leaves the Coachella Valley at Palm Desert and ascends the gentle slope of the alluvial fan of Dead Indian Canyon to the base of the steep eastern escarpment. At this point, the Seven Level Grade takes an auto from 1,300 feet elevation to 2,400 feet at the vista point -- a 4.5 mile drive over the switchbacks to reach a point that is fewer than three quarters of a mile from the base of the grade. Climbing the grade, numerous road cuts expose the metamorphic rocks of the Palm Canyon Complex. These rocks are conspicuous in appearance, and contrast sharply with the granitic rocks at the top of the grade. Look for highly deformed, sheared and contorted layers. They are thinly bedded and in various shades of white to light tan to brown, with occasional pink to greenish layers.
The photograph above shows some of the switchbacks described, but doesn’t convey just how breathtaking it is in reality.
The place I stayed was situated at about 3000 feet above sea level and overlooked the entire desert floor.
I spent a lot of my time here hiking. Unfortunately I can’t find many photographs that aren’t filled with either my children or my friends. The picture below shows that even children can hike the area as long they are careful. The smaller of the two was only seven at the time.
The dog in the photograph was appropriately called Roccia which is Italian for rock.
The most dangerous thing we ever encountered while hiking was the Jumping Cholla (Cylindropuntia bigelovii) , a deceptively fuzzy and innocuous looking cactus.
Here’s what enature has to say about the peril’s of the Jumping Cholla:
Warning The spines of the Teddybear Cholla stick instantly and hold tightly by means of minute, backwardly directed barbs. When a joint (which seems to "jump" when detached by a light touch or bump) is severely stuck, the victim's best solution is to cut the spines with scissors or clippers and pull them from the flesh with pliers.
Poor Roccia accidentally brushed against one and a segment immediately broke off and attached itself to the underside of her paw. Before we could stop her, she tried to remove it with her teeth and ended up with clusters attached to both her foot and the inside of her mouth. I used my leather jacket, which the spines easily penetrated even when folded multiple times, as protection and tried to remove as much of the cactus as possible. It was a horrible half hour or so, but we got as much off as possible and a friend of mine carried her back to the house. We all ended up with numerous spines deeply embedded in our flesh. One in my index finger was still there 6 months later. The spines even penetrated the sole’s of our boots. What amazes me is that the Cactus Wren (Campylorhynchus brunneicapillus) has figured out a way to safely build it’s nest in some of the taller chollas in order to protect it’s young from predation.
Unlike the adjacent San Jacinto Mountains, the Santa Rosas have no permanent streams and very few springs. You can see how dry the vegetation is in the next two photographs.
For a great in depth look check out Geology of the Imperial Valley, it has a lot of information and is a fascinating read.
For information on the Flora of the Santa Rosa Mountains.
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