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San Andreas Fault
San Andreas Fault
The community of Wrightwood sits directly on top of the San Andreas Fault which is the boundary between two tectonic plates: the North American Plate and the Pacific Plate.
The community of Wrightwood sits directly on top of the San Andreas Fault which is the boundary between two tectonic plates: the North American Plate and the Pacific Plate.
In addition to going through Lone Pine Canyon, the city of Wrightwood, and directly under Jackson Lake, the San Andreas Fault extends 800 miles in total. It is a strike-slip fault which occurs at a transform boundary where the North American Plate and the Pacific Plate are sliding past each other horizontally. The plates move relative to each other at a rate of about 1 inch per year on average. However, the movement is not smooth and continuous, but rather often occurs in abrupt shifts, increasing the potential for destructive earthquakes. During the 1906 earthquake in northern California, for example, parts of the fault line moved as much as 21 feet in a matter of seconds.
In addition to going through Lone Pine Canyon, the city of Wrightwood, and directly under Jackson Lake, the San Andreas Fault extends 800 miles in total. It is a strike-slip fault which occurs at a transform boundary where the North American Plate and the Pacific Plate are sliding past each other horizontally. The plates move relative to each other at a rate of about 1 inch per year on average. However, the movement is not smooth and continuous, but rather often occurs in abrupt shifts, increasing the potential for destructive earthquakes. During the 1906 earthquake in northern California, for example, parts of the fault line moved as much as 21 feet in a matter of seconds.
The San Andreas fault is responsible for much of our local geography from the San Gabriel Mountains and Mormon Rocks to the Wrightwood Country Club and Jackson Lake, which are sag ponds created due to the presence of the fault. The rock tower near the Big Pines Visitor Center across from Mt. High West has the distinction of being the highest point on the San Andreas Fault. I’m not sure of the precision of this map, but if you would like to get a rough idea of how close the fault line is to various points of interest, such as your home, check out this website: http://www.thulescientific.com/san-andreas-fault-map.html
The San Andreas fault is responsible for much of our local geography from the San Gabriel Mountains and Mormon Rocks to the Wrightwood Country Club and Jackson Lake, which are sag ponds created due to the presence of the fault. The rock tower near the Big Pines Visitor Center across from Mt. High West has the distinction of being the highest point on the San Andreas Fault. I’m not sure of the precision of this map, but if you would like to get a rough idea of how close the fault line is to various points of interest, such as your home, check out this website: http://www.thulescientific.com/san-andreas-fault-map.html
To see direct evidence of tectonic activity up close, take a hike at Appletree Campground. To the left of the parking area is 1/2 mile trail along a dirt road. Along this path, you can see evidence of outcroppings created by vertical uplift, a red varnish called slickenside, fault gouge, and fault flour, all created by tectonic movement.
To see direct evidence of tectonic activity up close, take a hike at Appletree Campground. To the left of the parking area is 1/2 mile trail along a dirt road. Along this path, you can see evidence of outcroppings created by vertical uplift, a red varnish called slickenside, fault gouge, and fault flour, all created by tectonic movement.
Two trees in the Wrightwood area, the Lone Pine Tree and the Pool Tree, both show evidence that there was a massive earthquake along the San Andreas fault near Wrightwood in 1812. Their tops broke off and their roots were damaged due to their proximity to the fault itself. As a result, ring patterns show that the trees did not grow radially for several years following the earthquake as the trees healed from the damage done by the quake. It took over 20 years for growth patterns to approach normal rates.
Two trees in the Wrightwood area, the Lone Pine Tree and the Pool Tree, both show evidence that there was a massive earthquake along the San Andreas fault near Wrightwood in 1812. Their tops broke off and their roots were damaged due to their proximity to the fault itself. As a result, ring patterns show that the trees did not grow radially for several years following the earthquake as the trees healed from the damage done by the quake. It took over 20 years for growth patterns to approach normal rates.
There a well-produced History Channel video called The San Andreas Fault: Disaster About to Strike| How the Earth Was Made. While it is an exciting and fascinating way to learn about our local geology, note that it might not be for everyone. While the sensationalized depiction might be engaging for some, sensitive kiddos might find it a tad anxiety-producing!
There a well-produced History Channel video called The San Andreas Fault: Disaster About to Strike| How the Earth Was Made. While it is an exciting and fascinating way to learn about our local geology, note that it might not be for everyone. While the sensationalized depiction might be engaging for some, sensitive kiddos might find it a tad anxiety-producing!
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