The Shape of Beauty* By Dr. William Lama
The Shape of Beauty*
By Dr. William Lama
Residents of the Palos Verdes peninsula become accustomed to the spectacular natural beauty that surrounds us. But when I arrived from upstate New York in July, 2000 I was stunned. Entering Malaga Cove I spotted the vast blue ocean. Going through the plaza I turned left on Via Campesina and encountered a large walking bird with a bright blue head. It was a peacock, the first I had ever seen in the middle of a street. While driving around the peninsula I encountered one spectacular scene after another. Two years later I retired and joined the docent class at the Point Vicente Interpretive Center. That’s when I really learned about our little piece of paradise.
I was particularly intrigued by the shape of the place, what the scientists call geomorphology. I was amazed by the natural variation, from the rolling hills, to the rugged canyons, broad terraces, steep ocean cliffs, points and coves, rocky beaches and tide pools.
Approaching Palos Verdes from any direction, you are struck by its great natural beauty. Any view of the Palos Verdes Peninsula, with its 18 miles of spectacular coastline, is breathtaking.
You can’t help but wonder about the foundation of all this varied natural beauty. What were the forces that gave rise to the gentle terraces and the rugged crevices and the shoreline cliffs as high as 300 feet? How has the surface topography changed over time and has the change been rapid or gradual? How did it get to be so beautifully complex?
The story of Palos Verdes is short on the geological time scale, only 20 million years or so, less than 1% of the time since the earth was formed. What’s more, the rate of change is still quite rapid. About 20 million years ago (MYA), the Palos Verdes Fault was formed (roughly parallel to and between Pacific Coast Highway and Palos Verdes Drive North). Motion relative to this fault has governed much of the geologic history of the Peninsula. Around 3 MYA, slips along the fault raised the sea floor into a pronounced undersea knoll. Then around 2 MYA the vertical slips on the fault raised the knoll above sea level and the Palos Verdes Island emerged.
It is believed that the island has been rising at an average rate of 0.4 mm per year (0.016 inch/year). At that rate, Palos Verdes achieved its present elevation in about 1 million years. Around 100,000 years ago, sedimentary filling of the LA basin was sufficient to reach sea level and the island became the Palos Verdes Peninsula.
During that time the 13 marine terraces (currently 80 to 1300 feet in elevation) were formed by wave action accompanied by uplift. The marine terraces, once ancient beaches, are color coded in the following figure.
The "Ancient Beaches" image, adapted from a book by Woodring (1946), is on display at the Point Vicente Interpretive Center.
Note that Point Vicente is located on the lowest terrace about 80 feet above sea level. Most of the coast line is rimmed by the next highest terrace, 180 feet above the shore.
The following picture shows the terraces rising above Malaga Cove. Note the Palos Verdes Estates Beach Club on the beach.
In addition to uplifts associated with slips along the PV Fault, the shape of Palos Verdes has been dramatically altered by earthquakes, “the beauty-making love-beats of Nature’s heart” (John Muir). Compared to the giant San Andreas Fault, the Palos Verdes Fault is a small fry. But it can change the terrain and cause damage. (It is interesting to note that we PV residents live on the Pacific tectonic plate rather than the North American plate, which is on the other side of the San Andreas Fault.)
This table compares the two faults, their horizontal and vertical slip rates and the largest magnitude earthquakes that are likely to occur in 1 year and in 1000 years.
In 2005 the PV Library board decided to upgrade the Peninsula Center Library to current seismic code. I was the trustee chosen to interface with the geotechnical and construction firms. IDS Geotech analyzed faults within 50 km of the library and found 14 capable of M6 to M7 earthquakes. The PV fault is capable of an M7 earthquake within 1000 years and due to its proximity the PV fault is the most dangerous. The seismic upgrade was designed to withstand the maximum earthquake, an acceleration (shaking) of 44% of gravity.
Based on the geological history, it is interesting to speculate what Palos Verdes will be like in 100,000 years? Los Angeles will have moved 3 miles closer to San Francisco due to slip along the San Andreas Fault. Concurrently Palos Verdes will move 1/6 mile toward Santa Monica due to slip along the PV Fault. Palos Verdes will be 130 feet higher, reaching 1600 feet. There will be a new terrace 130 feet above the shore. There will have been 2000 M4 earthquakes due to the PV Fault. And land will be even more costly due to the next Ice Age.
In the mean time I intend to take a walk and enjoy this little bit of paradise.
* Agusta Fink (Time and the Terraced Land) used the phrase “the shape of beauty” to describe Palos Verdes.
Dr. William Lama PhD in physics from the University of Rochester. Taught physics in college and worked at Xerox as a principle scientist and engineering manager. Upon retiring, joined the PVIC docents; served on the board of the RPV Council of Home Owners Associations; served as a PV Library trustee for eight years; served on the PV school district Measure M oversight committee; was president of the Malaga Cove Homeowner's Association. Writes about science, technology and politics, mostly for my friends.
email: wlama@outlook.com