This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
California is home to many natural wonders due to its varied climate and topography which includes both forest and coastal lands. For the July 6, 1901, issue of Scientific American, author, big-game fisher, and former curator at the American Museum of Natural History Charles F. Holder wrote a piece on some of the interesting and beautiful results of erosion on California’s southern coast.
Pyramid Cliff, located on the coast of Del Mar, got its name from the conical shaped rocks that remained where the cliff had been eroded by sea water. The cones were made up of sandstone, adobe, and pebbles. Water from the mesa above would cascade down the cliff in a single stream until it hit an obstruction (like a rock), causing it to split into two streams that went around either side of the rock. This process continued and eventually a cone or “pyramid” would take shape out of the negative space.
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The Santa Monica Mountains, which extended 10 miles inland and stretched down to the Santa Monica coast, ended in the North with 25-foot high Arch Rock. “The mountains here are a mass of conglomerate formed by water-worn pebbles, from the size of an egg to a man’s head, firmly cemented in a solid mass. There is every evidence that this mountain range once extended farther out into the ocean, but the sea battered it down, leaving a pseudo flying buttress which is submerged at high tide.” The arch was exposed to strong seawaters, especially on its side, making it a wonder how it was the middle that came to be eroded first.
On Point Firman in the L.A. Harbor, a bluff jutting out into the ocean formed Sentinel Rock. Layers of sediment formed the rock, and its strata naturally tipped to a 45-degree angle leaving the front of the rock exposed to the ocean’s harsh spray. The water caused the bluff to take on a “saw tooth” shape. “The sea has smoothed off the softer strata until in places a level, slightly inclined, smooth floor of rock is left from which runs a lofty tower composed of layers of different strata which for some reason have sufficient hardness to resist the rush and swirl of the waters.”
I have no idea if this remains true of Sentinel Rock nor if any of these rock formations are still standing. Do any of you? And more importantly, what is that woman up to on the edge of that bluff?
