Do you see that large exposed rock? Once upon a time, nearly 23 million years ago, that was a lava flow. A whole lot of hot lava came flowing out of volcanos that happened to be situated on a fault, a crack in the Earth’s crust, where the west side of the fault moved north slowly but surely in fits and starts punctuated by earthquakes in California. Today, this now solid rock is in northern California, less than 90 miles by car south of San Jose. The volcanoes themselves, mountains made of softer rock, have eroded away leaving these giant hardened and ancient lava flows to stand out and be explored and appreciated. What about the rest of the volcano flows that happened to land on the east side of that fault millions of years ago? Well, those hardened flows are in southern California, 195 miles away near Los Angeles.
Yes, that giant rock pictured, and there is a WHOLE lot more not pictured – the lava flow area was huge from several volcanos, has traveled north 195 miles since it formed from cooling lava, along with much of coastal California. I told my children that in a few million years more, it will only take a couple of minutes to drive to Pinnacles National Park from San Jose.