Story and photo by
www.PhotoByVivian.com
About 20 million years ago when ‘the Seven Sisters’ peaks were formed (Morro Rock, Bishop’s Peak, etc.) the tide line in Pismo Beach was up more or less where the freeway is and the waves were probably crashing against the hills.
Move ahead 20 million years and now in-between the foothills where waves once crashed and where we now enjoy our beautiful beach you will see several huge rock formations. One sits right in the middle of the highway (where Marie Calendar’s once was) and another stands in the middle of the beach, close to the bottom of the steps you can take from several hotels or the steps at the end of Wilmar Avenue (pictured).
These huge rock formations are Sea Stacks. The Sea Stacks, called tuffs, are made from volcanic ash that landed on the ocean, settled to the bottom, built up over years, eventually petrified and later pushed back up where we see it today. Thousands of years of erosion and clearing away of softer rock shaped the unusual rocks that seem to come out of nowhere. The Stacks started as caves that collapsed, which then formed arches and then as the arches collapsed a pillar or Stack was left behind. The white and yellow rock along the cliffs in this area are also tuffs, the same material as the Sea Stacks.
Nearby the Sea Stack in this photo are many small caves, better known as the Dinosaur Caves. These caves were formed the same way as the Sea Stacks were, in reverse, but that is a story for another time.
