America Day 3 - Monday 7th October

Monday was the day of our first obstacle. At 9am we arrived at San Onofre State Beach, where we expected to examine the rock units exposed around the Christianitos Fault to see if there were any potential hazards that would affect the San Onofre Nuclear Generating Station just down the road. Everyone wandered down to the beach, when disaster struck! The sand had been eroded further than before, meaning that the tide was around 1m higher than expected. We all ran around to a path further down the beach to see if we could find another way through, getting a bit damp in the process! There was a track that went through the vegetation and we found our way to a small clearing, where there was a wall that we climbed to get back to the mini buses.

A bit damp!

Our climbing wall!

We attempted to find another way around, but at 10:45am we gave up and went back to San Clemente Beach Cliffs to look at the rock units there. We examined the Channel Axis Facies (a facies is a body of rock with certain characteristics that forms under certain sedimentary conditions), and the Channel Margin Facies, which are both turbidites deposited in turbidity currents which are currents of rapidly moving, sediment laden water which moves down a slope through another body of water.

Channel Axis Facies

At 4pm we arrived at Lamont Odett Viewpoint, near Palmdale, which is on the edge of the Pacific Plate. We then moved just down the road to the Anaverde Cut on Highway 14, which is on the edge of the North American Plate (other side of the San Andreas Fault) to discuss deformation in an outcrop that we could see as it had been cut for the road. The rock units had been highly folded and faulted due to movement on the San Andreas Fault, which is a dextral strike slip fault (that basically means that if you stand on one side of the fault, over a long time you would see the other side of the fault move to the right). At 5:50pm we left there and headed to Palmdale Motel where we stayed for the night. 

Folded rocks on Anaverde Cut