Saturday Field Trips

Saturday, October 15th

8:00AM-5:00PM

Transportation from ELAC and Box Lunch provided

Thrust Duplexing and Syntectonic Deposition of the Saugus Formation along the Southern San Gabriel Fault Zone

Led by: Rob West, Professor Emeritus, ELAC

We will explore the tectonic setting of the Los Angeles region enroute to its first stop in the Sunland area at the mouth of the Big Tujunga River. From there we will inquire into the interplay between past and ongoing thrust faulting and associated folding of the Saugus Formation and older strata within an evolving source/sink geometry at the southern end of the San Gabriel Fault. Right lateral displacement along the San Gabriel Fault has displaced the source area of Saugus sediments over the last roughly 1Ma. These sediments have been laid down as a time-trangressive sequence in a series of deforming basins that lie largely west of the San Gabriel fault. We will look at folds and faults in, erosion of, and unconformities above Saugus deposits in the Little Tujunga River drainage basin and discuss their implications for landscape evolution of the region in response to ongoing deformation.

Details: Transportation from ELAC provided. Only one stop has significant walking on a graded dirt road about 1/4 mile at stream gradient.

Geologic History of Ridge Basin

Led by: Brian Olson, CEG, Seismic Hazards Program, California Geological Survey

We will visit the geology of the Ridge Basin near Castaic Lake, and examine the rocks beginning with Late Paleocene submarine fan deposits in a subduction zone setting, and ending with Miocene fluvial deposits.

Details: Transportation from ELAC provided. The first stop involves walking up a sandy creek bed with occasional cobbles and boulders (less than 0.25 mile). The other stops don’t involve any significant walking.

Sunday Field Trips

Sunday, October 16th

8AM-12PM

Personal transportation required.

Urban Geology on the LA Red Line

Led by: Rob West, Professor Emeritus, ELAC

This trip will depart by bus from East LA College and discuss the East LA fold and thrust belt en route to Union Station. We will examine the texture and minerals of stone work at the Gateway Transit Plaza and several Red Line stations and downtown buildings. We will identify, compare and contrast rock types at these stops and discuss their origins. We will consider how fossils uncovered in the excavation of these light rail tunnels inform us of past environs.

Details: This trip has an added cost of transit fares — but travel is entirely by mass transit, so no vehicles are required. There will be considerable walking and climbing of stairs at certain stations, and ADA access is limited at some points.