2017 - Trip Report - Geology Run, Inbound Rondy
Inbound Rondy Geology Run
Trip Leader: Bill Neill
Participants: Bill & Gwenn Neill, Allan & Ding Wicker, Norma & Danny Siler, Steven Faulstich, Fredric Raab. We met at Chiriaco Summit and caravaned in 5 vehicles down Box Canyon to Painted Canyon.
Photo 1 – 11.30.30: Our group is at an exposure of Orocopia Schist near Shaver’s Well, at the upper end of Box Canyon, formed in a subduction zone during Mesozoic time (age of dinosaurs) when the North America’s continental margin was located at present Coachella Valley. The San Gabriel Mountains have an identical and formerly adjacent rock called Pelona Schist that has moved 160 miles northwest along the San Andreas Fault.
Photo 2 – 11.48.06: Also near Shaver’s Well, we viewed “slickenlines” — rock smoothed and polished by fault movement -- and abundant lupine flowers surrounding Steven Faulstich.
Photo 3 – 12.48.31: Gwenn and Ding are resting on trail into Painted Canyon. Sandstone and conglomerate in canyon walls are relatively young, deposited as early movement on the San Andreas Fault formed Coachella Valley.
Photo 4 – 12.56.58: In Painted Canyon, Danny Siler stands on ancient metamorphic rock named the Pinto Gneiss that’s about 1.7 billion years old and similar in age and origin to the Vishnu Schist at the bottom of Grand Canyon.
Photo 5 – 13.01.18: In Painted Canyon, Fredric Raab views the banded and folded Pinto Gneiss, named for exposures in the Pinto Basin of Joshua Tree National Park.