GEOTREK IV-D
WESTERN SANTA MONICA MOUNTAINS
Wednesday, March 2, 2011
Topic: Early Neogene sedimentary and structural history of the western Santa Monica Mountains; discovering a Neogene volcano.
Participants: Gene and Sue Fritsche, George Milkovich, Syrus Parvizian, and Vicki Pedone. See the first photo below (the group photo) to pick out these people.
Distance and Route: About 9.8 miles, mostly along Sycamore Canyon in Point Mugu State Park. From the Satwiwa trailhead in Potrero Valley we went south on Sycamore Canyon Road to Fossil Trail, took Fossil Trail east to the Old Boney Trail, went on Old Boney Trail south to the Blue Canyon Trail, followed the Blue Canyon Trail west back to Sycamore Canyon Fire Road, and finally hiked on down the Sycamore Canyon Fire Road to near the beach at Sycamore Canyon Campground. See Google Earth route map below.
Profile: On the profile below the start of the hike is on the left end. Elevation gain was 1,235 feet; elevation loss was 2,007 feet.
Geology: The hike began on the Dibblee Newbury Park quadrangle (DF-28) and ended on the Dibblee Point Mugu quadrangle (DF-29). Formations seen included the Miocene Topanga Canyon Formation and the Conejo Volcanics. Depositional environments, stratigraphic problems, and structural history of the area were discussed along th trail, including evidence for the large volcano that existed in this area during the Miocene.
PHOTOS TAKEN IN THE WESTERN SANTA
MONICA MOUNTAINS ON GEOTREK IV-D
Photos taken by Gene Fritsche.
Click on the small picture to see an enlargement.
 | Ready to start our hike down Sycamore Canyon. Participants from left to right are Syrus Parvizian, Sue Fritsche, Vicki Pedone, and George Milkovitch.
 | Dike (left) intruding into lower Miocene Conejo Volcanics (right).
 | Gene points to the northeast-trending canyon formed along the Sycamore Canyon fault. Syrus, George, and Vicki seem more interested in the camera. Rocks behind Gene on the southeast side of the fault are the lower Miocene Topanga Canyon Formation. Rocks on the far northwest side of the fault are the younger lower Miocene Conejo Volcanics.
 | Hiking up the Fossil Trail east of Sycamore Canyon. Everyone was watching carefully for fossils in the trailside rocks.
 | Oyster fossil fragments in a coarse-grained sandstone of the lower Miocene Topanga Canyon Formation.
 | Exposure of coarse-grained sandstone in lower Miocene Topanga Canyon Formation. Storm deposit of oyster fossil fragments in the center.
 | A fine specimen of Dudleya growing along the Fossil Trail.
 | Scallop fossils exposed on the Fossil Trail. These fossils help to date the Topanga Canyon Formation as early Miocene in age.
 | Behind the group are the slopes of Boney Mountain composed of sandstone belonging to the lower Miocene Topanga Canyon Formation.
 | Paintbrush flowers exposed along the Old Boney Trail.
 | Lunchtime at the Danielson Multi-Use Area of Point Mugu State Park.
 | Spheroidally weathered outcrops of the lower Miocene Topanga Canyon Formation exposed along the west side of Sycamore Canyon.
 | Hiking in Sycamore Canyon along the Sycamore Canyon Fire Road. The trail from here to the ocean was just an easy downhill slope.
 | Exposure of lower Miocene intrusive diabase on west side of Sycamore Canyon.
 | Closeup view of the lower Miocene diabase intrusive rocks in Sycamore Canyon.
 | Lower Miocene Topanga Canyon Formation exposed in a roadcut along Highway 1 at the end of the Sycamore Canyon Trail.
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THIS PAGE LAST MODIFIED ON JUNE 12, 2011
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