GeoTrek IV-H – Western Topatopa Mountains
Date and Topic: Saturday, May 14, 2011. Cretaceous and Paleogene sedimentary and structural history of the Topatopa Mountains and a Quaternary lake. Traverse from Sespe Creek at Lion Canyon to Ojai.
Distance and Route: About 11 miles along the following trails: starting at Middle Lion campground, east of Rose Valley and south of Sespe Creek, go south on Lion Canyon Trail (22W06), west on Nordhoff Road (5N08), and south on Horn Canyon Trail (22W08) to Thacher School. Total elevation gain is 2,498 feet and total elevation loss is 4,180 feet (see profile on next page).
Meeting Time and Place: Meet at 8:00 a.m. at the Thacher School parking lot described below. Take Highway 33 north from Ventura. Highway 33 eventually is joined by Highway 150. At a signal light on the west end of Ojai, Highway 33 turns left and Highway 150 continues straight east. Stay straight on Highway 150, which is Ojai Ave. Go 3.3 miles on Ojai Ave. to Reeves Road and turn left. Go 1.1 miles on Reeves Road to McAndrew Road and turn left (north). Go 1.0 mile on McAndrew Road to the entrance to Thacher School. Enter Thacher School and at the first junction in the road take the right fork, Thacher Road. Do not stop at the first parking lot! Continue on Thacher Road to the second parking lot and park there (see Thacher School parking map on next page).
Contact Telephone Numbers: My home phone is 818-882-8468; my cell phone is 818-235-2304.
Bad Weather Cancellation: In the event that bad weather is predicted, check your email on Saturday morning at 7:00 a.m. to see if I have cancelled the hike, or call me if necessary.
What To Bring: Dress in layers appropriate for the predicted weather and wear good walking shoes. Bring plenty of water, lunch, snacks, hat, dark glasses, sunscreen, and lots of enthusiasm. Also bring some wading shoes or sandals in the event that Lion Creek is too wide to boulder-hop across. Optional items include hand lens, camera, notebook and pencil, and a copy of the Dibblee map noted below. If you want to have copies of the maps in this announcement, please print them out yourself and bring them with you.
Post-hike Snacks: At the end of the hike, Connie Hanstedt, a GeoTrek participant in 2006, 2008, and 2011 and who is now a teacher at the Thacher School, will provide snacks for the hikers. The menu will be simple, including such things as cold drinks, sandwiches, fruit salad, etc. Plan on staying a short time for a snack and let her know how much you appreciate her generosity.
Geology: The hike is on the Dibblee Lion Canyon quadrangle (DF-14) and the Ojai quadrangle (DF-13). Formations we will see include an unnamed Upper Cretaceous marine unit, the lower to middle Eocene Juncal Formation, the middle to upper Eocene Matilja Sandstone, and the upper Eocene Cozy Dell Shale and Coldwater Sandstone. Depositional environments, stratigraphic problems, and structural history of the area will be reviewed. Also we will analyze the origin of a Pleistocene lake deposit.