Redwood National Park Lower Creek Basin Geology Field Trip.pdf

The field trip covers geology, geomorphology, land use, and watershed rehabilitation in Redwood National Park's lower Redwood Creek basin. Starting at Eureka, the route follows US Highway 101 north through Arcata and the Mad River floodplain, then climbs onto marine terraces near Trinidad—the best preserved multiple terrace sequence between Fort Bragg and the Oregon border. The highway passes Big Lagoon (the largest coastal lagoon), Stone Lagoon, and Freshwater Lagoon, where water levels fluctuate tens of feet due to repeated breaching of sand spits by coastal processes. For example, Big Lagoon breached its north end in November 1977, dropping 17 feet in under six hours before resealing in four weeks. Freshwater Lagoon no longer breaches due to a culvert under US 101. The route proceeds to Orick, where the town sits in Redwood Creek's floodplain and is protected by a levee built after the 1964 flood. The trip continues to the Bald Hills Road, entering Redwood National Park. At Stop 1 (Redwood National Park Overlook), the view reveals the park's original 1968 boundary, with virgin redwood/Douglas-fir forest dominating the landscape. Visible below are logged areas: isolated old-growth redwoods from late 1950s clearcuts using the "seed tree method" (scattered trees left to reseed), and upper slopes cleared via clearcutting, including a 1975 cut block. The log landing adjacent to the overlook was used for hauling timber before park acquisition.