Continental Rifts, Dramatic Deserts and Supervolcanoes
The third stage of the trip looks at the leading edge of the North American plate in the dramatic scenery of the high desert of the Owen’s Valley. This is part of the East California Shear Zone – a 200km wide zone where the Earth surface is being torn apart. This has generated dramatic basin and range geomorphology, but also zones of recently active and highly explosive volcanicity. This includes the Long Valley Caldera, a ‘supervolcano’ which erupted around 760,000 years ago in one of the largest eruptions in recent geological history, during which 600km3 of material was erupted in a two-day period. This area is one of the most monitored active volcanoes on Earth, and the site of geothermal activity and energy generation. While in the Owen’s Valley, we also learn how to help understand future earthquake events and look at the role of climate change and man-made environmental impacts.
The field trip then crosses the East California Shear zone to reach Death Valley for the penultimate stage of the trip. Death Valley is a major continental rift basin, where the crust is being locally stretched east-west. This has created enormous faults which have displaced the Earth surface to form high mountains and a deep valley, which is currently 86m below sea-level (the lowest point in the western hemisphere). The tectonically generated topography of the region has also dramatically modified the climate, making Death Valley one of the hottest places on Earth (though not when we visit in April). When in Death Valley, students learn how continental rifts evolve and how tectonic movements control desert processes, environments and landforms (canyons, sand dunes, alluvial fans, salt pans).