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The thalweg of a river. In geography, hydrography, and fluvial geomorphology, a thalweg or talweg (/ ˈ t ɑː l v ɛ ɡ /) is the line or curve of lowest elevation within a valley or watercourse. [1] Its vertical position in maps is the nadir (greatest depth, sounding) in the stream profile.
Convergent boundaries are areas where plates move toward each other and collide. These are also known as compressional or destructive boundaries. Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This ...
The Juan de Fuca and Gorda plates are moving east-northeast, subducting under the North American plate at a much slower rate of 2.5 to 3 cm per year. [6] Because the ridge is divided into three distinct parts, each section has its own spreading rate, caused by the slab-pull and ridge-push of the surrounding tectonic plates .
Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago.
The Gorda plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon plate. It is sometimes referred to (by, for example, publications from the USGS Earthquake Hazards Program) [ 1 ] as simply the southernmost portion of the neighboring Juan de Fuca plate , another Farallon ...
The Mendocino fracture zone is a fracture zone and transform boundary over 4000 km (2500 miles) long, [1] starting off the coast of Cape Mendocino in far northern California. It runs westward from a triple junction with the San Andreas Fault and the Cascadia subduction zone for about 300 km to the southern end of the Gorda Ridge .
As the edge of North America moved away from the hot rift zone, it began to cool and subside beneath the new Atlantic Ocean. This once-active divergent plate boundary became the passive, trailing edge of westward moving North America. In plate tectonic terms, the Atlantic Plain is known as a classic example of a passive continental margin. [20]
Neenach Volcano is an extinct Miocene volcano in the Coastal Ranges of California. After formation, the volcanic field was split by a fault in the San Andreas Fault Zone , and over the last 23 million years, the two halves of the volcano have moved about 195 miles (314 kilometers) apart.