Plate Tectonics. Continental Drift. Historical Landmass Locations. Fossil Evidence Supporting Plate Tectonics. Developing the Theory. (1) demonstration of the ruggedness and youth of the ocean floor; (2) confirmation of repeated reversals of the Earth magnetic field in the geologic past;
Red triangles denote active volcanoes
Aerial view of the area around Thingvellir, Iceland, showing a fissure zone (in shadow) that is the on-land exposure of the Mid-Atlantic Ridge.
Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) -- a so-called triple junction (or triple point), where three plates are pulling away from one another
The collision between the Indian and Eurasian plates has pushed up the Himalayas and the Tibetan Plateau
The Himalayas: a fissure zone (in shadow) that is the on-land exposure of the Mid-Atlantic Ridge. Two Continents CollideThe 6,000-km-plus journey of the India landmass (Indian Plate) before its collision with Asia (Eurasian Plate) about 40 to 50 million years ago. India was once situated well south of the Equator, near the continent of Australia.
The Blanco, Mendocino, Murray, and Molokai fracture zones are some of the many fracture zones (transform faults) that scar the ocean floor and offset ridges (see text). The San Andreas is one of the few transform faults exposed on land.
Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo.
Map of part of the Pacific basin showing the volcanic trail of the Hawaiian hotspot-- 6,000-km-long Hawaiian Ridge-Emperor Seamounts chain.
Aerial view, looking north toward San Francisco, of Crystal Springs Reservoir, which follows the San Andreas fault zone.
Map of the San Andreas and a few of the other faults in California, segments of which display different behavior: locked or creeping
Left:Creeping along the Calaveras fault has bent the retaining wall and offset the sidewalk along 5th Street in Hollister, California (about 75 km south-southeast of San Jose). Right:Close-up of the offset of the curb.
Faults are classified on the basis of the kind of motion that occurs on them
21 feet in 1906
Alaska, 1964 - up to 150 Ft