Elena Rossi
@elena_rossi • 1 months ago
Converts a chapter into a text concept map: core idea, key concepts, labeled links and cross-links, a tree outline, and gaps the chapter leaves open.
chapter_text{{chapter_text}}chapter_text: Earth's outer shell, the lithosphere, is broken into large pieces called tectonic plates. The lithosphere includes the crust and the rigid upper part of the mantle. The plates rest on the asthenosphere, a hotter, partly molten layer of the mantle that can flow slowly. Heat from Earth's interior drives convection currents in the mantle, which help move the plates a few centimeters per year. Where plates meet, we find plate boundaries. At divergent boundaries, plates move apart; magma rises to fill the gap and forms new crust, as at the Mid-Atlantic Ridge. At convergent boundaries, plates collide. When an oceanic plate meets a continental plate, the denser oceanic plate sinks beneath it in a process called subduction, producing deep ocean trenches and volcanoes, as in the Andes. When two continental plates collide, neither sinks easily, so the crust crumples upward into mountain ranges like the Himalayas. At transform boundaries, plates slide past each other horizontally; stress builds up and is released as earthquakes, as along the San Andreas Fault. Evidence for plate movement includes matching fossils on continents now separated by oceans, the fit of coastlines such as South America and Africa, and the pattern of earthquakes and volcanoes, which cluster along plate boundaries. The idea of moving plates grew out of Alfred Wegener's earlier theory of continental drift, which lacked a mechanism to explain the motion.