Question

The plate tectonic had an earlier theory . What was the explanation of that thoery

Answer 1

Answer:

EARTH'S TECTONIC PLATES

Seafloor and continents move around on Earth’s surface, but what is actually moving? What portion of the Earth makes up the “plates” in plate tectonics? This question was also answered because of technology developed during war times – in this case, the Cold War. The plates are made up of the lithosphere.

A map of the world with all earthquakes from 1963 to 1998 plotted. The earthquakes all line up around the plate boundaries.

Earthquakes outline the plates.

During the 1950s and early 1960s, scientists set up seismograph networks to see if enemy nations were testing atomic bombs. These seismographs also recorded all of the earthquakes around the planet. The seismic records could be used to locate an earthquake’s epicenter, the point on Earth’s surface directly above the place where the earthquake occurs.

Movement of the plates over Earth’s surface is termed plate tectonics. Plates move at a rate of a few centimeters a year, about the same rate fingernails grow.

HOW PLATES MOVE

Cross-section of the earth. At the center of the earth is the inner core. Surrounding that is the outer core and surrounding that is the mantle, which has convection cells. At the surface is the ocean, upon which is the mid-oceanic ridge. Mantle convection drives plate tectonics. Hot material rises at mid-ocean ridges and sinks at deep sea trenches, which keeps the plates moving along the Earth’s surface.

Hot mantle from the two adjacent cells rises at the ridge axis, creating new ocean crust.

The top limb of the convection cell moves horizontally away from the ridge crest, as does the new seafloor.

The outer limbs of the convection cells plunge down into the deeper mantle, dragging oceanic crust as well. This takes place at the deep sea trenches.

The material sinks to the core and moves horizontally.

The material heats up and reaches the zone where it rises again.

PLATES BOUNDARIES

Plate boundaries are the edges where two plates meet. Most geologic activities, including volcanoes, earthquakes, and mountain building, take place at plate boundaries.

How can two plates move relative to each other?

•Divergent plate boundaries: the two plates move away from each other.

•Convergent plate boundaries: the two plates move towards each other.

•Transform plate boundaries: the two plates slip past each other.