Changes

Twelve or so plates slide over a partially molten lithosphere, and the continents, embedded in some of the plates, are carried by them. Where plates collide, mountains such as the [[Himalayas]] or the [[Rocky Mountains]] are formed. In some places, called subduction zones, one plate sinks beneath another plate and returns to the molten regions of the athenosphere. Along mid-oceanic ridges magma emerges to expand the plate and create new sea floor.

Twelve or so plates slide over a partially molten lithosphere, and the continents, embedded in some of the plates, are carried by them. Where plates collide, mountains such as the [[Himalayas]] or the [[Rocky Mountains]] are formed. In some places, called subduction zones, one plate sinks beneath another plate and returns to the molten regions of the athenosphere. Along mid-oceanic ridges magma emerges to expand the plate and create new sea floor.

==How Old is the Earth==

==Age of the Earth==

There is not universal agreement on how old the Earth is.  Modern geologists calculate an age for the Earth based on their observations and assumptions.

There is not universal agreement on how old the Earth is.  Modern geologists calculate an age for the Earth based on their observations and assumptions.

Most geologists conclude that the Earth is approximately 4.6 billion years old

Most geologists conclude that the Earth is approximately 4.6 billion years old