1. What causes mountains, volcanoes, and ridges to form? Why do earthquakes happen? All of these things happen because of the movement
of the earth
plates. These “plates” form the top part of the earth
, called the earth
. They are constantly moving.
2. The crust
can be thought
of as a mixture
, like crackers floating on a bowl of hot soup. The soup (the lava
) is gently stirred by currents below. The crackers (the plates) move slowly and gently, but there’s friction
where two plates push against each other. When one suddenly
gives way, a big change occurs.
3. Scientists who have studied
of these plates have come to these conclusions:
4. One plate
may slide under the other. This may cause
a volcanic eruption
. An example
of this can be found in the Northwestern U.S., where a line of volcanoes stretches from California to Canada.
5. Plates can pull away from each other. Then magma
wells up in between. Magma is lava
that’s still under the ground. The built-up magma
creates a ridge
. An example
of this is occurring under the Atlantic Ocean, where the seafloor is expanding as molten
rock pushes up, and it’s widening the distance
between America and Europe by about 3 inches each year!
6. Plates can push against each other, going in opposite
directions. One can move north and one south, or one east and one west. A split
occurs between the two, called a fault
. This allows the two plates to move in opposite
directions. An example
of this is the San Andreas Fault in California.
7. Two plates may crash directly
into each other. This causes each to buckle
up and creates mountain ranges. An example
of this is the Himalaya mountain range
, where the plate
carrying India crashed into the plate
8. So, although we cannot feel or see the movement
plates, we can see the results. And we can conclude
that these tiny
many great changes.