Changes on earth .
地球上的变化。
Earth's landforms are always changing.
地球的地貌总是在变化。
They usually change very very slowly
它们的变化通常非常非常缓慢。
When continents move against each other land can be moved upwards .
当大陆相互移动时，陆地可以向上移动。
This is how mountains are made
山就是这样造出来的
weathering can change landforms.
风化可以改变地貌。
weathering is caused by rain and wind.
风化是由风雨造成的。
rain soaks into rock and the rock wears away .
雨水渗入岩石，岩石磨损。
the wind also wears away rock .
风也会吹走岩石。
mountains can be worn down to become hills
山可以被磨损成小山
A glacier moves down a mountain very slowly .
冰川非常缓慢地下山。
it wears away the mountain and takes rock with it
它会把山磨掉并带走岩石
glaciers can make valleys.
冰川可以形成山谷。
sometimes landforms can change quickly.
有时地貌会迅速变化。
the moving continents can cause earthquakes.
移动的大陆会引起地震。
the land moves up and down quickly.
土地快速上下移动。
an earthquake can cause a landslide
地震会引起山体滑坡
many rocks fall down and landforms change.
许多岩石倒下，地貌发生变化。
when a volcano erupts lava comes up from the earth's mantle
当火山爆发时熔岩从地幔中喷出
lava can make new land and landforms quickly.
熔岩可以迅速形成新的土地和地貌。
the islands of hawai were made by a volcano
夏威夷群岛是由火山形成的