• Question: What's the difference between the sea rock and the mountain rocks? And is there a special reason why

    Asked by anon-275839 to Rachel on 12 Jan 2021.
    • Photo: Rachel Brackenridge

      Rachel Brackenridge answered on 12 Jan 2021:

      This is an excellent question. The rocks that make up the mountains tend to be very old, squeezed and pushed up onto land to make high mountain chains. Over time, rain and ice breaks up these old rocks and transports them towards the sea. So the rocks in the ocean are made up of small pieces of the mountains and land. But there are other things the ocean there are also other bits that make up the rocks – shells of animals (like you find at the beach and under the microscope) and submarine lavas from underwater volcanoes.

Comments

  • Photo: Graham

    Graham commented on :

    Rocks beneath the seafloor have a higher density than most rocks on land. Because of that difference, rocks on land bob up (like ice bergs on water) above sea level. Where you have mountains, that means that the low density rocks underground (the crust) are really thick, as much as 70 km under the ?Himalayas!