The Rock Cycle Loop

In the picture

1. 1Basalt crust: lava cools and hardens into igneous rock
2. 2River pebbles: wind, water and ice wear rock down and carry it away
3. 3Sea floor layers: buried sediment is compacted and cemented into sedimentary rock
4. 4Folded glowing layers: heat and pressure change rock into metamorphic rock without melting it
5. 5Magma pool: rock melts deep underground and can rise again

Examples

• Pumice in a bathroom, used to scrub skin, is an igneous rock that formed from frothy lava cooling very fast.
• Marble kitchen worktops are metamorphic rock that was once limestone, a sedimentary rock made from shells.

Quiz: The Rock Cycle Loop (Age 14)

1. 1

   How does metamorphic rock form?

   • Lava cools and hardens at the surface
   • Heat and pressure deep underground change existing rock without melting it
   • Buried layers of sediment are squeezed and cemented together
2. 2

   A sedimentary rock is part of the rock cycle. What can it eventually become?

   • Either an igneous rock or a metamorphic rock
   • Only another sedimentary rock
   • Only a metamorphic rock, never an igneous one
3. 3

   What drives the rock cycle, and how long does it take?

   • Ocean tides grinding rocks down, over a few thousand years
   • Sunlight melting rocks at the surface, over a few centuries
   • Earth’s internal heat and weathering at the surface, over millions of years

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.