Back to OlogistsMeet the OlogistMore from Chuck

BackNext
Do all rocks come from volcanoes? This sedimentary rock has layers of iron-rich minerals.
This sedimentary rock has layers of iron-rich minerals.
   
Chuck Said
No, there are many rocks that don't come from volcanoes.

For example, some rocks are created when sediments are deposited in water. Sediments can be sand or silt, which are fine grains of minerals. This might occur along the beach, or at the mouths of streams and rivers. Over time, more and more silt and sand accumulate, eventually forming a thick pile.

Because of the great weight of the thick layer of sediments, water is driven out. The loose grains of sediment join together to form a rock.