We've learned now about sandstone, marble, basalt and limestone rock.
Another type of metamorphic rock is slate.
Slate is made up of volcanic ash and clay that has been squished together over many years, until they become hard and flat.
(from: wikipedia - slate)
Since slate is so hard and flat, it was used to build many things like roof tiles.
(from: wikipedia - slate)
Kid Facts - Blast from the past: Solid, Liquid, Gas
