When the mountains got eroded, sediments broke off, and rolled down the mountain into the lowlands, that were oceans at the time, and the pressure from all the rocks fused them together, making it a sheet of sedimentary rock.
When the mountains got eroded, sediments broke off, and rolled down the mountain into the lowlands, that were oceans at the time, and the pressure from all the rocks fused them together, making it a...