Randomly arranged interlocking crystals and no fossils Randomly arranged interlocking crystals and fossils Banded crystals and no fossils No crystals and no fossils
Large crystals Small crystals Banded crystals No crystals
An extrusive igneous rock An intrusive igneous rock An extrusive sedimentary rock An intrusive metamorphic rock
Chemical erosion over thousands of years Wind erosion over millions of years Nuclear reactions over thousands of years Heat and pressure over millions of years
Very cold running water Tree roots An igneous intrusion Strong winds
Sand Sandstone Mud Limestone
Always contains fossils Sometimes contains fossils Never contains fossils Is made from fossils