Geologic History of Yellowstone What is the sequence of geologic events that resulted in the Yellowstone that we see today? How can we know that present day Yellowstone was a marine/beach environment ~500 million years ago? When did the 3 most recent supereruptions occur? Earth Materials What defines and characterizes matter? What distinguishes different elements? What distinguishes minerals from matter? In other words, what criteria do geoscientists use to decide if something is a mineral? What gives a mineral its unique physical character? What distinguishes rocks from minerals? What is the most common mineral class on Earth? Why? How do we classify rocks? What are the distinguishing characteristics of the three rock types? And what do they tell us about different Earth processes? What are the different compositions of igneous rocks? On what basis do we define these different compositions? .