Geology is the study of the Earth — its materials, structures, and the slow, powerful processes that shape it over deep time. Mountains rise and wear away, oceans open and close, and layer upon layer of rock records hundreds of millions of years of history. Reading that record is how we know a Stegosaurus walked Wyoming some 150 million years ago.
The three kinds of rock
Every rock on Earth belongs to one of three families, each formed a different way:
- Igneous — cooled and hardened from molten rock. Granite cools slowly deep underground; basalt and pumice erupt from volcanoes.
- Sedimentary — built from layers of sediment (sand, mud, shells) pressed and cemented over time. This is the rock that preserves fossils. The dinosaurs of Bosco’s RockPile came from the Morrison Formation, a sedimentary layer laid down across the American West in the Late Jurassic.
- Metamorphic — existing rock transformed by heat and pressure deep in the crust. Limestone becomes marble; shale becomes slate.
These aren’t fixed states. Over millions of years rock is melted, eroded, buried, and remade in an endless loop geologists call the rock cycle.
Reading deep time
Sedimentary rock builds up in layers — oldest at the bottom, youngest on top — a stacked diary of the past. By reading those layers, and the fossils and minerals within them, geologists reconstruct ancient environments, date events, and trace the Earth’s restless history. That same restless Earth is still at work today, which is why this site also tracks live seismic activity from Soquel.
Explore the earth science here
- Rocks — specimens from the collection
- Minerals — and how they’re identified
- Mohs Hardness Scale
- Volcanoes
- Paleontology & Fossils
- Earth Science Station — seismology & earthquakes