Yellowstone National Park is home to some 10,000 thermal features, over 500 hundred of which are geysers. In fact, Yellowstone contains the majority of the worlds geysers. Within Yellowstone's thermal features can be seen the product of millions of years of geology at work. Much of Yellowstone sits inside an ancient volcanic caldera (the exploded crater of a volcano). The last major caldera forming eruption occurred 600,000 years ago. For hundreds of thousands of years following that, subsequent lava flows slowly filled in most of the caldera. Even now, in some places, nearly molten rock resides as little as 2-5 miles below the surface. Heat from the volcanic activity makes its presence known by heating ground water and creating the therma features we now see. The four basic types of thermal features present in the Park are geysers, hot springs, fumaroles, and mudpots. Many of these are concentrated in Yellowstone's major geyser basins: Upper, Midway, Lower, Norris, West Thumb, Shoshone and Heart Lake.

PETROLIUM

Oil and natural gas touch our lives in countless ways every day. Together, they supply 65 percent of our nation’s energy. They fuel our cars, heat our homes and cook our food. 

But did you know that oil and natural gas also help generate the electricity that powers our daily lives? Or that crude oil supplies the building blocks for everything from dent-resistant car fenders to soft drink bottles to camping equipment?

Explore this area to learn more about oil and natural gas, how they are produced and how they become the products you count on. You’ll also find useful tips on how to conserve energy and use oil and natural gas products in ways that protect you, your family and our environment.

CAVES

A cave or cavern is any naturally occurring void, recess, or system of interconnecting passages beneath the earth.  Caves underlie 20% of the United States.  These unique and sensitive environments harbor rare animal life, fragile mineral formations and valuable ground water resources.

Cave formations, such as stalactites and stalagmites, take hundreds to thousands of years to form.  These irreplaceable resources provide aesthetic enjoyment for cave visitors.  Mineral deposits, such as onyx and amethyst clusters, also give caves their natural beauty.

Clues from past people and past cultures can be found in caves.  Artifacts such as arrowheads, pottery, woven slippers and tools help archaeologists answer questions about how past cultures lived.  Caves provided shelter and natural resources for prehistoric people.  Rock carvings and mudglyphs inside caves also offer us insight into the lives of these people.

MOUNTAINS

Mountains are produced by forces in the earth that cause parts of the earth's crust to rise while others sink. Uplift of the crust, combined with chemical and physical erosion by air, water, and ice over millions of years, produces the spectacular scenery found in mountains. 

At the very high temperatures and pressures found miles below the earth's surface, rocks can actually flow when density differences are produced by differential heating and cooling of parts of the mantle and lithosphere. The flowing of rocks in the mantle and lithosphere subjects parts of the crust to tension (pulling apart), while other parts are subjected to compression (squeezing together). Rocks are relatively weak and brittle under tension and, consequently, crust under tension tends to break up into giant blocks. Rocks are stronger under compression but when the compressive forces get very large, rocks deform by flowing, folding, and breaking.