Rocks and Earth Materials

Craters, vents, and sills are all recognized geological features or structures associated with volcanoes. A lump is not a recognized geological term for a part of a volcano.

Magma is the term for molten rock stored within the Earth's crust or mantle, which is inside the volcano.

Yellowstone sits atop a volcanic hotspot. The heat from the underlying molten rock (magma) warms the groundwater, creating the park's famous geysers and hot springs.

Clay and granite are both impermeable materials. Clay particles are packed too tightly for water to pass through, and solid granite lacks the interconnected pores needed for permeability.

Plinian eruptions are characterized by violent explosions and the ejection of ash and pumice.

Stalactites and stalagmites are composed primarily of calcium carbonate, which is deposited from water seeping through limestone or other carbonate rocks.

Stalactites form when water seeps through the ceiling of a cave and drips onto the floor. As the water evaporates, the calcium carbonate it contains is deposited, forming a stalactite.

Stalagmites form when water seeps through the walls of a cave and drips onto the floor. As the water evaporates, the calcium carbonate it contains is deposited, forming a stalagmite.

Soda straws are not speleothems, but rather a type of mineral deposit found in caves.

Stalactites and stalagmites are made of calcium carbonate, which is deposited from water seeping through limestone or other carbonate rocks.

Basalt is the most common type of rock found in asteroid impact craters.

Olivine is the most common type of mineral found in asteroid impact craters.

The Hoba meteorite is the largest known meteorite, weighing over 60 tons.

The Tunguska meteorite is the most famous meteorite, due to the large explosion it caused in 1908.

Solution caves are formed when water seeps into cracks and crevices in soluble rocks, gradually dissolving the rock and creating cave passages over time.