Earth's Structure

Basalt

A dark, dense igneous rock. Basalt. Basalt is a volcanic rock formed from the rapid cooling of lava at Earth's surface.

Cementation

A process where sediment grains are cemented together. Cementation. It is when minerals fill the spaces between sand grains, gluing them to form solid rock.

Clastic rock

Sedimentary rock that forms when rock fragments are squeezed together, like sandstone. Clastic rock. Clastic rocks are formed from pieces of other rocks compacted and cemented together.

Compaction

The process by which sediments are compressed by the weight of layers above. Compaction. In simple terms, compaction is when layers of sediment are pressed together tightly over time.

Deposition

The process of dropping sediment by water or wind is called deposition. Deposition is when particles are carried by wind or water and are eventually dropped in a new location.

Erosion

The process in which rock is worn away and transported by water, wind, or ice erosion. Erosion is when natural forces like water or wind gradually wear away and move rocks and soil from one place to another.

Extrusive rock

Igneous rock that forms when lava cools on Earth's surface. Extrusive rock. Extrusive rock is formed from lava that cools quickly on the Earth's surface, creating fine-grained textures.

Foliated

Metamorphic rocks with mineral grains arranged in parallel layers. Foliated. Foliated means that the mineral grains in the rock are aligned in flat, parallel layers.

Granite

A light-colored igneous rock. Granite. Granite is a type of rock formed from cooled and solidified magma, made mostly of minerals like quartz and feldspar.

Intrusive rock

Igneous rock that forms when magma hardens beneath Earth's surface. Intrusive rock. Intrusive rock is a type of igneous rock that solidifies from magma beneath the Earth's surface.

Metamorphic rock

The rock that forms when existing rock is changed by heat, pressure, or chemicals. Metamorphic rock is rock that has been transformed by heat, pressure, or chemical processes.

Nonfoliated

Metamorphic rock with mineral grains not arranged in layers. Nonfoliated. In simple terms, nonfoliated rocks have mineral grains that are randomly arranged, not in layers or sheets.

Rock cycle

A process that changes rocks from one form to another. Rock cycle. The rock cycle is the journey of rocks transforming through stages like melting, cooling, eroding, and reforming over time.

Sediment

Particles of rock and other materials deposited by water or wind. Sediment. Sediment is the tiny pieces of rock and remains that settle at the bottom of bodies of water or are carried by the wind.

Sedimentary rock

A rock that forms when sediment is pressed and cemented together. Sedimentary rock. Sedimentary rock is formed from layers of smaller rocks and minerals that are compressed over time.

Stalactite

A deposit that hangs from the roof of a cave stalactite. Stalactites are icicle-shaped formations created by mineral-rich water dripping and depositing minerals from the ceiling of a cave over time.

Stalagmite

A cone-shaped deposit that builds up from the floor of a cave. Stalagmite. A stalagmite is a mineral formation that grows upward from the floor of a cave as minerals from dripping water accumulate over time.

Texture

The size, shape, and grains of a rock. Texture. Texture is the feel or appearance of a surface, determined by the size and arrangement of its particles.