Rocks and Earth Materials

Continental crust is predominantly composed of granitic rocks, which are coarse-grained, light-colored igneous rocks. Basalt is the main component of oceanic crust, while iron and nickel are elements found mostly in the Earth's core.

The mantle is the thickest compositional layer of the Earth and is composed of hot, solid silicate rock that can flow very slowly under high pressure. While it is solid, it is often described in introductory science as behaving like a thick, semi-solid fluid or containing magma sources. The crust and core are the other compositional layers, with the inner core being solid metal.

Igneous rocks are formed from the cooling and solidification of molten rock, which is called magma when underground and lava when it erupts onto the surface.

Sedimentary, metamorphic, and igneous are the three main types of rocks. A mineral is a naturally occurring, inorganic solid with a definite chemical composition and crystalline structure, which serves as a building block of rocks rather than being a rock type itself.

Fossils are almost exclusively found in sedimentary rocks because these rocks form at temperatures and pressures that do not destroy fossil remains. Igneous and metamorphic rocks involve heat and pressure that would melt or crush any organic remains.

Weathering breaks down existing rocks into smaller particles called sediment. Over time, these sediments accumulate, compact, and cement together to form sedimentary rocks. Igneous and metamorphic rocks are formed by heat, pressure, or cooling magma rather than surface weathering.

For loose sediment to become solid sedimentary rock, it must undergo compaction and cementation, which binds the particles together. This process of bonding and hardening is known as lithification. Volcanic heat or deep burial would instead lead to igneous or metamorphic rock formation.

Quartzite is a metamorphic rock formed when quartz-rich sandstone is subjected to high heat and pressure. Limestone is a sedimentary rock, while basalt and granite are igneous rocks.

Both granite and basalt are igneous rocks formed from the cooling and solidification of molten rock. Granite forms slowly underground from magma, while basalt forms quickly on the surface from lava.

Sand is primarily formed by the weathering and erosion of rocks over long periods, where waves and wind break down larger rocks into tiny grains. Option A correctly identifies this process of waves breaking down rocks.

The Altar Stone is a monumental gray-green sandstone block lying flat near the center of Stonehenge. It is distinct from the surrounding sarsen and bluestone megaliths.

Cinder cones, composite volcanoes, and shield volcanoes are all well-established types of volcanic structures. Magma dome is not a standard classification; instead, the term lava dome is used to describe mounds formed by slow-moving, viscous lava.

Rocks are naturally occurring solid aggregates of one or more minerals. Minerals are the building blocks of rocks.

The Law of Crosscutting Relationships states that any feature that cuts across a body of sediment or rock is younger than the body it cuts across.

The Law of Superposition states that in an undisturbed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it.