Test: Rocks - Grade 7 MCQ

Gneiss is a metamorphic rock, whereas basalt, granite, and pumice are types of igneous rocks. Understanding the classification of rocks helps in identifying their origins and characteristics.

The rock cycle illustrates the continuous process through which rocks change from one type to another over time, including igneous, sedimentary, and metamorphic forms, driven by geological processes.

Organically formed rocks, such as limestone, are created from the compression of plant and animal remains over geological time. This type of sedimentary rock is significant for understanding past life on Earth.

Sedimentary rocks are most likely to contain fossils, as they are formed from the accumulation of sediments, including organic remains, which can be preserved over time. Fossils provide valuable insights into the history of life on Earth.

Granite primarily consists of quartz, feldspar, and mica. Quartz is a major component, contributing to granite's durability and resistance to weathering.

Lithification is the process of compacting and cementing loose sediments to form solid sedimentary rocks. It involves both compaction under pressure and the binding of particles together by natural cements.

Extrusive igneous rocks cool rapidly on the Earth's surface, resulting in a fine-grained texture. An example is basalt, which is commonly found in volcanic areas.

Igneous rocks are formed through the cooling and solidification of molten magma, either beneath the Earth's surface (intrusive) or on the surface (extrusive). They are the primary type of rock and serve as the foundation for other rock types.

Mechanical metamorphism primarily changes the texture of rocks through physical processes such as crushing, while chemical metamorphism involves chemical reactions that change the mineral composition of the rocks.

Marble is formed from the metamorphism of limestone under high temperatures and pressures. This process alters the mineral structure, resulting in a rock that is often used in sculptures and buildings due to its aesthetic qualities.

Metamorphism is the process that alters the mineral composition and structure of existing rocks due to high pressure and temperature, resulting in the formation of metamorphic rocks.

Sedimentary rocks, such as limestone, are formed from the accumulation of the remains of marine organisms, including shells and skeletons, over time. This process highlights the importance of biological activity in rock formation.

Thermal metamorphism occurs when rocks are subjected to extreme heat from magma or lava, leading to changes in mineral composition and texture. This type of metamorphism typically affects rocks in close proximity to igneous intrusions.

Sedimentary rocks can form through evaporation, leading to the deposition of minerals as water evaporates, which can result in rocks like rock salt or gypsum.

Sedimentary rocks cover approximately 75% of the Earth's surface. They form from the accumulation of sediments and are often layered, providing insights into the Earth's history.

Granite is an example of an intrusive igneous rock, formed from magma that cools slowly beneath the Earth's surface, resulting in large crystals. In contrast, basalt is an extrusive igneous rock that cools quickly on the surface.

Rocks contribute to soil formation by undergoing weathering processes that break them down into smaller particles, enriching the soil with minerals essential for plant growth.

Lithification is the process by which loose sediments are compacted and cemented to form solid sedimentary rock. This process can occur through compaction and cementation, turning loose particles into a cohesive mass.

Rocks are composed of one or more minerals and do not have a definite chemical composition, whereas minerals have a specific chemical structure and composition. This distinction is fundamental in geology.

Water is the primary agent of erosion that transports and deposits sediments, which are then compacted and cemented to form sedimentary rocks. This process is pivotal in shaping the Earth's surface.