Science Olympiad Dynamic Planet Practice Test

What is the characteristic of basalt in geological terms?

1. A dark, dense rock that underlies the ocean floor

2. A lightweight rock found primarily on land

3. A sedimentary rock formed from organic remains

4. A type of metamorphic rock formed under high pressure

The correct answer is: A dark, dense rock that underlies the ocean floor

Basalt is primarily characterized as a dark, dense volcanic rock that commonly underlies ocean floors. It is an igneous rock formed from the rapid cooling and solidification of lava that is rich in iron and magnesium, which contributes to its darker color and high density. This makes basalt a fundamental component of oceanic crust, providing support to the structure of the seafloor and playing a critical role in plate tectonics and volcanic activity. The presence of basalt in oceanic regions is significant for understanding geological processes such as seafloor spreading and plate subduction. Its composition and formation process distinguish it clearly from other rock types, such as the lightweight rocks typically found on land, sedimentary rocks, which form from the accumulation of organic materials, or metamorphic rocks, which develop under extreme temperatures and pressures from existing rocks.