7th grade exam - all topics

Metamorphic rocks are formed when existing rocks are transformed due to intense heat and pressure deep within the Earth.

Magma is molten rock found beneath the Earth's surface. When it reaches the surface, it's called lava, and the eruption is called a volcanic eruption.

Minerals have a specific chemical formula that determines their composition and properties.

Sedimentary rocks are formed from the accumulation and cementation of weathered sediments, like sand, gravel, or clay.

A white dwarf is a dense, compact star that forms after a red giant star runs out of fuel and sheds its outer layers.

As the Sun evolves into a red giant, it will expand drastically, engulfing Earth and likely, its neighboring planets. This will mark the ultimate fate of our solar system.

The red giant phase occurs when a star exhausts its hydrogen fuel supply, causing the star to expand and cool, becoming a red giant.

Supernova explosions are incredibly powerful events in the universe, marking the explosive death of massive stars. They release vast amounts of energy and create heavy elements.

Temperature changes cause rocks to expand and contract. This repeated process weakens the rock, leading to cracks and ultimately, breakdown.

Glaciers are massive ice sheets that carve out U-shaped valleys as they move. They scrape and erode the surrounding rocks, leaving behind distinct landforms.

Acid rain is a form of precipitation that contains acids, mainly sulfuric acid and nitric acid. These acids can dissolve certain minerals, contributing to the weathering of rocks.

As ice freezes, it expands, putting pressure on any cracks or fissures in rocks. This repeated freezing and thawing cycle widens the cracks, leading to the eventual breakdown of the rock.

Removal is the process of transporting weathered rock fragments from their original location to a new place. This movement can be caused by wind, water, or gravity.

Pangaea was a supercontinent that existed millions of years ago, encompassing all the Earth's landmasses. Over time, it broke apart into the continents we know today.

Wegener used various pieces of evidence to support his theory of continental drift. This included the matching shapes of continents, the distribution of fossils, and geological similarities across distant landmasses.

Tectonic plates are massive slabs of rock that make up the Earth's lithosphere. They move slowly over the molten asthenosphere, causing earthquakes, volcanic activity, and mountain formation.

A subduction zone is an area where one tectonic plate slides beneath another. This process can generate earthquakes, volcanic arcs, and deep ocean trenches.

The Mohs scale of hardness is a scale used to compare the relative hardness of minerals. It ranges from 1 (softest) to 10 (hardest), with each mineral able to scratch those below it.

The streak of a mineral is the color of the powder produced when a mineral is rubbed against a streak plate. This can be a helpful diagnostic tool in mineral identification.

Cleavage refers to the tendency of a mineral to break along specific planes of weakness, resulting in smooth, flat surfaces. Different minerals have different cleavage patterns.

Fracture describes the way a mineral breaks when it doesn't follow specific cleavage planes. This can be irregular, conchoidal (shell-like), or other patterns.

Friedrich Mohs was a German mineralogist who devised the Mohs scale of hardness, a standard method for comparing the resistance of minerals to scratching.

The Mohs scale of hardness ranges from 1 (softest) to 10 (hardest), with 10 being the hardest mineral, diamond.

Rocks buried deep in the Earth, exposed to high temperatures and pressures, undergo changes in their mineral composition and texture. This process forms metamorphic rocks.

Pangaea was a supercontinent that existed millions of years ago, encompassing all the Earth's landmasses. Over time, it broke apart into the continents we know today.