Geology Midterm 1: Earth, Minerals, and System Concepts

What is the Principle of Uniformitarianism?

The principle that geological processes occurring today are similar to those that occurred in the past.

What is the estimated age of the Earth?

4.54 billion years (Ga).

What are the two types of planets in the solar system?

Inner (rocky) planets and outer planets.

What is the chemical composition of the Sun?

98% hydrogen and helium.

What nuclear reaction produces the Sun's heat?

Nuclear fusion.

What are the main compositional layers of the Earth?

Crust, mantle, and core.

What are the mechanical layers of the Earth?

Lithosphere, asthenosphere, mesosphere, outer core, and inner core.

What distinguishes continental crust from oceanic crust?

Density and thickness.

What are the important variables in geology?

Composition, temperature, pressure, volume, and density.

What is the Giant-impact hypothesis?

A theory explaining the formation of the Moon by a collision between Earth and a Mars-sized body.

What is the composition of the modern atmosphere?

Mostly nitrogen (N2), oxygen (O2), argon (Ar), and trace gases like carbon dioxide (CO2).

What is the role of atmospheric ozone (O3)?

It protects life on Earth by absorbing harmful ultraviolet radiation.

What are the classes of minerals?

Silicates, oxides, sulfides, sulfates, halides, and carbonates.

What defines a mineral?

A naturally occurring, inorganic solid with a definite chemical composition and crystalline structure.

What is a silica tetrahedron?

A fundamental building block of silicate minerals, consisting of one silicon atom surrounded by four oxygen atoms.

What are the most common minerals in the Earth's crust?

Feldspar and quartz.

What is the Mohs Hardness Scale used for?

To rank minerals based on their hardness.

What is a polymorph?

Minerals that have the same chemical composition but different crystal structures, such as diamond vs. graphite.

What is nitrogen fixation?

The process by which atmospheric nitrogen is converted into a form usable by living organisms.

What are convection currents?

Circulating movements of fluid caused by temperature differences, important in geology for plate tectonics.

What is the carbon cycle?

The process by which carbon is exchanged among the atmosphere, oceans, soil, and living organisms.

What is the significance of the tidal force in the context of Earth's formation?

It played a role in shaping the early Earth and its interactions with the Moon.