Geology Exam I Study Guide Flashcards

Flashcards covering Earth's interior, plate tectonics, mineralogy, civil engineering applications, and soil science based on the Exam I study guide.

What is uniformitarianism?

The geological principle that the physical processes operating on Earth today operated in the same manner in the past.

How are the different layers of the Earth oriented, and why are they arranged this way?

Earth's layers are arranged by density, with the densest materials located at the center (core) and the least dense materials forming the outermost layer (crust).

Who proposed the hypothesis of continental drift?

Alfred Wegener.

What are the two types of tectonic plates, and what characteristics differentiate them?

Continental crust and oceanic crust. Continental crust is thicker, less dense, and primarily granitic, whereas oceanic crust is thinner, denser, and primarily basaltic.

How far have humans drilled into the interior of the Earth?

Humans have drilled to a maximum depth of approximately $12.2\,\text{km}$ ($7.6\,\text{mi}$) at the Kola Superdeep Borehole, reaching only a tiny fraction of the distance to Earth's center.

What causes the motion inside Earth's interior, and how does it relate to plate motion?

Internal heat drives mantle convection currents. These circulating currents move the overlying tectonic plates through processes like ridge push, slab pull, and mantle drag.

What are the three main types of plate boundaries and what occurs at them?

Divergent boundaries (plates move apart, creating new crust), convergent boundaries (plates collide, forming subduction zones or mountains), and transform boundaries (plates slide horizontally past each other).

What are hot spots in plate tectonics?

Unusually hot areas in the mantle that produce volcanic activity independently of tectonic plate boundaries as plates move over stationary mantle plumes.

What hazards are associated with plate boundaries, and where do volcanoes form?

Hazards include earthquakes, volcanic eruptions, tsunamis, and landslides. Volcanoes form primarily along subduction zones at convergent boundaries, rift zones at divergent boundaries, and at mantle hot spots.

What are the essential requirements for a substance to be defined as a mineral?

A mineral must be naturally occurring, inorganic, solid, have a definite chemical composition, and possess an ordered internal crystalline structure.

What is the primary difference between a mineral and a rock?

A mineral is a single naturally occurring inorganic solid with a specific chemical composition and crystal structure, while a rock is an aggregate made up of one or more minerals or mineraloids.

What are atoms and molecules in geological contexts?

Atoms are the fundamental units of chemical elements consisting of protons, neutrons, and electrons. Molecules and compounds are structures formed when two or more atoms bond chemically.

In what ways do minerals form?

Minerals form through crystallization from magma or lava, precipitation from aqueous solutions, organic activity, or metamorphic recrystallization under high heat and pressure.

What are the primary ways to break apart or alter minerals?

Minerals can be physically broken along planes of weak bonding (cleavage) or irregular surfaces (fracture), and chemically broken down through weathering processes like dissolution, oxidation, and hydrolysis.

What is Bowen's reaction series and how does it relate to mineral assemblages?

Bowen's reaction series illustrates the specific sequence in which silicate minerals crystallize from cooling magma at predictable temperatures, determining which minerals can naturally coexist together.

Why is mineralogy important for civil engineering, and what major problems can occur?

It dictates the mechanical strength and stability of rock and soil for construction. Major engineering problems include swelling clays that damage foundations, soluble minerals causing sinkholes, and acid producing sulfide minerals.

What is the difference between soil and regolith?

Regolith is the entire layer of loose, uncompressed rock debris and weathered material covering solid bedrock, whereas soil is the uppermost portion of regolith containing organic matter, water, air, and supporting plant life.

What is the difference between weathering and erosion?

Weathering is the physical or chemical breakdown of rocks and minerals in place at Earth's surface, whereas erosion is the transportation of that weathered material by wind, water, ice, or gravity.

What key factors influence soil formation?

Parent material, climate, biological activity (organisms), topography/relief, and time.

What are soil horizons, and what are the main horizon designations?

Soil horizons are distinct layers parallel to the soil surface that differ in physical and chemical properties. The main horizons are O (organic), A (topsoil), E (eluviated layer), B (subsoil), C (parent material), and R (unweathered bedrock).