Introduction to Geology

Geology Introduction

• Geology is the study of Earth.

Science

• Science is a systematic process to understand the natural world through observation, experiment, and analysis.

Kola Superdeep Borehole

• The Kola Superdeep Borehole was a deep drilling project in Russia's Kola Peninsula.

• It aimed to investigate Earth's deep interior.

• The project was unlikely to reach the mantle due to the extreme temperatures and pressures at depth, combined with technical limitations.

Continental vs. Oceanic Crust

• Continental crust is thicker and less dense than oceanic crust.

• Continental crust is primarily composed of granite.

• Oceanic crust is primarily composed of basalt.

Earth in Context

Scientific Method

• A systematic approach to understanding the natural world.

Geocentric Model

• Earth-centered model of the universe.

Heliocentric Model

• Sun-centered model of the universe.

Milky Way

• The Milky Way galaxy is vast, containing billions of stars. (Approximate size & number of stars not provided)

Galaxies

• Hubble and James Webb telescopes have yielded estimates of the number of galaxies in the universe. (Estimate not provided)

Doppler Effect

• The change in frequency of a wave in relation to an observer who is moving relative to the source of the wave.

• It provides information about the movement of celestial objects (e.g., galaxies).

Big Bang Theory

• The prevailing cosmological model for the universe's origin. (Key points not given in detail.)

• Elements beyond Hydrogen and Helium were formed in stars and supernovae.

Early Universe

• The early universe consisted predominantly of hydrogen and helium. (Details not provided.)

Nebular Theory

• The theory explaining the formation of planetary systems. (Details not provided.)

Solar System

• Order of planets from the Sun (not provided).

Earth’s Interior

• Earth's interior differentiated into layers (crust, mantle, core) due to density differences.

Formation of the Moon

• The formation of the moon is believed to have been caused by a collision between Earth and a Mars-sized object. (Exact time not provided)

Earth’s Magnetic Field

• Earth's magnetic field is caused by the motions of molten iron in the outer core.

• Protects Earth from harmful solar radiation.

Earth's Atmosphere

• Primarily composed of nitrogen and oxygen.

Glass vs. Mineral

• Glass is not a mineral because it's not crystalline.

Silica

• Silica is composed of silicon and oxygen.

Pressure and Temperature with Depth

• Pressure and temperature increase with depth into the Earth.

Geothermal Gradient

• The rate at which temperature increases with depth within the Earth.

Crust, Mantle, Core

• Layers of Earth's structure (basic characteristics).

Moho

• The boundary between Earth's crust and mantle.

Asthenosphere and Lithosphere

• The asthenosphere is a semi-molten layer within the upper mantle.

• The lithosphere is the rigid outer layer, comprising the crust and upper mantle.

Plate Tectonics

Alfred Wegener

• Alfred Wegener proposed the continental drift hypothesis based on several observations.

Wegener's Observations

• Continents' fit
• Paleoclimate data
• Distribution of fossils
• Matching geologic units

Pangea

• A supercontinent that existed millions of years ago.

Paleomagnetism

• The study of Earth's ancient magnetic field recorded in rocks.

Seafloor Spreading

• The process where new oceanic crust forms at mid-ocean ridges.

Volcano/Earthquake Distribution

• Volcanoes and earthquakes are concentrated along plate boundaries.

Geographic vs. Magnetic Poles

• These poles are distinct; their locations vary.

Bathymetry

• The measurement of ocean depths.

Age of Seafloor

• The age of seafloor rock increases away from mid-ocean ridges due to seafloor spreading.

Magnetic Reversals

• Changes in Earth's magnetic field direction.

Plate Tectonic Theory

• The theory explaining the movement and interaction of Earth's lithospheric plates.

Oceanic Crust

• Oceanic crust is relatively young.

Plate Boundaries

• Divergent (plates move apart)
• Convergent (plates collide)
• Transform (plates slide past each other)

Plate Movement Rates

• Plate movement rates vary.

Continental Margins

• Active (dynamic) and passive (stable).

Hot Spots

• Volcanic activity localized above mantle plumes.

Triple Junctions

• Where three plate boundaries meet.

Ridge-Push vs. Slab-Pull

• Forces driving plate movement.

Minerals

Elements

• Fundamental building blocks of matter.

Atomic Number vs. Atomic Mass

• Atomic number = number of protons; Atomic mass = mass of protons and neutrons

Ions (cations, anions)

• Atoms with electrical charges.

Chemical Bonds

• Attractive forces holding atoms together in compounds.
• ionic, covalent, metallic, van der Waals

Molecules vs. Compounds

• Molecules are groups of atoms bonded together; Compounds are molecules made of different elements.

Mineral Definition

• A naturally occurring, inorganic solid with a specific chemical composition and ordered atomic arrangement.

Polymorphs

• Minerals with the same chemical composition but different crystal structures.

Anhedral vs. Euhedral

• Anhedral crystals grow without crystal faces. Euhedral crystals have well-formed faces.

Mineral Identification

• Methods for identifying minerals (color, streak, luster, hardness, specific gravity, crystal habit, cleavage, fracture, special properties).

Color Issues

• Color is not reliable for mineral identification.

Mohs Hardness Scale

• A scale for measuring mineral hardness.

Mineral Groups

• Silicates, oxides, sulfides, carbonates, halides, native metals
• Silicates are most abundant in continental crust.

Silica Tetrahedron

• The fundamental building block of silicate minerals.