Geology 101 Chapter 2 Flashcards

Geology Concepts and Terms

• Continental Arc: Volcanic arcs that form along continental margins where subduction occurs; displays arc-shaped topographic high regions.

• Continental Drift: Hypothesis by Alfred Wegener asserting all continents were once connected as a supercontinent and began drifting apart around 200 million years ago.

• Continental Rift: Linear zones indicating the stretching and pulling apart of continental lithosphere, potentially marking the start of a new ocean basin.

• Continental Shelf: Submerged continental margin extending gently from coastlines to the continental slope.

• Convection: Heat transfer through the circulation of substances, crucial in mantle dynamics.

• Convergent Boundary: Area where two tectonic plates collide, leading to the subduction of oceanic lithosphere or the formation of mountain ranges from continental collisions.

• Divergent Boundary: Plates move away from each other, allowing mantle material to rise and create new oceanic crust.

• Fault: A fracture in rock where movement has occurred, affecting rock formations.

• Fracture Zone: Irregular topographic regions on the ocean floor, associated with transform faults and their extensions.

• Gabbro: Dark, intrusive igneous rock that forms a significant part of the oceanic crust.

• Granite: A coarse-grained igneous rock, primarily composed of quartz and potassium feldspar, widely utilized in construction.

Influential Figures and Theories

• Harry Hess: Geologist known for sea-floor spreading theories, analyzing relationships between geological features and mantle convection, pivotal for plate tectonic theory.

• Hot Spot: Areas of concentrated heat in the mantle leading to magma production, exemplified by Hawaiian Islands' intraplate volcanism.

• Island Arc: Chains of volcanic islands formed due to subduction of one oceanic plate beneath another, located near oceanic trenches.

• Lithospheric Mantle: The upper layer of the mantle lying beneath the crust, differing in thickness under continental regions.

Geological Processes

• Magnetic Reversal: Changes in Earth’s magnetic field from normal to reverse polarity, impacting geological formations.

• Mantle Plume: An upward movement of hot mantle material, often leading to volcanic activity at the surface.

• Marine Magnetic Anomaly: Variations in Earth’s magnetic field due to the magnetism of ocean floor rocks.

• Mid-ocean Ridge: A continuous underwater mountain range at divergent plate boundaries, varying in width substantially across ocean basins.

• Oceanic Transform Fault: A fracture in the Earth's crust resulting from horizontal motion of tectonic plates.

Paleogeography and Past Climates

• Paleoclimate: Climate existing during a specific time in geological history, essential for understanding past environmental conditions.

• Paleogeography: Exploration of ancient geographical features and how they have changed over time.

• Paleomagnetism: Study of magnetic records in rocks that were formed under the influence of the Earth’s magnetic field at the time of their formation.

• Pangaea: The hypothesized supercontinent that began to break apart approximately 200 million years ago into current continents.

Rock Types and Geological Features

• Peridotite: Ultramafic igneous rock, theorized to be abundant in Earth's upper mantle.

• Plate Boundary: Field divisions between moving plates in Earth’s crust where diverse geological processes occur.

• Plate Tectonics: Theory detailing Earth's outer shell's composition and interactions, responsible for significant geological phenomena including earthquakes and volcanoes.

• Sea-floor Spreading: Hypothesis proposing that new oceanic crust forms at mid-ocean ridges, indicative of divergent activity.

• Subduction and Subduction Zones: Key geological processes and locations at convergent boundaries where one plate is forced under another into the mantle.

Other Geological Terms

• Till: Unsorted sediment deposited by glaciers, providing insights into past climatic conditions.

• Transform Boundary: Fault lines where two tectonic plates slide past each other without generating or recycling crust.

• Trench: Deep, narrow depressions in the ocean floor, significant for subduction zones.

• Volcanic Arc: Chains of volcanoes formed from subduction processes, characterized by distinct arc shapes.

• Alfred Wegener: The scientist who introduced the Continental Drift Theory in the early 20th century, laying foundational concepts for modern geology.