Introduction to Physical Geology & Plate Tectonics

Comprehensive vocabulary flashcards covering basic geology concepts, plate tectonics, mineral identification, and classification of igneous and metamorphic rocks based on transcript notes.

Density

Mass per unit volume; calculated as mass ÷ volume.

Formula for Density

D = rac{m}{v}

High Density

More mass packed into the same volume.

Low Density

Less mass packed into the same volume.

Oceanic Crust

Thin, dense crust made mostly of basalt and gabbro.

Continental Crust

Thick, less dense crust made mostly of granite and intermediate rocks.

Thickness of Oceanic Crust

About $5-10\,\text{km}$.

Thickness of Continental Crust

About $30-70\,\text{km}$.

Why Oceanic Crust Sinks

It is denser than continental crust.

Why Continental Crust Stands Higher

It is less dense and more buoyant.

Plate Tectonics

Movement of Earth’s lithospheric plates over the asthenosphere.

Topography

The shape and elevation of Earth’s surface.

How Density Affects Topography

Less dense crust sits higher; denser crust sits lower.

Subduction

Process where one tectonic plate sinks beneath another.

Ancient Mountain Building (Field Trip Note)

Plate collisions formed mountains and metamorphic rocks in New England.

Erosion

Wearing away of rock by wind, water, and weathering.

Glacier

Large moving mass of ice that erodes and deposits sediment.

Ice Age Effect on Connecticut

Glaciers reshaped the land and left sediments behind.

Drumlin

Elongated hill made of glacial till, shaped by glacier movement.

Till

Unsorted sediment deposited directly by a glacier.

Why UConn Has Rolling Hills

Glaciation plus long-term erosion.

Modern UConn Landscape

Result of bedrock, glaciers, erosion, and human construction.

Gneiss (UConn Locality)

Banded metamorphic rock formed under high heat and pressure.

Schist (UConn Locality)

Metamorphic rock with visible mica and strong foliation.

Quartz (Field Trip Context)

Hard common mineral made of silicon dioxide ($SiO_2$).

Mineral

Naturally occurring, inorganic solid with a definite chemical composition and crystal structure.

Color

Visible surface color of a mineral; not always reliable.

Streak

Color of a mineral in powdered form.

Luster

How a mineral reflects light.

Metallic Luster

Shines like metal.

Nonmetallic Luster

Glassy, dull, pearly, earthy, etc.

Hardness

Resistance to scratching.

Mohs Hardness Scale

Scale from 1 (softest) to 10 (hardest).

Cleavage

Breaks along flat, smooth planes.

Fracture

Breaks irregularly or unevenly.

Specific Gravity

Density compared to water.

Crystal Shape

Natural geometric form of a mineral crystal.

Quartz (Properties)

Hardness 7, glassy, no cleavage, conchoidal fracture.

Feldspar

Hardness 6, two cleavage planes, pink/white/gray.

Calcite

Hardness 3, fizzes in acid, three cleavage planes.

Halite

Hardness 2.5, cubic cleavage, salty taste.

Gypsum

Hardness 2, scratched by fingernail.

Mica

Splits into thin sheets; shiny.

Pyrite

Metallic, gold-colored, “fool’s gold.”

Magnetite

Magnetic mineral, black streak.

Hematite

Red-brown streak.

Igneous Rock

Rock formed from cooling and solidification of magma or lava.

Magma

Molten rock below Earth’s surface.

Lava

Molten rock at Earth’s surface.

Intrusive Igneous Rock

Forms underground; slow cooling; large crystals.

Extrusive Igneous Rock

Forms at surface; fast cooling; small crystals.

Texture

Size and arrangement of crystals in a rock.

Coarse-Grained (Phaneritic)

Large visible crystals; slow cooling.

Fine-Grained (Aphanitic)

Small crystals; rapid cooling.

Glassy Texture

No crystals; extremely rapid cooling.

Vesicular Texture

Contains holes from trapped gas bubbles.

Porphyritic Texture

Large crystals in a fine-grained background.

Felsic

Light colored; high silica; quartz/feldspar rich.

Intermediate

Between felsic and mafic composition.

Mafic

Dark colored; rich in iron and magnesium.

Ultramafic

Very dark/green; extremely rich in iron and magnesium.

Granite

Intrusive, coarse-grained, felsic.

Basalt

Extrusive, fine-grained, mafic.

Gabbro

Intrusive, coarse-grained, mafic.

Diorite

Intrusive, coarse-grained, intermediate.

Andesite

Extrusive, fine-grained, intermediate.

Obsidian

Glassy volcanic rock.

Pumice

Vesicular, lightweight volcanic rock.

Oceanic Crust Rocks

Mainly basalt and gabbro.

Continental Crust Rocks

Mainly granite, diorite, and andesite.

What Crystal Size Tells You

Cooling rate (large = slow, small = fast).

What Color Tells You

Mineral composition (light = felsic, dark = mafic).

Metamorphic Rock

Rock changed by heat, pressure, and fluids without melting.

Protolith

Original parent rock before metamorphism.

Metamorphism

Solid-state change caused by heat and pressure.

Recrystallization

Growth/rearrangement of minerals during metamorphism.

Foliation

Alignment of minerals into layers or bands.

Nonfoliated

No layers or banding.

Regional Metamorphism

Large-scale metamorphism during mountain building.

Contact Metamorphism

Metamorphism caused mainly by nearby magma heat.

Low-Grade Metamorphism

Low heat/pressure; slight changes; example: slate.

Medium-Grade Metamorphism

Moderate heat/pressure; larger minerals; example: schist.

High-Grade Metamorphism

High heat/pressure; strong changes; example: gneiss.

Slate

Fine-grained foliated rock from shale.

Phyllite

Slightly shiny foliated rock.

Schist (Metamorphic Rock)

Foliated rock with visible mica.

Gneiss (Metamorphic Rock)

Coarse rock with light/dark banding.

Marble

Nonfoliated rock from limestone.

Quartzite

Nonfoliated rock from sandstone; very hard.

Metamorphic Grade

Degree of change caused by heat and pressure.

Relation of Pressure/Temperature to Grade

More heat and pressure = higher metamorphic grade.