Comprehensive Earth Science Study Guide

Comprehensive vocabulary flashcards covering Earth Science principles, including geologic time, plate tectonics, rock types, Earth's layers, and atmospheric science history.

Earth science

The group of sciences, including geology, oceanography, meteorology, and astronomy, that study Earth and its place in space.

Law of Superposition

The principle stating that in undisturbed sedimentary rock, the oldest layer is at the bottom and each layer is younger than the one below it.

Radioactive dating

A technique used to determine the age of materials based on the known rate at which specific elements change into other materials.

Uranium-lead method

A dating technique involving the decay of Uranium 238 into lead, used to estimate the age of rocks.

Half-life

The time required for one-half of the atoms in a radioactive element to decay; for Uranium 238, this is $4.5$ billion years.

Paleontologists

Scientists specialized in the study of plant and animal fossils.

Fossils

Hardened remains or imprints of organisms that lived in the distant past.

Petrified fossils

Fossils formed when sediment seeps into a dead organism, fills open spaces, and hardens into rock.

Amber

Hardened resin from coniferous trees that can trap and preserve small organisms for millions of years.

Geologic time scale

The chronological system used by scientists to divide Earth's history into chapters characterized by dominant life forms.

Precambrian era

The earliest span of geologic time, lasting from Earth's beginning until about $600$ million years ago, characterized by primitive life like algae and sponges.

Paleozoic Era

A geologic era meaning 'ancient life' that saw the development of marine invertebrates, amphibians during the Devonian Period, and early reptiles.

Mesozoic Era

The era of 'intermediate life' characterized by the breakup of Pangaea and the dominance of dinosaurs.

Tyrannosaurus

The largest meat-eating dinosaur of the Mesozoic era, standing approximately $6\,m$ tall and $15\,m$ long.

Cenozoic Era

The era of 'recent life' which saw the rise of modern mammals, deciduous trees, and the Pleistocene Ice Age.

Pleistocene Ice Age

A period near the end of the Cenozoic era lasting about $2$ million years during which humans began leaving records such as stone tools.

Oblate spheroid

The physical shape of Earth, which is nearly spherical but bulges at the equator and is flattened at the poles due to rotation.

Hayford spheroid

A standard physical model of Earth's dimensions established in 1910 that approximates the planet's actual contours.

Eratosthenes

The Greek astronomer who calculated Earth's circumference to be approximately $40\,000\,km$ by measuring sun ray angles.

Henry Cavendish

The English scientist who first determined the mass of the Earth by measuring the gravitational constant.

Equator

The line of latitude numbered $0^{\circ}$ that is drawn around the middle of the globe.

Prime meridian

The line of longitude passing through Greenwich, England, representing $0^{\circ}$ longitude.

International Date Line

The line at the $180^{\circ}$ meridian where a day is added when crossing westward.

Topographic map

A scale model representing surface features and elevation of an area, often using contour lines.

Contour line

A line on a map that connects all points having the same elevation.

Crust

The thin, outermost layer of Earth where all life exists, containing elements like silicon, oxygen, and aluminum.

Theory of Isostasy

The concept that equal-diameter columns of the Earth's crust have equal weights, maintaining a balance as the crust floats on the mantle.

Mohorovicic Discontinuity (Moho)

The boundary between the Earth's crust and the mantle discovered by Andrija Mohorovicic in 1909.

Mantle

A layer of heavy rock-like material approximately $2\,900\,km$ thick that makes up about $80\%$ of Earth's volume.

Inner core

Earth's solid, dense innermost layer consisting of iron and nickel, where temperatures reach about $5\,000\,^{\circ}C$.

Outer core

The liquid layer of molten iron and nickel located between the inner core and the mantle.

William Gilbert

The physician who first concluded that the Earth behaves like a giant magnet.

Continental Drift Theory

The theory proposed by Alfred Wegener suggesting that continents were once part of a supercontinent called Pangaea and have since moved apart.

Panthalassa

The single, vast ocean that surrounded the supercontinent Pangaea.

Lithosphere

The rigid outer part of the Earth consisting of the crust and the upper portion of the mantle.

Asthenosphere

A soft layer of the mantle about $100\,km$ thick capable of plastic flow due to high temperature and pressure.

Echo sounding

A method using sound wave pulses to investigate the depth and structure of the seafloor.

Ocean Floor Spreading

The process where basaltic material rises through cracks in the seafloor, creating new crust and expanding ocean basins.

Plate Tectonics Theory

The theory that Earth's crust is divided into several large and small plates that float on the asthenosphere.

Convergent boundaries

Plate boundaries where two plates push against each other.

Subduction zone

An area where one plate is bent downward into a deep trench as it pushes against another plate.

Igneous rocks

Rocks formed from the cooling and hardening of magma or lava.

Obsidian

A glasslike igneous rock formed when magma cools so quickly that mineral crystals cannot form.

Sedimentary rocks

Rocks formed from deposits of gravel, sand, and organic matter that are cemented together in layers.

Metamorphic rocks

Rocks that have been changed from their original form by extreme pressure and high temperature deep underground.

Fossil fuels

Energy sources like petroleum, coal, and natural gas formed from the incomplete decomposition of organic matter millions of years ago.

Mineral

An inorganic, naturally occurring crystalline solid with a definite chemical composition.

Cleavage

The tendency of a mineral to split along specific flat planes determined by its internal particle arrangement.

Kaolin

A clay mineral used as an ingredient in ceramics, paint, paper, and certain plastics.

Desertification

The process by which productive soil in semiarid areas becomes unproductive due to human use and environmental factors.

Greenhouse effect

The process by which gases like carbon dioxide trap heat in the atmosphere, keeping the planet warm enough to sustain life.

Global warming

The potential increase in atmospheric temperature caused by rising levels of carbon dioxide from human activities like burning fossil fuels.

Troposphere

The atmospheric layer closest to Earth where most weather occurs and where humans live.

Stratosphere

The layer of the atmosphere containing a high concentration of ozone which filters out harmful ultraviolet radiation.