Physical Geography: A Living Planet

Vocabulary flashcards covering the Earth's interior and exterior structure, the hydrologic cycle, tectonic plate boundaries, plate motion mechanisms, and soil formation factors.

Pangaea

The ancient supercontinent (from the Greek meaning "All Earth") whose drifting shaped the modern continents.

Continental Drift

The process and theory describing the gradual movement and drifting of the continents that shaped the world we live in today.

Crust

The outermost, solid layer of the Earth, measuring $8\text{ to }40\text{ kilometers}$ ($19\text{--}37\text{ miles}$) in thickness.

Mantle

The Earth layer located directly below the crust, measuring approximately $2,900\text{ kilometers}$ thick, which includes an upper mantle (approx. $500\text{ miles}$ thick) and a lower mantle ($1,300\text{ miles}$ thick). And it’s also in charge of the tectonic plates movement which cause earthquakes

Outer Core

The liquid layer of the Earth's interior that surrounds the inner core, measuring approximately $2,250\text{ kilometers}$ in thickness.

Inner Core

The solid innermost layer of the Earth, measuring approximately $1,300\text{ kilometers}$ in thickness.

Lithosphere

The rigid outer zone of the Earth encompassing the crust and uppermost mantle, measuring approximately $30\text{--}90\text{ miles}$ thick.

Asthenosphere

The layer in the upper mantle beneath the lithosphere, measuring approximately $400\text{ miles}$ thick, upon which tectonic plates float and move.

Hydrologic Cycle

The continuous circulation of water between the atmosphere, the oceans, and the earth (also known as the water cycle).

Evaporation

The step in the water cycle where liquid water from bodies of water such as lakes, rivers, streams, or oceans turns into a gas known as water vapor.

Condensation

The water cycle step in which water vapor rises into the sky, cools down into droplets, and forms clouds.

Precipitation

The process where accumulated atmospheric moisture falls back to the Earth's surface in the form of rain, snow, hail, or sleet.

Divergent Boundary

A constructive tectonic plate boundary where plates move apart and spread horizontally, often resulting in volcanoes.

Convergent Boundary

A destructive tectonic plate boundary where plates collide, causing one plate to crumble or subduct, frequently resulting in earthquakes.

Transform Boundary

A conservative tectonic plate boundary where plates slide past each other horizontally, creating faults.

Plate Motion Mechanisms

The internal physical mechanisms that drive tectonic plate movements, consisting of mantle convection (convection traction), ridge push, and slab pull.

Ridge Push

A plate motion mechanism where cooling, elevated lithosphere at an oceanic spreading ridge slides downhill and pushes the tectonic plate outward.

Slab Pull

A plate motion mechanism where a dense, cooler subducting oceanic plate sinks into the mantle and pulls the trailing plate along with it.

Parent Material

A soil formation factor referring to the original rock (parent rock) whose chemical composition before decomposing determines the fertility of the resulting soil.

Relief

A soil formation factor referring to topography; steeper slopes, such as mountainsides, erode easily and do not produce soil quickly.

Organisms (Soil Formation)

Plants, small animals (such as worms and ants), and bacteria that decompose material, loosen the soil, and provide essential nutrients for plants.

Climate (Soil Formation)

A soil factor where variations in temperature and moisture (hot vs. cold, wet vs. dry) produce distinctly different types of soil.

Time (Soil Formation)

The soil factor addressing the variable duration needed to build soil, with a very rough average production rate of about $2.5\,\text{cm}^3$ per century.