Geography Ch. 3

Geomorphology

Study of the origin, characteristics and development of landforms

Minerals

A particular chemical combination that has a hardness, density, and definite crystal structure of its own

Intrusive igneous rock

formed below ground level by the solidification of magma

Extrusive igneous rock

created above ground level by the solidification of lava

Sedimentary rock

composed of particles of gravel, sand, silt, and clay that were eroded from existing rocks

Strata

horizontal beds under water

Metamorphic rock

formed from igneous and sedimentary rocks by Earth’s forces that generate heat, pressure, or chemical reaction

Rock cycle

Continental drift theory

• Based on early 20th-century work of Alfred Wegener.
• All land masses were once united in a supercontinent
called Pangaea; continents drifted apart over many
millions of years.
• Forerunner of today’s plate tectonics theory.

Pangaea

Theory of plate tectonics

Asthenosphere

Partially molten layer above the earth’s interior

Lithosphere

Outermost layer of the earth (the crust and upper mantle)

Divergent plate boundaries

Convergent plate boundaries

Transform boundaries

Faults

fractures in rock along which there has been movement

Zone of Subduction

Epicenters

Hot spots

breaks in earth’s crust where a rising plume of molten material reaches the surface

Diastrophism

the great pressure acting on the plates that deforms them by folding, twisting, warping, breaking, or compressing rock

Volcanism

the force that transports heated material to or toward the surface of Earth

Folding

Layers of rock are forced to buckle from compression caused by plate movements

The Richter Scale

Tsunami

caused by a volcanic eruption or underwater landslide below the ocean

Seismographs

instruments that record seismic waves

Gradational processes

reduction of land’s surface through weathering, mass movement, and erosion

The breakdown and decomposition of rocks and
minerals at or near the earth’s surface in response
to atmospheric factors (water, air and temperature)

Chemical weathering

Decomposition of rock as a result of chemical
reaction

Mechanical weathering

the physical disintegration of earth materials at or near the surface; that is, larger rocks are broken into smaller pieces

Soil

created by weathering processes

Mass wasting (mass movement)

the downslope movement of material due to gravity

Talus

dramatic, cone-like landform created by the accumulation of rock particles at the base of hills and mountains, especially in dry areas

Load of a stream

small particles, such as clay or silt, are suspended in water and constitute together with the material dissolved in the water or dragged along the bottom

Falls

a stream that flowed over precipices

Floodplains

Delta

silt and sand accumulation and intersections

Natural Levees

formed by deposition of silt at river edges during floods

Alluvium and alluvial fans

alluvium (sand and mud) builds up in the lakes and at lower elevations, and alluvial fans are formed along hillsides

Water table

the top zone of groundwater saturation

Aquifers

porous underground structure bearing water

Karst topography

a large limestone region marked by sinkholes, caverns, and underground streams

Stalactites

Stalagmites

Sinkholes

Glaciers and Ice Sheets

Tills

Glaciers, troughs, and fjords

Outwash plain

Permafrost

Coral reefs

Composed of coral organisms growing in shallow tropical water

Atolls

Reefs formed in shallow water around a volcano that has since been covered or nearly covered by water

Loess

deposit of windblown silt