NEW APES SOIL + PLATE TECT

Earth’s Structure

The internal organization of Earth into layers based on composition and physical properties

Core

Densest Earth layer made of iron, nickel, and radioactive elements that generate heat

Mantle

Thick layer of dense, mafic rock with high metal content and lower silica

Crust

Thin outermost Earth layer; oceanic crust is mafic and continental crust is felsic

Inner Core

Solid portion of Earth’s core composed mainly of iron and nickel

Outer Core

Liquid portion of the core that generates Earth’s magnetic field

Mesosphere

Solid lower mantle beneath the asthenosphere

Asthenosphere

Semi-molten, plastic-like mantle layer that allows plate movement

Lithosphere

Rigid outer Earth layer made of crust and upper mantle; divided into tectonic plates

Tectonic Plate

Large piece of lithosphere that moves over the asthenosphere

Plate Tectonics

Theory explaining movement of lithospheric plates and Earth’s surface changes

Pangaea

Ancient supercontinent where all continents were once joined

Alfred Wegener

Scientist who proposed continental drift in 1912

Seafloor Spreading

Creation of new oceanic crust at divergent boundaries

Convection Currents

Heat-driven circulation in the mantle that moves tectonic plates

Hotspot

Area where magma rises through the mantle independent of plate boundaries

Hotspot Island Chain

Line of volcanic islands formed as a plate moves over a hotspot

Divergent Plate Boundary

Plates move apart; magma rises and forms new crust

Mid Ocean Ridge

Underwater mountain chain formed at divergent boundaries

Rift Valley

Valley formed when continental crust pulls apart

Convergent Plate Boundary

Plates move toward each other, often causing subduction

Subduction

Process where a denser plate sinks beneath a less dense plate

Oceanic Oceanic Convergence

One oceanic plate subducts forming island arcs and trenches

Island Arc

Curved chain of volcanic islands formed at oceanic

Oceanic Continental Convergence

Oceanic plate subducts beneath continental plate forming volcanoes and mountains

Continental Continental Convergence

Collision of two continental plates forming large mountain ranges

Transform Fault Boundary

Plates slide past each other horizontally

Fault

Fracture in Earth’s crust where movement occurs

Earthquake

Sudden release of energy caused by movement along faults

Epicenter

Point on Earth’s surface directly above an earthquake focus

Richter Scale

Logarithmic scale measuring earthquake magnitude

Volcano

Opening in Earth’s crust that releases lava, ash, and gases

Tsunami

Series of large ocean waves caused by underwater earthquakes or volcanoes

Ring of Fire

Zone of intense volcanic and earthquake activity around the Pacific Ocean

Plate Movement Rate

Average movement of tectonic plates (~3

Allopatric Speciation

Formation of new species due to geographic isolation

Rock

Naturally occurring solid composed of minerals

Igneous Rock

Rock formed directly from cooled magma

Basaltic Rock

Dark, iron-rich igneous rock common in oceanic crust

Granitic Rock

Light-colored, silica-rich igneous rock common in continental crust

Sedimentary Rock

Rock formed from compressed and cemented sediments

Metamorphic Rock

Rock altered by heat and pressure without melting

Rock Cycle

Continuous process of rock formation, breakdown, and transformation

Weathering

Breakdown of rock into smaller pieces

Physical Weathering

Mechanical breakdown of rock without chemical change

Chemical Weathering

Chemical alteration of minerals releasing nutrients

Biological Weathering

Weathering caused by living organisms

Erosion

Transport of weathered material by wind, water, ice, or gravity

Deposition

Process where eroded material is dropped in a new location

Soil

Mixture of mineral particles, organic matter, water, air, and organisms

Parent Material

Original rock from which soil forms

Pioneer Species

First organisms to colonize bare rock and begin soil formation

Soil Formation

Process of soil developing from weathered rock and organic matter

Soil Horizons

Distinct layers of soil formed over time

O Horizon

Surface layer of organic matter and decomposing material

A Horizon

Topsoil rich in humus and biological activity

E Horizon

Zone of leaching where minerals are removed

B Horizon

Subsoil where minerals accumulate

C Horizon

Least-weathered layer closest to parent rock

Humus

Fully decomposed organic matter that improves soil fertility

Sand

Largest soil particle with high permeability

Silt

Medium-sized soil particle

Clay

Smallest soil particle with high water retention

Soil Texture

Percent of sand, silt, and clay in soil

Porosity

Amount of pore space in soil

Permeability

How easily water moves through soil

Water Holding Capacity

Ability of soil to retain water

Loam

Ideal soil texture with balanced sand, silt, and clay

Soil Fertility

Ability of soil to support plant growth

Nutrients

Essential elements for plant growth (N, P, K, Ca, Mg, Na)

Cation Exchange Capacity (CEC)

Soil’s ability to hold and exchange nutrient cations

Base Saturation

Proportion of nutrient bases relative to acids in soil

Soil Degradation

Decline in soil’s ability to support plants

Topsoil Erosion

Loss of nutrient-rich surface soil

Compaction

Compression of soil that reduces pore space

Nutrient Depletion

Loss of soil nutrients due to repeated cropping

Dust Bowl

Severe wind erosion event caused by poor farming practices

Biological Soil Activity

Actions of organisms that recycle nutrients and improve soil structure