Internal and External Forces that Shape the Earth

Internal and External Forces that Shape the Earth Chapter 2 Sections 3 and 4

Continental Drift • Scientific theory explaining how large landforms were formed. continental drift

Tectonic Plates- Enormous moving pieces of the earth’s lithosphere

RING OF FIRE

Divergent Boundary- plates move apart How it works What it forms/Effe cts Magma rises as tectonic plates spread apart and cools, forming new rock valleys

Convergent Boundary- plates move together How it works What it forms/ Effects Subduction- one Mountains plate slides under and the other volcanoes Collision- crumble into one another Mountain ridges Himalayas

Transform Boundary- plates slide past one another San Andreas Fault How it works Slides at fault line What it forms/Effects earthquakes

Earthquakes Location/ Epicenter- created by plates; point directly above where the quake starts Plates sliding No new landforms, but damage and tsunamis Tsunami- a giant wave in the ocean Starts at epicenter and travels through water Damage shores/ ports; erosion

Volcanoes Volcan Where gases, oes magma, and water pour out of a crack in the earth’s surface; usually along tectonic plates Creates lava at earth’s surface. Creates hills, mountains, and islands

Weathering • physical & chemical processes that change the characteristics of rock on or near the earth's surface

Mechanical Weathering- processes that break rock down into smaller pieces; does not change composition • How it works: ice crystals build up in a rock's crack, creating enough pressure to crack the rock • What it forms: soil, mud, sand, silt (sediment)

Chemical Weathering- rock is changed into new substance as a result of interaction between elements in the air or water & minerals in the rock How it works: minerals may react to oxygen & begin to crumble minerals may break down when combined with water or carbon dioxide-forming weak acids What it Forms: rust, acid rain, decomposed rocks, soil

Erosion • weathered material is moved by the action of wind, water, ice, gravity

Water Erosion- flow of water may pick up loose sediment, cause abrasion, change the composition of rock or wave action • How it works: motion may transport material ; wave actions can reduce or create beaches • What it forms: valleys, canyons, deltas, new beaches, or more coastline

Wind Erosion- transports & deposits sediment in other locations • How is works: winds pick up particles; dust storms • What it forms: sand dunes, rock sculptures

Glacial Erosion- changing of landforms by slowly moving glaciers • How it works: glaciers move down slope and move land • What it forms: valleys,

Soil building • mixing of weathered rock, organic matter, air, and water through the processes of weathering & erosion • How it works: organic matter provides food - water & air share pores in the soil • What it forms: different areas for different agricultural needs