Changes Within the Earth Chapter 1 Section 2

GEOGRAPHY – the study of the earth’s physical structure and history Physical Characteristics The Earth’s Layers Core – center (inner/outer) Mantle – mostly solid Crust – rocky surface layer Natural forces interact with the earth’s crust, creating landforms, or natural features, found on the earths surface

Land, Air, and Water Geographers often talk of the different elements of the earth’s natural environment as a set of related “spheres” dominated by different physical forms Lithosphere – layer of soil, land, rock, landforms Atmosphere – layer of air, water, and other substances above the surface Hydrosphere – consists of water, oceans, lakes and rivers Biosphere – the world of plants, animals, and other living things that occupy the land and water 70% water Continents – large landmasses in the oceans

Landforms are commonly classified according to differences in relief – the difference in elevations between the highest and lowest points Major landforms – mountains, hills, plateaus, and plains

Form when magma breaks through the earth’s crust Physical Processes – “What forces shaped the landforms here?” 1st – internal forces that originated in the earth’s interior Volcanism Form when magma breaks through the earth’s crust On the surface, molten rock is called lava

Movement in the Crust Bending and buckling breaks the earth’s crust Results in a fold Hardness of rock and strength of movement determines whether a fault or fold

Understanding the Past Plate Tectonics – theory states the earth’s outer shell is not one solid sheet of rock

Continental Drift Continental drift theory – Pangaea One large continent that broke apart

Seafloor Spreading Using sonar, scientists began to map the floor of the Atlantic Ocean, discovering that it was not flat Youngest rock was found nearest underwater ridge system

Plate Movement/Meeting Convection - a circular movement caused when a material is heated, expands and rises, then cools and falls Subduction – when a denser plate slides beneath the other, an arc of volcanic islands may form along the plate boundary When two oceanic plates collide, neither slides Buckling, bending, folding

Expanding Volcanoes Ring of Fire – circle of volcanoes surrounding the Pacific Ocean

Changes on the Earth’s Surface Chapter 1 Section 3

Weathering - the breakdown of rock at or near the earth’s surface into smaller pieces Physical/Mechanical Weathering – when rock is actually broken or weakened physically Freezing water Frost wedging Seeds taking root in cracks of rock

Chemical Weathering – altering a rock’s chemical makeup by changing the minerals that form the rock or combining them with new chemical elements Water and carbon dioxide Moisture Acid Rain – chemicals in polluted air combine with water vapor and fall back to earth

Erosion - movement of weathered material such as gravel, soil, and sand Water – largest canyons and deepest valleys created by moving water Sediment – small particles of soil, sand, and gravel Wind – 2nd major cause Loess – windblown deposits of mineral-rich dust and silt Sandstorms

Glaciers - huge, slow-moving sheets of ice Moraines – ridge like piles of rocks and debris