Unit 1: The World

A Living Planet

The Earth Inside and Out

Earth’s Structure

• Inside Earth:– Core: center, iron and nickel• Inside = solid; outside = liquid

– Mantle: outside of the core, has multiple layers and contains most of the earth’s mass • Magma: molten rock

– Crust: thin layer of rock at earth’s surface

Earth’s Structure

• On and Above Earth:– Atmosphere: layer of gases surrounding the earth– Lithosphere: solid rock portion of the earth’s

surface • uppermost mantle and crust• Seafloor

– Hydrosphere: all the oceans, seas, rivers, lake, and water in the atmosphere

– Biosphere: part of earth where plants and animals live.

Earth’s Continents

How Has the Earth Changed?

• Continental Drift– Alfred Wegener

(1912)– Earth was once

a supercontinent that divided and drifted apart over millions of years

Bodies of Water and Landforms

Bodies of Water

• Hydrologic cycle- continuous circulation of water between atmosphere, oceans, and earth.

Bodies of Water

• Lakes, rivers, streams– Drainage basin-area drained by

a major river and its tributaries– Ground water-water held in

pores of rock– Water table- level at which the

rock is saturated • Rise or fall depending on amount

of precipitation in the region

Landforms

• Naturally formed features on the surface of the earth– Examples???

Landforms• Oceanic– Continental shelf- edge of a continent to the deep

part of the ocean• Ridges, valleys, canyons, plains, mountain ranges

Forces Shaping the Earth

Plate Tectonics

• Enormous moving pieces of the earth’s lithosphere

Plate Tectonics

• Divergent boundary-plates move apart, spreading horizontally

• Convergent boundary- plates collide, causing either one to dive under the other or the edges of both to crumple

• Transform boundary- plates slide past one another

Earthquakes• As plates grind past at a fault, earthquakes

happen. – Measure using seismograph– Richter Scale: determines strength

• The point directly above the focus of the earthquake is the epicenter

Tsunami• Caused by

earthquakes, giant wave in the ocean

• 50-100 feet tall

Volcanoes

• Magma, gasses, water from lower part of the crust collect in underground chambers

• Magma pours out of a crack in the earth’s surface– Lava

Weathering

• Physical and chemical processes that change the characteristics of rock– Breaks down rocks into smaller pieces: sediment

• Mud, silt, sand

• Mechanical Weathering– Physical, does not change the composition of the rock,

just the size• Chemical Weathering– Rock is changed into a new substance due to reactions

w/ elements in air or water

Erosion

• Weathered material is moved by wind, water, ice, gravity

Building Soil

• Loose mixture of weathered rock, organic matter, air, and water that supports plant growth

• Soil factors:– Parent material– Relief– Organisms– Climate– Time