Processes Shaping Planet Earth

Essential Question:What forces have helped shape Earth’s landforms, climate, and plant life?

Lithosphere

• Consists of Earth’s crust and the top section of solid mantle.

• Divided into shifting tectonic plates.

Plate Tectonic Motion• Scientists believe all continents formed 1 giant land

mass and these have moved over time.– Effects: Earthquakes, Volcanoes, Seafloor Spreading,

Mountains and Rift Valleys.

Causes of Plate Tectonic Motion• Believed heat and gravity may be responsible for

the movement of tectonic plates.• Gravity pulls oceanic plates under land plates.

Effects of Plate Tectonic Motion

Mountain Building Seafloor Spreading and Rift Valleys

Effects of Plate Tectonic Motion

Volcanoes Earthquakes and Tsunamis

Weathering and Erosion

• Weathering: Rocks broken apart by wind, water, ice and organisms.

• Erosion: Rocks and particles are broken down and carried to a new location.

Weathering Erosion

The Hydrosphere• It is made up of all

water on Earth’s surface. 70% of Earth’s surface is covered by oceans.

• Water circulates through evaporation, condensation, precipitation, and runoff.

• Forms– saltwater—97 percent of world’s water– freshwater—most frozen in ice caps; less than 1

percent in vapor and liquid form• Where liquid fresh water is found– surface water—in rivers, lakes, estuaries,

wetlands– groundwater—stored in soil and water table• (aquifers)

12

The Hydrosphere

Tides and Currents• Gravitational pull of the moon causes tides, a cyclic

rise and fall of the oceans.• Ocean water is moved by surface and deep sea

currents.

The Atmosphere and Weather• The atmosphere is an envelope of gases around Earth. • The gases of the atmosphere absorb solar radiation,

moderate temperatures and distribute water.

Orographic Precipitation

Windward Side Leeward Side

Effects of mountains and elevation on weather and climate:

16

• Increase in elevation causes drop in temperature.

• Mountains cause orographic effect: moist air meets a barrier and is pushed upward, causing cooling, condensation, and precipitation.

• Mountainside facing wind is the windward, wetter side; side facing away from wind is the leeward, drier side, called the rain shadow.

Rain Shadow

The Atmosphere and Weather• Weather consists of temperature, humidity,

precipitation, and wind.• Heating of the atmosphere and Earth’s spin create

wind patterns. Surface features like mountains also affect weather.

Climate• Climate is determined by average weather conditions

over a long period of time.– Influenced by: Latitude, Elevation, Winds, Ocean Currents,

Mountain Barriers

Climate• Climate Regions based on similarities in climate.

Examples include Polar Climates and Tropical Climates.– High-Latitude Climates: North/South Poles have similar

climates with very cold winter temperatures.– Mid-Latitude Climates: warm summers and cool

winters. Located North of Tropic of Cancer and South of Tropic of Capricorn

– Low-Latitude Climates: tropical climates with warm temperatures. Located between the Tropic of Cancer and Capricorn.

The Biosphere and Biomes• Biosphere refers to all life on Earth.• Biomes are variations in climate which lead to distinct

regions based on similarities of plant and animal life.– Temperate Deciduous Forest: ample rain, moderate

temperatures, trees change colors in fall– Tropical Rainforests: found in the tropics/near the equator.

Great abundance of plant/animal life.– Grasslands/Savanna/Steppes: climate is drier, not enough

rainfall to support trees. Grasses dominate with grazing animals.

– Deserts: Receive less than 10 inches of rain/year.– Tundra: Soil is so cold trees cannot grow. Found near the

poles.

Temperate Deciduous Forest

Tropical Rainforests

Grasslands/Savanna/Steppes

Deserts

Tundra

Review1. Can you think of any examples of weathering, erosion

or deposition that have affected your own community?2. Which best explains why we experience four season on

Earth?A. the gravitational pull of the moonB. The distance between Earth and the sunC. The tilt of the Earth on its axis as it revolves around the sunD. the effect of tectonic plate movement on Earth’s oceans

Answer: C

3. In what way are climate regions and biomes related?The type of climate determines the types of animals and plant

life in the area where the climate exists.

•stop

• Confluence-when two rivers meet