Chapter 2 Physical Geography: A Living Planet

CONTINENTAL DRIFT THEORY • • • Originally suggested by

Francis Bacon

in 1620 Presented theory in 1912 by

Wegner

of Germany

Alfred

Theory states that all continents were once a super continent that divided and slowly drifted apart

Where are we?

• 93,000,000 miles from the Sun • 3 rd Planet in from the Sun • 24,900 miles in circumference and 7900 miles in diameter • Only planet in Milky Way solar system that can sustain human life

THE MILKY WAY • • • • • Our Solar system consist of the sun 8 planets 1 dwarf planet (Pluto) Other celestial bodies that orbit the sun – Comets > spheres covered with ice and dust that leave trails of vapor as they race through space – Asteroids > large chunks of rocky material found in space By size: Pluto (dwarf), Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, Jupiter

Section 1: The Earth Inside and Out

• • 1. The earth is the only living planet… Continents – landmasses above water on earth

• 2. The earth consists of plates that float…

• 3. The theory of continental drift explains the formation of continents

Inside the Earth Core – center of the earth (inner core- liquid iron and nickel; outer core – solid iron and nickel) Mantle – several layers surrounding the core Crust – thin layer of rock at the earth’s surface

Biosphere •

The part of the earth where plants and animals live (atmosphere, lithosphere and hydrosphere)

•

On and Above the Earth Atmosphere – layer of gases surrounding the earth (contains oxygen, protects the earth from radiation and space debris, and provides a medium for weather and climate

Lithosphere •

Solid rock portion of the earth (includes crust and uppermost mantle, ocean floor, etc.)

Hydrosphere •

Made up of water elements of the earth (oceans, seas, rivers, lakes and water in the atmosphere)

Section 2: Bodies of Water and Landforms

• Human Perspective – The earth is unlike any other observable planet in our solar system. It is a living planet.

– Where there is water there is LIFE.

Section 2: Bodies of Water and Landforms

The ocean is interconnected and covers over 70% of the earth.

Divided into 4 main parts. Pacific (largest), Atlantic, Arctic and Indian

• • Ocean Movements

Currents-

like rivers flowing through the ocean

Waves-

swells produced by winds •

Tides -

regular rises and falls of the ocean created by the gravitational pull of the moon or the sun

MOTION OF THE OCEAN • • The ocean distributes heat.

Winds blow over the ocean and are either heated or cooled by the water, moderating the temperature of the air over the land.

Hydrologic (water) Cycle • The water on earth is continuously circulated between the atmosphere, the oceans, and the earth

LAKES, RIVERS, & STREAMS

• Lakes hold more than 95% of all fresh water on earth.

• Rivers and streams move water to or from larger bodies of water.

LAKES, RIVERS, & STREAMS

• Saltwater lakes are created when creeks & rivers carry salts into a lake, and there is no outlet to carry the salt away.

Largest: Caspian Sea (West Asia)

• Drainage Basin Area drained by a major river and its tributaries

Ground Water – water held in the pores of rocks Water Table – the rim level at which rocks are saturated

Oceanic Landforms (topography) • • The ocean floor and the continents have a continental shelf and slope The ocean floor is similar to the land above water.

continental shelf

Continental Shelf • Earth’s surface from the edge of a continent to the deep part of the ocean

Continental Landforms

• Naturally formed features on the surface of the earth are landforms

Topography & Relief • Relief refers to the difference in elevation of a landform from lowest to highest point – Mountains, hills, plains, canyons • The combination of the surface shape and composition of the landforms and their distribution in a region > topography • Topographic Maps show the landforms with their vertical dimensions and their relationship to other landforms.

Section 3: Internal Forces

•

Shaping the Earth

The earth’s crust consists of number of tectonic plates • tectonic plates enormous moving pieces of the earth’s lithosphere – Spreading; subduction; collision; sliding past each other in a shearing motion

Movement of the plates produces earthquakes and volcanoes • Fault – fracture in the earth’s crust where plates move past each other

Types of boundary movements: • Divergent – plates move apart, spreading horizontally

(i.e. Saudi Arabia & Egypt making Red sea wider)

Types of boundary movements: • Convergent – Plates collide, causing either one plate to dive under the other or the edges of both plates to crumple

(i.e. South Asia forming the Himalayas)

Types of boundary movements: • Transform – plates slide past each other

(i.e. San Andreas Fault in California)

Volcanoes – crack in the earth’s surface where magma and gases pour out

Benefits > fertile soil & energy

Lava – magma that has reached the earth’s surface

•

Earthquake –

Violent movement of the earth as the plates grind or slip past each other at a fault –

95% around Pacific Rim (Ring of Fire)

•

Along plate boundaries

•

Seismograph –

measures the size of the waves created by and earthquake – Largest Earthquake measured> Kermadec Island, 8.9

Epicenter • • Point directly above the focus of an earthquake on the earth’s surface Richter Scale – uses information collected by seismographs to determine the strength of an earthquake

DAMAGE •

Landslides

•

Fires

•

Collapsed Buildings

•

Tsunami

(speeds up to 450 mph and waves 100 feet tall)

Tsunami •

A giant wave in the ocean caused by an underground earthquake

The Ring of Fire • The most active volcano and earthquake zone on earth

“Hot Spots” • • Volcanoes that are far from the margins of the tectonic plates are located on “Hot Spots”.

Hot springs & geysers are other features that indicate areas where the crust is thin.

External Forces Shaping the Earth

Human Perspective: In Egypt, a seasonal dry wind is called Khamsin (50) for the number of days the season occurs. These wind-driven sandstorms cause serious problem for the people of the region.

• •

External Forces Shaping the Earth

Weathering and erosion alter the surface of the earth Weathering – physical and chemical processes that change the characteristics of rock on or near the earth’s surface

• • Sediment – Small pieces of rock created by weathering (mud, sand or silt) Mechanical Weathering – processes that break rock into smaller pieces (doesn’t change the composition of rock, but the size) Example: road construction 4 causes > human activity, plants, frost, ice crystal in cracks of rocks

• Chemical Weathering – occurs when rock is changed into a

new substance

as a result of interaction between elements in the air or water and minerals • (example – iron rusting)

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

Water Erosion • The motion picks up loose material and moves it downstream • Delta – sediment is deposited in a fan-like landform when a river enters an ocean

Wind erosion • • Wind speeds have to reach 11 mph before fine sediments can be moved.

Depending on the types of wind, different types of landforms can be formed: –Loess, sand dunes, rock structures.

wind erosion Loess – windblown silt and clay sediment that produces very fertile soil

• Glacial Erosion Glacier - a large, long lasting mass of ice that moves because of gravity • (Form in mountainous regions) Glaciation – • changing of landforms by slowly moving glaciers Moraine – rocks left behind from a glacier that form a ridge or hill

BUILDING SOIL HUMUS Organic material in the soil.

Esker > snakelike ridge Created by melted ice

Kettle > depression in the ground created by blocks of trapped ice in the sediment that melts. They can fill with water to form lakes.

• Weathering and erosion help form soil. Soil consist of a loose mixture of weathered rock, organic matter, air, and water that supports plant growth • Factors that determine soil fertility: – Parent Material – Relief – Organisms – Climate – Time

• The variety – and the climates in which they are found – determine the types of vegetation that can grow in a location. Agricultural activities, such as farming, ranching, and herding, depend on this complex relationship.