FORCES OF CHANGE Chapter 2 Section 2

THINK ABOUT CHANGE…

How has change happening around you influenced your life? How have changes you made within yourself impacted your surrounding environment and the people in that environment?

ESSENTIAL QUESTION AND OBJECTIVEEQ: How have internal and external forces shaped Earth’s surface?OBJ: I will be able to use geographic terms and tools to explain how Earth’s internal changes and external changes influence the character of places.

LAYERS OF EARTH ORGANIZERLayer of Earth Distance (miles) Temperature

(Farenheit)Description

EARTH’S STRUCTURE

The Earth is composed of three main layersCore: intensely hot, solid inner section of Earth

Mantle: Thick layer of hot dense rockCrust: a rocky shell that makes up the Earth’s surface

At the very center of Earth is the superhot but solid inner coreScientists believe that it is made up of iron and nickel

under enormous pressure, and that a band of melted iron and nickel surround it, called the liquid core

EARTH’S STRUCTURE

Scientists theorize that 500 million years ago the planet looked completely differentPangea – the gigantic supercontinent where

our current continents originate fromThe theory is that the continents were once

joined and then slowly drifted apart, known as continental drift

Plate tectonics refers to all of the physical processes that create many of Earth’s physical featuresPlates moving around formed Earth’s physical

features—continents, oceans, volcanoes, mountains

When plates spread apart, magma, or molten rock, is pushed up from the mantle and ridges are formed

RECAP:

Which of Earth’s layers is between the crust and the outer core?How much does the temperature change from the inner core to the outer core? From the outer core to the mantle?

What is the theory of continental drift?

INTERNAL FORCES OF CHANGE Colliding and Spreading Plates

Mountains are formed where giant continental plates collideHimalaya mountain ranges in South Asia were pushed

upward when Indian landmass drifted against Eurasia

Mountains can also form when a sea plate collides with a continental plateSubduction: when the heavier sea plate dives beneath

the lighter continental plateThe Andes mountains in South America formed over millions of

years as a result of subduction when the Nazca plate slid under the South American plate

Accretion: pieces of Earth’s crust comes together slowly as the sea plates slide under the continental plateCreated underwater mountains and peaksCauses continents to grow outward

Spreading: when sea plates pull apart and causes a rift that allows magma to arise

Folds and Faults

Folds, or bends, are formed in layers of rock when moving plates squeeze Earth’s surface until it buckles

Plates may slide past each other creating cracks in the Earth’s crust called faultsSan Andreas Fault in California

Sheet glaciers are flat, broad sheets or ice and cover most of Greenland and all of Antarctica

Mountain glaciers are located in high mountain valleys

RECAP

How are mountains formed?How are volcanoes formed?

What is a fault?What is a fold?

INTERNAL FORCES OF CHANGEWater Erosion

When springwater and rainwater flow downhill in streams, it cuts into the land and wears away soil and rock

Soil Building

Soil is the product of thousands of years of weathering and biological activityWeathering breaks rock into smaller piecesWorms and other organisms help break

down organic material and add nutrients to allow air and water

Five Factors influence soil formationClimateTopographyGeologyBiologyTime

WHAT IS A VOLCANO? VIDEO

1. What is the general structure of a volcano?

2. When do eruptions occur?

3. What are the downsides to volcanic eruptions?

4. What are the benefits of volcanoes and their eruptions?

5. What happens when volcanoes stop erupting?

https://www.youtube.com/watch?v=WgktM2luLok