Constructive and Constructive and Destructive ForcesDestructive Forces

55thth grade Science GPS grade Science GPSS5E1S5E1

Margaret-Ellen LaettnerMargaret-Ellen LaettnerMurdock Elementary SchoolMurdock Elementary School

Layers of the EarthLayers of the Earth

Constructive ForcesConstructive ForcesIdentify surface features caused by destructive forces.Identify surface features caused by destructive forces.

• Construct means to build up.

• Forces that build up features on the surface of the Earth.– Deposition (Deltas, sand dunes, etc.)– Faults– Earthquakes– Volcanoes

DepositionDeposition

• The process of “depositing” soil through various means.– Wind – sand transported by the wind creates

sand dunes.– Water – bits of soil and rock can be carried

downstream and deposited.– Ice – glaciers pick up and move rock and

other materials, depositing it elsewhere.

Wind DepositionWind DepositionSand Dune Cumberland Island, GASand Dune Cumberland Island, GA

Water Deposition Water Deposition

Glacial DepositionGlacial Deposition

FaultsFaults• Faults are cracks in the Earth’s crust.• The surface of the Earth is made up of tectonic

plates that are floating on magma (molten rock).• It is along these fault lines that earthquakes and

volcanoes occur.

EarthquakesEarthquakes

• An earthquake is a phenomenon that results from the sudden release of stored energy in the Earth’s crust.

• It is caused by a strain on the fault lines of

the Earth’s crust. When the energy of the strain is released, similar to a rubber band snapping, the earthquake occurs.

• At the Earth's surface, earthquakes cause a shaking or displacement of the ground and sometimes cause the ground to break apart and change shape. Earthquake Animation!

• A volcano is an opening in the Earth's surface or crust, which allows hot, molten rock, ash and gases to escape from deep below the surface.

• Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.

• Hot spot video clip

VolcanoesVolcanoes

VolcanoesVolcanoes

• There are two main types of volcanoes: shield and composite.

• Shield volcanoes are usually found in the middle of tectonic plates. Islands like Hawaii are good examples of this type of volcano.

• There's a hole in the middle of the plate and magma moves out and piles on top of itself, slowly building a mountain of rock. Katmai Video Clip

VolcanoesVolcanoes

1. Magma reservoir2. Country rock3. Conduit (pipe)4. Base5. Sill6. Branch pipe7. Layers of ash emitted by the volcano8. Flank9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15. Ash cloud

Destructive ForcesDestructive ForcesIdentify examples of surface features caused by destructive processes.Identify examples of surface features caused by destructive processes. • Destruct means to destroy.

• Forces that destroy features on the Earth’s surface.– Erosion (water - rivers and oceans, wind) – Weathering – Impact of organisms – Earthquake – Volcano

ErosionErosion• Erosion is the breakdown of the continents and the land

around you. When it rains, rocks are washed down a mountain or down a stream. Soils are washed away. The ocean beats against a cliff and breaks it apart.

Mechanical WeatheringMechanical Weathering

• Mechanical weathering is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land. The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart. Roots and plants also push into the rocks and break them apart. They act like wedges and push the rocks apart. Little animals also help by burrowing and digging through the ground.

Chemical WeatheringChemical Weathering

• Chemical weathering includes the effect of weathering on molecules and atoms. As with all chemistry, the greater the surface area of an object, the more chemical reactions can take place. For these chemical reactions to happen in nature, moisture, and heat must be present.

Biological WeatheringBiological Weathering(Impact of Organisms)(Impact of Organisms)

• Biological weathering would include the effect of animals and plants on the landscape. This is more than roots digging in and wedging rocks. Biological weathering is the actual molecular breakdown of minerals.

EarthquakesEarthquakes

• More than buildings collapse when an earthquake hits. The land itself is totally changed. You can see scars across the landscape. Those scars appear when one block of land has moved compared to another. Roads often change their placement. They either become uneven or just crack. Streams can also change course. Sometimes rocks can fall and block the stream. Other times, the land is even lowered in certain areas. When it's lower, it's easier for the water to flow in the new direction .

VolcanoesVolcanoes

• Volcanic eruptions can cause massive death and destruction.

• Pompeii and Herculaneum

• Volcanic eruption

• Why a volcano erupts

Technology andTechnology andHuman InterventionsHuman Interventions

• Humans try to CONTROL these forces.

– seismological studies – flood control (dams, levees, storm drain

management, etc.) – beach reclamation (Georgia coastal islands)

Seismological StudiesSeismological Studies• Scientists study earthquakes so that they can

understand how they work and so that they can try to predict future quakes.

• Earthquakes are recorded by instruments called “seismographs”.

• A short wiggly line means a small earthquake and a large one means a large earthquake.

Flood ControlFlood Control

• The U.S. Army Corps of Engineers began constructing dams in Georgia for navigation and flood control in the 1940s and 1950s under the Flood Control Act of 1944 and the Watershed Protection and Flood Prevention Act of 1954.

Lake Allatoona was created in 1950 by the U.S. Army Corps of Engineers for flood control. At more than 12,000 acres, Allatoona is one of the larger lakes in the state.

Flood Control MethodsFlood Control Methods

• Dams control the water flow in a stream or river.

• A levee is an embankment designed to prevent the flooding of a river.

• Storm drains are for carrying off rainfall drained from paved surfaces, roofs, etc.

Beach ReclamationBeach Reclamation• Weather, waves and wind cause the

coastline to wash away.

• Keeping sand dunes intact helps to keep the beaches from eroding.

Georgia Landforms:Georgia Landforms:Stone MountainStone Mountain

Emerson faultEmerson fault

Tallulah Falls and GorgeTallulah Falls and Gorge

Providence CanyonProvidence Canyon

Appalachian MountainsAppalachian Mountains

Soapstone RidgeSoapstone Ridge

Fall LineFall Line

Sand MountainSand Mountain

Lime sinksLime sinks

Okefenokee SwampOkefenokee Swamp

Pine MountainPine Mountain

Altamaha River SystemAltamaha River System

Barrier IslandsBarrier Islands

Amicalola FallsAmicalola Falls

Cohutta MountainsCohutta Mountains

BeachesBeaches

Brasstown BaldBrasstown Bald

Brevard Fault ZoneBrevard Fault Zone

Cumberland PlateauCumberland Plateau

Lookout MountainLookout Mountain

Trail RidgeTrail Ridge

Blue Ridge MountainsBlue Ridge Mountains

Chattahoochee RiverChattahoochee River