Unit 1: Land and Water Forms World Geography Unit 1: Land and Water Forms

The Earth’s Surface and It’s Shape Looking at Earth from the moon what would we see? If we could put what we see on fast forward what would we observe? What could we explain about the earth from our observations?

The Structure of Earth Earth is not simply a ball of rock There are distinct layers that have different qualities. It is difficult to study the inside of the earth because we cannot simply gaze into the earth. One method for studying the inner structure of the planet is to study earthquakes The study of earthquakes is known as Seismology

The Structure of Earth

The Structure of Earth Inner Core 2700 km in diameter Solid Made mostly of iron but with some nickle Temperature of 40000C to 60000C

The Structure of Earth Outer Core 2300 km Liquid, molten iron and nickel Temperature above 40000C

The Structure of Earth Mantle 2900 km in thickness Divided into two layers, upper and lower Lower layer is mostly solid Upper layer is called asthenosphere The asthenosphere is in a plastic state, sometimes solid sometimes liquid. Made mostly of magnesium and iron silicates.

The Structure of Earth Mohorovicic Discontinuity The boundary between mantle and lithosphere This is where earthquake waves abrubtly change speed

The Structure of Earth Lithosphere 1-100km thick Made up mostly of lightest elements, magnesium, aluminum, and iron silicates such as granite Can be divided into two layers, one under ocean basins and one making up continents Rocks of continents are known as the crust Crust is 6-70km thick

Types of rock that make up the planet Igneous: Rock that forms when molten substances cool down and harden. Sedimentary: Rock that forms when small pieces of other rocks merge together. Metamorphic: Rock that undergoes some physical or chemical change due to the application of heat or pressure

Igneous Rock: Obsidian Sedimentary Rock Metamorphic Rock

Forms that make up Earth’s surface The different forms that make up the earth’s surfaces are generally known as its Topography. Relief is the differences in elevation and slope between the higher and lower parts of the land surface of a given area. Plains: Large flat expanses found at low elevations. Plateaus: Large flat expanses that are at higher elevations. Mountains: Described as elevations of more that 300m; Hills would be elevations less than 300m.

A World in Constant Change The world did not always appear as it does today 225 million years ago all of the continents were actually connected!!! We called this super continent Pangea, and the super ocean surrounding it Panthalas Overtime the continents eventually drifted into the positions they occupy today.

The Forces at Work The forces that continental drift create are responsible for many of the features we see on the surface of the earth. Mountains, volcanoes, and earthquakes are all a result of continental drift. Plate tectonics: the movement of plates

Forces at Work Compressional force: The force created when two plates move toward each other. Causes rock layers to bend, warp, and move upward. Tensional force: Forces of tension are created where two plates are moving away from each other. Causes large trenches where plates move appart. 1.1.1 Explain how compressional forces are caused. (k) 1.1.2 Explain how tensional forces are caused. (k)

Activity 1: Mapping the Plates On the provided map sketch, and label a map detailing the continental plates. Indicate with arrows in which direction the plate is moving. Complete the chart attached to the map Your map should include the following map elements. Legend North arrow Title 1.1.3 Relate selected plate movements to compressional and tensional forces. (a)

Compressional Forces What features are created by compressional forces? Fold mountains Reverse Faults Overthrust Faults

Compressional Forces: Fold Mountains Fold mountains: Occur where compressional forces cause the land to lift upwards, creating some of the worlds most spectacular mountains. 1.1.4 Explain how compressional forces create fold mountains. (k)

Compressional Forces: Fold Mountains Fold mountains take on a wave like appearance. The peak of these waves is called the anticline The trough of the wave is called the syncline 1.1.5 Differentiate between the terms anticline and syncline. (k)

Anticline and Syncline Folds

Compressional Forces: Reverse Faults Reverse Fault: When two plates push against each other one side can be pushed up over the other. 1.1.7 Explain how compressional forces create reverse and overthrust faults. (k)

Compressional Faults: Overthrust Faults Overthrust Faults: When folded rock gets pushed together and thrust over other layers we get an overthrust fault 1.1.7 Explain how compressional forces create reverse and overthrust faults. (k)

Tensional Forces What features are created by forces of tension? Normal Faults

Tensional Forces: Normal Fault Normal Fault: occurs when a plate on one side of a fault drops down lower than the other.

How Are Mountains Formed Mountains are formed in three main ways Tensional forces Compressional forces Volcanoes

How Do Volcanoes Build Mountains? There are three types of volcanoes that all have distinctive characteristics Ash-and-cinder cones Shield cones Composite Cones

Volcano Terms Volcano: most common landform that is associated with extrusive volcanic activity Vent: area of the volcano through which volcanic products erupt Magma: Super heated melted rock below the surface Lava: Liquid rock that has reached the surface Ash: Small molten rock fragments

Volcano Forms Ash-and-cinder cones: Typical form is symmetrical with steep sides and a large crater at the top They form from bits of cinder and ash being ejected from the vent and building up to form a cone These volcanoes can grow rapidly, forming mountains within a few years. 1.1.9 Describe the characteristics of an ashand- cinder cone, a shield cone, and a composite cone. (k)

At the start

Ash-and-Cinder Volcanoes: Paricutin

Ash-and-Cinder Volcanoes: Paricutin

1952 - Present day

Volcano Types Shield Cones: Broad flat cones Liquid lava Mild eruptions Little or no ash 1.1.9 Describe the characteristics of an ashand- cinder cone, a shield cone, and a composite cone. (k)

Types of Volcanoes Composite Volcano Layers of ash and cinders intermixed with layers of lava Weak points may develop along outer walls Periods of explosive activity, and relative quiet 1.1.9 Describe the characteristics of an ashand- cinder cone, a shield cone, and a composite cone. (k)

Composite Cone Volcano

What Causes Volcanoes to Erupt Heat is the major factor in Volcanic eruptions Where plates meet there is a great amount of heat When plates are pushed together one slides under another This heat present causes rock to melt, forming magma The pressure from the weight of the heavier rock drives the magma up through cracks in the earths crust Forming volcanoes. 1.1.8 Explain what causes a volcano to erupt. (k)

Global Distribution of Volcanoes Given what we know about what causes volcanoes to erupt we may say that volcanoes occur where plates meet The most famous region of volcanoes on earth is know as the Pacific Ring of Fire The Pacific Ring of Fire circles the Pacific Ocean. The west coast of north and south america. The east coast of Asia, and South toward The southern ocean. 1.1.10 Conclude how the location of active volcanoes is related to places where plates meet. (a)

The Pacific Ring of Fire 1.1.11 Describe global patterns in the location of landforms. (k)