Plate Tectonics

Exploring Inside the Earth Geologists have used evidence from rock samples and evidence from seismic waves to learn about Earth’s interior. Geologists are scientists who study the forces that make and shape planet Earth. Geology is the study of planet Earth.

Studying Surface Changes Constructive forces shape the surface by building up mountains. Destructive forces are those that slowly wear away mountains and, eventually, every other feature on the surface.

The Crust The crust is a layer of solid rock that includes both dry land and the ocean floor. Three main layers make up Earth’s interior: the crust, the mantle, and the core. Each layer has its own conditions and materials.

The Mantle Earth’s mantle is made up of rock that is very hot, but solid. The mantle is divided into layers based on the physical characteristics of those layers.

The Core The core is made mostly of the metals iron and nickel. It consists of two parts–a liquid outer core and a solid inner core.

The Plates and How They Move The lithosphere is broken into separate sections called plates. The theory of plate tectonics explains the formation, movement, and subduction of Earth’s plates.

Review: Heat Transfer There are three types of heat transfer: radiation, conduction, and convection. Radiation – the transfer of energy through empty space Heat transfer – the movement of energy from a warmer object to a cooler object Conduction – heat transfer by direct contact of particles of matter

Convection & Convection Currents Heating and cooling of the fluid, changes in the fluid’s density, and the force of gravity combine to set convection currents in motion. Convection – heat transfer by the movement of a heated fluid Convection currents – the flow that transfers heat within a fluid

Convection Currents in Earth Heat from the core and the mantle causes convection currents in the mantle. This is how the heat is transferred, and how the earth’s plates are able to move.

Plate Boundaries At the locations where two tectonic plates interact, a boundary between these plates exist. There are three types of boundaries that geologist observe. (Draw these pictures into your notes)

Plate Boundaries There are three kinds of plate boundaries: 1.divergent boundaries – when the plates slide apart and create a rift 2.convergent boundaries – two plates collide 3.transform boundaries – when two plates slide past each other A different type of plate movement occurs along each type of boundary.

The Continental Drift Theory An hypothesis was created that all the continents were once joined together in a single landmass. Continental Drift Theory – The idea that the continents slowly moved over Earth’s surface.

Scientists now believe that about 250 million years ago, a super-continent known as Pangaea existed. This super-continent was made up of all the continents on Earth.

Evidence for Continental Drift Fossils – any trace of an ancient organism that has been preserved in rock.

Continental Drift It has taken the continents about 225 million years since the breakup of Pangaea to move to their present locations.

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Plate Tectonics Review 1.Define Geology. 2.What does a geologist study? 3.How do constructive and destructive forces differ? 4.What are the 3 main layers of the Earth? Briefly describe each layer. 5.What are plates, and how do they move? 6.What is heat transfer? What are the 3 ways in which heat transfers? 7.What are plate boundaries ? What are the 3 types that geologists observe? Briefly describe each type. 8.Explain the Continental Drift Theory. 9.What was Pangaea? 10.What evidence was there of this super-continent existing?