Plate Tectonics Chapter 4 Lesson 1 Pages 166-177

What are Earth’s layers? Scientists have gathered evidence from earthquakes and volcanoes to form a model of Earth’s interior. Earth is made of layers Core- Earth’s central part The inner core is made of solid metals The outer core is made of liquid metals

What are Earth’s layers MANTLE- the thick layer of solid and molten rock that surrounds the core Top of upper mantle is solid rock Lower mantle is solid rock CRUST- a thin layer of solid rock that makes up the outermost layer of Earth Imagine it as the skin of an apple.

What are Earth’s layers?

Lithosphere The crust and the top of the upper mantle make up the lithosphere The lithosphere is the solid, rocky crust covering the entire planet which includes landforms

Hydrosphere The hydrosphere covers about 70 percent of Earth’s surface All Earth’s liquids and solid water-including oceans, lakes, and rivers, glaciers, and the water underground-makes up the hydrosphere The hydrosphere covers about 70 percent of Earth’s surface Most of Earth is salt water, a small fraction of Earth’s water is fresh and most fresh water is frozen (ice around North and South Pole)

Landforms Physical feature on Earth’s surface. You will find these located on the crust of Earth Mountains, hills, rivers, lakes, deserts are all examples of landforms

Are the continents moving? Alfred Wegener, a geologist, noticed that the continents appeared to fit together like pieces of a jigsaw puzzle A geologist is a scientist who examines rocks to find out more about Earth’s history and structure He believed that millions of years ago, the continents formed 1 huge landmass known as Pangea. The Theory of Continental Drift is responsible for Pangea breaking apart into the 7 continents Evidence: Wegener found evidence that the mountains of the East Coast of South America had the same type of rocks as the mountains of the West coast of Africa A Mesoraurus has been found in very old rocks in South America and Africa. It could not have been possible that this animal swam across the ocean to get from one continent to another.

Mesosaurus Fossil

What causes the continents to move? Earth’s continent moves with these plates (see picture on page 172) The lithosphere is described as being made of huge plates and solid rock and the asthenosphere acts as a conveyor belt that moves the plates Magma is being pushed from the mantle toward the surface (pg. 173) and causes the land to move. At the same time, plates are also colliding and one plate will sink under another The ocean floor between South America and Africa is spreading at a rate of about 4cm every year and has been for the past 130 million years Scientists developd a theory called Plate Tectonics Earth can cause seafloors to spread and continents to move This theory describes the lithosphere as being made of huge plates of solid rock

How do Mountains form?

How do mountains form? When plates collide, the force that results is called compression. This is the squeezing or pushing together of the crust When a continental plate is compressed, the ground is forced upward and creates folded mountains

How do mountains form? As the seafloor spreads, a mid-ocean ridge forms When this occurs on land, tension pulls the crust apart and form faults Faults are deep cracks in Earth’s crust where rocks move in opposite directions Fault block mountains are formed as a result of this tension