Chapter 21- Planet Earth

2nd Semester Earth Science Ch 21- Planet Earth & Ch 22 Climate Chapter 21- Section 1: all; Section 2: p 709-710, 714 middle; 716-717; Section 3: all Chapter 22- Section 3 Climate 760-762

Section 1: Earth’s Interior and Plate Tectonics What is Earth’s Interior Like? • The Earth is made up of three layers: the crust, the mantle and the core.

• ______the thin and solid outermost layer of Earth above the mantle

• ______the layer of rock between Earth’s crust and core

• ______the center part of the Earth below the mantle

Structure of the Earth DRAW AND LABEL your own diagram

• Earth’s interior gets ______.

• Geologists believe that the mantle is much hotter than the crust, reaching temperatures higher than 1250° C (2280° F).

• The core is hotter than the mantle, reaching temperatures higher than 6000° C (10,800° F).

• Radioactive elements contribute to Earth’s high internal temperature.

• The breakdown of ______uranium, thorium and potassium ______that contributes to Earth’s ______.

Plate Tectonics • Around 1915, German scientist Alfred Wegener proposed the idea that the continents were once united as a ______.

• He pieced the continents together like a ______and called the supercontinent they formed ______.

1 • Wegener found ______on widely separate continents, which supported his idea.

• Evidence for Wegener’s ideas came later.

• Wegener’s theory of continental drift was ignored until structures discovered on the ocean floor provided evidence for a mechanism for the movement of continents.

• Symmetrical bands on either side of a mid-ocean ridge indicate that the two sides of the ridge were moving away from each other and new ocean floor was rising up between them.

• ______supports the theory of moving plates. • Iron in molten rock aligns itself with Earth’s magnetic field as it cools.

• The Earth’s magnetic field reverses polarity about every 200,000 years

• The process is recorded as magnetic bands in rock, based on the age of the rock.

• Symmetrical bands on either side of the Mid Atlantic Ridge suggest that the crust was moving away from the ridge.

• Earth has ______that ______.

• The crust and upper portion of the mantle are divided into about seven large pieces called ______.

• ______the solid, outer layer of Earth, that consists of the ______and the rigid ______

Plate tectonics the theory that explains how the outer parts of Earth ______, and that explains the relationships between ______, sea-floor spreading, ______, and volcanic activity

• It is unknown exactly why tectonic plates move.

• One hypothesis suggests that plate movement results from ______in the asthenosphere, the hot, fluid portion of the mantle.

• Another hypothesis suggests that plate movement results from the ______acting on the plates.

Plate Boundaries • Mid-ocean ridges result from ______. • The border between two plates is called a boundary.

2 • Divergent boundary a place where two plates are ______

• ______forms between divergent boundaries.

• Magma ______produced under Earth’s surface

• Oceanic plates ______continental plates at convergent boundaries. • Plates ______at a convergent boundary.

• ______the process by which one lithospheric plate moves ______as a result of tectonic forces

• The area where one plate slides over another is called a subduction zone. Subduction zones produce ______, ______, and ______.

• Subduction of ocean crust generates ______.

• Chains of volcanoes form on the upper plate in a subduction zone.

• These volcanoes can form far inland from their associated oceanic trench.

• Colliding tectonic plates create ______.

• When two ______, mountains are formed at the boundary of the collision.

• The ______formed during the collision between the continental tectonic plate containing India and the Eurasian continental plate.

• Transform fault boundaries can ______.

3 • Plate movement can cause ______.

• ______a crack in Earth created when rocks on either side of a break move

• Plate movement at transform fault boundaries is ______.

Section 2 Earthquakes and Volcanoes What are Earthquakes? • Earthquakes ______.

• Earthquakes are ______resulting from rocks ______each other at ______

• Seismic waves are ______during an earthquake

• Focus= the area along a fault at which the ______of an earthquake occurs

• ______= the point on Earth’s surface directly above an earthquake’s focus

• Energy from earthquakes is ______. • Earthquakes generate three types of waves: • ______

• ______

• Longitudinal waves travel by ______and ______crust, also called primary waves (P waves) (SLINKY!)

• Transverse waves travel in an ______movement, also called secondary waves (S waves)

• Surface waves seismic waves that can ______, move in a ______motion

DRAW! Longitudinal Wave Transverse Wave

4 Volcanoes • A volcano is ______in Earth’s ______through which magma has reached Earth’s surface.

• ______= an opening at the surface of Earth through which volcanic material passes

• Volcanoes generally have one central vent, but they can also have several smaller vents. • Magma that reaches Earth’s surface is called ______.

• Shield volcanoes have ______.

• Lava from shield volcanoes is ______and forms a gently sloping mountain.

• Shield volcanoes are some of the ______volcanoes.

• Composite volcanoes have ______.

• Composite volcanoes are made up of alternating layers of ash, cinders, and lava.

• The lava is thicker than that of shield volcanoes.

• Gases are trapped in the magma, causing eruptions that alternate between ______and ______that produces cinders and ash.

• Composite volcanoes are typically ______.

• Most volcanoes occur at ______boundaries. 5 • 75% of the active volcanoes on Earth are located in an area known as the ______.

• The Ring of Fire is located along the edges of the ______, where ______tectonic plates are ______with ______plates.

• Underwater volcanoes occur at ______plate boundaries.

• As plates move apart at divergent boundaries, magma rises to fill the gap.

• This magma creates the volcanic mountains that form ocean ridges.

• ______is a volcanic island on the Mid-Atlantic ridge that is growing outward in opposite directions.

• Volcanoes occur at ______. • Some volcanoes occur in the middle of plates.

• ______are mushroom shaped trails of hot rock that rise from deep inside the mantle, melt as they rise, and erupt from volcanoes at hot spots at the surface.

• The plumes remain in the same place as the tectonic plate moves, creating a trail of volcanoes.

• The ______are an example of this type of volcanic activity.

Section 3 Minerals and Rocks Structure and Origin of Rocks • All rocks are composed of ______.

• There are about 3500 known minerals in Earth’s crust. • Each combination of rock-forming minerals results in a rock with a unique set of properties.

• ______a natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties

• Molten rock cools to form igneous rock.

• Nearly all igneous rocks are made of crystals of various minerals.

• ______rock that forms with magma cools and solidifies

6 • Extrusive igneous rock cools _____ Earths surface

• Intrusive igneous rock cools while ______Earth’s surface

• Remains of older rocks and organisms form ______.

• All rock breaks down over thousands of years.

• ______the natural process by which atmospheric and environmental agents, such as ______, ______, and ______, disintegrate and ______rocks

• As pieces of rock accumulate, they can form another type of rock.

• ______a rock formed from compressed or cemented layers of sediment

• Sediment= accumulated pieces of rock and other particles

• Loose sediment forms rock in two ways.

1. Layers of sediment ______from weight above, forming rock.

2. ______seep between bits of sediment and “______” them together.

• Sedimentary rocks are named according to the size of the fragments they contain.

• Rocks that undergo pressure and heating without melting form ______rock.

• Heat and pressure within Earth cause changes in the texture and mineral content of rocks.

• Metamorphic rock= a rock that forms from other rocks as a result of intense ______, ______, or ______

• ______rocks in the rock cycle form ______rocks.

• The sequence of events in which rocks can be weathered, melted, altered, and formed is described by the ______.

• Rock formation occurs ______, often over tens of thousands to millions of years.

7 How Old Are Rocks? • The relative age of rocks can be determined using the ______. • The principle of superposition states the following: • Assuming no disturbance in the position of the rock layers, the ______will be on the ______, and the ______will be on ______. Law of Superposition

• ______can determine a more exact, or ______, age of rocks. • The radioactive elements that make up minerals in rocks ______over billions of years. • Physicists have determined the ______at which these elements decay. • Geologists can use this data to determine the ______.

8 CHAPTER 22 Section 3: Pages 760(climate) – 762 Climate • Climate the ______in an area over a ______of time.

• Temperatures tend to be higher close to the ______.

• Sunlight strikes the earth ______close to the equator.

• The suns rays are less concentrated at ______, and do not warm the atmosphere as much.

• Earth’s ______account for our ______. • When the North Pole is tilted toward the sun, the ______Hemisphere experiences ______.

• When the South Pole is tilted toward the sun, the ______experience summer.

• Summer solstice the ______of the year

• Winter solstice the ______of the year

• Vernal equinox the point in the ______when the ______are ______

• Autumnal equinox the point in the ______when the ______are ______• Global climate changes over time. • Many factors produce changes in Earth’s climate, such as: • ______

• slight changes in Earth’s ______

• ______

• changes in the ______

• Earth’s climate is likely to continue changing over the millennia to come.