Chapter 19.3Earth Science

The Lithosphere GEE Science

Summer RemediationMr. Nash

Donnie Bickham Middle SchoolRoom 204

The Lithosphere Most dynamic of the four spheres and recycles

elements in a variety of ways. Some methods are considered fast in a geological

sense, while others may occur over billions of years. The rock cycle explains how rocks are built and

recycled. Processes:

Volcanic activity Weathering Erosion Mass wasting

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Volcanoes Volcano – a mountain formed from lava and

rocks made from materials that have emerged from inside the earth.

Lava – magma that has reached the surface. Magma – liquid rock and dissolved gases still

inside the earth. Dissolved gases:

Water vapor Carbon dioxide Nitrogen Sulfur

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Volcanoes Magma reaches earth’s surface

through a vent. Vents begin deep in the earth.

Once out of the vent lava hardens to build a mountainous structure.

Once the mountain/volcano is built lava still releases from the crater. Crater is a hole in the top of the volcano.

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Volcanoes Magma is under pressure inside the

earth. When this pressure is released the sudden expansion of gases causes an eruption. Example: Mount St. Helens 1980

Lava can also slowly flow from a volcano. Example: Kilauea in Hawaii

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Volcanoes Volcanoes affect the other sphere b y

causing physical damage, depositing elements, and creating rocks.

During eruptions, sulfur and carbon gases, dirt, and ash are thrown into the atmosphere.

This is sent high into the atmosphere.

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Volcanoes This debris can become suspended in the

atmosphere for a period of time. This debris can block sunlight, decreasing

the temperature. A decrease in temperature can affect wind

and precipitation. The gases form acids with the water in the

atmosphere to form acid rain. Sulfur reacts with water to form Sulfuric Acid. Theory of dinosaur extinction similar to this.

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External Processes External processes close to the surface

include: Weathering-decomposition of rock by

mechanical, biological, or chemical means. Mass wasting-transport of rock down slope

under the effect of gravity. Erosion-movement of soil or rock material

by water, wind, or ice.

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Weathering Rock weathers as a response to

changes in the environment. Weathering occurs by three

processes: Mechanical Weathering Chemical Weathering Biological Weathering

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Mechanical Weathering Process where rocks are physically

broken into smaller pieces by wind, water, ice or heat.

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Chemical Weathering Process where minerals within the

rocks are broken down by removing or altering elements that make up the minerals.

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Biological Weathering Caused by living organisms using both

mechanical or chemical means. Examples:

Mechanical – Burrowing plants or animals break up the soil and rock mechanically.

Chemical – Lichens secreting enzymes removing nutrients from the rock and soil while living on them.

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Mass Wasting Transports rock down slope gradually or

rapidly. Major types of mass wasting:

Slumping – mass of rock moves as a single unit down slope along a curved surface.

Rockslides – large sections of rock break away down slope

Does not follow a curve like slumping Mudflows – sediment becomes saturated with

water and flows down slope Occur rapidly after large rainfalls.

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Erosion The breakdown and transport of soil or

rock by water, ice, or wind. Streams and rivers break down rocks,

but also transport them. Rivers alter their course cutting through

rock and soil. Also occurs along shorelines where

waves break down and transport rocks.

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Erosion Ice erodes and transports rock by

glacial movement. Rocks trapped in the ice erode by

hitting each other or the walls of valleys.

Glacial ice carves out valleys and erodes mountain tops.

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Erosion Wind erosion is most apparent in

desert environments. Rock fragments are carried by winds

and pushed until they meet a hill. The fragments act like a sand blaster

eroding the rock of the hill over time. Wind also transports large amounts of

rock and soil over large distances.

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Rock Types Three Types:

Igneous – formed from magma deep inside the earth.

Sedimentary – formed from deposited and compressed sediment.

Metamorphic – changed by heat and pressure

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Igneous Rocks Magma cools and solidifies. Cooling below the earth’s surface

creates large crystals and are called intrusive igneous rocks.

Cooling outside the earth’s surface creates small crystals and are called extrusive igneous rocks.

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Sedimentary Rocks Can be either land derived or precipitated

from ocean water. Land derived are usually transported, then

deposited, compacted and cemented in another location. Sandstone, mudstone, and conglomerates.

Ocean precipitates fall to the ocean floor as sediment and compacted. Limestone, halite (salt), and gypsum.

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Metamorphic Rock Occurs when rocks change within the

earth. Can be caused by heat and pressure

or by chemical means. Examples:

Carbon into diamond. Limestone into marble Sandstone into quartzite

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Rock Cycle Begins with igneous rocks, then undergoes

weathering and erosion to create sediment. Sediment becomes deposited and

compacted forming sedimentary rocks. Sedimentary rocks are exposed to heat and

pressure and form metamorphic rocks. Metamorphic rocks can melt inside the earth

to erupt and from igneous rocks again.

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