1

Chapter 14

Geology

&

Earth Resources

2

OUTLINE

Tectonic Processes 14.1

Rocks and Minerals 14.2

Rock Cycle

Geological Hazards 14.6

Earthquakes

Volcanoes

Landslides

3

GEOLOGIC HISTORY – add to Gaia Theory

4

GEOLOGIC TIME FRAMES

• EON – an extremely long time period

ie: a billion years

• ERA – portion of an eon usually marked by

an event, ie: mass extinctions

• PERIOD – portions of an era

• EPOCH – portions of a period

• AGE – portions of an epoch

Use the ESRT as a guide to determine our

current placement in geologic history.

5

EARTH IS A DYNAMIC PLANET

GEOMORPHOLOGY is the

study of the processes

that shape the earth’s

surface and the structures

they create.

Humans have shaped the Earth’s surface more than any other single geomorphic process except plate tectonics.

6

IMPORTANT GEOLOGISTS

7

EARTH’S CROSS-SECTION

INNER CORE - interior

composed of dense, intensely

hot metal

Composed of ____________.

Temp: _________________

State: _________________

OUTER CORE – less dense

Composed of ____________.

State: _________________

8

EARTH’S CROSS-SECTION

OUTER CORE –

Generates the magnetic field

enveloping the earth.

Differences in temperature,

pressure and composition

within the outer core cause

convection currents.

The Coriolis effect causes the

liquid to spin.

This flow of liquid iron generates electric currents,

which in turn produce Earth’s magnetic fields.

This is a self-sustaining loop known as the

GEODYNAMO.

9

EARTH IS A DYNAMIC PLANET

MANTLE - hot, molten layer

surrounding the core. Less

dense than core.

ASTHENOSPHERE is

denser layer beneath the

crust. The temperature &

pressure very high - rocks

soften and partly melt,

becoming semi-molten

CONVECTION CURRENTS

in asthenosphere keep rock

material circulating in the

mantle

10

EARTH IS A DYNAMIC PLANET

CRUST –

a.k.a. LITHOSPHERE

cool, lightweight, brittle

outermost layer. Less

dense than Mantle.

“Floats” on top of mantle.

CONTINENTAL __________

_______________________

OCEANIC ______________

_______________________

11

TECTONIC PROCESSES

• Upper layer of mantle contains convection currents

that break overlying crust into TECTONIC PLATES.

Plates slide slowly across earth’s surface

- Ocean basins form where continents crack and

pull apart.

- MAGMA (molten rock) forced up through the

cracks forms new oceanic crust that piles up

underwater in MID-OCEAN RIDGES. Longest

and tallest mountain chain in the world.

12

PANGAEA

Geologists suggest that

several times in Earth’s

history most, or all, of the

continents gathered to form

a single super-continent,

Pangaea, surrounded by a

single global ocean.

This redistribution of continents affects the Earth’s

climate and may help explain the periodic mass

extinction of organisms.

13

TECTONIC PLATE MOVEMENT

https://www.youtube.com/watch?v=ryrXAGY1dmE

14

TECTONIC PROCESSES - EARTHQUAKES

• EARTHQUAKES are caused by grinding and jerking as plates slide past each other.

1. CONVERGENT PLATE BOUNDARY:

- When an oceanic plate collides with a continental landmass, the continental plate (lighter) will ride up over the seafloor and the oceanic plate (denser) will SUBDUCT down into the mantle where it melts causing volcanoes to form.

- Deep ocean trenches mark subduction zones. Mariana trench – 11,000 meters

15

1. CONVERGENT

PLATE

BOUNDARY

Mountain ranges are also formed when two continental plates collide.

ie: Himalayas are still growing as the Indian

and Asian plates collide.

ie: Ring of Fire in Pacific Ocean – areas of subduction with frequent volcanoes & earthquakes

16

TECTONIC PROCESSES

2. TRANSFORM PLATE BOUNDARY occurs where two plates slide passed each other. This create TRANSFORM FAULT LINES ie: California’s San Andreas Fault

17

TECTONIC PROCESSES

3. DIVERGENT PLATE BOUNDARY where two plates are spreading apart.

- Mostly found at MID-OCEAN RIDGES.

- Magma rises, solidifies and pushes the plate margins apart. Causes oceans to grow!

Creating new oceanic crust and undersea mountain range all around the earth. These are the sites of Hydrothermal vents

18

TECTONIC PROCESSES

IN WATER, DIVERGENT PLATE BOUNDARIES FORM MID-OCEAN RIDGES

19

TECTONIC PLATES

7 MAJOR PLATES: African, Indian-Australian, Pacific,

North American, South American, Eurasian, Antarctic

20

On your page, draw and Label each major and minor plate.

21

Mark all plate boundaries: Transform, Convergent, Divergent

22

Using arrows, show general direction of plate movement

23

Identify Hawaiian, Yellowstone, Galapagos, & Canary Hot Spots

24

Identify the Ring of Fire

25

ROCKS AND MINERALS

• A MINERAL is a naturally occurring, inorganic,

solid element or compound with a definite chemical

composition and regular internal crystal structure.

• A ROCK is a solid, cohesive,

aggregate of one or more minerals.

Each rock has a characteristic

mixture of minerals, grain sizes,

and ways in which the grains

are held together.

26

ROCK TYPES

• ROCK CYCLE - cycle of creation, destruction, and

metamorphosis

Three major rock classifications:

IGNEOUS - ____________________________

_____________________________________

SEDIMENTARY - _______________________

_____________________________________

METAMORPHIC - _______________________

_____________________________________

27

ROCK CYCLE

28

IGNEOUS ROCKS

• Most common type of rock in Earth’s crust.

Solidified from magma extruded onto the surface

from volcanic activity

- EXTRUSIVE:

Quick cooling of magma

produces fine-grained

rocks. ie: Basalt

- INTRUSIVE:

Slow cooling of magma

produces coarse-grained

rocks. ie: Granite

29

METAMORPHIC ROCK • Pre-existing rocks modified by heat, pressure, and

chemical agents

• Chemical reactions can alter both the composition

and structure of rocks as they are metamorphosed.

30

WEATHERING & SEDIMENTATION

• MECHANICAL WEATHERING - physical break-up

of rocks into smaller particles without a change in

chemical composition (glaciers, water, frost, roots)

• CHEMICAL WEATHERING - selective removal or

alteration of specific components that leads to

weakening and disintegration of rock

Oxidation – minerals combine with oxygen

(“rusting” of rocks)

Hydrolysis (formation of acids: carbonic/sulfuric)

• SEDIMENTATION - deposition of particles of rock

transported by wind, water, ice and gravity until

they come to rest in a new location

31

Nicolaus Steno

1. The LAW OF SUPERPOSITION: layers on top are younger than layers below,

(assuming no folding of rocks has occurred)

IMPORTANT GEOLOGISTS

32

Nicolaus Steno 2. The PRINCIPLE OF ORIGINAL HORIZONTALITY: layers of sediment are

originally deposited horizontally under the action of gravity

IMPORTANT GEOLOGISTS

33

Nicolaus Steno 3. The PRINCIPLES OF LATERAL CONTINUITY:

> layers of sediment initially extend laterally in all directions and as a result, rocks that

are otherwise similar, but are now separated by a valley or other feature, can be

assumed to be originally continuous.

> Horizontal strata extend laterally until they thin to zero thickness at the edge of their

basin of deposition.

IMPORTANT GEOLOGISTS

34

Chemical

weathering

of a statue

Copper oxidized in Malachite

CHEMICAL WEATHERING

Lichens

on a rock

35

SEDIMENTARY ROCK

• Deposited materials that remain in place long enough, or are covered with enough material for compaction, may again become rock. Examples: sandstone, shale

• Can also be formed from crystals that precipitate out of, or grow from, a solution.

ie: Halite or other salts from ancient sea beds

36

ECONOMIC GEOLOGY (Intro only... More to come)

• ECONOMIC MINERALOGY is the study of

minerals that are valuable for manufacturing.

• METALS

Metals consumed in greatest quantity by world

industry: Iron, Aluminum, Manganese, Copper,

Chromium, Nickel

• NON-METAL MINERAL RESOURCES

Gemstones, Precious Metals, Sand & Gravel

Limestone, Evaporites (salts), Sulfur

37

GEOLOGIC HAZARDS See Table 14.5 for Worst Natural Disasters and total deaths

• ASTEROID IMPACT possibly wiped out dinosaurs

Chicxulub

65 million years ago

10 km (6.2 mile) diameter

180 km crater (110 miles)

• FLOODS take the greatest number of lives

(rivers, sea level rise, storm surge, tsunamis)

• WIND causes the most property damage

(hurricanes, cyclones, tornados)

38

GEOLOGIC HAZARDS • EARTHQUAKES - sudden movements of the

Earth’s crust that occur along faults where one rock mass slides past another

Gradual movement – usually unnoticed is called creep or seismic slip

- When friction prevents creep, stress builds up until eventually released with a sudden jerk.

Hypocenter or Focus - the actual point inside the earth

where the rupture occurred

Fault – a fracture or crack in the rocks of a tectonic plate

Epicenter – the point on the surface of earth directly

above the hypocenter.

39

40

41

Seismic waves – energy waves created by the earthquake

Primary (P) waves – series of compression waves where

particle motion is parallel to the propagation direction.

FASTEST waves, move through all materials (solid & liquid)

http://www.geometrics.com/what-are-the-different-types-of-seismic-waves/

Secondary (S) waves – shear waves characterized by

side to side motion that is perpendicular to the propagation

direction. Slower, only travel through solids.

Rayleigh waves – are surface waves characterized by up

& down motion perpendicular to the surface (like water waves)

Love waves – are surface waves characterized by side to

side movement perpendicular to the propagation direction.

These are the most destructive

42

Richter Magnitude Scale

- scale used to assign a

magnitude number to quantify

the energy released by an

earthquake.

**Each number is 10x greater

ie: a quake of magnitude 6 is

_____ times stronger than a 4.

Mercalli Scale – measures

intensity of an earthquake

based on damage. Not based

on instrumentation.

43

EARTHQUAKES CONTINUED

• Worst death tolls from earthquakes occur where construction is poor. Now most buildings in earthquake zones are reinforced. Where gov’t regs apply. Poor areas/countries still at risk.

• Most seismically active region in U.S. is west coast, but largest earthquake recorded was in New Madrid, Missouri.

• Earthquakes are often followed by aftershocks – smaller seismic activity at/near the same fault zone

• No way to fully predict where or when an earthquake will occur. **Historical Data is best reference.

44

TSUNAMIS

• TSUNAMIS are large oceanic waves

usually generated by undersea earthquakes generated from epicenters below the ocean. ie: tsunami in Indonesia in 2004

Can be generated by underwater landslides or volcanic eruptions

U.S. has installed warning buoys in ocean.

Cumbre Vieja volcano in the

Canary Islands could collapse

and create a tsunami

45

VOLCANOES

• Volcanoes and undersea magma vents at mid-ocean ridges (deep-sea vents/hydrothermal vents) are the sources of most of the Earth’s crust.

• Most volcanoes occur at plate boundaries

Many of the world’s fertile soils are weathered volcanic material. Rich in minerals.

500 million people live in danger zones.

NUEES ARDENTES - deadly clouds of hot gas and ash. Temperatures exceed 1000 oC and move at 60 mph! Kill within minutes. ie: Mt. Vesuvius destroyed Pompeii

Mudslides/landslides often accompany eruptions.

46

VOLCANO CLASSIFICATION

Inactive / Extinct: haven’t erupted for 10,000+ years and are affected by erosion/weathering.

Dormant: not recently active but could erupt again

Active: recently erupted or showing signs of activity.

47

VOLCANOES

Water Vapor & CO2 are most common high temperature gases released from a volcano

Volcanic dust and sulfur emissions reduce sunlight and temperature around the globe. Can cause climate change.

Sulfur dioxide emitted from volcanoes mixes with water vapor to form Sulfuric acid (H2SO4). This blocks solar radiation causing a cooling of the atmosphere. Sulfuric acid in the stratosphere will reduced ozone increasing UV radiation.

Low Temperature Gases include: hydrogen sulfide (H2S), nitrogen, argon, helium, neon, methane, carbon monoxide and hydrogen

48

LANDSLIDES

• Landslides are examples of MASS WASTING, in

which geologic materials are moved downslope

from one place to another.

Can be slow and subtle or swift and dangerous

as in rockslides and avalanches

• Road construction,

forest clearing,

cultivation, and

building on steep,

unstable slopes

increase the frequency

and damage done by

landslides.