Lesson 2: Rocks & Minerals

Unit 5

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Topic: MineralsWhat is a Mineral?

Mineral UsesQuartz

Graphite

Talc

Gypsum

4,000 known minerals

Matter

•anything with mass and volume

Elements

•Building blocks of matter

•Made of Atoms

Atoms make up Elements…

Elements make up MINERALS!!!

Topic: Rocks

Naturally occurring & made of minerals

Rock Classification

1) Igneous

2) Sedimentary

3) Metamorphic

**Classifications are based on formation

( how the rocks are made or formed).

Monominerallic

•Rock made of only one mineral•Ex: Dunite made of Olivine

Topic: Igneous Rocks

• Form as molten rocks (magma or lava) cool.

• Lava – molten rock on Earth’s Surface

•Magma – molten rock inside the Earth

Igneous Classification

• Mineral composition (what it is made of)

• Texture = crystal sizes*Crystal sizes depend on _______________.Longer the cooling → the bigger the crystals!

• ESRT pg 6

Cooling Rate

Identifying Igneous RocksIgneous Rock Names

Extrusive Igneous Rocks

• “Volcanic” (from Lava)

• Cools quickly

• Small (fine) or no crystals

Intrusive Igneous Rocks

• “Plutonic” (from Magma) •Cools slowly •Large (coarse) crystals

Sedimentary rocks

Boulder, Cobble, Pebble, Sand, Silt, Clay

Boulders

Sand

Cobbles

Pebbles

Sedimentary Rocks Form from:

• Weathering & Erosion

• Sediments are deposited in watery environments

Types of sedimentary rocks

• Inorganically formed-• sediments compacted, cemented together

• Organically formed- from dead plant material – coal

• Chemically formed • Evaporates – formed from evaporation of sea

water • Limestone- compacted and cemented seashells

• Key notes: • Sedimentary rocks are the only rock group that

contains fossils!!!!!!!! • This is because sedimentary rocks that forms in

watery environments bury organisms QUICKLY preserving their skeletons

• There is no heat or pressure to destroy their remains

Special Characteristics• Contain sediments (fragments of rocks)

• Often layered

• Contain fossils

http://geology.com/rocks/breccia.shtml

Salt mining on Bonneville Salt Flats, Utah.

Organically Formed

Pressure

Topic: Metamorphic Rocks

Metamorphic Rocksform due to heat and/or

pressure without melting.

Special Features

Warped/distorted Banded(stripes)

Flakes/foliated Dense

Type of Metamorphism

1) Regional: Caused by extreme pressureand heat.

Regional Metamorphism

Type of Metamorphism

1) Regional: Caused by extreme pressure and heat.

2) Contact: caused by extreme heat. (shown by hachured lines)

Sandstone Sandstone

Metamorphic environments associated with Plate Tectonics

Metamorphic rocks in Arizona show formerly flat sedimentary layers squeezed into new shapes.

Metamorphic rocks in Arizona show formerly flat sedimentary layers squeezed into new shapes.

50

51

Igneous Characteristics• Intergrown crystals• Bubbles or Vesicular• Glassy

52

• Layers

• Fossils

• Fragments (Clastic)

Sedimentary Characteristics

53

Metamorphic

• Warped/distorted

• Bands

• Flakes/foliation

• Dense

54

FQ: What rock type are metamorphic rocks formed from?

• Sedimentary

• Igneous

• Metamorphic

Any rock group can form

turn into another type

under the right conditions!

Lesson 3: plate tectonics

Evidence for plate tectonics

• The idea of plate tectonics was not recognized by the scientific community until the 20th century

• Can you imagine something as large as the continent of Africa Moving? How is this possible? What evidence do you think scientist have that proves this idea?

1) Continents appear to “fit” together

Continental Drift Theory

2) Similar minerals, fossils, & rocks found on continents oceans apart

HMH page 48

3) Glacial evidence on equator

4) Matching mountain chains in US & Europe

5) Rocks on the Earth’s surface are deformed (folded, faulted, tilted)

• Marine limestone ( containing shell fossils) is found near the top of Mt. Everest

What is under the Atlantic Ocean? Mid-Atlantic Ridge

7) Rocks on opposite sides of ocean ridges

match in type, age & magnetic polarity.

HMH pages 53- 55

The Theory of Plate Tectonics is

• the lithosphere is broken into pieces that move around

What would cause the lithosphere plates to move?

*The driving force behind plate tectonics is

•Convection (Density differences) in asthenosphere

3 things can happen at plate boundaries

•Converging

•Diverging

•Transform

Convergent• Plates collide

Oceanic crust vs. Continental Crust

Granite, less denseBasalt, Denser

Example: Cascade Mountains

Continental vs. Oceanic • Result: Subducting oceanic crust

• Features:

1) Deep Sea Trench

2) Volcanoes & Mountains on continental crust

3) Earthquakes

Example: Cascade Mts., West USA

Oceanic crust vs. Oceanic crust

Guam

HMH page 61

Oceanic vs. Oceanic • Result: Subducting oceanic crust

• Features:

1) Deep Sea Trench

2) Volcanoes Island Arc

3) Earthquakes

Example: Mariania Islands, Pacific Ocean

Continental crust vs. Continental crust

http://www.pbs.org/wnet/savageearth/animations/rift-collide.html

Diverging Plates • Result: Magma rises to surface, new crust forms

• Features:

1) Mid-Ocean Ridges

2) Rift Valleys

3) Earthquakes

4) Volcanoes

Example: Mid-Atlantic Ridge

Transform

• Plates slide past each other

Transform Features:

1) Earthquakes

Example: San Andreas Fault, CA

Major Concepts

• The lithosphere is divided into 6 major plates• Pacific, American, Indian, African, Eurasian, Antarctic

• There are also many smaller plates as well

• Earthquakes result as the result of shifting plates- can occur at any type of plate boundary

• Volcanoes are also indicators of plate boundaries- although they may occur in the middle of a plate boundary – HOT SPOT –HAWAII

Bryce Canyon Country (Garfield County, Utah)

What formed the canyon in the picture?

• Weathering

breaking rocks into smaller pieces called sediments

• Erosion

Moving rocks from one place to another

• Deposition

placement of sediments when they STOP moving

Topic: Physical (Mechanical) Weathering• Breaking rocks into smaller pieces without

chemical change.

1) Frost Action

Temp. drops, water

freezes & expands

Freezing &

thawing repeats

Frost action occurs mainly in Mid-latitudes (45oN or S)due to temperature change

Potholes

&

Frost Heaves

2) Organic Activity: plants & animals break rocks apart

Niagara Glen, Niagara-on-

the-Lake, Ontario, Canada

Root Action

Burns 2007

Changes in sediments -

Abrasion:

• Sediments come in contact with other sediments

• Rocks become

smaller, rounder, and/or smoother

due to abrasion

Breakdown of rock

by changing the

chemical

composition.

**Water is the #1 agent of chemical weathering.**

Powerful Solutions:

Acid RainH2O (rain) + CO2 (carbon dioxide) = H2CO3 (carbonic acid)

Result:

*Dissolves limestone, calcite, and marble rock

*Underground cave systems

Sinkhole—Winter Park, FL

Rust –Oxidation of Iron

• Sinkhole Tour in Florida by CNN

• http://abcnews.go.com/WNT/video/sinkhole-strike-back-26846775

Chemical weathering occurs in warm, humidclimates

Environments of erosion and deposition

• Rocks become weather ( chemically or physically) and becomes sediments

• What happens to these sediments on Earth’s surface? Where do they go?

• Erosion = the transportation of weathered sediments

• Deposition = the placement of weathered sediments

A. Mainly in arid (dry) regions – little vegetation

B. Carries only small sediments

Wind erosion mainly occurs:

Erosional features of wind erosion • Ventifact – rock abraded by wind-driven sand

Depositional features of wind

•Sand dunes

Erosion by streams

** V-shaped valleys – formed from Streams and Rivers **

Taughannock Falls in NY

Black River Meander

HMH page 13

FQ:

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

FvUMlE

Glacier• Naturally-formed mass of ice & snow that

moves under gravity’s influence.

• http://swisseduc.ch/glaciers/aletsch-livecam/index-en.html

Glaciers form a ** U Shaped Valley **

Ex) U shaped valley in Greenland

Type 1: Valley Glacier

Type 2

Continental Glaciers

Greenland’s Ice Sheet

Mass Movement• Large section of land and/or snow moved by

gravity

Ex) landslide, soil creep, avalanches, mudslides