Agenda Jan. 29, 2013

Mr. King

1. Rock Powerpoint – take notes2. Assignment #15: Rock or Mineral

Lab3. Fossil Vocabulary4. Homework: #19 Fossil Vocabulary

Flash Cards

ROCKSROCKSTYPES OF ROCKS TYPES OF ROCKS AND THE ROCK CYCLEAND THE ROCK CYCLE

Rocks or Mineral?Rocks or Mineral?

Rocks• No definite

composition

• Can have organic parts

• No definite properties

• Classified by how formed

•  

Minerals• Definite

composition

• Inorganic – no living remains

• Definite properties

• Classified by composition and crystal shape

TYPES OF ROCKSTYPES OF ROCKSTYPES OF ROCKSTYPES OF ROCKS

• Unlike minerals, rocks cannot be classified by their properties

• Rocks are classified by HOW they formed TEXTURE tells the pressure & temperature;

COMPOSITION tells where formed:

Igneous: Melting & Cooling

Sedimentary: Compacting & Cementing

Metamorphic: Heat & Pressure

IGNEOUS ROCKSIGNEOUS ROCKS

Rocks that have been MELTED and COOLED

• magma: molten rock below earth’s surface

• lava: molten rock above earth’s surface

IGNEOUS ROCKS IGNEOUS ROCKS MELTED & COOLEDMELTED & COOLED

Classified by HOW FAST and WHERE they cool:

• Intrusive rocks - cooled INSIDE the earth

Cooling takes a LONG time because the earth insulates the heat; Slow cooling time means LARGE crystals

• Extrusive rocks - cooled OUTSIDE the earth’s crust

They are cooled quickly and form SMALL crystals

IGNEOUS ROCKS IGNEOUS ROCKS MELTED & COOLEDMELTED & COOLED

Granite

Intrusive Large grains

Basalt* Extrusive

Small grains **makes up new ocean makes up new ocean

floorfloor

Gases released near the surface of a lava flow create bubbles or that are “frozen” in stone

IGNEOUS ROCKS IGNEOUS ROCKS MELTED & COOLEDMELTED & COOLED

Pumice

Extrusive - Small grains

IGNEOUS ROCKS IGNEOUS ROCKS MELTED & COOLEDMELTED & COOLED

Obsidian

ExtrusiveSmall grains - glassy

Snowflake

IGNEOUS ROCKS IGNEOUS ROCKS MELTED & COOLEDMELTED & COOLED

IGNEOUS ROCKS IGNEOUS ROCKS SummarySummary

When magma (melted rock) cools & crystallizes underground crystals grow large, and the rock is called

GRANITE.

HOT MAGMA

When magma breaks through a weak part of the

earth's crust the rock is called LAVA.

Crystals are too small to see because volcanic rocks cool quickly. Examples: BASALT, SCORPIA, TUFF, PUMICE,

and OBSIDIAN

SEDIMENTARY ROCKSSEDIMENTARY ROCKS• Formed by COMPACTION & CEMENTATION• Composed of layers of sediments • Process :

1. Weathering: breaking down of rock at the Earth’s surface (mechanical or chemical) producing Sediments (rock fragments, sand, mud)

2. Erosion: transportation of weathered rock pieces3. Deposition: eroded particles settle (often in layers)4. Compaction: pressure applied squeezes out water5. Cementation: fills in the gaps and “glues” rock

SEDIMENTARY ROCKSSEDIMENTARY ROCKS COMPACTED & CEMENTED COMPACTED & CEMENTED

How to recognize sedimentary rocks:

• Composed of various rock fragments

• Composed of layers (strata)

• Can contain fossils

• Crumble easily

CONGLOMERATES

form in stream beds and pebble beaches

SEDIMENTARY ROCKSSEDIMENTARY ROCKSCOMPACTED & CEMENTEDCOMPACTED & CEMENTED

SANDSTONE made up of fine-grained particles, has a sandy texture (feels gritty)

Sandstones form in sandy environments such as beaches, sand bars, deltas and dunes

SEDIMENTARY ROCKSSEDIMENTARY ROCKSCOMPACTED & CEMENTEDCOMPACTED & CEMENTED

LIMESTONE – chemical

weathering

SEDIMENTARY ROCKSSEDIMENTARY ROCKSCOMPACTED & CEMENTEDCOMPACTED & CEMENTED

SEDIMENTARY ROCKSSEDIMENTARY ROCKSSummarySummary

Sedimentary Rocks, like

sandstone, shale, &

limestone are made

from PIECES that were

buried COMPRESSED)

& CEMENTED together.

METAMORPHIC ROCKSMETAMORPHIC ROCKS

Rocks changed by heat and pressure

• NO MELTING

• Recrystallization: the crystals of old rock reform into new crystals and sometimes new minerals

• Occurs below earth’s surface, usually between plates

• Foliated (distinct layers of flatten minerals) vs. Nonfoliated (no layers)

SLATE - foliated

Uses include roofing, fireplaces, and “blackboards”.

METAMORPHIC ROCKSMETAMORPHIC ROCKSPRESSURE & HEATPRESSURE & HEAT

Parallel planes.

Gray, black, green or red.

METAMORPHIC ROCKSMETAMORPHIC ROCKSPRESSURE & HEATPRESSURE & HEAT

GNEISS – foliated• Black and white banding

• Banding is “squiggly” because heat makes the rock “plastic (flexible)”

METAMORPHIC ROCKSMETAMORPHIC ROCKSSummarySummary

METAMORPHIC ROCKS

have been CHANGED because of HEAT & PRESSURE

Sedimentary

Rocks

Igneous

Rocks

Metamorphic

Rocks

ConglomerateConglomerate

THE ROCK CYCLETHE ROCK CYCLEThe Story of METACONGLOMERATE

Once was a SEDAMENTARY conglomerate.....

• It was subjected to high temperatures and pressure;

• The pebbles squished and elongated to form layers (foliated)

• Kept pebbly appearance

• It became a metamorphosed conglomerate, and received a new name: metaconglomerate.

THE ROCK CYCLETHE ROCK CYCLEThe Story of Marble

Once was a SEDAMENTARY limestone .....

• It was subjected to high temperatures and pressure;

• The layers were flattened and twisted

• It became a metamorphosed limestone, andreceived a new name: marble.

• People polished it and used it in their homes as tiles. Some marble was even carved into statues!

limestonelimestone

Shale

Metamorphosis of Shale to GneissMetamorphosis of Shale to GneissFrom Sedimentary to MetamorphicFrom Sedimentary to Metamorphic

SHALE is the most common sedimentary rock.

Through pressure and heat, (metamorphism), it changes into other rocks.

These changes take place without melting the rock!

Increasing Temperature and PressureIncreasing Temperature and Pressure

Slate Phyllite

Schist

Gneiss

SHALE becomes SLATESLATE becomes PHYLLITE

PHYLLITE becomes SCHIST SCHIST becomes GNEISS

Metamorphosis of Gneiss to GraniteMetamorphosis of Gneiss to Granite

When gneiss melts and cools, it becomes granite!

Gneiss

Granite

From Metamorphic to Igneous!

THE ROCK CYCLETHE ROCK CYCLE

• Series of changes that “recycle” rocks from one type to another

A model that sums up the formation, breakdown, and reformation of rock

Assignment #15: Rock or Mineral Lab

Fossil Vocabulary (p. 30)

• Law of Superposition: Top layer is the youngest in undisturbed layers of rocks

• Strata/Stratified/Stratification: Layer of rocks

• Fossils: Remain or trace of living thing• Index Fossil: Fossil remains of organism

that lived a very brief time – often found in only one layer of rock

• Mass Extinction: Disappearance of large number of species over short time

Fossil Vocabulary Cont.

• Relative Time: Time compared to another time; younger or older than _____

• Resident Time: Time an element occupies a place

• Absolute Time: Exact time – usually AD or BC are specified

• Geologic Time Scale: Outline of major events in Earth’s history – based upon mass extinction periods

Homework: #19 Fossil Vocabulary Flash Cards