agenda jan. 29, 2013 mr. king 1.rock powerpoint – take notes 2.assignment #15: rock or mineral lab...
TRANSCRIPT
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
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
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
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
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