HOW TO READ THE PAGES OF EARTH HISTORY.

A Helpful Laws:

1) Law of Superposition: In a series of sedimentary rock layers, younger rocks normally lie on top of older rocks.

More Helpful Laws:

2) Law of Cross cutting Relationships: Rocks or structures that cut across other structures are younger than what they cross.

More Helpful Laws:

3) Law of Original Horizontality: Sedimentary Rocks are normally laid down horizontally or flat, and not tilted.

Tilted Sedimentary Rocks were originally flat.

Folded Sedimentary Rocks were originally flat and later folded.

Sedimentary Rocks in original horizontal (flat) position.

Stop and practice with worksheet.

“Long, long ago there was once an ocean here. During this time sedimentary layers began to build up on the bottom of the ocean beginning with layer “F” and then “E”. Continental plates began to shift and shortly after, layer “D” formed when hot magma came up from deep within the Earth and began to flow as lava forming volcanic igneous rock. Additional sedimentary rock layers then covered up the volcanic rock layer. This formed first sedimentary layer “C” then “B” and finally “A”. After this the land rose above the ocean.”

“What are them there rocks?”

1) IGNEOUS: Rocks that were once red hot molten lava that flowed into place.

A) Two types of igneous rocks:

i) Volcanic: lava that flows over earth’s

surface and cools fast.

ii) Plutonic: magma that cools beneath

earth’s surface and cools slowly.

Plutonic

Volcanic

Volcanic Rocks

Volcanic Rocks

Volcanic Rocks

Plutonic

Volcanic

Plutonic Rocks

Plutonic Rocks

Plutonic Rocks

Plutonic

Volcanic

2) SEDIMENTARY: Rocks originally layed down in water or by the wind.

A) They are made of mega amounts, of tiny sand, silt

or clay particles.

B) They form horizontal layers called “Strata.”

C) They are uncemented at first and called “Sediments” and then later turn into rock.

2) SEDIMENTARY: Rocks originally layed down in water or by the wind.

A) They are made of mega amounts, of tiny sand, silt

or clay particles.

B) They form horizontal layers called “Strata.”

C) They are uncemented at first and called “Sediments” and then later turn into rock.

3) METAMORPHIC: Igneous or sedimentary rocks that have been heated and put under pressure until they start to melt.

A) They form three ways:

i) when shoved or buried several miles under

the earth.

ii) when hit by an asteroid.

iii) when heated by a lava flow

Metamorphic Rocks

Metamorphic Rocks

Metamorphic Rocks

A. KEY WORDS:

1. Sediments - Sand, silt, clay & rocks in the bottom of a valley, river, lake, or ocean, that is uncemented.

2. Sedimentary Rock - Cemented sediments.

3. Igneous Rock - Hot melted rock known as magma that either flows over land from a volcano, or….

moves from and cools deep within the

Earth to form granite mountains.

4. Deposition - The buildup of sediments on the bottom of a basin which later may become sedimentary rock.

5. Sedimentation - Same as Deposition.

2 DEFORMATION & UPLIFT

1 DEPOSITION

3 EROSION

6. Fossilization - Burying and turning the parts of a living organism into hard, petrified remains or making an imprint of the organism in the rock.

7. Terrestrial Fossils - Fossils of organisms that lived on land.

8. Freshwater Fossils - Fossils of organisms that lived in lakes or rivers.

9. Marine Fossils - Fossils of organisms that lived in saltwater such as a lagoon, ocean or inland sea.

10. Alluvial Fans - A fan shaped deposit with boulders, rocks, and sand that forms next to a mountain.

You see these most clearly in the desert.

B. ENVIRONMENTS OF DEPOSITION:

1. Terrestrial Environments:

a) Desert - has sand dunes or alluvial fans w/ boulders.

b) Glacial - has boulders & angular rocks moved by glaciers.

c) Tropical - has tropical plant fossils.

d) If you find fossils of plants or animals that normally live on land than the deposition environment was on land (or we normally say, “it was a terrestrial environment”).

2. Freshwater Environments:

a) River or stream - has rocks, sand & silt.

b) Lake - has silt & clay.

c) Sedimentary rocks deposited in freshwater environments can have fossil organisms that lived in lakes or rivers.

3. Marine:

a) Lagoon - silt & clay w/lagoonal fossils.

b) Open ocean - limestone, coral reef and protist fossils.

c) Inland sea - has salt or other chemical deposits.