ROCK & FOSSIL RECORD

What are igneous, sedimentary, and metamorphic rocks and which picture is a representation of that rock type.

A

B

C

TYPES OF ROCK Igneous -

think of the word “ignites” Formed from solidified molten rocks

Metamorphic – Think of the word “magma” Formed when other rocks are changed by heat, pressure, and

chemical reactions

Sedimentary - Formed when combinations of rock fragments, seashells, and

chemicals are composed in layers and hardens

THE EARTH’S STORY

Uniformitarianism

Theory: Geologic change is gradual

Scientist: Hutton

To help me remember:

think of uniform

Catasrophism

Theory: Geologic change is sudden

Scientist: Lyell

To help me remember:

Think of catastrophe (disaster)

CURRENT THEORY Modern geology (current theory):

Gradual geologic change is interrupted by catastrophes

To study geologic change involves studying past life. Using fossils to study past life is called paleontology.

RELATIVE DATING Relative Dating: what scientist use to

determine whether an event or object is older or younger than another event or object

____________ the order of events. There is no __________ information

What type of rock do you think contains relative age about events and objects in the Earth’s history? _____________________________

LAW OF SUPERPOSITION The Law of Superposition states:

Younger rock lies above older rock in an undisturbed sequence.

GEOLOGIC COLUMN Geologic column is an arrangement of

rock layers in which the older rocks are at the bottom

Geologic columns help scientist find the relative age of the Earth.

HOW GEOLOGIC COLUMNS ARE FORMED?

Stratigraphic sections are pieced together to from short columns Stratigraphic – layered rock

Short columns are pieced together to from longer columns

All columns are pieced together to form the entire Earth’s geologic column

CROSS CUTTING LAW Any feature that cuts across a body of

sediment or rock is younger than the body of sediment or rock that it cuts

SO WHAT ABOUT DISTURBED ROCK? Features:

Faults – break in the Earth’s crust, where blocks of crust shift past one another

FEATURES Intrusion – Igneous rock (molted rock)

from the Earth’s interior that squeezes into existing rock and cools (younger then sedimentary layers)

EVENTS Folding – Occurs when rock layers bend

and buckle from Earth’s internal forces

EVENTS Tilting -occurs when Earth’s forces

move rock layers until they become slanted.