EARTH HISTORY EARTH HISTORY Review

Created by Beverley SuttonPueblo Gardens PreK-8

Our Changing EarthOur Changing Earth

• Earth is a geologically active planet.

• Huge quantities of energy are always acting on the surface of the Earth and its interior.

• Observable evidence in the present gives information about processes and events that occurred in the past.

How Scientists work:Observation

How Scientists work:Observation

• Using one or more of the five senses

How Scientists work:Inference

How Scientists work:Inference

• Based on what you already know about footprints and the footprints you see …

What happened here?

Layers of the EarthLayers of the Earth

Let’s take them apart …Let’s take them apart …

… and look at them one by one … and look at them one by one

CrustCrust• The outermost “skin” of Earth. Two types:

Oceanic crust (thinner, mostly basalt) and Continental crust (thicker, mostly granite)

LithosphereLithosphere

• The crust and the uppermost part of the mantle – brittle and cool

LithosphereLithosphere

• Like the skin and a little of the white of an apple

MantleMantle

• Molten rock – between the crust and the core

CoreCore• Center of the Earth: Made up of mostly

iron and some nickel.• Outer core (liquid)• Inner Core (solid)

MineralMineral

• a crystalline inorganic solid that occurs naturally in the Earth’s crust.

PHYSICAL properties of mineralsPHYSICAL properties of minerals

RockRock

• inorganic solid that occurs naturally in the Earth’s crust.

Rock Cycle – a process that constantly recycles rock

Rock Cycle – a process that constantly recycles rock

Rock CycleRock Cycle

ErosionErosion• The wearing away of rocks by weather

(wind, water), or chemical means

SedimentsSediments

• small particles of sand, dirt, broken up rocks

Shale

Sedimentary RockSedimentary Rock• Formed by compaction and cementation.

Sediments are compacted (packed down) and glued together (cemented). Grains are in layers sandwiched between a muddy matrix

Limestone

Coal

Sandstone

Metamorphic RocksMetamorphic Rocks

• Rock that was once one type of rock but has changed to another under the influence of heat and pressure. Grains arranged in bands.

Marble – which was once limestone

Slate – which was once shale

Quartzite –which was once sandstone

Igneous RockIgneous Rock

• rocks that form from magma (melted, liquid rock) that cools and crystallizes. The crystals are randomly arranged and interlocking.

Pumice

Granite

Gabbro

Tectonic PlatesTectonic Plates

• Solid plates of lithosphere that float on the mantle

ConvectionConvection

• Convection -- Heat transfer in a gas or liquid by the circulation of currents from one region to another.

Divergent BoundaryDivergent Boundary

• At divergent boundaries new crust is created as plates pull away from each other.

Convergent BoundariesConvergent Boundaries

• Here crust is destroyed and recycled back into the interior of the Earth as one plate dives under another.

These are known as Subduction Zones - mountains and volcanoes are often found where plates converge.

Oceanic-Continental ConvergenceOceanic-Continental Convergence

Oceanic-Oceanic ConvergenceOceanic-Oceanic Convergence

Continental-Continental Convergence

Continental-Continental Convergence

Transform-Fault BoundariesTransform-Fault Boundaries

• Transform-Fault Boundaries are where two plates are sliding past one another.

These are also known as transform boundaries or more commonly as faults.

FaultFault• a crack in the earth's crust resulting from

the displacement of one side with respect to the other

Strike-slip Fault

Normal Fault

Law of SuperpositionLaw of Superposition• In a sequence of

layered rocks, a given bed must be older than any bed on top of it.

In other words, each layer is younger than those underneath it.

Law of Original HorizontalityLaw of Original Horizontality• Most sediments, when originally

formed, were laid down horizontally. In other words, most sediments settle in flat horizontal layers. If the layers are no longer horizontalthen somethinghappened to move them.

How landforms change

Seismologist Seismologist

• scientist who studies earthquakes

Seismograph Seismograph

• an instrument that records the magnitude (size) and duration (how long it lasted) of an earthquake.

Richter scaleRichter scale• the logarithmic scale used to measure

earthquakes.

Epicenter Epicenter

• The point of the earth's surface directly above the focus of an earthquake

Rock ColumnRock Column• A diagram that

shows the sequence of rocks in a particular area.

• Stratigraphy – the science of layered rocks.

Index fossilIndex fossil

• The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found. Also called guide fossil.

Our Changing EarthOur Changing Earth

• Earth is a geologically active planet.

• Huge quantities of energy are always acting on the surface of the Earth and its interior.

• Observable evidence in the present gives information about processes and events that occurred in the past.

Serene, still, and peaceful?Serene, still, and peaceful?

Wrong! A dynamic, always changing world!