the earth's history, structure and composition

The Earth’s History, Structure &

Composition Earshad B. BanjalInstructor – Physical Sciences Math & Science DepartmentCollege of Arts & Sciences EducationUniversity of MindanaoBolton, Davao City

The Moving Earth

Continental Drift TheoryContinental Drift Theory by Alfred WegenerAll continents were once connected and united as one supercontinent called Pangaea.

Pangaea broke off into Laurasia and Gondwanaland

The Moving Earth•The ground below you travels at a rate of 10 cm. per year•This is because of Plate Tectonics, or the large scale movement of Earth’s continents.

Layers of the EarthThree main structures (inner)1. Crust2. Mantle3. Corei. Outerii. Inner

Layers of the Earth1. Crust - outermost layer of the

Earth composed mainly of alumino-silicates

Layers of the EarthTwo main structures1. Crusta. Continental

crust Thicker layer; forms the continents and shallow water close to the shores; made of granite rocks

Two main structures1. Crust

b. Oceanic crustThinner layer; forms the ocean basins; made of basaltic rocks

Layers of the EarthTwo main structures2. Mantle - Denser than the

crust; consist mostly of iron;

i. upper part is bounded by Mohorovicic discontinuity (Andrija Mohorovicic)

ii. Lower part is bounded by Gutenberg discontinuity (Beno Gutenberg)

The Mantle

Layers of the EarthTwo main structures3. Core

i. Outer core – fluid molten Fe and Ni

ii. Inner coure – solid made of Fe

Collective Layers of the EarthMain inner layers:1. Lithosphere2. Asthenosphe

re

Structure of the Earth1. Lithosphere which includes the

crust and the uppermost mantle, comprises the land around you.

2. Asthenosphere – the highly viscous but solid rock portion of the upper mantle, wrapping around the core; 80 – 120 km below the surface

The Asthenosphere

Separated by Tectonic Plates

The Tectonic PlateThe South American Plate is an example of a Tectonic Plate made of two crusts: Continental Crust (the continent South America) and the Oceanic Crust (large region of Atlantic Ocean).

Tectonic Plates Collectively comprising the lithosphere, Tectonic Plates are more brittle and stiff than the heated malleable layer of Asthenosphere.Thus, the Tectonic Plates float on top of the Asthenosphere and move independently of one another.

Tectonic Plates

Three Basic Types of Plate BoundariesDivergent

ConvergentTransform

Subduction, Faulting & FoldingSubduction – one plate goes below the otherFolding – when rocks undergo tremendous pressure producing folds which give rise into land formationsFaulting – the formation of cracks in crust layers

Faults & EarthquakesFaults – cracks in rock layersFocus – the point where the fault movedi. intermediate focus

– happens in upper mantle (70-350 km)

Epicenter – place on top of the focus

FaultingNormal Faults – the hanging wall block moves downward relative to the footwall blockReverse Faults – the hanging wall block moves upward relative to the footwall block

a. Thrust – horizontal movement of the ground

b. Uplift – rising of crust

Faults & EarthquakesEarthquake – any movement or shaking of the ground1. Tectonic2. Volcanici. Tsunami

Richter scale-measures magnitude/quantity of freed energy- by Charles Richter

Mercalli Intensity Scale-assigns a degree to the effects on the environment (Intensity)- By Giuseppe Mercalli

Earthquakes can be detected by a Seismograph

2011 Sendai Japan, Mag. 9.0

Worst Earthquakes and Tsunami in the History

Source: US Geological Survey1. The Great Chilean Earthquake (1960) – 6,000 people

died; magnitude 9.5/ intensity IX2. Sendai, Japan Earthquake (2011) - most powerful

earthquake ever recorded in Japan with 15,890 deaths, 6,152 injured and 2,590 missing; magnitude 9.0

3. Sichuan, China Earthquake (2008) – millions of people were left homeless after their house fell down; lasted for 2 minutes; magnitude 8.0

4. Haiti Earthquake (2010) – magnitude 7.0; 200,000 deaths

5. Sumatra, Indonesia (Dec. 26, 2004) – magnitude 9.3; deadliest tsunami ever 215,000 people died from Indonesia, Sri Lanka, Thailand, India and Somalia

The Pacific Ring of Fire

Intensity Scale used by the Philippine Volcanology & Seismology (PHILVOLCS)

INTENSITY DESCRIPTIONI Scarcely perceptibleII Slightly felt – still waters oscillates

slowlyIII Weak – dizziness; hanging objects

swingIV Strong – sleeping people are

awakenedV Very Strong – very old or poorly built

house toppleVI Destructive – landslides are observed

Intensity Scale used by the Philippine Volcanology & Seismology (PHILVOLCS)INTENSITY DESCRIPTION

VIII Very Destructive – people panicky. Difficult to stand.

IX Devastating – people are forcibly thrown to ground.

X Completely Devastating – All man made structures are

destroyed

DiastrophismFolds – warps in layered bedrocksDiastrophism refers to the series of processes (folding and faulting) by which the major features of the Earth’s crust are formed and changed because of relative changes of positions and deformation of rock.

Minerals Minerals – naturally occurring, solid, has definite chemical composition, and generally inorganic; may be identified by its:1. Crystal form2. Hardness3. Cleavage and Fracture4. Color or Streak5. Specific Gravity

Mineral DepositsOre is a kind of mineral deposit with a high concentration of at least one metallic element.Example: GOLD ORE & COPPER ORE

Mineral DepositsMetallic minerals: Cadmium, chromium, cobalt, copper, gold, silver, lead, iron, manganese, mercury, nickel, palladium, uranium and zinc.

Mineral DepositsNon-metallic minerals: asbestos, cement raw material, dolomite, feldspar, gypsum, marble, phosphate, sulfur and talc.

Minerals Mineral ores

ChalcopyriteChromiteGalenaMagnetitePitchblende

Minerals obtained

CopperChromium

LeadIron

Uranium

Mineral Deposits•Philippine mineral deposits are thought to be at 30.8 billion MT, of which 37% are metals and 63% are non-metals•Our prime contributions to foreign exchange earnings valued at 3 billion USD in 2000

How are oil and gas made ?

Why use Oil & Natural Gas?

Since 1910, oil and natural gas have replaced coal because they are “environmentally clean”.They can also be refined.Almost all countries in the world burn fossil fuels for energy.

In the Philippine settingFirst Oil Well in the Cebu, Philippines was drilled in 1986.We rely from OPEC and its 13 member countries.Organization of Petroleum Exporting Countries (OPEC) processes 56-84% of the world’s oil production and export.

OPEC, the War in the Mideast, & Oil Crisis

•Saudi Arabia has the largest oil reserves producing at a cost of 12 cents a barrel to 3 USD.•1973 18-day War with Israel, OPEC instituted Oil Embargo (12 USD/ barrel)•1979, Iranian revolution (35 USD/ barrel) •1990, Iraq’s invasion of Kuwait (40 USD/ barrel)

Geothermal ResourcesNon renewable but perpetual energy resources.1. Hot springs2. Wells3. Near vents4. Caldera

Geothermal ResourcesIn the Philippines, we have geothermal power plants in:1. Leyte2. Tiwi, Albay3. Makban, Quezon4. Laguna5. Negros Occidental6. Mt. Apo

Rocks Rocks - aggregate of minerals; formed by weathering, erosionTypes:1. Igneous - cooled and crystallized magma or lava2. Sedimentary - from pre-existing rock, or from

dissolved compounds worn away from other rocks, that are transported by wind, water, or ice

3. Metamorphic - from pre-existing rocks, that, without melting, are transformed by high temperature, high pressure, or both

Igneous Rocks•Formed by the cooling of Magma

magma

volcano

Igneous Rocks 1. Intrusive or

Plutonic rocks – when cooled and solidified underground

2. Extrusive - when cooled and solidified on land or seafloor

Granite

Gabbro

Basalt

Rhyolite

Sedimentary Rocks• Sedimentary Rocks are rocks

formed when particles of sediment build up and are “cemented together” by the effect of pressure and minerals.

sea

Fragments washed to the sea

Sedimentary rocks

Rocks are brokenup by the actionof weather

Getting older

Sedimentary Rocks Coal is chemical sedimentary rock formed through stages of:a. Peatb. Lignitec. Bituminousd. Anthracite

How is coal formed ?

Sedimentary Rocks Generally made of Calcium carbonate1. Limestone2. Sandstone3. Shale4. Chalk5. Dolomite

Limestone

Sedimentary Rocks

Clastic (Calcite + Quartz)

Coal

Metamorphic Rock• The literal meaning

is to “change shape”

Rocks change with temperature and pressure, but remains solid

Usually takes place deep in the Earth

Metamorphic Rocks• Metamorphic rocks are formed by the effect of heat

and pressure on existing rocks.• This can greatly affect the hardness, texture or

layer patterns of the rocks.

Magma

metamorphicrock forming here

heat

Pressure from surface rocks

Metamorphic Rocks Metamorphic rocks are formed by the effect of heat and pressure on existing rocks.

Marble

Quartzite

Gneiss