Welcome to

GEOL 107: Physical Geology

Dr. Lijun Liu

Department of Geology

Labs

• Labs meet in Davenport 219

• Labs will meet this week (Aug 27 & 28)

• Lab manual available in book store

• You must earn > 60% on the lab portion to pass the course

I->Clicker registration

• Register your i->clicker in compass 2g.

• We use i->clicker in every lecture, so bring it every time.

• This is the majority of our in-class assignments

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Modern view on the origin and evolution of the universe.

Big Bang theory

+

Nebula theory

Evolution of Earth

The proto-Earth was likely uniform in composition

As it grew, it heated up

Subsequent differentiation

Present-day Earth

Evolution of the Moon

• Moon is the closet planetary bodies to Earth.• Moon affects the Earth in multiple ways

– Changing Earth’s spinning rate over time– Generating tides on Earth– Sheltering Earth from meteorite bombardment

Formation of the Moon

• A very large meteorite (Mars sized!) collided with earth about 4.5 billion years ago

Formation of the Moon

• A numerical simulation

• The moon was mostly made of the Earth’s mantle material, with little iron

• Following the formation of the Moon, Earth underwent differentiation again – resulting in compositional layering

Chemical composition of the Moon is similar to____

A. Average composition of the universe

B. Average composition of comets

C. Composition of the Earth’s mantle

D. Composition of the Earth’s core

I-clicker question:

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Earth internal differentiation

Iron and Nickel melt from the mantle and sink to the center to form the core.

Light molten rocks rise toward surface and form primitive crust when freeze.

Earth’s internal structure - largely 1-DC

ompo

sitio

nal L

ayer

s Rheological Layers

Compositional Layers

►Crust: Silicates

►Mantle: Silicates

►Core: Iron alloy2900 km >80% Earth volume

<20% Earth volume

Oceanic vs. Continental

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The crust

Oceanic crust: thin (~7 km)

Continental crust: thick (~35-40 km, up to 70 km)Basaltic rocks, ~3.0x103 kg/m3

Andesitic-granitic rocks, ~2.7x103 kg/m3

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The mantle

From the base of the crust to about 2900 km depth

Peridotite rocks3.3x103 kg/m3

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The core

From 2900 km to center of Earth

Made of mostly iron,~8x103 kg/m3

Rheological Layers(mechanical strength;

detected by seismology)

• Lithosphere• Asthenosphere• Mesosphere• Outer Core • Inner Core

Rheological Layers(mechanical strength;

detected by seismology)

• Lithosphere• Asthenosphere• Mesosphere• Outer Core • Inner Core

Crust

Mantle Lithosphere

Asthenosphere

Lithosphere & asthenosphere

• A strong lithosphere• A ‘soft’ asthenosphere –

it flows

Outer core is liquid: generating the geomagnetic field

Inner core is solid: conducting metal

Outer & Inner Core

Lateral variation of crust makes Continents

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Present-day continents distribution

Which is NOT true about Earth’s structure

A. Innermost Earth has the largest density.B. The deeper into the Earth, the softer the

material becomes.C. The outer part of Earth is made of silicate

rocks, and the inner part of metal.D. Earth’s outer shell (i.e., crust) has large lateral

variations in composition and density.

I-clicker question: