Chapter 1: Introduction

Etymology of Geology

Greek words geo (Earth) and logos (discourse)

What is Geology?

The study of Earth

Earth constantly changes at rates that vary in size and space. What are some examples of this?

• volcanic eruptions and earthquakes (rapid)

• the movement of lithospheric plates and mountain building (slow)

What are the 2 types of geology?

• physical geology

• historic geology

Physical Geology

Examines the materials composing Earth

Historic Geology

Seeks an understanding of Earth’s origins and development

What are some problems Geology addresses?

• natural hazards

• mineral resources

• world population growth

• environmental issues

What does science assume?

The natural world is consistent and predictable.

What is the goal of science?

To discover patterns and nature to make predictions

How do scientists collect data?

Through observation and measurements

Scientific method involves:

• gathering facts through observations

• formulation of hypotheses and theories

True/False: There is no fixed path that scientists follow to gain knowledge

True; depends on study at hand

Hypothesis

A tentative (or untested) explanation

Theory

A widely accepted view the scientific community agrees best explains phenomena

The best hypothesis is one that…

explains ALL of the existing observations

A hypothesis must be:

• able to predict/deduce future observations

• falsifiable (possibility to be proven wrong)

Testing a hypothesis must include:

collecting data and examining if the data supports the prediction

If a hypothesis is proven wrong

it must be abandoned

Theory

A well tested and widely accepted view scientists agree best explain phenomena (must be testable and falsifiable, provisional)

What is Earth?

A dynamic planet with many interacting parts and spheres

Earth Study Science

• Aims to study Earth as a system with many interacting parts

• Employs an interdisciplinary approach to environmental problems

What is a system?

Any size of interacting parts that form a complex whole

Open System

Energy and matter flow into and out of system

Closed System

shut off from surroundings, energy does not leave or enter system. self contained

Is the ocean an open or closed system

Open

Is the Earth an open or closed system?

Closed; no matter is exchanged between the Earth and the universe

Are the spheres inside earth open or closed?

Open; exchange matter and energy

2 heat engines that power Earth

internal and external

Earth’s External Heat Engine is powered by

the Sun

What does the Sun do?

drive Earth’s fluid envelopes (atmosphere and hydrosphere) and biosphere

Earth’s Internal Heat Engine is powered by

geothermal heat

What does geothermal heat do?

drive tectonic plates and rock cycled within solid earth

What is the Rock Cycle?

The loop that involves the processes by which one rock type changes to another

Igneous Rocks

Formed from cooling and solidification of magma (molten rock)

EX: granite and basalt

Sedimentary Rocks

Sediments from weathering of preexisting rocks, accumulate at the surface, converted into rocks

EX: sandstone and limestone

Metamorphic Rocks

Formed by changing preexisting igneous, sedimentary, or other metamorphic rocks

EX: gneiss and marble

Driving forces of metamorphic rocks

heat and pressure

How is magma formed?

melted rock

What are the terrestial planets?

Mercury, Mars, Venus, and Earth

What are the Jovian planets?

The giant planets: Jupiter, Neptune, Uranus, Saturn

Characteristics of terrestrial planets:

• closest to the sun

• small rocky bodies greater than 3 gm/cm³ density

• composed of Fe, Ni, and silicate minerals

Characteristics of jovian planets:

• solid rocky core

• multiple moons

• rings

Nebular Hypothesis

Objects in our solar system formed from a giant cloud of gas and dust called the solar nebula

Planet differentiation

the chemical seperation that established the basic divisions of earth’s interior and surface

Earth’s 4 major subdivisions

• atmosphere

• crust

• mantle

• core

how thick is the oceanic crust and what is it made of?

• ranges from 0-10 km thick

• made of basalt

how thick is the continental crust and what is it made of?

• ranges from 33 - 70 km thick

• made mostly of granite

the surface of the earth is envisioned as a…

mosaic of lithospheric plates

lithosphere

• very top portion of upper mantle

• rigid, solid outer later of earth

outer core

• consists of liquid iron

• source of earth’s magnetic field

inner core

• composed of solid iron and nickel

How old is earth?

4.57 billion years old

T/F: little is known about the first 4 billion years of earth’s life because rocks have been remelted and deformed numerous times

true

What are the 2 things you should know about geological time?

• spans millions to billions of years

• geological processes are gradual and only noticeable after thousands to millions of years