Welcome to Earth Science!!

What is Earth Science?

• Earth Science is the name for all the sciences that collectively seek to understand Earth and its neighbors in space.

Branches of Earth Science

• Geology

• Oceanography

• Meteorology

• Astronomy

Geology• Geology is the study of the earth

• Geo=earth, -ology=study of

• Physical Geology – study of materials composing Earth and the processes that operate beneath and upon the surface ( earthquakes, water, wind, ice)

• Historical Geology – origin of the Earth and its development of the planet through its 4.6 billion year history

Oceanography

• Oceanography is the study of the composition and movements of seawater, coastal processes, seafloor topography, and marine life.

• Uses chemistry, physics, geology and biology

Meteorology• Meteorology is the study of the

atmosphere and the processes that produce weather and climate

• Uses other sciences to study thin layer of air that surrounds the Earth

• What is the difference between weather and climate?

Astronomy

study of the universe beyond the Earth

Environmental Science

• The study of how humans interact with their environment

• What major event(s) happened recently in the news?

Importance of Interdisciplinary Science

Why do you think the study of Earth Science is important?

The goal of science is to explain natural phenomena then use the knowledge to

make predictions about what should or should not

happen

“If we all worked from the assumption that what is

accepted as true is really true, there would be little

hope of advance.”Orville Wright

Assumptions of Science

• Nature is understandable

• Similar forces in similar situations will cause similar results

• Future events can be predicted based on past events

• Nature is complex – many factors acting at the same time.

Science Skills Scientists approach a problem by thinking

logically.

• Critical thinking is the ability and willingness to assess claims critically and to make judgments on the basis of objective and supported reasons.

Science Skills• “The” scientific method – there is no such

thing

• The scientific method is a general description of scientific thinking not an exact path to follow.

• Testing hypotheses

• Hypothesis a possible explanation or answer that can be tested

• Scientists test a hypothesis by doing a controlled experiment.

• In a controlled experiment, all variables that could affect the results are kept constant except for the one that you are interested in studying

• Variable a factor that changes in an experiment in order to test a hypothesis

Controlled Experiments and Variables

Variables – Independent (Manipulated)

• Variables / factors / things that are under the control of the scientist

• Plotted on the x- axis

– Dependent (Responding)• What is being measured• Plotted on the y-axis

– Control Variable• Variables that are the same in every group

• This is different from a control group – a group in which nothing is done to ; Why is this important?

• Conducting experiments

• No experiment is a failure

• The results of every experiment can be used to revise the hypothesis or plan tests of a different variable.

• Drawing Conclusions

–What was learned that is new?

–Was my hypothesis and / or my prediction correct? If not, why?

–What do I need to change?

• Experiment

• Questions

• Hypothesis

–What next?

Hypothesis or Theory

• Once a hypothesis has been well tested and widely accepted by the scientific community, it maybe elevated to the level of a theory.

Acceptance of Scientific Ideas

• For an idea to be accepted, people must know about it.

• Peer Review – experts in a given field examine the results and conclusion of a scientist’s study before that study is accepted for publication– Filter out the “garbage” so that only well –

supported ideas are published

• Publications – Print or Digital

Scales of Space and Time in Earth Science

Geologic Time Scale

Units of Measurement• SI units are used for consistency.

• Scientists use the International System of Units (SI) to make sharing data and results easier.

yotta- (Y-) 1024 1 septillion

zetta- (Z-) 1021 1 sextillion

exa- (E-) 1018 1 quintillion

peta- (P-) 1015 1 quadrillion

tera- (T-) 1012 1 trillion

giga- (G-) 109 1 billion

mega- (M-) 106 1 million

kilo- (k-) 103 1 thousand

hecto- (h-) 102 1 hundred

deka- (da-) 10 1 ten

deci- (d-) 10-1 1 tenth

centi- (c-) 10-2 1 hundredth

milli- (m-) 10-3 1 thousandth

micro- (µ-) 10-6 1 millionth

nano- (n-) 10-9 1 billionth

pico- (p-) 10-12 1 trillionth

femto- (f-) 10-15 1 quadrillionth

atto- (a-) 10-18 1 quintillionth

zepto- (z-) 10-21 1 sextillionth

yocto- (y-) 10-24 1 septillionth

SI Prefixes

Non- SI UsersU.S., Burma, and Liberia

Accuracy and Precision

Experimental Error

• A measure of how much imprecision or variability was introduced into an experiment

Observations and Models

• Controlled experiments in Earth science are often difficult to achieve since you can’t control “Mother Nature”

• Models are often used to simulate conditions in the natural world

• Model - a description, representation, or imitation of an object, process, concept or system.

Types of Models • Physical

• Conceptual – Graphical

– Verbal

• Computer

• Mathematical

F = maF = ma

An object in motion will stay in constant motion unless something gets in its way.

How does Science affect Society

• New technology – Tools, machines, materials, processes

• Indirect results – Space exploration lead to improvements to

computers, medical equipment, and airplanes

• New Problems – Antibiotic resistant bacteria – Amplified climate change– Radiation contamination

Science and Society

• How does science impact society? – To drill or not to drill?

• Global Warming?

The Earth as a System

Why are we so special?

• Liquid water on the surface.

• Atmosphere that is oxygen rich

• Only planet known to support life?

• Earth is the third planet from the sun in our solar system.

• Earth formed about 4.6 billion years ago and is made mostly of rock.

Earth Basics

• 70% of Earth’s surface is covered by a thin layer of water; global ocean.

• Earth is an oblate sphere, or a slightly flattened sphere. – Rotation of Earth causes the poles to flatten

and the equator to bulge• pole-to-pole circumference = 40,007 km. • equatorial circumference = 40,074 km.

Factors affected by the curvature of the Earth

• Intensity and duration of solar radiation on the surface of the earth

• Temperature differences

• Currents in the oceans and atmosphere

How do we know what the inside of the Earth is like?

• Scientists have made important discoveries about Earth’s interior composition and structure through studies of seismic waves.

• Seismic waves : vibrations that travel through Earth; caused by earthquakes and by explosions near Earth’s surface.

Compositional Layers: Crust

• crust the thin and solid outermost layer of Earth that lies above the mantle; product of the mantle melting

Compositional Layers: Crust• Oceanic Crust

– Higher density rock • Mafic - silicate mineral or rock that is rich in magnesium and

iron ex. Basalt or gabbro • Common rock-forming mafic minerals: olivine, pyroxene,

amphibole, and biotite

• Continental Crust – lower density rocks

• Felsic: refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminum, sodium, and potassium. Ex. granite

• Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars ,

Mohorovičić Discontinuity“Moho”

• the boundary between the crust and the mantle.

• "discontinuity“ = a surface at which seismic waves change velocity.

• Beneath the continental crust: 32 km

• Beneath Oceanic crust = 8 km

• At this discontinuity, seismic waves accelerate (increase speed and change directions

Compositional Layers: Mantle• mantle

– layer of rock that lies between Earth’s crust and core

• ~ 2,900 km thick; makes up almost 2/3 of the earth’s mass

Gutenburg Discontinuity• the boundary between the lower mantle (which

is considered solid) and the underlying outer core (believed to be molten).

• occurs 2,900 km below the surface

• primary seismic waves (P waves) decrease in velocity while secondary seismic waves (S waves) disappear completely. S waves cannot transmit through liquids, so it is believed that the unit above the discontinuity is solid, while the unit below is in a liquid, or molten, form.

• core the central part of Earth that lies below the mantle

• The center of Earth is a sphere composed mainly of Ni and Fe whose radius is about 3,500 km.

• ~ 1/3 of the Earth’s mass

Compositional Layers: Core

Structural Layers

• the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle

• The rigid lithosphere is between 15km and 300 km thick.

Lithosphere(as strong as rock)

Asthenosphere(no strength)

• the solid, plastic layer of the upper mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it

• about 200 km thick.

• literally, the “middle sphere”; the strong, lower part of the mantle between the asthenosphere and the outer core

• reaches from the bottom of the asthenosphere to a depth of about 2,900 km.

Mesosphere

Inner and Outer Core• Below the mesosphere is the molten

(liquid) outer core.

• Outer core -surrounds the solid inner core, which begins at a depth of 5,150 km.

• Inner core – dense rigid solid; made mainly of Ni and Fe

Earth’s Interior

Explain why scientists have to rely on indirect observations to study Earth’s interior.

Indirect observations are the only means available for exploring Earth’s interior at depths too great to be reached by drilling.

Reading Check

Earth as a Magnet• Earth’s magnetic field extends

beyond the atmosphere and affects a region of space called the magnetosphere.

• Scientists think that motions within the liquid iron of Earth’s outer core produce electric currents that in turn create Earth’s magnetic field.

Earth’s Gravity• Gravity is the force of attraction that

exists between all matter in the universe.

• The larger the masses of two objects are and the closer together the objects are, the greater the force of gravity between the objects will be.

Weight and Mass

• Weight is a measure of the strength of the pull of gravity on an object.

• SI Unit of Weight: Newton (≈ ¼ lb)

• An object’s weight depends on its mass and its distance from Earth’s center.

• Because the distance between Earth’s surface and its center is greater at the equator than at the poles, the weight of an object at the equator is about 0.3% less than its weight at the North Pole.

Weight and Location

Earth-System Science

• Earth scientists combine knowledge of several fields of knowledge in order to study Earth as a system.

• system a group of interacting parts that form a complex whol

• Why should we consider the Earth a system?

Earth-System Science

• All systems have boundaries, and many systems have matter and energy that flow though them.

• Even though each system can be described separately, all systems are linked. A large and complex system, such as the Earth system, operates as a result of the combination of smaller, interrelated systems.

Earth-System Science• The operation of the Earth system is a

result of interaction between the two most basic components of the universe: matter and energy.

• Matter is anything that has mass and takes up space.

• Energy is defined as the ability to do work. Energy can be transferred in a variety of forms, including heat, light, vibrations, or electromagnetic waves.

Earth-System Science

Closed Systems

• a system in which energy, but not matter is exchanged with the surroundings.

Open Systems

• a system in which both energy and matter are exchanged with the surroundings.

Earth-System Science

Earth-System Science• Technically, all systems that make up the

Earth system are open.

• However, the Earth system is almost a closed system because matter exchange is limited.

• Energy enters the system in the form of sunlight and is released into space as heat.

• Only a small amount of dust and rock from space enters the system, and only a fraction of the hydrogen atoms in the atmosphere escape into space.

Feedback Mechanisms• Feedback mechanism - when physical

processes in the earth-atmosphere system further impact the initial change

• if the impact is such that the initial perturbation is enhanced, then it is called a positive feedback mechanism

• if the impact is such that the initial perturbation is reduced, or weakened, then it is called a negative feedback mechanism.

What types of matter and energy are exchanged between Earth and space?

Dust and rock come to Earth from space, while hydrogen atoms from the atmosphere enter space from Earth. Solar energy enters Earth’s atmosphere and reradiated energy leaves Earth.

Reading Check

The Atmosphere

• a mixture of gases that surrounds a planet or moon

• Movements and processes create weather and climate

• The atmosphere provides the air you breathe and shields Earth from the sun’s harmful radiation.

The Hydrosphere

• the portion of Earth that is water

• Water covers 71% of Earth’s surface.

• Water in the hydrosphere occur in the form of oceans, lakes, rivers, streams, glaciers, ice sheets and groundwater.

The Geosphere• Earth’s landfroms – crust, rocks, minerals, and

soil

• the mostly solid, rocky part of Earth; extends from the center of the core to the surface of the crust

• includes all of the rock and soil on the surface of the continents and on the ocean floor.

• includes the solid and molten interior of Earth.

The Biosphere• The part of Earth where life exists; includes

all of the living organisms on Earth

• all of the forms of life in the geosphere, in the hydrosphere, and in the atmosphere, as well as any organic matter that has not decomposed.

• extends from the deepest parts of the ocean to a few kilometers above Earth’s surface

Earth’s Energy Budget

• The transfers of energy between Earth’s spheres can be thought of as parts of an energy budget.

• The 1st law of thermodynamics = energy can be transferred between systems, but it cannot be created or destroyed.

Earth’s Energy Budget• 2nd law of thermodynamics : when energy

transfer occurs, energy becomes less organized with time. Thus, the universe’s energy is spread out more uniformly over time.

• The constant exchange of matter and energy between Earth’s spheres happens through chemical reactions, radioactive decay, the radiation of heat ,and the growth and decay of organisms.

Earth’s Energy Budget,

Define energy budget.

An energy budget is the total distribution of energy to, from, and between Earth’s various spheres.

Internal Sources of Energy

• When Earth formed about 4.6 billion years ago, its interior was heated by radioactive decay and gravitational contraction.

Earth’s Energy Budget

• The decay of radioactive atoms still generates enough heat to keep Earth’s interior hot. Earth’ interior also retains much of the energy from the planet’s formation.

• By the process of convection, the heat in Earth’s interior is transferred through the layers of Earth and is released at Earth’s surface.

External Energy Sources

• Earth’s most important external energy source is the sun.

Earth’s Energy Budget

• Solar radiation warms Earth’s atmosphere and surface. This heating causes the movement of air masses, which generates winds and ocean currents. Many chemical reactions on Earth also require solar energy (ex. Photosynthesis)

• Another important external source of energy is gravitational energy from the moon and sun. This energy helps generate tides that cause currents and drive the mixing of ocean water.

Cycles in the Earth System

• A cycle is a group of processes in which matter and energy repeatedly move through a series of reservoirs.

• A reservoir is a place where matter or energy is stored. (Also called a sink)

Cycles in the Earth System

• Many elements on Earth cycle or move between reservoirs. These cycles rely on energy sources to drive them.

• The length of time that energy or matter spends in a reservoir can vary from a few hours to several million years.

Biogeochemical Cycle

Nitrogen Cycle

Phosphorus Cycle

Water Cycle