Earth Science

Chapter 1: Introduction to Earth

Science

Edward J. Tarbuck & Frederick K. Lutgens

Earth Science v Encompasses all sciences that seek to

understand: •  Earth •  Earth's neighbors in space

v Earth Science includes •  Geology - literally the “study of Earth”

•  Geochemistry, Geophysics, Geobiology, Paleontology, etc

•  Oceanography – a study of the ocean

Earth Science

v Earth Science includes: •  Meteorology - the study of the atmosphere and

the processes that produce weather •  Astronomy - the study of the universe •  Many of these areas integrate other sciences

like chemistry, physics, biology, as well as various branches of Earth Science.

Formation of Earth v Origin of Earth

•  Most researchers believe that Earth and the other planets formed at essentially the same time and from the same material.

•  Nebular hypothesis •  Solar system evolved from an enormous rotating

cloud called the solar nebula •  Nebula was composed mostly of hydrogen and

helium, with smaller amounts of heavier elements.

Formation of Earth v Origin of Earth

•  Nebular hypothesis continued •  About 5 billion years ago the nebula began to

contract •  Assumes a flat, disk shape with the protosun (pre-

Sun) at the center •  Inner planets begin to form from metallic and rocky

clumps – Mercury, Venus, Earth & Mars •  Larger outer planets began forming from lighter

materials and gases combined farther away from the center with a high percentage of ices – Jupiter, Saturn, Uranus, & Neptune

Formation of Earth v Origin of Earth

•  Nebular hypothesis continued •  High temps and weak fields of gravity characterized

the inner planets – could not hold onto lighter gases. •  Hydrogen and Helium whisked away toward the

heavier planets by solar wind. – Earth, Mars & Venus were able to retain some

heavier gases including water vapor and carbon dioxide.

•  Outer planets contain mostly H and He, but also high percentages of water, CO2, ammonia, and methane in addition to rock and metal cores.

The Nebular hypothesis

Formation of Earth

v Layers Form on Earth •  As Earth formed, the decay of radioactive

elements and heat from high-velocity impacts caused the temperature to increase

•  Iron and nickel began to sink toward the center •  Lighter rocky components floated outward, toward

the surface •  Gaseous material escaped from Earth’s interior

to produce the primitive atmosphere

1.2 - A View of Earth v  Earth’s Major Spheres v Hydrosphere

•  Ocean – the most prominent feature of the hydrosphere

•  Nearly 71% of Earth's surface •  About 97% of Earth's water

•  Also includes fresh water found in streams, lakes, and glaciers, as well as that found underground

Earth's “Spheres" v Atmosphere

•  A life-sustaining, thin, tenuous blanket of air •  Over half of the mass lies below 5.6 kilometers

(3.5 miles) •  Provides air we breathe, protects us from the

sun’s intense heat and radiation. •  The energy exchanges between space, the

atmosphere, and Earth’s surface produce weather and climate.

Earth's “Spheres"

v  Geosphere •  Based on compositional differences, it consists

of the crust, mantle, and core •  Divisions of the outer portion are based on how

materials behave •  Lithosphere - rigid outer layer •  Divisions of Earth’s surface - continents and ocean

basins

Earth’s layered structure

Earth's “Spheres" v Biosphere

•  Includes all life •  Concentrated near the surface in a zone that

extends from the ocean floor upward for several kilometers into the atmosphere

v  Interactions •  Our environment is characterized by the

continuous interactions of air and rock, rock and water, and water and air.

A View of Earth v  Plate Tectonics

•  Two forces affecting Earth’s surface: •  Destructive – weathering and erosion working to

wear away high points and flatten out the surface. •  Constructive – mountain building & volcanism build

up the surface and depend on Earth’s internal heat for energy

•  In the early 20th Century a revolution began with the idea that the continents had moved!

A View of Earth v  Plate Tectonics

•  A new theory emerges – Plate Tectonics! •  Provided geologists with a model to explain how

earthquakes and volcanic eruptions occur and how continents move

•  The lithosphere is broken up into several sections called plates that move slowly and continually driven by unequal distribution of internal heat.

•  The movement of plates generates earthquakes, volcanic activity, and deforms large masses of land into mountains.

1.3 – Representing Earth’s Surface

v  Determining Location •  Latitude and Longitude are lines on a map used

to determine location •  Latitude– distance North or South of the equator. •  Longitude– distance east or west of the prime

meridian •  Divided the Earth into Hemispheres – North,

South, East and West.

Representing Earth’s Surface

v Maps and Mapping •  A map is flat, the Earth is round…

•  No matter what kind of map is made, some portion of the surface will always look too small, too big, or out of place. Mapmakers have found ways to limit the distortion of shape, size, distance, and direction.

•  There are many different types of maps, such as the Mercator projection map (used by sailors), Robinson Projection, Conic Projection, & Gnomic Projection

Topographic Maps v  Shape of the land

•  Represents 3-D surface in 2-D •  Show elevation, water bodies, roads, government

and public buildings, political boundaries, and place names.

•  Important for geologists, hikers, campers and anyone else interested in the ‘lay of the land’

•  Contour lines – indicate elevation, every position along a line is the same elevation

•  Contour interval – difference in elevation between 2 adjacent lines.

Topographic Maps

v  Scale •  A map represents a certain amount of area on

earth’s surface. •  A certain distance on the map = a certain distance at

the surface. •  1:24,000 – 1 unit on map = 24,000 units on surface.

Topographic Maps

v  Geologic Maps •  Shows the type and age of the rocks that are

exposed, or crop out, at the surface. •  Rock formations are assigned colors and

sometimes a pattern.

Satellites & Information Technology

v  Technology •  Satellites and computers send and receive data,

converted to images and accurate maps. •  Remote Sensing – process of collecting data

about Earth from a distance. •  Data is used to study rivers, pollution, oceans, fires,

natural resources, etc

Satellites & Information Technology

v  Technology •  GPS – Global Positioning Systems – can

provide maps in our cars to help us reach destinations.

•  Consists of an instrument that receives signals to compute the user’s lat and lon as well as speed, direction, and elevation.

•  Used by ships and airplanes for navigation. •  Used by scientists to track wildlife, study

earthquakes, measure erosion, etc

1.4 - Earth System Science

v Earth is a dynamic body with many separate but highly interacting parts or spheres

v Earth system science studies Earth as a system composed of numerous parts, or subsystems

v System - any size group of interacting parts that form a complex whole

Earth System Science

v System •  Closed systems are self-contained (e.g. an

automobile cooling system) •  Open systems - both energy and matter flow

into and out of the system (e.g. a river system)

Earth System Science

v Earth as a System •  The Earth System is powered by energy from

two sources: •  The Sun – drives external processes that occur in the

atmosphere, hydrosphere and at the surface •  Earth’s Interior – heat generated by the decay of

radioactive elements, powers internal processes that produce volcanoes, earthquakes and mountains.

•  Parts are linked together so a change in one area can produce changes in any or all of the other parts.

The hydrologic cycle

Earth System Science

v  Earth as a System •  Humans are a part of the Earth System.

•  Our actions produce changes in all of the other parts of the Earth System.

v  People & The Environment •  Environment refers to everything that surrounds

and influences an organism. •  Nonliving factors – water, air, soil, rock,

temperature, humidity, and sunlight, etc •  Living (biological) factors

People and the Environment

v Environment •  Physical environment encompasses water, air,

soil, and rock •  Term “environmental” is usually reserved for

those aspects that focus on the relationships between people and the natural environment

People and the Environment v  Resources

•  Important focus of Earth Science •  Include water and soil, metallic and nonmetallic

minerals, and energy – forms the foundation of modern civilization

•  Renewable resources can be replenished over relatively short time spans.

•  Nonrenewable resources are so slow to form that it takes millions of years for significant deposits to form

•  Limited quantities

People and the Environment

v Population •  Population of the planet is growing rapidly •  Rate of mineral and energy usage has climbed

more rapidly than the overall growth of population

v Environmental problems •  Local, regional, and global

Growth of world population

People and the Environment

v  Environmental problems •  Human-induced and accentuated

•  Urban air pollution •  Acid rain •  Ozone depletion •  Global warming

People and the Environment v Environmental problems

•  Natural hazards continued •  Earthquakes •  Landslides •  Floods •  Hurricanes

•  World population pressures • An understanding of Earth is essential for

locating and recovering resources, dealing with the human impact on the environment and minimizing the effects of natural hazards

People and the Environment

v  Knowledge about the earth and how it works is necessary for our survival and well being.

v  It is the only suitable habitat we have, and its

resources are limited!

1.5 – What is Scientific Inquiry?

v Science assumes the natural world is •  Consistent •  Predictable

v Goal of science •  To discover patterns in nature •  To use the knowledge to predict

Scientific Inquiry v An idea can become a

•  Hypothesis (tentative or untested explanation) •  Theory (tested and confirmed hypothesis) •  Paradigm (a theory that explains a large number

of interrelated aspects of the natural world) v Scientific method

•  Gather facts through observation and measurement

•  Formulate hypotheses and theories

Scientific Inquiry

v Scientific knowledge is gained through •  (1) Following systematic steps

•  Collecting facts •  Developing a hypothesis •  Conduct experiments •  Reexamine the hypothesis and accept, modify, or

reject

•  (2) Theories that withstand examination •  (3) Totally unexpected occurrences

Scientific Inquiry

v  “Science is not a great many things, but in the end they all return to this: Science is the acceptance of what works and the rejection of what does not.” – Jacob Bronowski (mathematician)

•  Thus, science is ever-changing!

End of Chapter 1