Earth Science, Earth Science, 12e12e

Introduction to Introduction to Earth ScienceEarth Science

Chapter 1Chapter 1

Earth ScienceEarth Science

Encompasses all sciences that seek to understand • Earth • Earth’s neighbors in space

Earth Science includes• Geology – literally the “study of Earth” • Oceanography – a study of the ocean

Earth ScienceEarth Science

Earth Science includes• Meteorology – the study of the atmosphere

and the processes that produce weather • Astronomy – the study of the universe

People and the environment People and the environment

Environment • Surrounds and influences organisms • 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 People and the environment

Resources • An important focus of the Earth sciences • Includes water, soil, minerals, and energy• Two broad categories

• Renewable – can be replenished (examples include plants and energy from water and wind)

• Nonrenewable – metals (examples include metals and fuels)

People and the environment People and the environment

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

climbed more rapidly than the overall growth of population

Environmental problems• Local, regional, and global

People and the environment People and the environment

Environmental problems• Human-induced and accentuated

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

• Natural hazards • Earthquakes • Landslides

People and the environment People and the environment

Environmental problems• Natural hazards continued

• Floods• Hurricanes

• World population pressures

Scientific inquiry Scientific inquiry

Science assumes the natural world is • Consistent• Predictable

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

Scientific inquiry Scientific inquiry

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)

Scientific method • Gather facts through observation • Formulate hypotheses and theories

Scientific inquiry Scientific inquiry

Scientific knowledge is gained through • Following systematic steps

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

or reject

• Theories that withstand examination • Totally unexpected occurrences

Early evolution of Earth Early evolution of Earth

Origin of Earth • Most researchers believe that Earth and the

other planets formed at essentially the same time

• Nebular hypothesis • Solar system evolved from an enormous rotating

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

helium

Early evolution of Earth Early evolution of Earth

Origin of Earth • Nebular hypothesis (cont’d)

• 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

• Larger outer planets began forming from fragments with a high percentage of ices

The Nebular hypothesisThe Nebular hypothesis

Figure 1.8

Early evolution of Earth Early evolution of Earth

Formation of Earth’s layered structure • As Earth formed, the decay of radioactive

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

• Iron and nickel began to melt and sink toward the center

• Lighter rocky components floated outward, toward the surface

• Gaseous material escaped from Earth’s interior to produce the primitive atmosphere

Earth’s “Spheres”Earth’s “Spheres”

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”Earth’s “Spheres”

Atmosphere • Thin, tenuous blanket of air • One-half lies below 5.6 kilometers (3.5

miles)

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

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

Earth’s “Spheres”Earth’s “Spheres”

Solid Earth • 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 structureEarth’s layered structure

Figure 1.13

Earth system science Earth system science

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

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

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

Earth system science Earth system science

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 Earth system science

Feedback mechanisms • Negative-feedback mechanisms resist

change and stabilize the system • Positive-feedback mechanisms enhance

the system

Earth as a system • Consists of a nearly endless array of

subsystems (e.g., hydrologic cycle, rock cycle)

Earth system cyclesEarth system cycles

Figure 1.21

Earth system science Earth system science

Earth as a system • Sources of energy

• Sun – drives external processes such as weather, ocean circulation, and erosional processes

• Earth’s interior – drives internal processes including volcanoes, earthquakes, and mountain building

• Humans are part of the Earth system