Transcript 1. Earth Science and the Earth System

Visualizing Earth Science
By Z. Merali and B. F. Skinner
Chapter 1 – Introduction to Earth Science
Chapter Overview
• Earth Science
• The Earth in Space
• Humans and Earth
Science and the Scientific Method
• The Scientific Method
– Systematic approach to studying natural processes
• Make observations
• Formulate a hypothesis
• Conduct tests of the hypothesis
• Evaluate and generalize
• Earth Science
– The scientific study of aspects of Earth
Science and the
Scientific Method
Systems
• The Systems approach
- Deconstruct Universe into
interconnected elements or
units
• Identify processes
connecting and boundaries
separating systems
Types of Systems
•Systems classified
according to boundary
interactions with the
environment
-Isolated: No energy or
matter is exchanged
-Closed: energy is
exchanged but not matter.
-Open: energy and matter
can be exchanged with
environment
The Earth System
• A(n almost) closed system
• Earth System Science
–Treat Earth Science as a single field of study
–Emphasis on studying interconnections between Earth subsystems
The Earth System
Principal subsystems of the Earth System
• Four principal open
subsystems or “spheres”
- The lithosphere
– The hydrosphere
– The atmosphere
– The biosphere
• Each interacts with the
others
– Most intensely in the life zone
Feedback Mechanisms
• Feedback Mechanisms
- System – Environment
interaction cycles that
change open systems
• Positive feedback
– Enhance change in
systems
• Negative feedback
– Reduce change in
systems
How feedback works
• System interacts with
environment
• Interaction produces change in
the system
• System responds to the
change
• System response “feeds back”
or affects the change in the
system
The Earth in Space
The Solar System
• The Earth – Our planet
– One of eight large, spherical bodies orbiting the
Sun
• Third from the sun
• A relatively smaller, denser body
- The inner planets: Mercury, Venus , Earth and
Mars are the terrestrial planets
- Larger, less dense planets: Jupiter, Saturn,
Uranus and Neptune are jovian planets
• The Earth is uniquely suitable for sustaining
life
The Earth in Space
The Solar System
The Earth in Space
The Terrestrial Planets
• General characteristics of terrestrial planets
– Similar densities – a little greater than common rocks
– Dense metallic core surrounded by less dense rocky layer
• A result of partial melting of planets in their early history
- Thin atmospheres
- Warmer temperatures
The Layers of the Earth
Layers by composition
• A dense two-layer metallic core
– A solid inner core
– A liquid outer core – responsible for the Earth’s magnetic field
– Composed of iron and nickel
• A less dense rocky middle layer – the mantle
• A thin brittle rocky outer layer – the crust
The Layers of the Earth
Layers by composition
The Layers of the Earth
Layers by rock strength
• Rocky layers (mantle and crust) have distinct structures
based on rock strength
– The lithosphere
• The crust and upper mantle
• Strong but brittle cool rock
– The asthenosphere
• Easily deformed rock
• Higher temperature and increased pressure
– The mesosphere
•
Very high temperature and intense pressure
• Strong rock
The Layers of the Earth
Layers by rock strength
The unique Earth
The life supporting planet
• Presence of Oxygen in the atmosphere
• Presence of Water
- Hydrosphere contains solid, liquid and gaseous water
• The Biosphere (System)
- Contains all life on Earth
- Interacts with surroundings and with itself
- Changes and shapes its own environment
• Soil – layer of loose debris formed by weathering
The unique Earth
The geologically active planet
• Tectonic activity
- The lithosphere is broken into large slabs or plates
- There is large scale movement of plates
- Plate tectonics continually reshapes the surface of the Earth
The unique Earth
The unique Earth
The geologically active planet
• Lithosphere shaped by
tectonics
- Older lighter plates float higher
over the asthenosphere
• Form the continents
• Composed mainly of granitic
rock
- Newer dense plates sink
deeper into the asthenosphere
• Form the oceans
• Composed of basaltic rock
Humans and Earth
Population growth
• Growth in human
population demands
increasing resources
- Population growth and
its effects on food and
resources
• Debated among policy
makers and academia
• Needs a response to
sustain present
resource levels
Humans and Earth
Resource management
• Natural resources are
often scarce
– Renewable resources
• Can be replaced through
natural processes
• The timescale of
replacement is shorter than
the timescale of use
– Nonrenewable resources
• Cannot be replaced within
the timescale of use
Humans and Earth
Resources and Modern Society
• Use of resources in the US
and the most industrialized
economies
- Disproportionately large in
comparison with the world
- Energy resources
• Used at rate over four times the
world average
• Dependence on external imports
to sustain levels of use
Humans and Earth
Resources and Modern Society
Motivation for the study of Earth Science
• Understanding the Earth system
– Provides an appreciation of the Earth System as a closed
system
• All material resources are limited
• Sustaining resources requires
-
understanding processes and
- understanding time-scales
- Provides an understanding of
- Geological features
- Phenomena and
- Natural hazards
Motivation for the study of Earth Science
What ?
Chapter Summary
• Earth Science and Earth Scientists
– Use the scientific method
– Study the Earth as a closed System
– Study Earth System mechanisms and processes
• Earth’s place in the Universe
– Earth is a planetary body in the solar system
– Earth is unique in many aspects
• It sustains life
• It is geologically active
• Human interaction with the Earth
– Earth’s resources are limited
• Resources management must be understood and applied