Earth From Space

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Earth From Space
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Introduction

• The science of geology
• Geologic time
• The nature of scientific inquiry
• Earth as a system
• Early evolution of Earth
• Dynamic Earth

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Quartz
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Galena
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Granite
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The science of Geology

• Geology is the science that pursues an
  understanding of planet Earth
• Physical geology - examines the materials
  composing Earth and seeks to understand the many
  processes that operate beneath and upon its
  surface
• Historical geology - seeks an understanding of
  the origin of Earth and its development through
  time

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The science of Geology

• Geology, people, and the environment
• There are many important relationships between
  people and the natural environment
• Some of the problems and issues addressed by
  geology involve natural hazards, resources, world
  population growth, and environmental issues

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El Salvador Landslide 2001
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Remotely Sensed Image
Mt. Vesuvius and Naples Italy. This is the
volcano that buried Pompeii and Herculaneum in
A.D. 79.
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The science of Geology

• Some historical notes about geology
• The nature of Earth has been a focus of study for
  centuries
• Catastrophism Developed in the mid-1600s. Great
  catastrophes shaped the landscape.
• Uniformitarianism - Late 1700s. The present is
  the key to the past.

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Geologic time

• Geologists are now able to assign fairly accurate
  dates to events in Earth history
• Relative dating
• Relative dating means that dates are placed in
  their proper sequence or order without knowing
  their age in years
• Absolute dating
• With absolute dating we can determine the age of
  an object

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Fossil Evidence
Extinct amphibian from the Permian age, found in
Texas
Fossil Fish from the Eocene age, found in Wyoming
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Geologic time

• The magnitude of geologic time
• Involves vast amounts of times millions or
  billions of years
• An appreciation for the magnitude of geologic
  time is important because many processes are very
  gradual

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The Geologic Time Scale
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Idealized Geologic Time Scale
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The nature of scientific inquiry

• Science assumes the natural world is consistent
  and predictable
• Goal of science is to discover patterns in nature
  and use the knowledge to make predictions
• Scientists collect facts through observation
  and measurements

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The nature of scientific inquiry

• How or why things happen are explained using a
• Hypothesis a tentative (or untested)
  explanation
• Theory a well-tested and widely accepted view
  that the scientific community agrees best
  explains certain observable facts

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The nature of scientific inquiry

• Scientific methods
• Scientific method involves gathering facts
  through observations and formulation of
  hypotheses and theories
• There is no fixed path that scientists follow
  that leads to scientific knowledge

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Death Valley From Space
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Flooding in New Orleans
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Flooding in New Orleans
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A view of Earth

• Earths four spheres
• Hydrosphere
• Atmosphere
• Biosphere
• Solid Earth

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Earth as a system

• Earth is a dynamic planet with many interacting
  parts or spheres
• Parts of the Earth system are linked
• Characterized by processes that
• Vary on spatial scales from fractions of
  millimeter to thousands of kilometers
• Have time scales that range from milliseconds to
  billions of years

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Earth as a system

• The Earth system is powered by the Sun that
  drives external processes in the
• Atmosphere
• Hydrosphere
• At Earths surface

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Earth as a system

• The Earth system is also powered by the Earths
  interior
• Heat remaining from the formation and heat that
  is continuously generated by radioactive decay
  powers the internal processes that produce
  volcanoes, earthquakes, and mountains

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The rock cycle part of the Earth system

• The loop that involves the processes by which one
  rock changes to another
• Illustrates the various processes and paths as
  earth materials change both on the surface and
  inside the Earth

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The Rock Cycle
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The face of Earth

• Earths surface has two principal divisions
• Continents
• Ocean basins
• Significant difference between the continents and
  ocean basins is their relative levels

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The face of Earth

• Continents
• Most prominent features are linear mountain belts
  
• Shields
• Ocean basins
• Ocean ridge system the most prominent
  topographic feature on Earth
• Deep-ocean trenches

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Earths Physical Features
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Early evolution of Earth

• Origin of planet Earth
• Most researchers believe that Earth and the other
  planets formed at essentially the same time from
  the same primordial material as the Sun
• Nebular hypothesis

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Nebular Hypothesis
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Earths internal structure

• Layered structure developed by chemical
  segregation early in the formation of Earth
• Earths internal layers can be defined by
• Chemical composition
• Physical properties
• Layers defined by composition
• Crust
• Mantle
• Core

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Earths internal structure

• Four main layers of Earth are based on physical
  properties
• Lithosphere
• Asthenosphere
• Mesosphere
• Core

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Cross section of the Earth
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Earths Layered Structure
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Distance to the center of the Earth
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Dynamic Earth

• The theory of plate tectonics
• Involves understanding the workings of our
  dynamic planet
• Began in the early part of the twentieth century
  with a proposal called continental drift the
  idea that continents moved about the face of the
  planet

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Dynamic Earth

• The theory of plate tectonics
• Theory, called plate tectonics, has now emerged
  that provides geologists with the first
  comprehensive model of Earths internal workings
• Plate boundaries
• All major interactions among individual plates
  occurs along their boundaries

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Dynamic Earth

• Plate boundaries
• Divergent boundary two plates move apart,
  resulting in upwelling of material from the
  mantle to create new seafloor
• Convergent boundary two plates move together
  with subduction of oceanic plates or collision of
  two continental plates

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Dynamic Earth

• Plate boundaries
• Transform boundaries - located where plates grind
  past each other without either generating new
  lithosphere or consuming old lithosphere
• Changing boundaries - new plate boundaries are
  created in response to changes in the forces
  acting on the lithosphere

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Earths Plate Boundaries
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Continental Plate Collision
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