Chapter 1: Introduction to
Earth Science
Section 2: A View of Earth
Section 3: Representing Earth’s
Surface
Section 2: A View of Earth
• Key Concepts
– 4 major spheres into which Earth is divided
– 3 main parts of the solid Earth
– Theory of plate tectonics
Earth’s Major Spheres
• 4 major spheres:
–Hydrosphere
–Atmosphere
–Geosphere
–Biosphere
Hydrosphere
• All water on Earth
• Oceans: ~97%
• Fresh water (lakes,
streams, groundwater,
glaciers): ~3%
Atmosphere
• Reaches beyond 100 km above Earth
– 90% occurs within 16 km of Earth’s surface
• Provides protection from Sun’s heat & radiation
• No atmosphere life would not exist
– No erosion/weathering surface resemble
moon
Geosphere
• Beneath atmosphere & ocean
• Not uniform
– 3 main parts (composition):
• Core: dense
• Mantle: less dense than core
• Crust: lightest & thin; oceanic/thinner,
continental/thicker
Biosphere
• Includes all life on Earth
at U of
• Ocean floor up into atmosphere Biosphere buildingArizona
• Without life, the makeup & nature of the
other spheres of Earth would be very
different.
Plate Tectonics
• 2 types of forces affecting Earth’s surface:
1. Destructive forces: weathering, erosion
2. Constructive forces: mountain building,
volcanism
• Theory of plate tectonics emerged early 20th
century
– More than 50 years later hypothesis
theory
– Explained how EQ and volcanic eruptions
occur and how continents move.
• Plates motion driven by unequal
distribution of heat
Section 3: Representing Earth’s
Surface
• Key Concepts
– Lines on the globe & location
– Mapmaker challenges
– Topographic maps vs. other maps
To locate places N or S on Earth,
cartographers use…
• Latitude: distance in
degrees North/South of
Equator; lines that run
parallel to Equator
• Equator: 0°runs
horizontally equidistance
from the poles
– points North of equator=
degrees N
– points South =degrees S
To locate places E or W on Earth,
cartographers use…
• Longitude: distance in degrees E
or W of the prime meridian
– halves of giant circles running thru
Earth
– Long. lines aka meridians
• Prime meridian: 0° long.
– runs through Greenwich, England-Royal Naval Observatory
– Points west of PM designated W
– Points east of PM designated E
• International Date Line: 180° long
• Longitude and Latitude song
•
Note convergence of
longitude lines as you
approach the Poles…1°
long=111km at the equator
and 0 km at the poles
Degrees, minutes, seconds
– To precisely describe the latitude of a place
degrees, minutes and seconds are used. It looks
like: ##°##’##”
– Why it matters? See below!
•1º lat=111 km on Earth’s surface
=(40,000 km circumf./360°)
•1’ lat=1.85 km on Earth’s surface
=(111 km/60’)
• 1” lat=.03 km on Earth’s surface
=(1.85 km/60”)
Minutes and
Seconds For precision
purposes, degrees of
longitude and latitude
have been divided into
minutes (') and seconds
("). There are 60 minutes
in each degree. Each
minute is divided into
60 seconds. Seconds
can be further divided
into tenths, hundredths,
or even thousandths.
Types of Maps
• Globes (not a map)
• Projection Maps
– Mercator projection
– Robinson projection
– Conic Projection
– Gnomonic Projection
• Topographic Maps
– Geologic Maps
• Legends & Scales
Globes
• Mapmakers wanted to present
information accurately
– Mimics shape of Earth
– Can’t be complete enough to be useful for finding
directions and can’t be small enough to be
convenient for everyday use.
Projection Maps
• Imagine a light inside a globe shining out. Wrap a
clear transparency around the globe. Trace the outline
of the shadow of the land on the transparency.
• Takes the round globe & flatten it out
Pro: Easy to travel with
Con: Creates a lot of distortion
at poles
• Types: Types Visually
o
o
o
o
Mercator
Conic
Robinson
Gnomonic
Proportional?
flattening the earth
animation flattened globe to map
Robinson
• Most widely used
• Pro: Show most distances, sizes, and
shapes accurately
• Con: distortion around edges of map
Mercator Projection
• Sheet wrapped
around the globe
• Creates parallel lines
of lat & long
Pro: straight lines allow
easier navigation
(planes/ships)
Con: lots of distortion of
land shapes as you
reach higher
latitudes
• Greenland appears as big as
S. America but it’s really 1/8th
the size of S. America!!
Conic Projection
• Projecting points/lines
from globe onto cone @
lines of latitude
• Pro: Little distortion of
spots touching cone/
line of lat., used to
map small areas
(road/weather maps)
• Con: Lots of distortion near
top and bottom of
map
• Areas below red line
would appear HUGE
as areas near poles
look smaller.
Gnomonic Projection
• Points/lines from globe
projected on paper that
touches globe at 1 point
• Pro: No distortion at
contact point
• Con: Lots of distortion in
direction & distance
between landmasses
• Note little distortion near
Greenland & much in the S.
US
• Great accuracy the shortest
distance between two
points—straight line great
for
navigation!
Amelia Earhart: Sonar Discovery
Sonar Article
1937
Topographic Maps
• Bird’s eye view of an
area
• Show Earth’s 3-D in 2-D
• Shows how
steep/gentle a slope is
• Shows the elevation &
shape of the land and
other geographic or
cultural (bridges, schools,
churches, cemeteries, etc)
features
Vocab: Topographic Maps
• Contour lines: connect
points of equal
elevation
• Contour interval:
difference in elevation
between adjacent
contour lines
• Relief: difference in
elevation between
highest & lowest points
on map
• Index contour: every
5th line on the map is
bold and elevation is
marked for reference
Contour line rules…
• Contour lines are continuous closed loops; they
never just appear or end on a map except at the
edges
• Separate higher elevations from lower elevations
• Never cross (run together=cliff)
• Closer lines=steeper slope
• Closed depressions are marked with hachures
(point in direction of drop)
• Water flows perpendicular to
contour lines
Geologic map
• Color coded to show
rocks below the soil
–
–
–
–
Distribution
Arrangement
Type of rock/minerals
Age of rock
• Often superimposed
over topographic
maps
All maps have…
Map Legends
Map Scales
• Shows symbol images
• Decodes their meanings
• Shows distances on a
map
• Ratio between distances
on map and actual
distances on Earth’s
surface
Remote Sensing: gather data about
Earth using instruments on satellites,
planes or ships; more accurate
Landsat satellites
Weather satellites
Navigation satellites
Very Long Baseline
Interferometry (VLBI)
• Global Positioning
System (GPS)
• Geographic
Information System
(GIS)
•
•
•
•
Landsat
• Satellites detect
features based on the
warmth (diff
frequencies) they
radiate
• Detectors on mirrors
measure the intensity
of energy received
digital images
Weather Satellites
• Monitor atmospheric temperature, humidity,
cloud cover, etc.
• Help locate sources of distress signals
• Able to scan surface in one 24-hour period
The first picture of Earth from a
weather satellite, taken by the
TIROS-1 satellite on April 1,
1960. Although primitive in
comparison with the images we
now receive from satellites, this
first picture was a major
advance.
Navigation Satellites
• Assist ships and submarines to determine
location
Very Long Baseline Interferometry
(VLBI)
• Utilizes large network of antennas globally to
receive radio waves from space objects
(quasars)
– Using the arrival times of radio waves
from quasars, the position of radio
telescopes on Earth are determined
to within millimeters of their position.
– Able to study tectonic plate movement
 due to changes in telescope position
GPS
[Global Positioning System]
• Satellite navigation system
using microwaves
– 27 satellites 12,000 miles
from Earth
– Constantly orbit
– Orbit Earth twice/day
– Accuracy 10 m
• Triangulate location based
on signals received from 3
sats.
• Signal from 4 sats. would
allow for elevation
calculations
• GPS tutorial
Importance of Triangulation
•Able to pinpoint
given location
•Minimum of 3
satellites needed
to
triangulatewhere
all 3 circles
intersect is where
your given location
is!
GIS
Geographic Information System
[computer based program]
• Combines map types we’ve discussed
– Layers info one on top of another
• Topography of land
• Elevation
• Roads, buildings, etc
– Monitor changes to a specific
area over time
•
•
•
•
Volcanic eruptions
Flooding of an area
Animal population trends
Define vector/raster!
• GIS in Rhody!