Transcript Earth Science: Unit 1 - School District of Grafton

Types of Maps
Mercator Projections
Conic Projections
Gnomonic Projections
Topographic Maps
Mercator Projections
Mercator Projection
Is a map that has parallel
lines of longitude and
latitude
Flaws
Land Near Poles is
exaggerated
Shapes are correct, but
land area is distorted
Conic Projections
Conic Projection
Is made by projecting
points and lines from
globe onto a cone.
Very Little Distortion,
High Degree of accuracy
Best for Mapping Small
Areas
Used to make road and
weather maps
Gnomonic Projections
Gnomonic Projections
is made by projecting points and lines from a globe onto a
piece of paper that touches the globe at a single point
Distort Directions and Distance
Used For Plotting great Circle Routes (Airplanes)
Topographic Maps
Topographic Maps
Detailed maps that show
the hills and valleys of an
area
Use Lines, Symbols, and
Colors to represent
change in elevation
Map Features
Map Legends
Map Scales
Map Legends
Include symbols for both man made and natural
features
Specific Colors for Habitats
Green for Woods
Blue for Water
See Appendix D on p. 914
Map Scales
Ratio of distance on a map to actual distances on the
map
3 Types
Verbal: “one inch equals one mile”
Graphic: consists of a line that represents a certain
distance on Earth
Fractional: one unit on map represents one unit on Earth


Large Ratio: map covering large area (minor detail)
Small Ratio: map covering little are (major detail)
Isolines
An isoline is a line connecting points of equal
value.
Examples of isolines:
Isotherms:
points of equal temperature
Isobar:
points of equal barometric (air) pressure
Contour:
points of equal altitude
Concentration of chemicals
Anything else you can get a value for.
(The weather channel loves isolines!)
Rules for Drawing
Isolines:
1. Isolines connect points of
equal value.
5
5
10
10
10
10
15
15
2. Isolines are gentle, curving
lines- no sharp corners.
5
5
10
10
10
10
15
15
3. Isolines are always closed
curves even though the map
might only show part of it.
4. Isolines NEVER cross- this
would mean that one point
has two different values. Ex:
one spot has two temperatures?
40 °
50 °
30 °
60 °
X
20°
Y
Z
5. Isolines usually are parallel.
(They have a parallel trend.)
Visualizations of contour lines
http://geology.asu.edu/~sreynolds/topo_gallery/t
opo_gallery.htm
Gradient
Gradient shows how quickly the
value changes from one point
to another.
 value
Gradient 
distance
A steep (high) gradient changes quickly and the
isolines are close together.
A gentle (low) gradient changes slowly and the
lines are far apart.
Steep area
Gentle area
Making Contours worksheets
Worksheets can be printed from:
http://www.rcmurphy.net/Medina%202005/docum
ents/Contours123.doc
Highlight
data
points.
Fill in
gaps in
data.
Connect
the dots.
Go on
to the
next
value.
Making a Contour Map II
Drawing Contour Maps III