HPU NCS2200 Earth Science for elementary education majors summer 2014 online class Topography lecture

1. Topographic Maps
Topography of Mount Saint Helens from Google Maps (Terrain)

2. Zoomed in view of Mt. St. Helens Caldera - USGS Topographic Map of Mt. St. Helens

3. Prime Meridian & Tropics

4. Latitude and Longitude
• Latitude lines run laterally,
East to West.
• Longitude Line run vertically,
North to South

5. Latitude and Longitude
Based on TRUE NORTH (not magnetic north).

6. Divisions
• Like time and temperature, latitude
and longitude are divided into
degrees, minutes, and seconds.
• For example:
N88º30’45” = 88 degrees (out of
90) north of the equator; plus 30/60
minutes, and 45/60 seconds north
beyond that.

7. Declination
True North= North on a map
Magnetic North= North on your
compass
The difference between the MAGNETIC
NORTH and TRUE NORTH is called the
MAGNETIC DECLINATION.

8. Quadrangles

9. Scales
• Could be a ratio:
1:24000
• Could be a fraction:
1/24000
• Could be a bar:

10. Map symbols

11. Map symbols

12. TOPO MAPS
• A topographic map is a two
dimensional representation of three
dimensional space.
• Utilizes contour lines to show
elevation.
• Contour lines are lines of equal
elevation.

13. • Elevation is distance above sea
level.
• A contour line connects points of
the same elevation.
• If you walked around an entire
mountain staying on the same
contour line, you wouldn’t change
elevation.

14. Index contours
• If we wrote the elevation of every
contour line on that line, then our
map would be covered in numbers.
• Instead, we use index contour lines.
1. Usually darker lines
2. Have the elevation marked on them

15. Index contours

16. Contour interval
• How much vertical space (i.e.
elevation) there is between
contour lines.
• This is the Key to the topo map

17. 2005
2007
2655
What is
the
contour
interval
here?

18. Rules for Contour Lines
• Contour lines always close to
form an irregular circle, it’s just
that sometimes you can’t see
the complete thing.
• Contour lines will make a ‘v’ in
the upstream direction a of a
stream.

19. Contour Lines ‘V’ Upstream
Topography of Appalachian valley surrounding the Rapidan River, Va (from Google Maps - Terrain)

20. Rules Continued
• Lines always increase unless
indicated by hash marks. These
hash marks indicate a
depression.
• Page 150 and figures 9.4-9.7 in
your manual is a great resource

24. Relief
• The difference in elevation
between two points.
Total Relief
• The difference in elevation
between the highest point and
the lowest point on a map.

25. What is
the relief
between
point X
and point
Y?
40 ft

26. Gradient
• The change in elevation from one
point to another is the slope of the
terrain. This is a measure of how
steep the slope is, and also known
as the gradient.
12
12
XX
YY
Run
Rise
Gradient




27. What is
the gradient
between
point X and
point Y?
40 m / 3 km =
40 m / 3000 m =
0.013

28. Widely spaced contour lines = GENTLE
Close contour lines = STEEP
CRATER LAKE NATIONAL PARK USGS TOPOGRAPHIC MAP

29. Compass
42ºE

30. How to Measure a Bearing in Degrees
Mount Saint Helens USGS Quadrangle
BUTTE
CAMP
DOME
N
S
EW
45°
Bearing Measurement
Quadrant Method = S 45°
W
Azimuthal = 225°

31. Benchmark
a point that has been accurately measured for its position and elevation

33. Mount St. Helens

39. Volcanic Deformation and
Evolution of Mt. Saint Helens

40. B.A. Digital perspective view derived from USGS Digital Elevation Model (DEM) of Mount St. Helens as seen
from the northwest prior to the catastrophic eruption of May 18, 1980. Created with Geographic
Information Systems (GIS).

41. B. Digital perspective view derived from USGS DEM of Mount St. Helens following the catastrophic
eruption of May 18, 1980. The 1980-86 lava dome has begun growing in the center of the crater.

42. C. Light Detection And Ranging (LIDAR)-derived digital perspective view of the volcano on September 22,
2003, one year before the start of its latest eruption. The 1980-86 lava dome and Crater Glacier
occupy the crater.

43. D. Digital perspective view derived from both LIDAR DEM and DEM constructed by photogrammetric
techniques, showing new lava dome, 1980-86 dome, and advancing Crater Glacier on July 5, 2007.

44. September 22, 2003 – 1980-86 lava dome quiet

45. October 4, 2004 – Mt. St. Helens reawakened

46. February 21, 2005 – Whaleback Structure

47. July 14, 2005 – Whaleback breaks apart, tall spine extruded then crumbled

48. October 24, 2005 – New lava dome pushes west, cracking glacier

49. February 9, 2006 – Massive fin of hot lava projected skyward

50. February 21, 2005 – Whaleback Structure
photo by Steve P. Schilling

51. Actively growing fin of lava as seen from the 1980-86 lava dome on April 28,
2006. Fin is about 100 meters tall (Photograph by Daniel Dzurisin).

53. NASA Source

54. NASA Source

56. Mt. Saint Helens Resources
A Volcano Rekindled: The Renewed Eruption of Mount St. Helens, 2004–2006
http://pubs.usgs.gov/pp/1750/
Rebuilding Mount St. Helens
http://pubs.usgs.gov/sim/2006/2928/
A New Perspective on Mount St. Helens—Dramatic Landform Change and Associated Hazards at the Most Active
Volcano in the Cascade Range
http://pubs.usgs.gov/sim/3008/
Historic Digital Elevation Models (DEMs)
http://ned.usgs.gov/Ned/historic.asp
USGS Fact Sheet: Mount St. Helens – From the 1980 Eruption to 2000
http://pubs.usgs.gov/fs/2000/fs036-00/
Geologic Map of the Sasquatch Steps Area, North Flank of Mount St. Helens, Washington
http://geopubs.wr.usgs.gov/i-map/i2463/
360 ° Panoramic View of Mount St. Helens Crater
http://www.panoramas.dk/fullscreen6/f34-Mt-St-Helens.html
Teacher’s Corner – Mt. Saint Helens National Volcanic Monument
http://www.fs.fed.us/gpnf/mshnvm/education/teachers-corner/library/nasa-aster-series.shtml
Mount St. Helens National Volcanic Monument
http://www.fs.fed.us/gpnf/mshnvm/

57. Today’s Lab
• Construct a topographic map of the Egyptian
Pyramid of the Pharaoh Khafre
• Learn to read and navigate using topographic
maps
• Create a topographic profile
• Examine the topographic map of Mt. St. Helens
• Learn about volcanic deformation and evolution
of Mt. Saint Helens from digital topographic data

58. Giza topographical map
Khafre pyramid from
Khufu’s quarry
The Sphinx

59. The Great Sphnix of Giza and the Pyramid of Khafre

60. Topographic maps
• http://geology.isu.edu/geostac/Field_Exerc
ise/topomaps/topo_interp.htm
• http://www.tasagraphicarts.com/activities/p
rofile.html