mapping the sf bay overview sf bay: know the waterways and bridges
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Mapping the SF Bay
Overview
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SF Bay: Know the waterways and bridges
Topographic Maps
A. Definition:
A map showing changes in elevation
Contour Line
A. Definition:
A line that connects points of equal elevation.
Contour Interval
A. Definition:
The difference in elevation between two side by side contour lines.
Lines close together represent steep terrain.
Using Contour Lines
What is the contour interval on this map?
Contour interval = Change in elevation ÷ # lines
Go from bank of spillway (blue arrow: 800 ft) to next dark line (green arrow: 1000ft). There are 5 contour lines.
Contour interval = 200 ft ÷ 5 lines = 40 ft
What is the change in elevation from the spillway bank (blue arrow) to the end of the West Fork of Lauguanitas Creek (red arrow)?
Change in elevation = # lines x contour interval
Change in elevation = 24 lines x 40ft
Change in elevation = 960 ft
Map Legend/Key
A. Definition:
Explains what symbols on maps represent
Map Scale
A. Definition:
The ratio between the distances on a map and the actual distances on the surface of the earth
QuickTime™ and a decompressor
are needed to see this picture.In this example, 50 km = 1.8 cm
Using Map Scale
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50 km = 1.8 cm
So… area of entire shown map area is…
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Length: 10.6 cm x = =
Width: 3.2 cm x = =
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50km
1.8cm
€
50km
1.8cm€
530km
1.8
€
160km
1.8
294.4km88.9km
Area = Length x Width
Area = 294.4km x 88.9km
Area =
26,172.16 km2
Nautical Charts
A. Definition:
A map produced for marine navigation.
Water depths are recorded as soundings in feet, meters or fathoms.
Latitude A. Definition:
The distance in degrees North or South of the equator
The lines run parallel to the equator
Longitude
A. Definition:
The distance in degrees East or West of the Prime Meridian
The lines run perpendicular to the equator
Using Lat. And Long.: What is the latitude and longitude of New Orleans?
Answer: 29 degrees 57’ N, 90 degrees 04’ W.
Further consideration: Time Zones