1. Models of the Earth

2. Earth Very nearly perfect sphere
No top, bottom or sides
Earth’s axis of rotation can be used to establish reference points
Reference points:
North and South poles
Equator divides earth into northern and southern hemisphere

3. Latitude Parallels- Latitude describes north and south of the equator
Run east-west parallel of the equator
Latitude
Angular north or south of the equator

4. Degrees of Latitude Measured in degrees Equator is 0°
North Pole and South Pole is 90°
Each degree consists of 60 equal parts called minutes
1.85 km
Symbol is ‘
Each minute is divided into 60 equal parts called seconds
Symbol is ‘’

5. Longitude Meridian Longitude-
is a semicircle that runs from pole to pole
Prime meridian is 0°
Longitude-
is the angular distance east or west of the prime meridian

6. Degrees of Longitude
All locations have a longitude between 0° and 180° east or west of the prime meridian
A degree of longitude equals approximately 111 km
Decreases as you move towards the pole

7. Great Circle
Any circle that divides the glove into halves or marks the circumference of the globe
Any circle formed by two meridians of longitude that are directly across the globe from each other is a great circle
Can run in any direction around the globe
Air and sea routes often follow great circles

8. Finding Direction Use a magnetic compass
Geomagnetic poles- areas of earth’s surface above where the poles of the imaginary magnet
Needles of compass points to geomagnetic north pole

9. Magnetic Declination
Angle between the direction of the geographic pole and the direction in which the compass needle points is called magnetic declination.
Measured in degrees east or west of the geographic north pole

10. GPS (Global Positioning System)
GPS can be used to find their location on earth
Based on a global network of 24 satellites that transmit radio signals to Earth’s surface.
First one was NAVSTAR (launched in 1978)
Can be accurate within meters of position

11. Mapping Earth’s Surface

12. Mapping Globe- model of earth
Accurately represent locations, relative areas, and relative shapes
Useful for large surface features
Too small to show details of earth’s surface

13. Making maps Cartography Remote sensing Scientists who make maps
Collect data by a field survey or remote sensing
Remote sensing
The process of gathering and analyzing information about an object without physically being in touch with the object

14. Map projections Map is a flat representation of Earth’s curved surface
Area may be distorted in size, shape, distance or direction
Map of a city shows slight distortion
Map of earth shows greatest distortion
Map projection
A flat map that represents a spherical surface

15. Cylindrical Projections
Meridians appear as straight, parallel lines that have an equal amount of space between them
Advantage:
Parallels and meridians form a grid (locating positions is easier)

16. Azimuthal Projections
Place a sheet of paper against a transparent, lighted globe so that paper touches the globe at only one point
Great for air travel and finding great circles
Little distortion at point of contact
Unequal spacing between parallels causes distortion in both direction and distance

17. Conic Projections
Made by placing a paper cone over a lighted globe so that the axis of the cone aligns with the axis of a globe.
Touches the globe at a parallel
Where the cone and globe are in contact have the slightest distortion

18. Reading a Map
North on top, east on the right, south on the bottom, west on the left
Never Eat Soggy Waffles
Parallels run from side to side
Meridians run from top to bottom
Legend- a list of map symbols and their meanings

19. Map Scales
Scale- the relationship between the distance shown on a map and the actual distance
Graphic Scale- Printed line that has markings on it that are similar to those on a ruler
Fractional Scale- 1:25,000 (one unit of distance represents 25,000 of the same unit on earth
Verbal Scale- Sentence form (One cm is equal to one km)

20. Isograms
A line on a map that represents a constant or equal value of a given quantity
Meteorologists use to show atmospheric pressure

21. Types of Maps

22. Topographic Maps
The size and shape of the land surface features of a region including its relief
Natural features
Shows elevation
The height of an object above sea level

23. Topographic Maps More detailed information about the surface
Shows size, shape and elevation
Contour lines- a line that connects points of equal elevation on a map (is an isogram)
Relief- the difference between the highest and lowest elevations in a given area

24. Topographic Maps
Widely spaced contour lines indicate gradual change in elevation
Closely spaced contour lines is a rapid change in elevation
Contour lines that bend to form a V is a valley
Closed loop contour lines indicate a hilltop

25. Topographic Maps
Buildings, boundaries, roads, and railroads- normally in black
Major highways-red
Bodies of water-blue
Forest-green
Contour lines- brown and black

26. Geologic Maps Show distribution of geologic features
Types of rocks, locations of faults, folds, etc.

27. Geologic Maps
Geologic unit- volume of rock of a given age range and rock type
Assigned by color
Letters represent age
One capital letter- symbolizes age of rock
Lowercase letters- represent the name of the unit or type of rock

28. Geologic Maps
Contact lines-indicates places at which two geologic meet
Strikes-indicates direction in which beds run
Dips- Indicates the angle at which the beds tilt
Two types of contacts
Faults- cracks where rocks can move past each other
Depositional contacts-show where one rock layer formed above another

29. Soil Maps Classify, map and describe soils Based on soil surveys
NRCS (Natural Resources Conservation Service maps soil

30. Soil Maps Soil Survey Uses- agricultural and land management
Text- general information about the geology, topography and climate of area being mapped
Tables- describes and volumes of soils in the area
Maps-
General map shows the approximate location of different types of soil within the area
Detailed information about soils
Uses- agricultural and land management