1. 1 Ch. 1: “Introduction to Earth Science” 1.3: “Representing Earth’s Surface”

2. 2 Global Grid In order to describe location, two special Earth measurements are made. –Latitude: distance N or S of the equator, measured in degrees. Lines of latitude are E- W circles around the globe. –Longitude: distance E or W of the prime meridian, measured in degrees. These lines run N to S.

3. 3 Maps & Mapping A map is a flat representation of Earth’s surface. Since the Earth is round and it is represented on a flat surface some distortion will occur. Some portion of the surface will always look too big, too small, or out of place. –Mapmakers have found ways to limit the amount of distortion that can occur.

4. 4 Mercator and Robinson Projections Created to help sailors navigate around the Earth. Advantages: rectangular, longitude lines are parallel. Disadvantages: sizes & distances are distorted. One of the most widely used projection maps. Advantages: most distances, sizes, & shapes are accurate. Disadvantages: distortions around the map edges.

5. 5 Conic and Gnomonic Projections Made by wrapping a cone of paper around a globe at a particular line of latitude. Advantages: great accuracy over small areas; good for road & weather maps. Disadvantages: lots of distortion, particularly in areas away from latitude that cone is in contact with. Made by placing a piece of paper on a globe so that it touches a single point on the globe’s surface. Advantages: reliably shows the shortest distance between two points. Disadvantages: exact distances and directions are distorted.

6. 6 Topographic Maps Show the Earth’s 3-D features on a flat map. –Maps are drawn to a scale. Each distance on a map represents a certain distance on land. –Shows elevation by means of contour lines. All features on one contour line have the same elevation. Adjacent contour lines have different elevation. Interval between contour lines can vary from map to map. The contour interval tells you the difference in elevation between adjacent lines. –Usually every 5 th line is in bolder type called index contour. –The steeper the slope, the closer the contour lines. –When the lines are farther apart – gentle slope.