Earth Science Ch. 1 Mapping the Earth

Representing Earth’s Surface Latitude Latitude is distance North and South of the Equator. The Equator is 0° latitude. The poles are 90° latitude. The equator is the only line of latitude that divides the earth into equal halves. Lines of latitude are called parallels. The size of a degree of latitude is always the same 1˚= 69 miles Latitude is determined by the angle of the north star (Polaris) above the horizon Latitude of Bluefield VA: 37° N

Longitude Longitude is distance East and West of the Prime Meridian The longitude line designated 0° is the Prime Meridian. Lines of longitude are called meridians All meridians split a globe into 2 equal halves. The size of a degree of longitude changes. The largest distance is at the equator. The smallest distance is at the poles. Longitude of Bluefield VA: 81° W

Both latitude and longitude are measured in degrees, minutes, and seconds. One degree is divided into 60’ (minutes) One minute is divided into 60” (seconds)

How does the international date line work? Passes through the mid Pacific Ocean 180˚ longitude When you cross the line going west, its one day later. When you cross the line going east, its one day earlier.

Globes and Maps A globe is the most accurate representation of the earth. A map or projection is a flat representation of the earth’s surface. All flat maps originally have distortions because you are projecting a round surface onto a flat surface.

There are 4 types of map projections: Mercator Robinson Conic Gnomonic

Mercator Used for navigation. Lines of latitude and longitude are parallel. Sizes and distances are distorted. Directions are shown accurately. Produced by placing a cylinder of paper around a globe. Distortion occurs as you move toward the poles.

Robinson Most accurate map projection. Most distances, sizes, and shapes are accurate. Distortion only occurs around the edges.

Conic Very accurate over small areas. Used to make road and weather maps. Cone of paper is placed on a globe at a line of latitude.

Gnominic Useful for navigation because the shortest distance between 2 points is very accurate. Distances and directions are distorted. Created by one piece of paper touching one point on the globe.

Features of a Topographic Map (elevation) Contour lines: connect points of equal elevation Contour interval: the distance between one contour line and the next Index contours: darker lines making elevation easier to determine, every 5th line Relief: Distance between the lowest and highest points on a map Hachured marks: represent a depression Valleys: represented by a V-shape on a map Mountain tops: represented by the smallest complete circle on a map. Lines that are close together represent a steep slope Lines that are farther apart represent a gradual slope

Index Contour Contour Lines Steep slope Hilltop Valley Gradual Slope

Hatchured Lines Represent Depressions How to read hatchured lines

Match the topographic map to the correct profile B E D C F A

Scale The scale of a map compares the actual distance to the distance on a map. The most common scale used in geology is the 7.5 minute quadrangle. The scale is 1: 24,000 Both units remain the same unless noted on the map.

Geologic Maps A map that shows the type and age of exposed rock

GPS The process of collecting data from satellites is called remote sensing. Remote sensing is used for GPS GPS stands for Global Positioning Systems GPS receives information from satellites to compute latitude, longitude, speed, direction, and elevation In order to find locations, GPS devices receive information from 4 satellites. GPS is not only used in navigation but is also used in Earth Science for the study of features on Earth’s surface.

How GPS Finds Location