Models of the Earth Chapter 3

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Geographic North Pole and South Pole - the points at which Earth’s axis of rotation intersects Earth’s surface Used as reference points for defining direction. Equator - halfway between the poles, divides Earth into the North and South Hemispheres. A reference grid that is made up of additional circles is used to locate places on Earth‘s surface.

parallel - any circle that runs east and west around Earth and that is parallel to the equator; a line of latitude latitude - the angular distance north or south from the equator; expressed in degrees  the equator is 0° latitude  The latitude of both the North Pole and the South Pole is 90°  1° latitude equals about 111 km

Parallels of the Earth

Minutes and Seconds Minutes - Each degree of latitude consists of 60 equal parts, called. One minute (°) of latitude equals 1.85 km Seconds - each minute is divided into 60 equal parts (°)

Meridian - any semicircle that runs north and south around Earth from the geographic North Pole to the geographic South Pole; establishes East-west locations Longitude - the angular distance east or west from the prime meridian; expressed in degrees  Distance covered by a degree of longitude depends on where the degree is measured  Decreases as you move from the equator toward the poles.

Prime meridian -passes through Greenwich, England  represents 0° longitude. International Date Line - The meridian opposite the prime meridian, halfway around the world, is labeled 180°

Great circle - any circle that divides the globe into halves; marks the circumference of the globe  Any circle formed by two meridians of longitude that are directly across the globe from each other  The equator is the only line of latitude that is a great circle.  The route along a great circle is the shortest distance between two points on a sphere.  Great circles are commonly used in navigation, Ex. air and sea routes

magnetic compass - used to find direction on Earth Geomagnetic poles - areas on Earth’s surface just above the poles of the imaginary magnet The geomagnetic poles and the geographic poles are located in different places.

Magnetic declination - angle between the direction of the geographic pole and the direction in which the compass needle points  In the Northern Hemisphere, magnetic declination is measured in degrees east or west of the geographic North Pole. Earth’s magnetic field is constantly changing, as is the magnetic declinations of locations around the globe By using magnetic declination, a person can use a compass to determine geographic north for any place on Earth

GPS (global positioning system) - another way people can find their location on Earth  A satellite navigation system that is based on a global network of 24 satellites that transmit radio signals to Earth’s surface  A receiver held by a person on the ground receives signals from three satellites to calculate the latitude, longitude, and altitude of the receiver on Earth

Topographic Map Symbols Symbols are used to show certain features on topographic maps. Symbol color indicates the type of feature  Constructed features - black  Highways - red  Bodies of water - blue,  Forested areas - green.  Contour lines - brown or black

Geologic maps Show geologic features  types of rocks found  locations of faults, folds, and other structures Rock Units on Geologic Maps Geologic units are distinguished by color. Units of similar ages are generally assigned colors in the same color family, ex. different shades of blue. Letters are assigned to each rock unit  symbolizes the age of the rock and the name of the unit or the type of rock

Contact line Other markings on geologic maps Contacts - indicates places at which two geologic units meet  faults  depositional contacts Geologic maps also indicate the strike and slip of rock beds. Strike - indicates the direction in which the beds run, slip - indicates the angle at which the beds tilt.

Uses of soil maps: classify map describe soils, based on surveys of soils in a given area. 3 main parts of soil surveys:  text,  maps  tables.

Text - general information about the geology, topography, and climate of the area. Tables - describe the types and volumes of soils in the area. Maps - show the approximate locations and types of the different soils.

Valuable tools for agriculture and land management. Used by farmers, agricultural engineers, and government agencies. The information in soil maps and soil surveys helps developers and agencies identify ways to conserve and use soil and plan sites for future development.

Maps are useful to every branch of Earth science. Maps that are only one useful type of map. Benefits of using maps:  show the location and flow of water and air  study changes in Earth’s surface over time  show topography and rock and soil types