In this Unit:
Contours - Lines on a map connecting points of equal altitude (height).
Depression - An area of the Earth's surface that is lower than the surrounding areas; a sunken or depressed geological formation.
Elevation - The distance of some point above a reference point (usually sea level).
GIS (Geographic Information Systems) - Technology that analyzes, stores, and displays both spatial and non-spatial data.
GPS - "Global Positioning System." A navigational system using satellite signals to fix the location of a receiver on or above the Earth's surface.
GPS Receiver - Electronic equipment that passively receives a GPS signal for processing. Typically this is the instrument a user would hold in her hand.
Latitude - Angular distance north or south from the Earth's equator, measured from 0 degrees at the equator to 90 degrees at the poles.
Longitude - The arc or portion of the Earth's equator intersected between the meridian of a given place and the prime meridian, and expressed either in degrees or in time.
Navigation - The method of determining position, course, and distance traveled.
Planetable - A device for plotting survey data directly from field observation. Consists of a drawing board on a tripod with a sighting instrument to measure and plot angles.
Satellite - A manufactured object or vehicle intended to orbit the earth, the moon, or another celestial body. Satellites orbiting the Earth broadcast signals used by Global Positioning System receivers.
USGS - The United States Geological Survey. The mission of the U.S. Geological Survey is to provide geologic, topographic, and hydrologic information that contributes to the wise management of the nation's natural resources.