MAP TERMINOLOGY


CARTOGRAPHY
Cartography is actually the art of making maps or charts, but it has also been misused as a general term for the study of maps. The cartographer is the map maker and they tend to limit the definition of the term to the final stages of making and printing the map. Others include the planning, aerial photography, field surveys, editing, etc.

CADASTER
A cadaster is a map showing the extent, value, and ownership of land as a basis for taxation. The adjective, cadastral, or cadastral map, is used in many family history textbooks. It is simply a land ownership map.

CONTOUR
A contour map is one that shows elevations by drawing curved lines along the same elevation. It therefore clearly marks hills and valleys. The difference between two contour lines is termed the contour interval.

DOQ
DOQ stands for Digital Orthophoto Quadrangles. These are aerial photographs available digitally on the computer which cover large rectangular sections of land.

DRG
DRG stands for Digital Rastergraphics. These are simply topographical maps that have been digitized for the computer.

GRID
A grid is a framework of parallel or crisscrossed bars. It is short for the word "gridiron." On a map the bars form squares of uniform size, and they are used as starting points for drawing maps. Numbers used to indicate these points are called grid coordinates.

LATITUDE
Latitude is the angular distance north or south of the equator. The rings around the earth form parallel horizontal lines.

LEGEND
A legend is simply the key to a map. It is an explanatory caption to a map which explains what all the symbols mean.

LONGITUDE
Longitude is an angular distance east and west of an imaginary vertical line that runs through Greenwich, England, called the Prime MERIDIAN. A meridian is a great vertical circle passing from pole to pole. These bands form parallel vertical lines around the earth. Together, latitude and longitude form a grid on which the starting point for maps are marked.

PLAT
The word "plat" means braided, and the plat maps show owners of seemingly interwoven or braided tracts of land. It is a diagram of that land drawn to scale using surveys. The phrase "Plat map" did not appear in the American Heritage dictionary. A mosaic is an assemblage of overlapped aerial photographs.

QUADRANGLE
The word quadrangle is a term actually specific to the map sheets put out by the US Geological Survey. They created the term. In geometry, the four sides of the plane do not have to be rectangular. On college campuses, the quad is a rectangular area surrounded by buildings.

RELIEF
In art and architecture, relief is defined as the projection of forms or figures from a flat background; however, in map making, the relieve map does show the land configuration through the use of contour lines, shading, and coloring, but it can be flat. If the map is three dimensional, it is termed a raised relief map.

THEMATIC
A thematic map follows a theme. Perhaps the map shows the area of grape agriculture in Erie County, Ohio.

TOPOGRAPHIC
A topographic map shows the exact physical features of a region.

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