Earth Science Vodcast Network ESVN Topographic Maps Topographic

  • Slides: 14
Download presentation
Earth Science Vodcast Network ESVN

Earth Science Vodcast Network ESVN

Topographic Maps

Topographic Maps

Topographic or Contour Maps • Show surface features of the Earth - natural or

Topographic or Contour Maps • Show surface features of the Earth - natural or man made • Topography- size and shape of land • Show elevation -height above sea level • A top or aerial view

How is elevation shown on topographic maps? • Contour lines are drawn connecting areas

How is elevation shown on topographic maps? • Contour lines are drawn connecting areas of equal elevation (isograms) • Shape reveals land features • Contour interval is the distance between contour lines

Contour Lines cont. • Spacing of lines depends on RELIEFthe difference between the highest

Contour Lines cont. • Spacing of lines depends on RELIEFthe difference between the highest and lowest points • Every 5 th line is made in bold print & is called an INDEX CONTOUR

How do I interpret spacing on a contour map ? • Closely space lines

How do I interpret spacing on a contour map ? • Closely space lines mean the land is steep • Widely spaced lines mean the land is flatter or more gently sloping

Valleys, Streams & Mountain Tops • Contour lines make V’s when they form valleys

Valleys, Streams & Mountain Tops • Contour lines make V’s when they form valleys or cross streams • The V points uphill or upstream • A closed loop or circle represents a mountaintop or ridge

How do contour lines show decreases in elevation? • Contour lines drawn with short

How do contour lines show decreases in elevation? • Contour lines drawn with short , perpendicular lines are called HACHURES • They represent decreasing elevation • The first hachure is equal in elevation to the closest regular contour line • The next hachure represents a decrease in elevation equal to the contour interval

What do the following colors mean on a topographic map? See p 876 •

What do the following colors mean on a topographic map? See p 876 • Blue- water • Brown- contour line • Green- vegetation • Red- highways • Black- constructed features

What is a Bench Mark? • An exactly measured elevation • ▲ followed by

What is a Bench Mark? • An exactly measured elevation • ▲ followed by a number marks the spot

U. S. G. S. Maps-Quadrangles 15 minute 7. 5 minute • • 15’ lat/longitude

U. S. G. S. Maps-Quadrangles 15 minute 7. 5 minute • • 15’ lat/longitude 13 X 17. 5 miles 1: 62 500 1 inch on map equals 1 mile • ____ area • ____detail 7. 5’ lat/long 6. 5 X 8. 75 miles 1: 24 000 One inch on the map equals 2000 feet • ____area • ____detail

U. S. G. S. Maps-Quadrangles 15 minute 7. 5 minute • • 15’ lat/longitude

U. S. G. S. Maps-Quadrangles 15 minute 7. 5 minute • • 15’ lat/longitude 13 X 17. 5 miles 1: 62 500 1 inch on map equals 1 mile • _more_ area • _less detail 7. 5’ lat/long 6. 5 X 8. 75 miles 1: 24 000 One inch on the map equals 2000 feet • _less_ area • _more _detail