Topographic Maps

Day 2

Topographic Maps

Objective – “I will be able to compare and contrast latitude with longitude.”

Essential Question – “Besides the directions of the lines, what is the one big difference between latitude and longitude?”

Standard – SC 8-3.9

(Pre-assessment questions 1, 2, and 3)

• Models the change in elevation of the Earth’s surface

• Shows details of hills, depressions, river valleys, canyons, and volcanoes

Topographic Maps

(Pre-assessment question 4)

(Pre-assessment questions 7 & 8)

The contour interval is the set difference in elevation between

adjacent contour lines

Contour interval = 50 feet

Contour Lines connect points of equal elevation

(Pre-assessment questions 7 & 8)

Index Contours Thicker contour

lines marked with the elevation

Index Contour Lines

Elevation marked on index contour line

What is the contour interval of this

map? Use the index contour lines to get

your answer.

Hilltops and mountain peaks are shown as closed circles

Hilltops and mountain peaks are

shown as closed circles

Where contour lines cross a river or stream, they form a

“V” that opens downstream

Flow direction

Flow direction

Lines far apart = gradual slope

Close together = steep slope

1. Contour Lines close around hills and basins.Basins = holes (look for hachures – lines on the contour lines)

2. Contour Lines Never Cross.How could one spot have 2 elevations?

3. When contour lines cross streams, they form a “V” that opens in downstream direction.

Rules for contour lines

‘Elevation’ Terms• Topography - the configuration of the surface of

the land.• Elevation - vertical distance between a given

point and the datum plane.• Datum plane - zero elevation, usually sea level• Bench mark (BM) - a point of known elevation,

usually marked by an ‘X’ on the map.• Relief - difference in elevation between

points of higher and lower elevation.• Gradient - change in elevation over distance.

‘Elevation’ Terms (continued…)

• Contour line - lines connecting points of equal elevation

• Contour interval – set difference in elevation between adjacent contour lines

• Index contours - Thicker lines with elevations printed

• Hachure marks - used to identify depressions (such as a volcano crater)

MAP TERMS• Map Scale – relationship between the map and

actual distances on the ground• Shown as ratios

1:80,000 1 unit on the map = 80,000 units on land.

• Map Legend – explains map colors, symbols• Topographic Symbols on p. 600• Map Series – covers the same dimensions of

latitude and longitude

(Pre-assessment questions 5 & 6)

Map ScalesRatio – 1:24000

Graphic (Bar)

Fractional – 1/24000Verbal – “One unit on the map is equal to 24000 units on the ground.”

(The ‘unit’ stays the same.)