tlw, with 100% participation, define a topographic map and state its uses. describe how contour...

Lesson Objectives 12/2/13TLW, with 100% participation,Define a topographic map and state its uses.

Describe how contour lines show the elevations, shape, and slope of the land.

Identify the meanings of some symbols and colors used on topographic maps.

As we go through the power point, please do the following:

Take notes in your science notebook.

Map Notes

The study of the shapes and features of the Earth’s surface.

Topography

Shows the 3D shape and elevations of an

area of land in 2D. Also known as Contour Maps

Topographic Map

What do the colors on the topographic map represent?Blue lines/shapes - represent water features, such as streams and lakes.

Brown – contour linesBlack – Roads, buildings, railroads, other man made objects.

Green – Woodland areasRed - Highways

Height above sea level

Elevation

Sanger is 669 feet above sea level. The city of New Orleans is 6.5 feet below sea level. What does sea level mean?

PSC 121 Prince George's Community College

Map Scale

Maps always have a scale printed somewhere on the map. For USGS maps it is at the bottom.

On USGS the map portion below, the scale is 1:24,000. That means that 1” on the map is 24,000” on the ground or 1’ on the map is 24,000’ on the ground.


Map ScaleThere are also scales that can be used to

determine distance for many different units using a ruler and the map scale.

1 mile1 mile

1/2 mile

2000 feet

200 feet

1 kilometer


Contour LinesElevation is indicated by contour lines. A

contour line is a line of equal elevations (eventually a closed loop). All points on a contour line have the same elevation.

800 feet

700 feet

http://raider.muc.edu/~

mcnaugm

a/Topographic%20M

aps/contour.htm

http://raider.muc.edu/~mcnaugma/Topographic%20Maps/contour.htm



Contour Lines

The elevation difference from one line to another is called the contour interval. On the map portion below the contour interval is 20 ft.

20 ft elevation increase

20 ft elevation increase

20 ft elevation decreasehttp://raider.m

uc.edu/~m

cnaugma/Topographic%

20Maps/contour.

htm




Contour Lines

The contour interval is usually printed on a topographic map.

However, you can always calculate the interval from the lines with values.

The difference between the highest elevation point and the lowest elevation point on a map

Relief

200 300

400

Units = feetWhat is the relief of this map? What is the contour interval of this map?

Contour lines are closely spaced on steep slopes.

Contour lines are widely spaced on gentle slopes.

Topographic Map Rules

Contour lines near the top of a hill form closed, circular shapes. The top of the hill is higher than the highest closed contour line.



Contours and Profiles

You can generate a profile of a landform from the contour lines on a topographic map.

Simple contour map

Click on imageto see contoursdevelop

http

://re

ynol

ds.a

su.e

du/to

po_g

alle

ry/im

ages

/hill

map

.gif

http://reynolds.asu.edu/topo_gallery/movies/topocc_shd_hill.mov

Depressions without outlets are shown by closed hatched contours. The contour lines have short lines on the inside that are pointing down slope. The bottom of the depression is lower than the lowest closed contour line.


Topographic MapsIndex Contour –

Usually every 5th line is printed darker and has an elevation printed on it.

Rules for Contours1. Contour lines never cross

Rules for Contours2. Contours form closed loops (even if not

shown of the map.

Rules for Contours3. Contours bend upstream (uphill) when

crossing a stream.

Rules for Contours4. The maximum

possible elevation for a hill is “1” less than what the next contour “should” be.

The highest possible elevation of the hill is just below the value of the next line that is not shown

5060

70

80

90

Notice the two high points on the island. What is the elevation of the two high points?

Where a contour line crosses a stream or valley, the contour line bends to form a “V” that points upstream. In the upstream direction, the successive contours represent higher elevations.



Tracking Flowing WaterHow does water always flow?

DOWNHILLHow can we tell what direction (N,S,NW,ESE) is downhill?


Tracking Flowing WaterYou can look for

elevation changes since water will flow from higher to lower elevations.

Here the stream flows toward the northwest.

2100 ft2000 ft


Tracking Flowing Water

You can look at the contour lines as they cross the stream. They will always point upstream.

Downstream Upstream


Tracking Flowing Water

You can also look at where two streams merge. The merge will form a V that points downstream.

Direction of flow

A map made of pictures of the Earth taken from a satellite orbiting the Earth.

Satellite Map

tlw, with 100% participation, define a topographic map and state its uses. describe how contour...

Documents