Topographic MapsReading and Interpreting Topo Maps

Investigation and Experimentation(Standard 1h)

Sierra NevadaTopographic Maps

Yosemite Valley is located within the Sierra Nevada Province. Its topography shows great diversity with many peaks, valleys and rivers.

Maps - Introduction

Different maps show us different things.

Shaded Relief Map Shows us the shape of the land – mountains, valleys, rivers and lakes.

Topographic Map Uses contour lines to show elevation.

Road Map – Shows us how to get from one place to another.

Topographic Maps - Introduction

Topography is the study and description of the shape of the land and surface features.

Topographic Map: Shows the shape of the land by connecting points of the same elevation to form a line – contour line.

Topographic Maps - Contour

Contour lines: An imaginary line that connect points of equal elevation.

Contour interval: The vertical distance between contour lines.

Index Contours: The heavier, wider contour line (usually every 5th line) that gives us the elevation above sea level.

Map Reading Activity: Topography

Q: What is the contour interval for the map?

Q: What is the distance between each index contour?

40 feet

200 feet

Topographic Map – Contour Properties

Closely spaced contour lines represent steep slopes

Widely spaced contour lines represent gentle slopes.

Topographic Map – Contour Properties

Q: Approximately how tall is Able Hill?

Q: Approximately how tall is Baker Hill?

Q: Which hill is taller and by how much?

Q: How many feet of elevation are there between contour lines?

Q: Are the contour lines closer together at Able Hill or Baker Hill?

Q: Which mountain has steeper slopes?

About 42 feet

About 50 feet

Baker Hill, 8 feet

10 feet

Baker HillBaker Hill

Topographic Map – Contour Properties

Contour lines form a V when crossing Contour lines form a V when crossing streams. The V always points upstream streams. The V always points upstream (Upstream is NE).(Upstream is NE).

Concentric circles of hachured contour lines indicate a closed depression.

Concentric circles of contour lines indicate a hilltop or mountain peak.

Topographic Map - scale

1:250,0001:250,000Covers more area butCovers more area butin less detail. Notein less detail. NoteThe town of ApolloThe town of Apollo(center) and the(center) and theKiskiminetas River.Kiskiminetas River.

1:100,000Medium scaled map. Note the town of Apollo. You can see the streets and the Kiskiminetas in more detail.

1:24,000The small scale shows the most detail. It covers less area but with much more detail. Note Apollo. You can see houses and buildings.

•Map scale expresses the relationship between the distance on the map to the true distance on the earth’s surface.•This is usually represented as a ratio 1:24,000 or a fraction 1/24,000.•1:24,000 means that 1 unit on the map represents 24,000 of the same units of the earth.

Topographic Map – Colors

Blue Blue – water features– water featuresGreen Green – woodlands– woodlandsBrownBrown – contour lines– contour linesRed Red – roads, urban – roads, urban

areasareasBlack Black – Man-made – Man-made

featuresfeatures

Contour Scavenger Hunt