Topographic Maps

Joshua 18:8 As the men started on their way to map out the land, Joshua instructed them, "Go and make a survey of the land and write a description of it. Then return to me, and I will cast lots for you here at Shiloh in the presence of the LORD."

Topographic Maps*The study of landforms is an integral

part of any earth science course.*The topographic expression of an

area is the result of erosive and depositional forces acting to modify the underlying rocks.

*The types of agents and the duration of their activity determine the configuration of the landscape.

Terms Erosion- soil that can detach and

affect a stream. Watershed- is the land area drained

by an entire river system or by a river and it’s tributaries.

Tributaries- smaller streams that flow into the major trunk of streams.

Source- where a stream first begins; the headwaters of a stream.

Good to know: The way the water flows can impact

those living in the area. Consider the following nonpoint

source pollution: agricultural runoff, urban runoff, feedlots, constructed wetlands, septic systems, location of dams, mine seepage

Determine if the rivers in the area are used to make a living or do they provide recreation?

Topographic maps Take up to 5 years to make. They include aerial photos, field

survey, map accuracy, and field personnel to verify the map features.

Currently map data is being digitized; this should speed up the procedure.

Topographic maps use: Soil conservation Crime solving Emergency response planning Marketing/real estate

Map Scale 1:24,000 1 inch on the map is the same as

24,000 inches on the ground. This is sometimes referred to as a

7.5 minute quadrangle. 1 inch = 2,000 ft

Map Scale

1:62,500 15 minute Quadrangle

Map Scale 1:100,000 1 inch= 1.6 miles

Map Scale 1:250,000 1 inch = 4 miles

Reading maps Each contour line on a map

represents an imaginary line connecting points of equal elevation.

The vertical distance between two contour lines is the contour interval, which is usually noted at the bottom of the map.

Reading maps The contour interval might be 5 feet

for gently sloping areas to 50-100 feet for mountainous regions.

Every fifth contour line is darkened and marked with its elevation to make it easier to read the map. These marked lines are called index contours.

Demonstration*How to draw

contour lines from plastic sheets of model and transparency.

http://academic.brooklyn.cuny.edu/geology/leveson/core/linksa/contourlabel.html

USGS Introduction & symbols. http://erg.usgs.gov/isb/pubs/booklets/symbols/

Reading topographic maps http://www.ghosttowns.com/topotmaps.html

Map Practice Study the topographic maps given

to you and answer the question sheet.

Learn the symbols as you find them. We will play Topographic

Bingo….soon.

Exercise: Map Reading Model*Read the Study Guide Map Reading

Model start with the Introduction. Read pages 3-7.

*Complete questions 1-28. You will need a ruler, calculator, strip of paper, and graph paper.

*A 3-D model of the map is available at the front of the room. You may come observe it as needed.

Raised Relief Topographic Maps*Divide the class into groups.*Explain their task.

Raised Relief Topographic Maps1. Yakima, Washington2. Hoquiam, Washington-Oregon3. Monterey, California4. Death Valley, California-Nevada5. Grand Canyon, Arizona6. Portland, Maine-New Hampshire7. Harrisburg, Pennsylvania

Yakima, Washington*Located in south-central Washington state.*In the late Cenozoic at least half of the

Yakima map was covered by basaltic lava. The basalts in the east went through anticlinal and synclinal folds to form the Cascade Range and a series of volcanoes formed.

*Mount Rainier and Mount Adams, note glacial effects on both of these mountains.

Yakima Map Mt. Rainier Mt. Adams

Yukima Map* Find the major cities.* Find the major rivers.* Find Signal Peak, Lone Butte and

Goose Egg Mountain (these have been heavily eroded by streams)

YakimaSignal Peak lookout

tower for firesLone Butte

Yakima, Washington Goose Egg Mountain

Yakima, Washington*Look through the various national

parks for ranger stations, lookout towers, pumping stations.

*Find the orchards.

Hoquiam, Washington-Oregon*This map covers an area in SW Washington,

plus a smaller extreme NW portion of Oregon*Note the Pacific Ocean, Willapa Bay and Grays

Harbor*The Columbia River is a dominate feature.

Find the Lewis and Clark National Wildlife Refuge.

*The center of the map is dominated by prairies (formed by glacial outwash) then you enter the Cascade mountains on the East. Find Mt. St. Helens.

HoquiamWillapa Bay Willapa Bay National

Life Refuge

HoquiamGrays Harbor-

Rennie marshGrays Horbor City

HoquaimPath of Columbia

RiverColumbia River

Gorge

HoquiamLewis & Clark

National Wildlife Refuge

HoquiamSilver Lake with Mt.

St. Helens in the background

HoquiamMt. St. Helens from

Spirit Lake

Mt. St. Helens explosion*First signs of eruption May 18, 1980*The north flank had bulged 400 feet and

gave way to a gigantic landslide.*Gas and ash vented NNW.*200 square miles was devastated in

minutes.*The landslide rushed into Spirit Lake and

swept down the North Fork of the Toutle River for 12 miles filling the valley with debris to a depth of over 200 feet.

May 18, 1980Spirit Lake after

Mt. St. Helens May, 1980Blow down of trees

around Toutle River

After some has drained away

Monterey, California*This map is located in west-central

California and encompasses the Great Valley of California westward to the Pacific Ocean.

*It includes the San Joaquin Valley, Diablo Range, Santa Lucia Range and the San Andreas Rift Zone.

*Major cities include Santa Cruz, Salinas, and Monterey

Monterey, California*The region was affected by

compression forces during the Cenozoic period with the most intense deformation near the coast.

*There was large vertical scale movement and strike-slip movements along the San Andreas fault system.

*The Gabilan Range is almost all granite and the others are a mixture of granite, metamorphic and sedimentary rocks.

Monterey, California*Erosion forms considerable debris that finds

its way to the valleys, beaches and to the sea floor.

*Note the sea floor canyons: Monterey Canyon, Carmel Canyon and Partington Canyon; check out their depths.

*Note the intricate canals in the San Joaquin Valley.

*Find the orchards in the NW, mines, windmills, grain elevators and oil fields in the E and SE.

Monterey, CaliforniaSan Joaquin Valley Vineyards

Monterey, CaliforniaSan Joaquin Valley,

canal

Raised Relief Topographic Maps*You will study the following maps

and write 20 questions to leave for the next group.

*You must be referring to the map symbols and require the reading and interpretation of the map.

*You have 45 minutes to write your questions. Then we move.