# Lab 3 – Topographic Maps

Lab 3

Topographic Maps

GEO101 Earth Science

Colorado State University Global

Topographic Maps Lab

NOTE: For all of the following figures, assume North is up.

The following topographic map (Map 3.1) is from a coastal area and features an interesting geological hazard in addition to the Ocean. Using a contour interval of 40 feet, label the elevation of every contour line on the map below. (Note: elevation is meters above sea level, which makes sea level = 0m).

Map 3.1 l Tefend and Deline

For questions 2 through 6, refer to Map 3.2. The topographic map shows an interesting and informative geological feature called a drumlin, which is a pile of sediment left behind by a retreating glacier.

Map 3.2 l Tefend and Deline

What is the contour interval on Map 3.2?

The contour interval is 20ft

What is the regional relief on Map 3.2?

The regional relief is 220ft

Using the contour lines on Map 3.2, which area along the red line is steeper, from A to B or from B to C? Explain how you came to this conclusion.

The area between points A and B are steeper because the contour lines are closer together. When contour lines are closer together it means that the elevation is increasing rapidly.

What is the gradient from A to B and B to C on Map 3.2? Show your work.

The distance between points A and B is about 1500ft and the change in elevation is 120ft.

120/1500 = 0.08*100 = 8% gradient

The distance between points B and C is about 5000ft and the change in elevation is 120ft.

120/5000 = 0.024*100 = 2.4% gradient

Construct a topographic profile from A to A’ on the graph paper.

Drumlins can be used to determine the direction of movement in the glacier with the glacier moving toward the shallower side of the structure. Using your previous answers for Map 3.3, what direction was the glacier traveling? Note: unless indicated otherwise, assume that North is up (towards the top of the map).

The glacier is moving West.

Based on the scale you choose for the topography (vertical axis) in question 7, calculate the amount of vertical exaggeration on the topographic profile you constructed above. Show your work.

The horizontal scale is 1 inch = 2,000 feet. The vertical scale is 1 inch = 100 feet.

VE = = 2000/100 = 20.

Questions 8-15: Rome North Quadrangle

What is the ratio scale of this map?

The scale ratio is 1:24,000

Explain in a sentence how this type of scale works.

This scale tells us that one inch on the map is equal to 24,000 inches/2,000 feet/610 meters in real life.

What is the latitude on the north edge of the map?

85°07’30”

What is the longitude on the east edge of the map?

34°22’30”

Find Big Dry Creek, which is north of Rome. What direction does that river flow? Explain two reasons why you came to this conclusion.

The river flows south. The river feeds into a larger river that also flows south and the contour lines that cross over the river also indicate that the river flows south.

Examine the large Ridge in the Northwestern portion of the map. What is the tallest point in this ridge? How tall is it?

The tallest point on the ridge is Lavender Mountain at a height of 1,530ft.

How much higher is that point from Lake Conasauga?

The lake is at about 630ft, indicating that the highest point is 900ft above the lake.

What is the gradient between Lake Conasauga and the tallest point in the ridge? Show your work (Hint: zooming out will let you see both features on the map at the same time and may make it easier to measure.

The change in elevation is 900ft and the distance between the two points is 15,000ft.

900/15000 = 0.06*100 = 6% gradient

Questions 16-24: Your Home Place Topo Map

What state is your topographic map located in?

What is the name of your 1:24K topographic map?

Northwest Pueblo, Lake Pueblo State Park Law Enforcement

What is the largest town on the map? Estimate its population. Explain the reasoning behind your population estimate.

There is not a town on this map but the City of Pueblo is the closest. Pueblo has an estimated population of 110,000.

What is the nature of the topography in this area? Flat? Rolling? Sharp? Mixed? Other?

The topography is rather mixed with areas that are relatively flat and areas with steep elevation gains.

What is the range of elevation in this area? (Highest and lowest points, in feet)

The lowest point is 4748ft, the highest is 5148ft

Does the highest point on the map have a name? If so, what is it?

No, this point doesn’t have a name

Which direction(s) do the rivers flow in this area? How can you tell?

The rivers flow East. I can tell this because to the West the elevation increases while to the East the land flattens out. I also know this because the road shown in the map is one I travel frequently and I live a stone’s throw from where one of the rivers flows, East of this map.