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ACTIVITY 1: TOPO MAPS AND BLOCKS
This is an activity that will help students understand what topographic maps display and how to use topographic maps.

A. Making a topo map from a landscape

Materials: lots of small blocks, graph paper, pencil

1. Construct a very simple stepped pyramid-like structure using the blocks. It might be easiest to make each layer of the pyramid a different color. This is your initial landscape to map.

2. Take a piece of graph paper. Decide on a scale; for instance, one small block could equal one square on the graph paper, so a rectangular block is two squares by one square.

3. Decide what your contour interval is going to be. The contour interval could be one block height.

4. Map the perimeter of the lowest tier on your building -- contour 1.

5. Map the perimeter of the next tiers, one by one until you are finished. If you built a pyramid like the one shown above, your topo map should look like this.

**An astute student will notice that each block is essentially a cliff. You will have to decide whether to contour the base of each block or the top of each block. A true contour map of a block pyramid would show these cliff faces, but it is easiest to ignore them for now.

B. Envisioning (and creating) a landscape using a topo map

1. Make a topo map of a landscape that you want to have built. Have a friend do the same thing.

2. Switch your topo map with your friend's.

3. Before trying to build your friend's landscape, look at it for a while and think about what it is trying to show.

4. Use the blocks to build the landscape.



Geologic Maps

In general, a geologic map shows what kind of rocks are at the surface or just below the surface in a particular area. There are different kinds of geologic maps.
 

Some show bedrock. Bedrock is the solid, hard rock below all of the loose sediments. Here is a bedrock map of Manhattan.

Surficial geologic maps tell you what sediments and loose rocks lie on the surface. Surficial maps tell you what were the most recent geologic events to shape the landscape.

Different geologic maps may group rocks in different ways. Some group rocks by age. This is a generalized geologic map of New York State.



ACTIVITY 2: BLOCK GEOLOGIC FORMATIONS
This exercise is similar to the topographic map exercise. Using different colored blocks to indicate different rock types, you can build geologic formations and then map them on graph paper.

Materials: different colored blocks, graph paper, colored pencils in the same colors as the blocks



Geologic Maps

In general, a geologic map shows what kind of rocks are at the surface or just below the surface in a particular area. There are different kinds of geologic maps.
 

1. Decide what colors represent what rock types.

2. Build a simple formation of flat-lying layers (image). To make things easy, use the same topography you used in Activity 1.

3. Use your topographic map as a basemap. Look at the formation you built from above. A geologic map shows only what rocks are on the surface. Color in the topographic map.



Cross-Sections

You've probably noticed that a simple geologic map can give you a lot of information, but it can't tell you everything. A map is only 2-dimensional, but the Earth is 3-dimensional. The map tells you where on the surface you will find different rocks, but it doesn't tell you how the formations are arranged underground. One geologic map could really describe a number of situations.

To describe rock formations underground, geologists draw cross-sections. A cross-section is a special kind of map that shows where rocks are underground. It is as if someone dug a deep trench across the area and then drew a map of the trench wall.
 

Remember Pyramid A? This is what it looks like in cross section.
This is a cross-section diagram of Pyramid A.
 
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