Building a Mound for the Birds!

Subject Areas:
Math, Social Studies

Objective:
The student will:

1. Use the topographic map of Mound A to construct an accurate three-dimensional model of the "Bird" Mound.

Time:
Two one-hour class periods

Materials:
Mound A Topographic Map overhead transparency
Eight pieces of 1/8 inch thick cardboard (18 x 24 inches)
Scissors or exacto knife
Glue
Cardboard base for model (at least 24 inches square)
Tape for the classroom floor
Matchsticks, tiny beads, or other objects which are 1/8 inch tall

Must Know Info:

This lesson is the second of three related activities on topography and creating a model of the Poverty Point site. Topography Training, the first lesson, was designed to teach students about topographic maps. The second lesson, Building a Mound for the Birds!, will result in the construction of a cardboard model of Mound A based on a topographic map of the site. A final activity will be The Run for the Ridges in which students run a 50-yard dash and use the map scale to determine what this distance would be on the model.

A topographic map is a type of physical geography map which shows the elevation of the land by connecting points with the same elevation to form a line. These curvy lines are superimposed upon a two-dimensional map to give a three-dimensional view of the landscape. Students will be able to determine the height of the land as well as distances from east to west, etc.

Look carefully at the Mound A topographic map. Notice that there are elevation lines given for every five feet, beginning with an elevation of 100 feet. These measurements do not indicate elevations above sea level. Notice that the caption for the map states that "the reference point was given an assumed elevation of 100 feet." This point became the "benchmark" for the surveyors. They simply measured the elevation above or below this arbitrary point. The elevation of the land around Mound A is 95 feet or lower.

Mound A is the tallest earthen structure at Poverty Point. This amazing mound is located along the western edge of the concentric rings of ridges and is thought by some to resemble a bird in flight. This is why some people call it the "Bird" Mound. It measures over 70 feet tall, 640 feet between the wing tips, and 710 feet from head to tail. Over 30 million basket loads of earth were needed to construct the mounds and ridges at the Poverty Point site. Each basket of soil would have weighed about 50 pounds. This adds up to a total of .75 million cubic yards of soil used to construct the mounds and ridges at the site.

 Several other mounds were built at the Poverty Point site. Mound B is a conical mound located .4 mile north of the "Bird" Mound. It is shaped like a dome or the top of a cupcake. Mound B is 180 feet in diameter and 20 feet tall. Motley Mound is located 1.5 miles north of the ridges. It seems to be in the shape of a bird, but it is smaller than Mound A. Motley Mound is oriented in a north/south position with a ramp-like "tail" extending to the south. Other mounds at the site include Mound D (Sarah's Mount), which is located next to the southern ridge section, and Mound E (Ballcourt Mound), a flat-topped structure about 300 feet square. Students might enjoy researching these mounds and constructing models of them to add to the class display. Building an accurate model of the "Bird" Mound will enhance student understanding of the immense size of the site when compared with the height of a person. A scaled version of a five foot tall Poverty Point person will demonstrate the relative size of humans to the site because the person would only be 1/8 inch tall. The scaled model will be about 20 inches long and 15 inches wide. This is approximately 800 feet in length and 625 feet in width according to the scale.

The size of the Poverty Point site will be illustrated by adding tape to the floor to show the six concentric ridges at the site. The outermost edges of the ridges are 3,950 feet apart (nearly 3/4 of a mile.) The ends of the inner ridges are 1,950 feet apart. The ridges now are about one to six feet high and over 100 feet broad. The Poverty Point site, shown on this scale, would measure over eight feet across the outer ridges (98.7 inches) while a person would be proportionally scaled to 1/8 inch tall, the width of a match stick cut into little cubes or a small bead. These items may be added to the display to simulate people. This amazing difference should really demonstrate the enormous size of the archaeological site.

Procedures:

1. Students will work in pairs to construct a three-dimensional cardboard model of the "Bird" Mound at Poverty Point using a topographic map as a guide. Each pair of students will build one elevation level of the topographic map and combine it with others to construct a class model of the "Bird" Mound. There are 14 elevation levels. Assign a pair of students to each elevation level such as 100, 105, 110, etc.

2. Tape the transparency of the Mound A Topographic Map on the overhead projector and adjust the size of the picture as follows. Using 1/8 inch thick cardboard to make this model, 200 feet on the scale should be enlarged to equal five inches on the projected image. In this way, 1/8 inch on the scale equals five feet on the model. Use a ruler to measure the projection of the scale on the wall and move the projector either closer or farther away until the scaled distance for 200 feet is five inches. This is the scale used to compute the distances given for the ridges and the 1/8 inch scaled person.

3. Student groups will need to take turns tracing their elevation levels from the overhead projection. Instruct students to hold or tape a piece of cardboard to the wall so that the map is projected on it. The students will need to trace both their assigned elevation and the elevation above it. Tracing the next elevation level will create a pattern to show where the next elevation level should go when students are assembling the model. Caution students to avoid jiggling the overhead projector as this will mess up the scale.

4. Tell students to cut out their piece of cardboard on the lines for their elevation. When all students have traced and cut out their pieces of cardboard, they will need to glue the levels together to form Mound A. Each upper elevation level piece will be glued to fit in the lines on the lower level. Glue the model on the cardboard base which would have an elevation level of 95 feet. Be sure to mark the direction north and draw in the map scale key.

5. After the "Bird" Mound has been constructed, challenge students to use the same scale to construct a two-dimensional model of the entire Poverty Point site on the floor of the classroom. The location of the ridges could be measured and marked with tape or a cardboard model could be built. Let students compute the scaled distances by themselves. Students could make a "compass" from a piece of string and a pencil to draw the outer ridges with a diameter of 3,950 feet. Remember that the ends of the inner edge ridges are 1,950 feet apart.

adapted from Clarence Webb (1982) map

Information for the 1/8 inch cardboard model is provided below for checking student work:

1/8 inch = 5 feet
1 inch = 40 feet

The "compass" should have a radius of about 49 inches to make the outer ridges and 24 inches to make the inner ridges. The ridges made to scale would stand about 1/8 inch tall. Poverty Point people drawn to scale would be about 1/8 inch tall. Find objects which are about 1/8 inch tall to simulate people. The width of a matchstick or a tiny bead would be about the correct size. Using this scale, the model will take up about eight feet of your classroom floor.

6. Some students may enjoy researching Mound B, Mound C (Dunbar Mound), Mound D (Sarah's Mount), and Mound E (Ballcourt Mound) before adding these to the display.