Potato Topo

When you go out to explore the wilderness be sure to take along your topographical map. It will provide information about your trail, and the surrounding mountains, canyons, roads, bridges, and other landmarks along your journey.

The word topography is derived from the Greek words topos, meaning a place, and graphien, meaning to write. Thus, topography is the written, or drawn, description of a place. Some of the earliest known maps were made to show property boundaries for the purpose of taxation in ancient Mesopotamia and Rome. In 1539 a Dutch mathematician, Reiner Gemma Frisius, introduced the use triangulation to more accurately survey an area. In 1793 the first topographical map was produced. Though it lacked much in the way of elevation detail, it did result in the first complete map of France. The concept of contour lines to show different elevations was developed in 1791 by J.L. Dupain-Triel. Yet the idea went largely unused. It took the birth of a rapidly expanding new nation, the United States of America, to recognize the need for accurate topographical maps that detailed lands few Americans of the time would ever have the opportunity to see. Our third President, Thomas Jefferson, hired surveys of the Atlantic coast and the interior for the purpose of travel and commerce. Meriwether Lewis, William Clark, John Fremont, and John Wesley Powell are just a few of our early geographic explorers. By 1879 the USGS was established to consolidate the various surveying efforts. Today the USGS has produced over 56,000 maps of the US as well as maps of the moon and planets.

A topographical map looks different from other maps because it contains many thin curved lines that don't branch or cross over each other. These lines are called contour lines and connect points of equal elevation. So all points along a contour line are the same elevation. When the lines are close together, the elevation is changing rapidly and the terrain is steep. Conversely when the lines are widely spaced, the area is relatively flat. Mountain peaks appear as smaller and smaller concentric circles as the summit is reached.

Here is a fun project to try that will give you an opportunity to take a three dimensional potato and map it in two dimensions.

First, take a large potato and carve a shallow "valley" so it looks like there are two peaks in your potato. Then with a sharp knife slice the potato into horizontal layers. Discard the bottom layer so the potato sits flat. Take the remaining layers and trace each one. Be sure to keep each layer in its proper position in regard to the previously traced layer. The resulting pattern will be a topographic representation of your potato hills and valley.

Now go find a topographical map and head outside with your family.