Last time we talked about topographical maps and using them to understand why ancestors might have migrated one way over another. Primarily looking at large land formations, like mountains. Let’s look at a topographical map on a smaller scale.
When you are looking at a topographical map, you will see lines that indicate changes in elevation, and if you “squint” at the map you can kind of imagine how flat or hilly an area might be. A topographical map shows you the contours of the land indicating mountains, valleys, rivers, vegetation (or the lack thereof), and other features. On a topographical map, you will see large swathes of green for vegetation, blue areas for water, grey areas for buildings and built-up areas. However, the contour lines tell the story of the three dimensional nature of the landscape.
Depending on the map, there will be a key that tells you at what elevation another contour line will be placed on the map. For example, if the map you are looking at uses a 10-foot contour spacing, then you will see a contour line for every 10 feet of elevation change. (i.e. a line will be in place at 0-, 10-, 20-, 30- foot change. A map might use a larger scale if the land is very elevated, showing the Rocky Mountains, for example. The lines on the map are only drawn for every interval of change, so every 10 feet, for example. If you have a relatively flat area of land, the map might be quite blank of the contour lines.
Let’s look at two examples. The map on the left is in Audrain County, Missouri, the map on the right is in Wood County, Ohio.
You can see the difference in the land shapes even though I’ve zoomed in a different levels. Wood County, Ohio is very flat, whereas Audrain County, Missouri is much more hilly. I have ancestors that farmed on land from both of these maps. And each map gives me a bit of a different picture of how that farming might have happened. Audrain County land probably couldn’t farm right up to the river banks due to the steepness and vegetation. Those green areas indicate a lot of trees and vegetation where the white areas were clear and flatter, better for farming. And while there are some swaths of trees in Wood County, most of the thickest parts have been cleared out and the land is largely flat farm land for miles.
We will learn about where to find topographical maps next time.