Geography Scales
We have maps showing entire continents and maps showing all the houses in a small town. We have maps telling us information about the people living there, how land is used, or even the concentration of an endangered species. An important part of a map is the scale it uses, but that depends on the type of data we want to know. There are two types of scales used in geography: map scales and relative scales. Each has a very different function, yet both also can work together.
Map Scales
The scales used in mapping, usually noted in a lower corner of the page, employ relative distance. You couldn't expect a map to be an exact match to the landscape or you would need to unfold miles of paper. By creating a smaller image of the actual landscape, the map becomes a useful tool. However, the relationships between places on the map must remain consistent with reality. This is where the map scale comes in, to tell us what a certain distance on a map represents in real space.
A map can inform us of the scale it uses in three different ways.
A verbal scale can tell us in words, like ''one inch equals one mile.''
A fraction or ratio can compare the distances with the relationship of the map's distance to the actual distance, such as 1 inch:10 miles; 1:10; 1 inch:10 miles; or 1:10.
A graphic scale is one in which the scale is written as a graph with the representation of the distance marked at consistent intervals on the line. This means that each line segment equals a certain distance. These scales are great if you don't have a ruler or tape measure handy to measure the map. You can mark the scale on the edge of some scrap paper and hold it up to the map to figure out how far apart two points are.
Relative Scale
Don't let the term ''relative'' confuse you into thinking this type of scale deals with relative distance like with a map scale. Relative scales, also called scales of analysis, refer to the amount of detail included in the map and the size of the units at which we are looking. This is called the level of aggregation, or many details get lumped together on the map based on the unit size we are analyzing. It's basically details about a place one might use in a research project instead of distance.
The lower the level of aggregation, the more specific we get with the detail. It's like zooming in and out from a satellite image. If we zoom in, we are at a low elevation and see very specific details. We can see the roof of a house and individual cars.
