Lab 8: Mapping - Landforms on Contour Maps - Depressions

 

Depressions tend to be low areas that are only slightly lower than surrounding areas, unlike hills which can be rather more dramatic. This is because any low area is likely to be filled in with sediment over time, whereas a hill is essentially an erosional landform that may become more peaked over the course of time. Scan the values on this map to find the lowest z values, which you see in the bottom center area of the map. Find the values near 500, the points with z values of 475 and 502. Observe how the z values increase all around this area. This area is a depression:

 

 

A depression is a low area that appears on a contour map as a set of closed contours (in "rings"), and where the contours are hachured to distinguish the landform from a hill (a hachure is a dash-like "prong" extending off a contour):