How is a Geologic Map Made?
To make a geologic map, geologists roam the landscape, plotting the location of geologic contacts, faults, folds, and other features on aerial photographs, or, occasionally, directly on a topographic base map. Aligned pairs of aerial photos give the geologist a three-dimensional, birdseye view of the landscape, greatly facilitating fieldwork. Back at the office, information from these photos is digitized and the final geologic map is edited and printed. New field methods are being developed for computerized data capture, but in the end there is no substitute for careful geologic fieldwork. Photo by Mike Hylland. In trying to explain the process of geologic mapping, one of my favorite analogies is to compare it to putting together a puzzle. To stretch the analogy even further, consider it a three-dimensional puzzle that is missing many pieces, and that is already out of its box (which has, much to your dismay, been thrown away!). You have no picture to refer to, so you start to scan the
