How geologists think - a quick introduction for earth-science students

This is the first of two pages designed to start geology students thinking like geologists. The second goes on to look at some modern landscapes and what geologists see in them.


The first key thought here is that geologists get information from a variety of sources with which the rest of us may not be acquainted. To increase that acquaintance, here's a diagram showing some (certainly not all) of the sources of information used by geologists on land:




The diagram above is a block diagram. It tries to show features in three dimensions by presenting a block with edges at right angles to each other. Block diagrams are great, but they're not easy to draw and commonly take more space than is needed. Instead, geologists commonly use maps and cross-sections:

     A map portrays the arrangement of features across a horizontal surface. That surface might be the land surface, or it might be above or (more commonly for geologists) below it.

     A cross-section portrays the arrangement of features across a vertical surface. It shows what you would see if you could slice through the Earth and look from the side at your newly-cut surface.

Our second illustration uses a standard Greek temple to show a block diagram, a map, and a cross-section. The cross-section shown is just one of an infinite number of vertical sections that you could choose to make through the temple.



Now you're ready to move on to the second page of these two pages.



e-mail to Bruce Railsback (
Railsback's main web page
UGA Geology Department web page




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