ASBOG Practice Exam

What does a narrow V in a geological map typically indicate about the bed's orientation?

1. It is steeply inclined

2. It is nearly horizontal or flat-lying

3. It is fractured

4. It is vertical

The correct answer is: It is nearly horizontal or flat-lying

A narrow V on a geological map typically indicates that the bed is nearly horizontal or flat-lying due to the way geological formations display their shape and relationships when plotted on a map. When beds are nearly horizontal, the elevation change across short lateral distances tends to create a more pronounced and narrower profile, resulting in a V shape. In contrast, if the beds were steeply inclined, one would anticipate a broader or more pronounced V shape as the slope would translate to greater elevation change over a shorter distance. A vertical bed would similarly not create a narrow V shape but would instead reflect the abrupt transition of elevation, resulting in a profile that would depict a different geometry on the map. Fractured beds could be represented in various shapes, but a narrow V doesn't inherently indicate fractures; it's more about the orientation of the bedding itself. Thus, the representation of a bed as a narrow V shape is a clear indicator of its nearly horizontal or flat-lying nature in geological mapping contexts.