ASBOG Practice Exam

What is represented by the teeth notation on a geologic map?

1. The upper plate of a thrust fault

2. The lower plate of a normal fault

3. The base of an unconformity

4. The top of a geological formation

The correct answer is: The upper plate of a thrust fault

The teeth notation on a geologic map specifically represents the upper plate of a thrust fault. In geological mapping, thrust faults indicate where one section of the Earth's crust has been pushed up over another due to compressional forces. The teeth symbol typically points toward the direction from which the upper plate has moved, symbolizing the displacement that has occurred along the fault. This notation helps geologists visualize and understand the geological structure of an area, particularly how rocks have been deformed and shifted over time. Other options, while related to geological concepts, do not accurately represent what the teeth notation illustrates. The lower plate of a normal fault would not be denoted by teeth but rather could be illustrated differently to indicate the vertical displacement in normal faulting. Similarly, the base of an unconformity and the top of a geological formation would have their own distinct symbols on a map, distinguishing them from fault-related features. Understanding this notation aids in interpreting the geological history and structural relationships within an area.