What is heave defined as in stratigraphy?

• A. The horizontal distance between any two parts of a disrupted bed
• B. The vertical distance between stratigraphic layers
• C. The angle of tilt between beds
• D. The depth to bedrock

Answer: (A)

The concept being tested is how movement of sedimentary beds is described when they are disrupted. Heave refers to the horizontal separation that develops between parts of the same bed after disruption. In other words, if a bed is broken and the pieces slide or are pulled apart laterally, the distance between corresponding points on those pieces measured along the surface is the bed’s heave. This is a horizontal metric, not a vertical one, so it’s different from the thickness of layers (vertical distance between stratigraphic layers) or the angle of tilt between beds (dip). It also isn’t about how deep bedrock lies, which is a depth measurement.