Studying plunge directions can clarify rock formations, such as icebergs.
In the study of the earth's rock formations, rock deformation plays an integral role. One type of rock deformation occurs when the rocks and strata fold under stress. Folding has various types of symmetry that impact how the earth is shaped and how geological formations occur. Plunging folds occur on an incline from a horizontal plane in the formation. The direction in which the plunge occurs is important for analyzing the earth's underground map and understanding future formation changes.
Instructions
1. Divide the fold into cross sections by finding the central axis that runs down the center of the fold. This line is vertical and cuts the fold in half. Use a ruler and pencil to create straight lines.
2. Identify the horizontal plane that travels downward to the fold axis. Draw this horizontal line so you can visualize it. The fold axis starts at the top point of the fold. A straight, horizontal line is drawn from the top point and down toward the point where the line would meet the curved strike line of the diagram. Angle the ruler at these points to draw a straight line.
3. Follow the fold axis. When a fold is plunging, the plunge direction travels along the same plane as the fold axis, which is how you know what the plunge direction is.
4. Draw the axial plane, which also begins at the top point of the fold. The axial plane runs back, maintaining the same plane and levels as the fold.
5. Calculate the angle between the fold axis and the axial plane to figure out the angle of the plunge. Use a protractor to measure the angle.
Tags: fold axis, axial plane, horizontal line, horizontal plane, plunge direction, point fold, rock deformation
