Читать книгу Structural Analysis and Synthesis - Stephen M. Rowland - Страница 36

The thickness of layers exposed on slopes may be determined trigonometrically if, in addition to dip δ and map width h, the vertical distance v (i.e. difference in elevation) from the base to the top of the layer is known. Figure 2.19a shows a layer and the slope dipping in the same direction. Relevant angles are added in Figure 2.19b, from which the following derivation is made:

This relationship applies to situations where bedding dips more steeply than topography and both dip in the same direction (right‐side example in Figure 2.20). Similar trigonometric derivations can be used to show that in situations where bedding dips more gently than topography and both dip in the same direction (left‐side example in Figure 2.20), the equation is:

Where bedding and topography dip in opposite directions (middle example of Figure 2.20) the equation is:

Figure 2.19 Determining stratigraphic thickness t on slopes. (a) Lengths h and v and dip angle δ are needed to derive t. (b) Geometry of derivation.