Layer Thickness and Map Width Width of a unit on the map is related to its true thickness… but they are not the same! Why? Because of topography and dip.

Layer Thickness and Map Width Thickness = distance between top and bottom surfaces of a layer measured perpendicular to those surfaces. Map width = distance between top and bottom contacts measured perpendicular those lines.

Layer Thickness and Map Width For vertical or horizontal beds, thickness can easily be measured from the map… Vertical: thickness = map width. Horizontal: thickness = elevation difference between upper and lower contact. Thickness of dipping beds needs to be calculated with trig or using a cross-section…