Determine the Strike and Dip of a Bed
This is your three-point problem friend again, but somewhat simplified.
Find a topographic contour that intersects the base of the unit twice: This is the strike. Draw that structure contour.
Find a different topographic contour that intersects the base of the unit twice. Draw that structure contour.
Use the diference in elevation, \(\Delta z\) and the horizontal distance in real-world units, \(\Delta x\) perpendicular to the structure contours, or the strike to determine the dip of the unit via $$\delta = \tan^{-1}\frac{\Delta z}{\Delta x}$$
Warning: Sometimes the units do not have more than one explicit contour that intersects the base. Be resourceful and creative.
Determining the Thickness of a Bed
The best place to measure the thickness is where the topography is flat or along a topographic contour; provided that contour is perpendicular to the strike \(\theta\). The dips of the bed are available. Use the equation $$t = \Delta x \sin \delta$$ where \(t\) is the thickness, \(\Delta x\) is the horizontal distance and \(\delta\) is the bed's dip.
If it is not flat, you will need to use a slightly more complex set of equations:
If the bedding dips more steeply than topography in the same direction $$ t = \Delta x \sin \delta - \Delta z \cos\delta $$
If the bedding dips less steeply than topography in the same direction $$ t = \Delta z \cos\delta - \Delta x \sin \delta $$
If the bedding dips in the opposite direction to topography $$ t = \Delta x \sin \delta + \Delta z \cos\delta $$