Geologists need a way to describe and illustrate the orientation of rocks on a map. The two descriptions used are strike and dip. The dip direction is the direction that the beds are tilted. If you were to imagine rolling a ball down a tilted table, it would roll down-dip. The strike is the direction exactly perpendicular to the dip. The symbol used on a map to illustrate the direction of strike is a short straight line pointing in the direction of strike.  A short tic mark at the center of the strike line points in the direction of the dip. The angle of the dip is printed next to the symbol.

 
 
A couple other symbols that are worth mentioning are the two symbols that represent:

	vertical beds
	horizontal beds