With the description of the rocks completed, the question which arises next is how to represent these three-dimensional contortions on the map. Figure 6 illustrates how the attitude of a particular layer may be expressed in terms of dip and strike. It is apparent that the _dip_ of the rock layer may vary from 0° to 90° and is measured as the angle between its plane and a horizontal plane. Also, it is apparent that the trend of the bed, or the _strike_, may correspond to any direction of the compass and can be measured as the intersection of that plane and a horizontal plane. The maximum dip is always at right angles to the direction of the strike. [Illustration: Figure 5. Diagrammatic three dimensional sketch illustrating the relations between outcrop patterns of folds on vertical planes perpendicular and parallel to the trend of the folding (front and sides of the block) and on a horizontal surface (top of block). Cut-away section of the block shows the folds and lineation lines on a given foliation surface. These folds can be more clearly visualized if the upper portion of the diagram is covered.] The dip and strike are used to measure the position and attitude of the layers of the rocks. In the case of the mica-albite-quartz schists these planes are called _foliation_ planes. If the structure of the rock is an anticline, most of the strikes of the foliation are parallel, but the dips are in different directions on either side of the crest. At the crest of the fold the foliation is horizontal if the fold is not plunging. On Mount Mansfield where the plunge is about ten degrees to the south, foliation along the crest strikes about east-west and dips about 10° south. Away from the crest, the dip of the sides of the anticline begin to be expressed in the readings so that the strike directions “swing back” toward the north-south direction. The majority of the layers on the east side of the mountain strike northeast and dip to the east with the angle of dip increasing away from the crest of the anticlinorium. On the west side of the mountain they trend to the northwest and dip to the west with the dips becoming steeper away from the crest. In addition to these variations in the dip and strike over the anticlinal crest, the smaller folds give local abnormal readings. For these reasons many of the dips and strikes shown on the geologic map represent the averages of a number of readings, and those of the minor folds and crinkles have been omitted in order to simplify the picture. [Illustration: Figure 6. Three dimensional diagrams showing variations in dip and strike. Plane in A strikes N 45° W and dips 45° SW; B strikes north-south and dips 60° east; and the plane in C strikes N 45° E and dips 30° SE.]