Unlike the sandstone and limestone, the beds of quartzite are not horizontal. The departure from horizontality, technically known as the _dip_, varies from point to point (Fig. 4). In the East bluff of the lake as shown in Plate VI, the dip is about 14° to the north. At the Upper and Lower narrows of the Baraboo (b and c, Plate II) the beds are essentially vertical, that is, they have a dip of about 90°. Between these extremes, many intermediate angles have been noted. Plate VII represents a view near Ablemans, in the Upper narrows, where the nearly vertical beds of quartzite are well exposed. The position of the beds in the quartzite is not always easy of recognition. The difficulty is occasioned by the presence of numerous cleavage planes developed in the rock after its conversion into quartzite. Some of these secondary cleavage planes are so regular and so nearly parallel to one another as to be easily confused with the bedding planes. This is especially liable to make determinations of the dip difficult, since the true bedding was often obscured when the cleavage was developed. In spite of the difficulties, the original stratification can usually be determined where there are good exposures of the rock. At some points the surfaces of the layers carry ripple marks, and where they are present, they serve as a ready means of identifying the bedding planes, even though the strata are now on edge. Layers of small pebbles are sometimes found. They were horizontal when the sands of the quartzite were accumulating, and where they are found they are sufficient to indicate the original position of the beds. Aside from the position of the beds, there is abundant evidence of dynamic action[2] in the quartzite. Along the railway at Devil's lake, half a mile south of the Cliff House, thin zones of schistose rock may be seen parallel to the bedding planes. These zones of schistose rock a few inches in thickness were developed from the quartzite by the slipping of the rock on either side. This slipping presumably occurred during the adjustment of the heavy beds of quartzite to their new positions, at the time of tilting and folding, for no thick series of rock can be folded without more or less slipping of the layers on one another. The slipping (adjustment) takes place along the weaker zones. Such zones of movement are sometimes known as _shear zones_, for the rock on the one side has been sheared (slipped) over that on the other. [2] Irving: "The Baraboo Quartzite Ranges." Vol. II, Geology of Wisconsin, pp. 504-519. Van Hise: "Some Dynamic Phenomena Shown by the Baraboo Quartzite Ranges of Central Wisconsin." Jour. of Geol., Vol. I, pp. 347-355.