Yet Another Gap in the Rock Record
Deposition of the Burro Canyon Formation was brought to a close by another uplift of the Plateau, and of course the uplift was followed by another period of erosion, which continued through the end of Early Cretaceous time. As noted in the caption for [figure 24], seemingly all but 58 feet of the Burro Canyon was eroded away, but 120 feet remains along East Creek, only about 12 miles to the southeast, which suggests that the old erosion surface was a bit uneven. That this period of erosion was of considerable duration is suggested by the abundance of the white clay mineral, kaolinite, beneath and in the overlying white basal conglomerate of the Dakota Sandstone. This type of clay commonly results from prolonged weathering of many types of rocks and indicates that the period of pre-Dakota erosion was of long duration.