The Slick Rock Member was named from its occurrence at and near the mining town of Slick Rock, Colo., which originally was named after the appearance of the rock because it generally forms slick, smooth cliffs. It reminds one of the chicken and egg conundrum. The Slick Rock is composed mainly of sand dunes that were piled up on the eastern shore of the Jurassic sea by winds blowing from the northeast. Occasional rainy spells created lakes and ponds in which some of the sand was laid down in level beds. This pile of sand later hardened into the cliff-forming Slick Rock Member, which looks something like the Wingate but is generally only half as thick, weathers into less abrupt cliffs, is mostly salmon red, and is almost free of joints. The joints in the Wingate (fig. 11) probably resulted from the uplift and tilting of the Plateau before the long period of pre-Entrada erosion; whereas the land seems to have been more stable during Entrada time. The Slick Rock is cemented with calcium carbonate (CaCO₃), which is soluble even in weak acid, such as rain or snow water containing dissolved carbon dioxide. For this reason solution openings or pits occur in some of the cliff faces, the most striking of which are those shown near the top of figure 15. The Slick Rock Member of the Entrada Sandstone forms a line of cliffs and isolated monoliths that are second in height and grandeur only to those of the Wingate. The Member is best displayed southwest of Rim Rock Drive between the Visitor Center and the Coke Ovens and along the western arm of Ute Canyon (fig. 16). It also forms the Saddlehorn just south of the camp and picnic grounds near the Visitor Center (fig. 50). Most of the smooth cliff faces show both the steeply dipping crossbeds of the old sand dunes and the flat-lying beds of the lake or pond deposits. [Illustration: ENTRADA SANDSTONE, just above normally dry waterfall in west arm of Ute Canyon. Note smooth unjointed cliff of Slick Rock Member protected at left by overhanging basal bed of Moab Member, which forms about lower half of slope in distance. Upper part of distant slope is the Summerville Formation overlain by Salt Wash Member of the Morrison Formation. Note Slick Rock at left resting upon eroded crossbedded sandstone in Kayenta Formation, in which the canyon was cut. (Fig. 16)]