The engraving of Mount Hillers (Figure 27) exhibits the south face with its revet-crags and bold spurs of trap. In nature the effect is heightened by the contrast of color, the bright red revetments being strongly relieved against the dark gray of the laccolite. The strata of the summits cannot be discriminated at a distance. They are too near the laccolite in hardness to differ from it in the style of their sculpture. Of the minor laccolites of the cluster there are three so closely joined to the chief that they merge topographically with the mountain. They are not well exposed for study. The smallest, which overlooks the pass between Mount Hillers and Mount Pennell (A, Figure 28) has probably lost the whole of its cover and with it so much of its substance that the original form and surface cannot be seen. Its floor is probably the Tununk sandstone. East of it and lying a little deeper in the Cretaceous series is a second laccolite (B), broader, lower, and less eroded. The third (C) joins the great one on the northeast, and is so closely united that it was at first supposed to be the same body. Later examinations have shown, however, that its immediate roof is the Henry’s Fork conglomerate, and its horizon is thus established as more than two thousand feet above that of its great companion. [Illustration: FIG. 30.—The Steward Laccolite. ] [Illustration: FIG. 28.—Diagram of the Hillers Cluster of Laccolites; Ground plan. ] [Illustration: FIG. 29.—Diagram of the Hillers Cluster of Laccolites; Elevation. The upper horizontal line marks the base of the Cretaceous; the middle, the base of the Jura-Trias; the lower, the level of the sea. ] The _Steward laccolite_ (Figure 30) is better exposed for study. It was buried in the soft bad-land sandstone of the Flaming Gorge Group, and its matrix has been so far washed away that nearly the whole body of trap is revealed. It is weathered out, like a chert-nodule on the face of a block of limestone. At one end it is bared quite to the base, and the sandstone floor on which it rests is brought in sight. The waste of the sandstone has undermined its edge, and a small portion of the laccolite has fallen away. Near the opposite end a fragment of its cover of arching sandstone survives—just enough to indicate that the sedimentaries were once bent over it, and that the smooth low-arching surface which now crowns it portrays the original form which the molten lava assumed. The laccolite is about two and a half miles long and one and one-half broad. The height of its eastward face, where it is sapped by the erosion of the bad-land rock, is six hundred feet, and the central depth must be more than eight hundred feet. [Illustration: