_The Newberry laccolite_ makes a knob 1,700 feet high, and stands by itself. Its cover of Henry’s Fork conglomerate is re-enforced by a number of trachyte sheets, and is broken through at one point only. At that point Lewis Creek cuts with a straight course across a flank of the arch, and exposes a portion of the nucleus in section (Figures 39 and 40). The conglomerate does not rest directly upon the trachyte, but is separated by one or two hundred feet of shale of the Flaming Gorge Group. [Illustration: FIG. 41.—The Geikie Laccolite (_G_), overlapped by the Henry’s Fork Conglomerate (_H H_), and the Shoulder Laccolite (_S_). ] Two miles to the northward is the _Geikie laccolite_, smaller than the rest but similar in character. It lies close to the top of the Flaming Gorge shale, and is enwrapped by the Henry’s Fork conglomerate. Upon three sides the conglomerate can be seen to curve over its margin from top to bottom, and upon two of these sides the curves are so broken through by erosion that the trachyte is visible within. On the north two cañons cut down to the nucleus, and on the south there is a broad face of trachyte framed all about by the cut edges of the conglomerate beds. _The Shoulder laccolite_ overlaps the Geikie, and the two are exposed in such manner as to show their relation in section. The conglomerate runs under the one and over the other and separates them. The upper laccolite is a broad and deep one, and takes its name from the fact that it makes a great shoulder or terrace on the mountain side. Toward the mountain it is buried; toward the valley it is uncovered, and in part bounded by a cliff. It is deeply cleft by cañons. It has not been subjected to measurement, but its depth is not overestimated at fifteen hundred feet nor its area at five square miles. In the sketch (Figure 42) many of these features can be traced—the Geikie laccolite at the left and the Shoulder in the center, with an outcrop of the conglomerate curving down from the roof of the one to the floor of the other, and the Newberry arch in the foreground with its cleft side. At the rear is the pyramidal Ellen Peak and the _F_ laccolite, overlooking the Shoulder. In the distance at the left is the Marvine laccolite. Little more can be said of the _F laccolite_ than that it exists and is the nucleus of a lofty spur. Its summit rises too nearly to the crest of the mountain to be well defined, and at its base the sedimentaries are hidden by talus. [Illustration: FIG. 42.—The Western Flank of Mount Ellen. _N_, Newberry Arch; _S_, Shoulder Laccolite; _G_, Geikie Laccolite. ] [Illustration: FIG. 43.—The Northern face of the Marvine Laccolite. ] [Illustration: FIG. 44.—The Western face of the Marvine Laccolite. ]