SLIDE 2 shows the view looking northeast at Spor Mountain (center of photo) and the principal area of beryllium mining. Open pits shown are the Roadside (lower left), Rainbow (lower right from center), and Blue Chalk beryllium mines (right of center). All three mines are in the beryllium tuff member of the Miocene Spor Mountain Formation. The open cuts to the right of the Blue Chalk are fluorspar prospects in a rhyolite dome.










SLIDE 3 looks directly north into the Roadside beryllium mine.













SLIDE 4 shows the view looking northwest over The Dell at Spor Mountain. The photo shows fluorspar mines on Spor Mountain (left center), Eagle Rock Ridge (center, dark ridge), and Yellow Chief uranium mine (right). The open cut on the east side of Eagle Rock Ridge is the Claybank beryllium prospect; the circular open cut below and to the left (south) of Eagle Rock Ridge is the Hogsback beryllium prospect. Both prospects, as well as the Yellow Chief mine, are in fault-bounded remnants of the beryllium tuff member of the Miocene Spor Mountain Formation. A basin-range normal fault extends along the east side of Eagle Rock Ridge, separating Paleozoic carbonate rocks on the ridge from Tertiary volcanic rocks east of the ridge.







SLIDE 5 shows the northern part of the Dell and a closer view of Eagle Rock Ridge (left center) and the Yellow Chief uranium mine (right center) than the previous photo. Beryllium prospects visible include the Claybank (right side of Eagle Rock Ridge) and the Hogsback (circular scar, lower part of photo). The dark exposures to the left (west) of the Hogsback are Eocene Drum Mountains Rhyodacite, a pre-caldera flow complex. The sequence (from top to bottom) of rhyolite flows, vitrophyre, and tuff of the Topaz Mountain Rhyolite is clearly visible in the cliffs at the top of the photo. The Topaz Mountain Rhyolite lies unconformably on the Oligocene Dell Tuff, an intracaldera ash flow of the Thomas caldera. The view is north from a point above the southern part of The Dell.







SLIDE 6 is a near-vertical view of the Yellow Chief uranium mine, looking slightly northeast. The north end of Eagle Rock Ridge appears in the lower left. The outcrops north of (above) the ridge are Oligocene Dell Tuff. Cliffs in the upper part of the photo are Topaz Mountain Rhyolite, which lies unconformably on Dell Tuff here.










SLIDE 7 shows Fish Springs Flat and the Fish Springs Range (middle distance), west of Spor Mountain (center), and the Thomas Range (foreground). The snow-capped peaks on the horizon are in the Deep Creek Mountains. The Dell is barely visible below the dark ridge running across the center of the photo (Eagle Rock Ridge); the Claybank beryllium prospect is visible on the side of the ridge. The view is to the west from a point above the Thomas Range.









SLIDE 8 is a black and white photo of the entire Thomas Range. The central part of the range is a dissected plateau of coalescing flows of Miocene Topaz Mountain Rhyolite (SLIDES 26-34). The stratigraphy of an individual eruptive sequence of rhyolite is visible on the south side of Topaz Mountain (center of photo). From bottom to top, stratigraphic units are rhyolite flows, dark vitrophyre at the base of the flows, and light-colored bedded tuff. South of Topaz Mountain, the Topaz Mountain Rhyolite unconformably overlies faulted older volcanic rocks and Paleozoic rocks. The view is to the north from a point above the northern Drum Mountains.








SLIDE 9 shows the great accumulation of Topaz Mountain Rhyolite flows in the northern part of the Thomas Range. The eastern part of The Dell is in the lower left. The Dugway Range is on the horizon. The Pony Express Road runs through the pass between the two ranges. The view is to the north from a point above Topaz Mountain.