a widespread encrustation throughout Wagon Box Draw on gentle slopes where the terrace landforms appear. It even occurs on hilltop locations in Wagon Box Draw. It resembles the Bonneville “capping tufa” of Felton et al. (2006). OBSERVATIONS—LANDFORMS IN DETAIL As we already have described, Wagon Box Draw landforms are linear and ridgelike being composed of three elements: “berm,” “face” and “flat.” The berm contains the crest line of exposed limestone that is the high point of the structure with the line of the berm crest expressing nearly horizontal orientation. It is a convex-upward, subtle ridgelike landform. Beneath the widespread yellow-brown encrustation of calcareous tufa, the berm is composed of resistant gray limestone of the upper Harrisburg Member. Where bedrock limestone is exposed within the berm, it is sometimes evident that strike and dip of the limestone is approximately concordant with the overall slope. The surface of the berm is often strewn with platy or bladelike clasts of Harrisburg Member limestone with a deficiency of rollable, spindlelike limestone clasts. The concentration of platy clasts, together with the presence of tufa, remind us of shorelines terraces we have inspected at Lake Bonneville and Salt Lake in Utah and at Salton Sea in California. The face is the most steeply dipping landform surface within the Wagon Box Draw landform field. The face is the dipping plucked limestone surface always just downslope of the berm. In other places the flat is loose gravel without tufa coating. Often, especially where tufa encrustation is missing, the face appears to be an erosional scarp where the strike of the scarp surface approximately parallels the strike of the Harrisburg Member limestone bedding. As one looks down the strike of the erosional scarp, that scarp appears to be the uppermost part of a concave-upward surface that is mostly buried by the adjacent flat. From this viewing angle, one can appreciate that the face is exposing information on the strike and dip of Harrisburg Member limestone strata. This viewing angle sometimes allows one to appreciate that the landform is inscribed laterally by erosion on the dip slope of the bedrock beneath. An unusual viewpoint effect occurs when one stands on the face of the landform and looks directly downslope. The face of the next landform downslope is invisible, because its exposed surface is directed downslope. What one sees looking downslope is the next berm (which conceals the next face below) whose topography appears indistinct because that berm is being observed from a low angle from above. Therefore, the downslope viewpoint shows just sediment-filled terraces with rather indistinct berms whose topography is not accentuated. Color contrast is the most noteworthy downslope property. That viewpoint effect can be contrasted with Figure 19. Field view of steplike terraces near the top of Chevron Hill. Landform terminology is applied. The slope is almost completely coated with thin, yellow-brown tufa encrustation. AUSTIN, HOLROYD, FOLKS, AND LOPER Shoreline Transgressive Terraces 2023 ICC 356
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