The Nounan Formation in north-central Utah thickens northward from 696 feet near Causey Dam to 1147 feet at High Creek in the Bear River Range, and northwestward to 1149 feet at Dry Canyon in Wellsville Mountain. The basal contact of the Nounan Formation is sharp, but dolomite extends irregularly downward into limestones of the Bloomington Formation as much as 6 feet. The Nounan Formation is divided into three members based on lithologic characters: (1) a lower member composed of dark, medium-crystalline dolomite; (2) a middle member composed of white, coarse-crystalline dolomite with tongues of dark dolomite; and (3) an upper member of interbedded light and dark dolomites and limestones with local arenites and sandy carbonates. The lower member was deposited in a high-energy, shallow-marine subtidal to intertidal environment. Evidence includes sets of low-angle cross stratification (dunes), oncolites, oolites, and rip-up clasts. The middle member forms distinctive ledges and cliffs. The presence of thinly laminated algal stromatolites and relict structures seen also in the lower member indicate a subtidal to intertidal environment similar to that inferred for the lower member. The white color and coarse crystallinity may have resulted from recrystallization of the dark, finer grained dolomite that comprises the lower member. The upper member is characterized by lithologic variability. Thicknesses of limestone are greatest in the north, and decrease to only a few feet in the south. Quartz and other terrigenous minerals are scattered at intervals throughout the upper member, with a marker of sandy (arenaceous) dolomites at the base and near the middle and an increase of sand near the top also. The upper contact, with quartz-rich arenites (subarkosic quartzites) of the Worm Creek Member of tho St. Charles Formation, is gradational overall, but is sharp and planar in each section and readily located. In the upper member, algal mats trapped a varying but overall increasing influx of quartz and feldspar, probably in shallow subtidal environments, and vertically stacked hemispheroids suggest that depositional conditions may have included intertidal. Virtually all of the dolomite in the Nounan Formation must have formed by replacement of lime sediments by downward-moving high-magnesium brines. It is that these brines originated in restricted, shallow, subtidal evaporating basins, such as the Great Bahama Banks today, and associated supratidal flats. Lateral changes from limestone to dolomite overall and also in individual beds of the upper member indicate that the brines travelled laterally as well as vertically, and dolomitization may have been limited as much by prior diagenetic alteration and cementation as by the volume, concentration, and proximity of the brine itself.

Holocene climate likely influenced prehistoric hunter-gatherer subsistence and mobility as changing climate patterns affected food resources. Of interest here is whether climate-driven resource variability influenced peoples in the central Rocky Mountains. This study employed the z-score model to predict how foragers coped with resource variability. The exercise enabled exploration of the relationship between climate, resources, and foraging strategies at High Rise Village (48FR5891), an alpine residential site in Wyoming's Wind River Range occupied between 2800-250 cal B.P. The test was applied to occupations dating to the Medieval Warm Period (1150-550 cal B.P.) and the Little Ice Age (550-100 cal B.P.). Using regional characterizations of temporal variability for these climate periods, a z-score model was employed to develop predictions of how foragers coped with resource variability and predictability during both periods. The model predicted foraging decisions at High Rise Village that managed the risk of caloric shortfall during the slow-changing Medieval Warm Period and the highly variable Little Ice Age. Predictions for each period were tested against corresponding archaeological expectations for subsistence remains, mobility and technology requirements, and the frequency of site use. Further, this study employed a dendroclimatological study to locally characterize the climate periods and test model assumptions of their contrasting patterns of variability. The dendroclimatological study corroborates model assumptions and finds that the Medieval Warm Period was a period of multidecadal climatic variability and resource predictability while the Little Ice Age was characterized by short-term variability and resource unpredictability. Poor preservation of subsistence remains hampered the archaeological study. However, as expected, lithic and chronometric data indicate the site was used residentially and relatively frequently during the Medieval Warm Period, and that use decreased during the Little Ice Age. Medieval use of the site appears to be by Uinta Phase (1800-900 cal B.P.) foragers from the adjacent lowlands, and likely related to regional population pressure, as well as resource accessibility and predictability at High Rise Village. A dramatic decrease in site use predates the Little Ice Age and is likely related to regional population decrease and not LIA conditions at High Rise Village.

The Mississippian (Kinderhookian-Osagean) Lodgepole Formation contains a diverse fossil assemblage. Taxa present include brachiopods, crinoids, gastropods, cephalopods, trilobites and corals. Corals and associated fauna were collected from four localities within the Bear River Range. These are, from north to south, Beirdneau Hollow, Spring Hollow, Leatham Hollow and Porcupine Dam. The well-preserved tabulate and rugose (compound and solitary) corals exhibit a high degree of morphologic variability. The colonial corals of the Lodgepole Formation (particularly Lithostrotionella, Syringopora) exhibit a morphologic gradient from platy to hemispherical forms. The six morphologic categories of colonial corals discussed in this study are identified by mean corallus diameter/corallum height ratios, by the corallite growth direction, and by the shape of the base of the colony. Type I corals have an average mean diameter/height ratio of 3.4; corallites are directed laterally away from the flat base. Type I corals are interpreted to have been adapted to offshore, quiet-water conditions. Type II corals are flattened hemispheres; they have an average mean diameter/height ratio of 4.1. Corallites are directed radially (i.e., with vertical as well as a lateral component) away from the flat colony base. Type II corals are interpreted in this study to have been adapted to shallow, moderately-turbulent environments in which vertical growth was inhibited. Type III corals have an average mean diameter/height ratio of 3.9 and are similar to Type II corals in all respects but one, namely that there is an absence of corallites on the crown of the corallum. This feature is called balding and is interpreted in this study to have been the result of desiccation and subsequent death of coral polyps. Type III corals are thus interpreted to have inhabited very shallow water wherein subaerial exposure of the crown of the corallum occurred during periods of exceptionally low tides. Type IV corals are dome-shaped or slightly-flattened hemispheres; they have an average mean diameter/height ratio of 2.3. Corallites are directed radially away from the flat base. Type IV corals are interpreted to have inhabited a depth zone intermediate between that of Type II corals (within or barely below tidal range) and Type I corals (near or below wave base). The average mean diameter/height ratio of Type V corals is 1.7. Corallites are directed almost entirely vertically away from the rounded-to-conical colony base. Type V corals are interpreted to have inhabited areas where sedimentation rates were sufficiently high to encourage vertical growth to the virtual exclusion of lateral growth. Type VI corals are composite corals, consisting of combinations of hemispherical forms and platy forms. This morphologic type is characterized by a change in the direction of growth during the astogenetic development of colony. The combinations of varying growth forms presumably reflect fluctuations in sedimentation rate.