The impact of Indigenous populations on historical fire regimes has been controversial and beset by mismatches in the geographic scale of paleofire reconstructions and the scale of land-use behaviors. It is often assumed that anthropogenic burning is linearly related to population density and not different cultural practices. Here we take an off-site geoarchaeology strategy to reconstruct variability in historical fire regimes (<1000 years ago) at geographic scales that match the archaeological, ethnohistorical, and oral tradition evidence for variability in the intensity of Indigenous land use by two different cultural groups (Ancestral Pueblo and Western Apache). We use multiple, independent proxies from three localities in ponderosa pine (Pinus ponderosa) forests in east-Central Arizona to reconstruct fire regime variability during four phases of cultural use of different intensities. Elevated charcoal with domesticate pollen (Zea spp.) but otherwise unchanged forest pollen assemblages characterized intensive land use by Ancestral Pueblo people during an early phase, suggesting fire use to support agricultural activities. By contrast, a phase of intensive pre-reservation Western Apache land use corresponded to little change in charcoal, but had elevated ash-derived phosphorus and elevated grass and ruderal pollen suggestive of enhanced burning in fine fuels to promote economically important wild plants.

In western North America, pollen data from highland lakes are often used to reconstruct vegetation on the adjacent lowlands. Plant macrofossils and pollen from packrat middens now provide a means to evaluate such reconstructions. On the basis of pollen diagrams from the Chuska Mountains, H. E. Wright, Jr., A. M. Bent, B. S. Hansen, and L. J. Maher, Jr., ((1973), Geological Society of America Bulletin, 84 , 1155–1180) arrived at conservative estimates for late Pleistocene depression of highland conifers. In their interpretation, a proposed slight depression of 500 m for lower tree line precluded expansion of Pinus ponderosa into elevations now in desertscrub. Instead, it was suggested that pinyon pine and Artemisia occupied the lowland plateaus. Packrat midden records on either side of the Chuskas fail to verify this model. Early Holocene middens from Chaco Canyon, New Mexico, and a terminal Pleistocene midden from Canyon de Chelly, Arizona, show that blue spruce, limber pine, Douglas fir, dwarf juniper, and Rocky Mountain juniper expanded at least down to 1770 m elevation Neither Colorado pinyon nor ponderosa pine was found as macrofossils in the middens. Artemisia pollen percentages are high in the terminal Pleistocene midden, as they are in the Chuska Mountain pollen sequence, suggesting regional dominance by sagebrush steppe. Of 38 taxa identified, only 3 are shared by middens dated 11,900 and 3120 yr B.P. from Canyon de Chelly, indicating a nearly complete turnover in the flora between the late Pleistocene and late Holocene. Although corn was previously thought to have been introduced to the Colorado plateaus after 2200 yr B.P., the midden dated 3120 yr B.P. contains pollen of corn and other indicators of incipient agriculture.

This study presents the first continuous record of fossil diatoms taken from an open spring-mound in southwestern United States. Diatoms were analyzed from a radiocarbon-dated core taken from Montezuma Well, a near thermally constant spring in northcentral Arizona. Fluctuations in total diatom density, oscillations in the relative abundance of Anomoeoneis sphaerophora, and intermittent deposition of calcite suggest that water levels in Montezuma Well underwent dramatic fluctuations to the degree of being intermittently dry, or at least very shallow, during the middle Holocene (∼8000-5000 yr B.P.). The fluctuations in water level probably correspond to oscillations in regional temperature and precipitation, which regulate hydrologic input and evaporation rates. The dramatic fluctuations in water level during the middle Holocene suggest that the endemic biota of Montezuma Well underwent relatively rapid speciation within the past ∼5000 yr. The appearance of endemic species (Gomphonema montezumense and Cyclotella pseudostelligera f. parva ) at ∼5000-3000 yr B.P. supports this hypothesis. Diatom indicators for organic enrichment (Aulacoseira granulata and A. islandica) closely coincide with the prehistoric native occupation of Montezuma Well.

Pollen analysis of a 752-cm core from Mono Lake, Mono County, California indicates generally high lake levels 11,600–7000 14C yr B.P., moderate lake levels until ca. 4000 14C yr B.P., and fluctuating levels to the present. Drying events, with lake levels near or below the historic minimum are dated ca. 8800, 4000, 2400, and 1100 14C yr B.P. Chronologic control is provided by six radiocarbon dates and six volcanic ashes. The rate of upland vegetation change is greatest 11,000, 4000, and 1130 14C yr B.P. Juniperus and Sequoaidendron pollen declines 11,000 yr B.P., marking the transition from late-glacial juniper woodland to Holocene steppe. High values (5–20%) of Sequoaidendron pollen are unique to this study and may indicate the presence of these trees east of the Sierra crest. The pollen-based reconstructions of climate are generally cooler and wetter than today, with relatively dry but cool climate during the early Holocene. The contrast between higher lake levels and more arid vegetation during the early Holocene can be explained by insolation-driven seasonality. Greater summer insolation produced summer drought, but lower winter insolation led to greater snowpack, greater spring runoff, and higher lake levels. Increased Artemisia and other Compositae pollen percentages mark the establishment of modern vegetation ca. 2000 14C yr B.P. During the late Holocene, the pollen-based reconstructions of climate generally match the Mono Lake fluctuations proposed by Stine (1990), but fewer fluctuations are recorded.

Ten sites near the Snake River Plain have consistent differences in their climatic histories. Sites at low elevation reflect the “early Holocene xerothermic” of the Pacific Northwest, whereas most climatic chronologies at high elevation indicate maximum warmth or aridity somewhat later, ca. 6000 yr ago. This elevational contrast in climatic histories is duplicated at three sites from the central Snake River Plain. For sites in such close proximity, the different chronologies cannot be explained by changes in atmospheric circulation during the late Quaternary. Rather, the differences are best explained by the autecology of the plants involved and the changing seasonal climate. The seasonal climatic sequence predicted by multiple thermal maxima explains the high- and low-elevation chronologies. During the early Holocene, maximum insolation and intensified summer drought in July forced low-elevation vegetation upward. However, moisture was not a limiting factor at high elevation, where vegetation moved upward in response to increased length of growing season coincident with maximum September insolation 6000 yr ago.

Pollen analysis and five radiocarbon dates of a 687-cm core provide a detailed chronology of environmental change in a marsh at the head of Newport Bay, Orange County, California. Sediment deposition kept pace with sea-level rise during the early history of the marsh. From ca. 7000 to 4500 yr B.P. the site was a freshwater marsh, trees were more abundant than today, and grassland was the regional vegetation. As sea level rose, salt marsh gradually invaded the site. Brief periods of freshwater marsh 3800, 2800, 2300, and after 560 yr B.P. correlate with episodes of global cooling during the Neoglacial. The historic period is marked by the appearance of exotic species (particularly Erodium cf. cicutarium and Eucalyptus) and the spores of fungi (Sporormiella and Thecaphora). Peak influx of pollen, spores, and charcoal probably reflect greater frequency of flooding and erosion ca. 5000 yr B.P. and during the last 1000 yr.

The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the dung of the extinct mammoths from the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains. The deposit buried beneath sand and rockfall is composed primarily of mammoth dung, estimated at over 300 m3. Radiocarbon dates on dung boluses indicate that the mammoths frequented the cave between approximately 14,700 and 11,000 yr B.P. (the range of ages at 2σ). The desiccated boluses, measuring approximately 230 × 170 × 85 mm, are nearly identical in size to dung from extant elephants. The largest contents in the dung are stalks measuring 60 × 4.5 mm. Grasses and sedges dominated the diet, although woody species were commonly eaten.

Sediments of Balsam Meadow have produced a 11,000-yr pollen record from the southern Sierra Nevada of California. The Balsam Meadow diagram is divided into three zones. (1) The Artemisia zone (11,000–7000 yr B.P.) is characterized by percentages of sagebrush (Artemisia) and other nonarboreal pollen higher than can be found in the modern local vegetation. Vegetation during this interval was probably similar to the modern vegetation on the east slope of the Sierra Nevada and the climate was drier than that of today. (2) Pinus pollen exceeded 80% from 7000 to 3000 yr B.P. in the Pinus zone. The climate was moister than during the Artemisia zone. (3) Fir (Abies, Cupressaceae, and oak (Quercus) percentages increased after 3000 yr B.P. in the Abies zone as the modern vegetation at the site developed and the present cool-moist climatic regime was established. Decreased fire frequency after 1200 yr B.P. is reflected in decreased abundance of macroscopic charcoal and increased concentration of Abies magnifica and Pinus murrayana needles.

Spores of the dung fungus Sporormiella become abundant following the historic introduction of grazing herbivores at seven sites in the western United States. During the Holocene they are generally rare, but at six sites Sporormiella spores are abundant before the extinction of Pleistocene megaherbivores ca. 11,000 yr B.P. Sporormiella spores are directly linked to extinct megaherbivores by their presence in mammoth dung preserved in Bechan Cave, Southern Utah. Their abundance in late-glacial sediments may reflect the abundance of megaherbivores during Quaternary, thereby indicating the age of Pleistocene extinctions where other indicators are absent.

Were Early Agricultural period (2100 B.C.–A.D. 50) maize cultivators in Southern Arizona sedentary farmers or seasonally mobile forager-farmers? Ethnographic analogs and ethnographically derived middle range theory support both claims. One argument for sedentism has been the abundance of large subterranean storage pits. These are often presumed to have been used for long-term food storage. This study of wetlands-indicator spores recovered from those pits indicates that the pits were often saturated and could not have been used for long-term food storage; these findings support the general contention that Early Agricultural period maize cultivators were seasonally mobile and tried to fit early agriculture into a subsistence regime focused on wild foods.

Since July 1996, 815 new names on features on bodies in the Solar System have been assigned by the WGPSN and approved at the IAU General Assembly in Kyoto in 1997. Of these names, 666 were for Venus, 17 for Mars, 3 for the Moon, 125 for the Galilean satellites, 3 for the Uranian satellite Miranda, and 1 for the minor planet Ida. 71 additional names mostly on Venus have been selected and have been given or are awaiting provisional approval by the IAU Executive Committee (EC). These names are up for final approval at the next IAU General Assembly.