Cool, wet conditions late in the Younger Dryas in semi-arid New Mexico

Abstract

A thick alluvial sequence in central New Mexico contains the Scholle wet meadow deposit that traces upstream to a paleospring. The wet meadow sediments contain an abundant fauna of twenty-one species of freshwater and terrestrial mollusks and ten species of ostracodes. The mollusks and ostracodes are indicative of a local high alluvial water table with spring-supported perennial flow but without standing water. Pollen analysis documents shrub grassland vegetation with sedges, willow, and alder in a riparian community. Stable carbon isotopes from the wet meadow sediments have δ13C values ranging from − 22.8 to − 23.3‰, indicating that 80% of the organic carbon in the sediment is derived from C3 species. The wet meadow deposit is AMS dated 10,400 to 9700 14C yr BP, corresponding to 12,300 to 11,100 cal yr BP and overlapping in time with the Younger Dryas event (YD). The wet meadow became active about 500 yr after the beginning of the YD and persisted 400 yr after the YD ended. The Scholle wet meadow is the only record of perennial flow and high water table conditions in the Abo Arroyo drainage basin during the past 13 ka.

Geoarchaeology of the Water Canyon Paleoindian site, west‐central New Mexico

“…The Terminal Pleistocene stratigraphic record at Water Canyon contrasts with that from other localities in the Southwest. The Mockingbird Gap site to the east‐southeast (Holliday et al, ) and the Scholle site to the northeast (Hall, Penner, Palacios‐Fest, Metcalf, & Smith, ) as well as Murray Springs and other Clovis sites in the upper San Pedro Valley of southeast Arizona (Haynes, ; Haynes & Huckell, ) all exhibit conformable stratigraphic sequences for the period ~13,500 to ~10,000 cal years. In particular, the Stratum 6 wetland mud is broadly similar lithologically and chronologically to that proposed for the “black mats” of the San Pedro Valley, the “wet meadow” zone at the Scholle site, and the palustrine muds (stratum 2) at the Mockingbird Gap site.…”

Paleoindians, paleolakes and paleoplayas: Landscape geoarchaeology of the Tularosa Basin, New Mexico

“…The data presented here build on and also test the settlement hypotheses provided by Wessel et al (1997) is indicated by the presence of paleolake Otero, although the lake chronology is very poorly dated. Other stratigraphic and paleoecological data are also indicative of wetter conditions and higher runoff (Holliday et al, 2009;Hall et al, 2012b;Hall and Penner, 2013). This runoff would provide at least seasonal if not perennial flows onto the basin floors.…”

Paleoecology of a ciénega at the Mockingbird Gap Site, Chupadera Draw, New Mexico

“…Geomorphologically, a ciénega is somewhat similar to a wet meadow; the former forms a depression that permits standing water to accumulate aquatic and riparian vegetation (e.g., cattails, grasses), trapping aeolian, alluvial, and/or fluvial sediments that contribute shelter to the organisms (see Hendrickson and Minckley, 1984 for a detailed description); whereas the latter consists of saturated grounds along perennial streams where spring and groundwater discharge moves over the surface without ponding (Hall et al, 2012). Both are fed by springs and seeps (Hall et al, 2012).…”

“…The patchy records of aquatic systems in the region during the post-last glacial maximum late Pleistocene-Holocene (here we are referring to the Allerød, Younger Dryas, and Holocene chronozones) transition is a major obstacle for understanding the patterns of paleoenvironmental change that characterized the YDC in the region. The recently studied Scholle wet meadow (sensu Hall et al, 2012) at Abo Canyon, ~60 km north-northwest of the Mockingbird Gap site, is a rare example. Hall et al (2012) reported a rich and diverse ostracode fauna during the transition from the Allerød-Younger Dryas to the Holocene, before the site turned too arid to host microinvertebrates.…”

“…The recently studied Scholle wet meadow (sensu Hall et al, 2012) at Abo Canyon, ~60 km north-northwest of the Mockingbird Gap site, is a rare example. Hall et al (2012) reported a rich and diverse ostracode fauna during the transition from the Allerød-Younger Dryas to the Holocene, before the site turned too arid to host microinvertebrates.…”