View of Airport Playa from the southeast (Natural Scene Designer generated view)
Airport Playa on the Southern Margin of the Coso Range, Southern Owens Valley, California, U.S.A.
Recent investigation of the plant macrofossils recovered from ancient woodrat middens from Airport Playa has revealed a late Holocene history of
Mojave Desert shrub response to changes in both precipitation amount and seasonality. Airport Playa lies close to the northwestern corner of the
Mojave Desert about 30 km due north of Ridgecrest, California. It encompasses roughly the southern third of the Coso Basin. The Coso Basin lies
within a 10-km diameter amphitheater-like depression opening to the southeast and enclosed on the northwest, north and northeast by the Coso Range.
Elevations range from just under 900 meters above sea level on the floor of Airport Playa to just under 2500 meters on Coso Peak. The region lies just
east of the crest of the Sierra Nevada Mountains and therefore is effected to some extent by its rainshadow. However, the Coso Range to the north
generates orographic rainfall. Models of regional moisture input generated from digital elevation model (DEM) data indicate that the driest areas lie
around Airport Playa and to the south while the wettest are to the north. The digital download of regional hydrology indicates that these areas are also
major sources of surface water. Most of the surface water input for Airport Playa comes from the north and northeast in the eastern portion of the Coso
Range. Although there are small drainages entering Airport Playa from the south the main ones are across the broad bajadas lying to the north.
The radiocarbon dated macrofossil record from woodrat middens recovered from Airport Playa reflects an environment dominated by creosote bush
shrub. The pollen record extracted from the middens indicates dramatic shifts in climate including: 1) seasonal dominance of rainfall as well as 2)
strong drought and wet episodes. Winter rainfall dominated Neoglacial climates 2,500 B.P. gave way to increased summer rainfall after 1950. Two wet
episodes during the very dry last 1,000 years are evidenced in the midden record as not as wet as around 1950, but still with a strong summer rainfall
component. The last 300 years are characterized by dramatic shifts in annual rainfall amount and seasonal rainfall contribution. Aeolian activity
centered between 910 and 310 B.P. may reflect the combined effects of wet episodes and the general drought of the last millennium which both
loosened playa surface sediment and removed vegetation as an impediment to sediment transport. Additional macrofossil evidence from a human
coprolite indicates Native American seed resource use with chia (Salvia columbariae) being an important component. Its sudden abundance may
reflect increasingly sandy soils during the last 1,000 years rather than a more straight-forward change in climate.
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