THE "MOTHER MIDDEN" AT PYRAMID LAKE, NORTHWESTERN NEVADA, U.S.A.
Forty-one radiocarbon-dated strata from a large indurated woodrat midden west of Pyramid Lake in west-central Nevada is providing a detailed
35,000-year record of terrestrial vegetation change and climatic stress in relationship to lake history during the last glacial cycle. Plant macrofossils
including those of the trees Utah Juniper (Juniperus osteosperma) and White-bark Pine (Pinus albicaulis) are providing a unique view of the
vegetation that covered the slopes of pluvial Lake Lahontan (the large "Ice Age" lake that once covered a large portion of northwestern Nevada). Pollen
and abundant twigs, and seeds from the midden layers indicates that around the nest Utah Juniper was quite abundant where today mixed sagebrush
steppe and saltbush shrub communities are found. In particular, the plant remains indicate that around 24,000 and 12,000 years ago White-bark Pine
actually grew on the shores of pluvial Lake Lahontan. Today White-bark Pine is found over 24 km (14.5 miles) away and at least 1,000 m (3,300 ft)
higher in elevation. Today areas where White-bark Pine grow receive around 560 mm (22 inches) of rainfall annually and are about 7°C (12.6°F)
cooler.
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