LITTLE ICE-AGE EVIDENCE FROM A SOUTH-CENTRAL NORTH-AMERICA ICE CORE, USA

In the past, ice-core records from mid-latitude glaciers in alpine are as of the continental United States were considered to be poor candida tes for paleoclimate records because of the influence of meltwater on isotopic stratigraphy. To evaluate the existence of reliable paleoclim atic records, a 160-m ice core, containing about 250 yr of record was obtained from Upper Fremont Glacier, at an altitude of 4000 m in the W ind River Range of south-central North America. The delta(18)O (SMOW) profile from the core shows a -0.95 parts per thousand shift to lighte r values in the interval from 101.8 to 150 m below the surface, corres ponding to the latter part of the Little Ice Age (LIA). Numerous high- amplitude oscillations in the section of the core from 101.8 to 150 m cannot be explained by site-specific lateral variability and probably reflect increased seasonality or better preservation of annual signals as a result of prolonged cooler temperatures that existed in this alp ine setting. An abrupt decrease in these large amplitude oscillations at the 101.8-m depth suggests a sudden termination of this period of l ower temperatures which generally coincides with the termination of th e LIA. Three common features in the delta(18)O profiles between Upper Fremont Glacier and the better dated Quelccaya Ice Cap cores indicate a global paleoclimate linkage, further supporting the first documented occurrence of the LIA in an ice-core record from a temperate glacier in southcentral North America.