A 19,000-year record of hydrologic and climatic change inferred from diatoms from Bear Lake, Utah and Idaho

Abstract

Changes in diatom fossil assemblages from lake sediment cores indicate variations in hydrologic and climatic conditions at Bear Lake (Utah-Idaho) during the late glacial and Holocene. From 19.1 to 13.8 cal ka there is an absence of well-preserved diatoms because prolonged ice cover and increased turbidity from glacier-fed Bear River reduced light and limited diatom growth. The fi rst well-preserved diatoms appear at 13.8 cal ka. Results of principal components analysis (PCA) of the fossil diatom assemblages from 13.8 cal ka to the present track changes related to fl uctuations of river inputs and variations of lake levels. Diatom abundance data indicate that the hydrologic balance between 13.8 and 7.6 cal ka is strongly tied to river inputs, whereas after 7.6 cal ka the hydrologic balance is more infl uenced by changes in lake evaporation. Wet conditions maintained high river inputs from 13.8 to 10.8 cal ka and from 9.2 to 7.6 cal ka, with a dry interval between 10.8 and 9.2 cal ka. After 9.2 cal ka until 2.9 cal ka lake levels were high except for two periods, one between 7.6 and 5.8 cal ka and one between 4.3 and 3.8 cal ka, as a result of decreased effective moisture. After 2.9 cal ka, fossil diatom assemblages suggest drier conditions until 1.6 cal ka to the present, when fragments of large, pennate diatoms appear, possibly the result of a rapid lake transgression. Although similarities exist between the Bear Lake records and other western hydrologic and climatic records, the covariations are not strong. Our data suggest that climatic regimes at Bear Lake have changed frequently over time, perhaps as a consequence of the position of several important climatic boundaries near Bear Lake.

Hydrologic changes in Colorado during the mid-Holocene and Younger Dryas

“…UBC followed these changes, as do linearly correlated reconstructions from Lake of the Woods and LWH (r = 0.802 ± 0.002; Pribyl and Shuman, 2014). The diatom record from Bear Lake, ID/UT, similarly indicates climatically-mediated episodes of low water from 7600 to 5800 and 4300 to 3800 cal yr BP, although this large lake has a more complex history than the small lakes discussed here (Moser and Kimball, 2009).…”

A computational approach to Quaternary lake-level reconstruction applied in the central Rocky Mountains, Wyoming, USA

“…5500 to 4700 cal yr BP (Fig. 9) correlates with high water at other lakes (Moser and Kimball, 2009), soil formation on eolian surfaces (Miao et al, 2005;Miao et al, 2007), and the growth of the human population in the region (Kelly et al, 2013).…”

Holocene fire occurrence and alluvial responses at the leading edge of pinyon–juniper migration in the Northern Great Basin, USA

“…5c) when regional climate was characteristically wetter and cooler, as indicated by lake records from Bear Lake, Idaho and the Uinta Range, Utah ( Fig. 6; Moser and Kimball, 2009;Corbett and Munroe, 2010) and by a 8300 cal yr BP Lake Bonneville highstand, possibly 60 m higher than the Gilbert shoreline ( Fig. 6; Oviatt, 1997;Patrickson et al, 2010).…”