The climatic and hydrologic history of southern Nevada during the Late Quaternary

Abstract

The Climatic and Hydrologic History of Southern Nevada During the Late Quaternary (C). Notice the importance of eccentricity on precesion (A) and the relation between precession and insolation; (B) Notice the similarity of insolation from about 400 to 300 ka versus that for the next 100 ky in the future, Berger and Loutre, 1991.

Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods 1 1Associate editor: S.J.G. Galer

“…Surface water, vegetation, and ground-water discharge records document greater surface-and ground-water fluxes associated with pluvial climate conditions at Yucca Mountain from ϳ70 ka to between 20 and 15 ka (Spaulding, 1985;Paces et al, 1993;Lundstrom et al, 1996;Bradbury, 1997;Forester et al, 1999;. The faster mineral growth rate (1.2 m/k.y.)…”

“…Infiltration rates have likely varied in the last several million years because of shifts in Pleistocene climate (Spaulding, 1985;Winograd et al, 1992;Quade et al, 1995;Forester et al, 1999). Mean annual precipitation during pluvial (glacial) climates may have been two to four times greater than present-day interpluvial conditions, and mean annual temperatures may have been as much as 5 to 10°C cooler (Spaulding, 1985, table 10;Forester and Smith, 1994;Forester et al, 1999, p. 2;Thompson et al, 1999, table 2).…”

Erosional decay of the Yucca Mountain crest, Nevada

“…Hillslope processes typically cause rounded crests, separated by V-shaped valleys. The absence of hillslope processes is in fact typical for desert regions: the variation of the Nevada climate over time was considered by Forester et al (1999). They suggested that Nevada responds to a global climate cycle of some 400,000 years and subcycles of 100,000 years with the next 100,000 years being similar to those between 400,000 and 300,000 years.…”

“…They suggested that Nevada responds to a global climate cycle of some 400,000 years and subcycles of 100,000 years with the next 100,000 years being similar to those between 400,000 and 300,000 years. On a shorter time scale, Forester et al (1999) report of a series of events that cause fluctuations in erosion rate on a scale of 10,000-50,000 years. These include the influence of glaciations, hill slope stabilisation by vegetation and others.…”

“…Particular focus has been made on the deformation history to investigate if the major structures in the region are active and if, therefore, they propose an active threat to the site (Morris et al, 2004;Potter et al, 2004;Wernicke et al, 2004;Hill and Blewitt, 2006). The erosional history on the other hand has only been studied with respect to the documentation of erosion features (e.g., Coe et al, 1997) and the climatic history (e.g., Forester et al, 1999), but no forward predictions of the incision rates of the valleys have been made. In this paper, we investigate the rate at which the Yucca Mountain crest may decay in response to erosion using numerical modelling.…”