Dating topography of the sierra nevada
Instead, we observe a mix-and-match of soil and bare rock on gently sloped treads and steeply sloped steps.This raises the possibility that exposure of bedrock arises from contrasts in material properties rather than from random erosional exposure, as suggested by the hypothesis.This suggests that the coupling between soil production and denudation in granitic landscapes harbors a crucial tipping point; if soils are stripped to bedrock, erosion slows and soil formation is restrained to the point that bare rock can persist and rise in relief relative to surrounding soil-mantled terrain.
Considered together, our data and analysis contribute to improved understanding of the dynamics of hybrid (bedrock/soil) landscapes by shedding light on feedbacks among erosion, rock strength, mineralogy and degree of chemical weathering in granitic terrain.
These ranges generally trend north–south; most are short, up to 75 mi (121 km) long and 15 mi (24 km) wide, and rise to altitudes of 7,000–10,000 ft (2,100–3,000m).
Chief among them are the Schell Creek, Ruby, Toiyabe, and Carson (within the Sierra Nevada).
Yet few studies have been able to realistically predict the co-occurrence of bedrock and granular soil and its implications for mountain-scale topography -- despite marked advances in quantitative landscape evolution modeling over the last few decades.
Here we use terrain analysis, together with cosmogenic-nuclide measurements of erosion and weathering, to quantitatively explore Wahrhaftig's decades-old hypothesis for the development of “stepped topography” by differential weathering of bare and soil-mantled granite.
Nevada's highest point is Boundary Peak, 13,140 ft (4,007 m), in the southwest.