The Sierra Nevada (California) Is a Relict Tropical Late Cretaceous Range: A Field Guide to the Evidence

Abstract

ABSTRACT:The notion of late-Cenozoic uplift was implied in 1865 by Whitney, who assumed a buried bedrock canyon lay beneath the Table Mountain latite flow and above the modern Stanislaus River canyon, with the difference between the two longitudinal profiles suggesting post-latite uplift. However, only a series of buried bedrock ridges exists and no uplift is inferred. I briefly present thirty-three key sites of about three hundred remnants in the entire Sierra Nevada, from north of the Feather River south to the Kern River. These include Late Cretaceous strata, Eocene strata, Oligocene rhyolites, Mio-Pliocene andesites, and Quaternary basalts, some remnants on canyon floors but most on lower slopes, preserving topography at the time of deposition. I found no evidence of late-Cenozoic incision, which is required under the late-Cenozoic uplift paradigm. Instead, each site contains verifiable field evidence that challenges the uplift paradigm. Moreover, the results are consistent with the range having a common uplift history: the crest elevation, drainage topography, and relief developed in the Late Cretaceous, and only minor changes occurred in post-Eocene time. This supports uplift studies in the northern Sierra based on hydrogen and oxygen isotopes on auriferous deposits, and supports pediment ages of 40+ Ma in the southern Sierra. Uplift studies based on thermochronology and numerical modeling, on cave-sediment dating and its implied incision, and on significant denudation on benchlands cannot be reconciled with verifiable field evidence. Finally, migration of giant sequoias southwest into the Sierra Nevada was possible only from late in the Cretaceous, when the Nevadaplano came into existence and the range was high, negating any Sierran late-Cenozoic uplift paradigm.