Using cave deposits as geologic tiltmeters: Application to postglacial rebound of the Sierra Nevada, California

Abstract

Secondary calcite shelfstone deposits in caves can be used to precisely measure tilting over geologic timescales. Calcite deposited along the edges of former pools can be surveyed to within a single millimeter, and can be dated using uranium-series disequilibrium. Two caves in the southern Sierra Nevada, California, contain tilted calcite deposits of glacial age. A third cave contains a similar but untilted deposit of older interglacial age. The cave deposits record glacio-isostatic rebound of the Sierra Nevada, following melting of an ice cap ∼15,000 years ago. Models of crustal flexure beneath mapped ice thickness reproduce the observed tilting with an effective elastic thickness (Tc) of approximately 5 km. Copyright 2004 by the American Geophysical Union.