upper 100 m or so of the Earth's crust (7-1 2), Unlike proxy methods for estimating
temperature change (such as tree ring thickness, oxygen isotopes, glacier termini, and so
forth), changes in subsurface temperature are a direct thermophysical consequence of
changes in GST (7). Studies to date have shown that changes in SAT tend to be tracked in
GST changes (10, 13, 14), and