Tectonic models of the Taconian orogeny in western New England must account for the rapid metamorphism of the Taconic klippen after thrusting. The most likely source of heat for this metamorphism is an overlying hot thrust sheet of accretionary wedge material, which overrode the continental margin of ancient North America, culminating in a continent-island arc collision. Thermal calculations indicate that rapid conductive heat transfer from such a sheet is possible. The dimensionless Peclet number suggests that conductive heat transfer is faster than, or operates at rates comparable to, advective heat transfer due to thrusting over a distance of at least...