The concept of extracting geothermal energy from hot granitic rock sources at depths of 3-
5 kilometres is enjoying a renaissance as a practical concept, and several prospects
worldwide are under development. It is noteworthy however that very few hot rock
prospects are being developed at latitudes affected by Pleistocene glaciation. Here we
examine three regions of high heat producing granites in the United Kingdom that were
located either beneath thick ice (Eastern Grampian Highlands of Scotland, North of
England) or beyond the ice limit (Cornubia). Heat flow measurements made in 30 relatively
shallow boreholes and mines (≤300 metres) do not correlate well with heat production as
estimated from the concentrations of radiothermal elements, with anomalously low heat
flow values restricted to boreholes located in areas covered by Pleistocene ice sheets.
Maximum ice sheet thickness is estimated using a model of glacio-isostatic rebound and
used as a proxy for the magnitude of the glacial cooling and inter-glacial warming effects
on near-surface heat flow. No significant correlation is observed between measured heat
flow and heat generation despite all areas having large negative Bouguer gravity
anomalies indicating thick batholithic masses of granite underlying all boreholes. However
a strong correlation is observed between heat flow and maximum ice thickness suggesting
this is a primary control on present day heat flow at shallow levels. A deep borehole is
required to test this hypothesis. The geochemistry of these high heat producing granites in
Scotland is examined and their potassic and fractionated characteristics are used to show
that other plutons in Scotland may share their heat generating potential. It is concluded
that the East Grampian batholith in Scotland may have been mistakenly excluded as a
region of hot rock geothermal potential, and its inclusion would add significantly to the
UK’s hot rock resources. If this is a generic feature of glaciated terrains then many more
hot resources may be hitherto unidentified in the higher latitudes of the northern
hemisphere.