q is typically around 60 mWm-2 for continental
crust (with a range of 30-100 mWm-2) equating to geothermal
gradients of ~ 20°C/km
(range of 10-35°C) for typical thermal conductivity of 3 Wm-1K-1
geotherms contributed by heat production (H) due to radioactive
decay of K, U, Th, and heat flow from the convective mantle
q decreases with depth balancing the distribution of the
heat producing elements (HPEs) in the crust, such that geotherms are curved.