the increase in depth in the earth’s crust (in meters) corresponding to a rise of 1° C in rock temperature. On the average the geothermal step amounts to 30-40 m; it is a few times greater in crystalline rocks (up to 120-140 m) than in sedimentary ones. It varies within considerable limits (from 5 to 150 m), depending on depth and place. The mean value of the geothermal step for Moscow is 38.4 m.
The inverse of the geothermal step, the measurement of the increase in temperature in rock with increasing depth of the beds, is defined as the geothermal gradient.