By absolute rock stress measurements the existence of a general horizontal compressive stress field in the Earth's crust is demonstrated; the sum of the horizontal principal stresses linearly increases with depth. The crust is in a state of dynamic stress-equilibrium but areas of instability at places exist. The maximum shearing stress that the bedrock can stand represents a material property and does not increase with depth. The results of extensive absolute stress measurements in the bedrock of Iceland are briefly described and the same from the rock massive of Mont Blanc measured in a rock tunnel between 2500 and 1750 m below the top levels. The mechanism of formation of the mountain is discussed.