The mechanism of mountain forming is based on the phenomenon of the formation of compressive normal horizontal stresses exceeding gravitational. These stresses are due to contact friction between the layers of rocks. To reveal the mechanism of mountain forming, the vector method of the body equilibrium on the path of maximum effective tangential stresses of a triangular element is used, taking into account the external and internal forces acting on it. It is shown that the total vector of these forces, taking into account internal and contact friction, is directed against the gravitational force and generates mountain forming. A generalization of experimental observations on the elevation of rock structures and anomalous manifestations of rock pressure is given.