To determine the age of geological rocks, we studied the thermoluminescence of the natural light sum stored as a result of uncontrolled radioactive radiation, as well as after annealing and exposure to a controlled irradiation dose. The magnitude of the stored light sum was determined from the area under the curve of thermoluminescence. It is shown that the thermoluminescent method allows to accurately determine the age of geological objects and can find practical application for creating sensors of dating.