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By analogy with the behavior of crystalline aggregates of the metals, rocks might be expected to fail by fatigue under repeated applications of stress much below the strength as measured in ordinary laboratory tests. To determine whether the temperature stresses set up in a rock by insolation are sufficiently great to cause failure by fatigue, an experiment has been performed in which a coarse-grained granite has been subject to temperature differences of 110° C. for a period corresponding to 244 years of natural insolation. Photomicrographs show no change in the rock.
D. T. Griggs (Thu,) studied this question.