Slides from a lecture presentation covering the following topics: Response of materials, point force applied to a semi-infinite elastic solid, trajectory of principal stresses due to a point force, contour of principal normal stresses, Hertzian contact, location of the max. radial stress, stress field due to line load, semi-infinite elastic solid loaded by a elliptical distributed load, contour and variation of stress, crack growth of hertzian crack, and sequence of crack formation and growth events during loading and unloading.