ABSTRACT The Great Pyramid of Giza, Egypt, was built of limestones and limy sandstones of varying resistances to weathering. As a result, the blocks exhibit several different surface textures. When the facing was removed approximately 1000 years ago, products of weathering formed talus slopes that overflowed the tiers of exposed blocks and banked against the base of the pyramid. An estimate of the rate of formation of talus indicates that the pyramid should remain standing at least 100,000 years unless its destruction is sped by man's activities.