The story of human activity in the land now known as Egypt streches back some five hundred thousand years to an early stage of present, or so-called Quaternary, era in the history of the earth's surface. As elsewhere on that surface this scarcely conceivable span of time covers only a minute fraction of the story of the land itself, the more recent chapters of which take us back approximately sixty million years, through a long chain of geological and climatic developments, to the initial phases of the preceding tertiary era.