Ancient Egyptian writings record several different and equally vivid metaphors for creation. Each year, the Nile Valley was flooded in late summer, and each year the fields emerged from the floodwaters later in the autumn, coated with black mud left by the floods. This powerfully repeated experience provided the principal motifs for expressing the mystery of creation.
http://www.ucl.ac.uk/museums-static/digitalegypt/religion/deitiescreation.html