우리의 옛 선조들
과학동아 1987년 12호
was what the Bible seemed to imply. As early as 1797, however, an Englishman, John Frere, discovered crudely fashioned flint tools that must have been made by primitive human beings. Those tools were discovered 13 feet underground. Objects that remain undisturbed are slowly covered by dust and mud that turns into rocks, and tools buried that deep must be far more than 6,000 years old. Later, ...