1. The Age of Copper.
2. The Age of Bronze.
3. The Age of Iron.
Still others classify with reference to the dominant industry of the period, giving:
I. The House Industries, or the Period of Domestic Economy.
1. The Hunting Stage.
2. The Fishing Stage.
3. The Pastoral Stage.
4. The Agricultural Stage, etc.
II. The Handicrafts, or the Period of Town Economy.