Provide some examples of "ages" named after the material used and explain why this is a poor method for identifying historical periods.

One of the least correct ways of naming the periods of history has been by naming the periods after the material that people used for their tools or weapons: such as, The Stone Age, The Bronze Age, The Iron Age and The Atomic Age. A real problem with naming them this way is that not all civilizations progressed at the same rate; therefore, some civilizations were in the atomic age while others were still in the stone age.