The whole history of the earth is divided into five eras, with corresponding rock-systems. These are: 1. Archæan or Eozoic1 era, embodied in the Laurentian system; 2. Palæozoic2 era, embodied in the Palæozoic or Primary system; 3. Mesozoic3 era, recorded in the Secondary system; 4. Cenozoic,4 recorded in the Tertiary and Quaternary systems; and, 5. The Psychozoic era, or era of Mind, recorded in the recent system.
1883, Joseph Le Conte, Elements of Geology: A Text-book for Colleges and for the General Reader, New York: D. Appleton and Company