+----------------------------------------+-----------+-----------------+ | Rock-Scale. -->| Group. | System. | | Time-Scale. -->| Era. | Period. | +------------+------------+--------------+-----------+-----------------+ |Zoic time: | Time of | Time of |Psychozoic.|Human. | |embracing | Mammals. | Palms and +-----------+-----------------+ |the history +------------+ Angiosperms. | |Pleistocene. | |of the | +--------------+Cenozoic. +-----------------+ |earth since | | | |Tertiary. | |the | Time of | +-----------+-----------------+ |appearance | Reptiles. | Time of | |Cretaceous. | |of life. | | Cycads. |Mesozoic. +-----------------+ | +------------+--------------+ |Jura-Trias. | | | Time of | +-----------+-----------------+ | |Amphibians. | Time of | |Carboniferous. | | | | Acrogens | +-----------------+ | +------------+(Ferns, club- | |Devonian. | | | Time of |mosses, etc.).| +-----------------+ | | Fishes. | |Paleozoic. |Silurian. | | +------------+ | +-----------------+ | | +--------------+ |Ordovician. | | | Time of | | +-----------------+ | |Molluscs and| | |Cambrian. | | |Crustaceans.| +-----------+-----------------+ | | | Time of | |Algonkian. | | +------------+ Algae. | +-----------------+ | | | |Eozoic. |(As yet unknown | | | Time of | | |pre-Algonkian | | | Protozoa? | | |sediments.) | +------------+------------+--------------+-----------+-----------------+ |Azoic time: preceding the dawn of life. |Azoic. |Archean or | | | |Basement Complex.| +----------------------------------------+-----------+-----------------+ | Solid Earth. | | Prehistoric Molten Earth. | | Gaseous Earth. | +----------------------------------------------------------------------+