The most common clave pattern used in Cuban popular music is called the son clave, named after the Cuban musical genre of the same name. Clave is the basic period, composed of two rhythmically opposed cells, one antecedent and the other consequent. Clave was initially written in two measures of 2 4 in Cuban music.
Eon, a variation of aeon, is defined as a unit of geological time equal to a billion years, or a very long period of time. An example of an eon is the unit of measure used when talking about how long ago the solar system was created.
This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga (billion years ago).