These are used in geochronologic and thermochronologic studies. It is important not to confuse geochronologic and chronostratigraphic units. The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. The geologic time (geochronologic) equivalent of the Hesperian System is the Hesperian Period. The geologic time (geochronologic) equivalent of the Noachian System is the Noachian Period.