Definitions Found:
formed in the third period of the Palaeozoic era
- silurianformed in the third period of the Palaeozoic era
- devonianrelating to a type of rock formed in the fourth period of the Palaeozoic era
- permianrelating to the last period of the Palaeozoic era
- quaternaryOf, relating to, or denoting the most recent period in the Cenozoic era, following the Tertiary period and comprising the Pleistocene and Holocene epochs (and thus including the present)
- eoceneof rock formed in the second epoch of the Tertiary geological period