Geological time

Capitalise the initial letters of formal names, including the formal modifiers, Early, Mid or Late:

• Cretaceous Period

• Late Jurassic

• Mesozoic Era

• Phanerozoic Eon

• Maastrichtian Stage

• Phanerozoic Eon

Use chronostratigraphic subdivisions in formal terms: Early, Mid, Late, rather than ‘time-rock’ divisions: Lower, Middle, Upper. Either set of terms can be used informally, with lower case initials e.g. early Mesozoic Era.

But general terms e.g. ice age are usually lower case.

Use the Stratigraphical charts of the United Kingdom: Northern and Southern Britain (Waters et al., 2008) for spelling and capitalisation of geological time units and named rock units.