Cryptic (geology)
The Cryptic era is an informal term for the earliest geologic evolution of the Earth and Moon. It is the oldest (informal) era of the Hadean eon, and it is commonly accepted to have begun close to 4533 million (about 4.533 billion) years ago when the Earth and Moon formed. No samples exist to date the transition between the Cryptic era and the following Basin Groups era for the Moon (see also Pre-Nectarian), though sometimes it is stated that this era ended 4150 million years ago for one or both of these bodies. Neither this time period, nor any other Hadean subdivision, has been officially recognized by the International Commission on Stratigraphy.
Mycenaean Greece
The Late Helladic period is further divided into LHI and LHII, both of which coincide with the early period of Mycenaean Greece (c. 1650–1425 BC), and LHIII (c. 1425–1050 BC), the period of expansion, decline and collapse of the Mycenaean civilization. The transition period from the Bronze Age to the Iron Age in Greece is known as Sub-Mycenaean (c. 1050–1000 BC).