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.
Helladic chronology
In Greece, the Middle Helladic period (or MH) was a period of cultural retrogression, which first manifested in the preceding EHIII period. The MH period is characterized by the wide-scale emergence of Minyan ware, which may be directly related to the people whom ancient Greek historians called Minyans; a group of monochrome burnished pottery from Middle Helladic sites was conventionally dubbed "Minyan" ware by Troy's discoverer Heinrich Schliemann.