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.
Geology of New England
In the Archean Eon Western Massachusetts and Vermont were the eastern edge of Laurentia (now the Canadian Shield). Laurentia is believed to have originated at the end of the Hadean, making it one of the oldest regions with continental crust, as evidenced by the discovery of Acasta Gneiss in Canada. At the end of the Hadean massive eruptions of felsic lava became cool enough to form permanent crust. The felsic nature of Laurentia allowed it to float over the denser ocean basins that surrounded it, so it was not submerged under the then-forming oceans. During the Archean Eon the surface of New England was a coastal desert covered by silica-rich sediments with outcroppings of granite bedrock.