Cryptic era
Encyclopedia
The Cryptic era is an informal term that refers to the earliest geologic evolution of the Earth
and Moon
. It is the oldest era of the (informal) Hadean eon, and it is commonly accepted to have begun close to 4567.17 million (about 4.6 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
.
This time is cryptic because very little geological
evidence has survived from this time. Most geological landforms and rocks were probably destroyed in the early bombardment phase, or by the continued effects of plate tectonics. The Earth accreted, its interior differentiated
and its molten surface solidified during the Cryptic era. The proposed collision that led to formation of the Moon
occurred also at this time. The oldest known minerals are from the Cryptic era.
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
. It is the oldest era of the (informal) Hadean eon, and it is commonly accepted to have begun close to 4567.17 million (about 4.6 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
Basin Groups
Basin Groups refers to 9 informal subdivisions of the lunar Pre-Nectarian geologic period.-Definition:The motivation for creating the Basin Groups subdivisions was to place 30 pre-Nectarian impact basins into 9 relative age groups...
era for the Moon (see also Pre-Nectarian
Pre-Nectarian
The Pre-Nectarian Period of the lunar geologic timescale runs from 4533 million years ago to 3920 million years ago, when the Nectaris Basin was formed by a large impact. It is followed by the Nectarian period...
), 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
International Commission on Stratigraphy
The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...
.
This time is cryptic because very little geological
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
evidence has survived from this time. Most geological landforms and rocks were probably destroyed in the early bombardment phase, or by the continued effects of plate tectonics. The Earth accreted, its interior differentiated
Planetary differentiation
In planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical behaviour, where the body develops into compositionally distinct layers; the denser materials of a planet sink to the center,...
and its molten surface solidified during the Cryptic era. The proposed collision that led to formation of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
occurred also at this time. The oldest known minerals are from the Cryptic era.