Crossword clues for archean
WordNet
archean
adj. used of the earliest known rocks [syn: archaean]
Wikipedia
Archean
The Archean Eon (, also spelled Archaean) is a geologic eon, (that is, 4 to 2.5 billion years ago), following the Hadean Eon and preceding the Proterozoic Eon. During the Archean, the earth's crust and layers had just formed, making the Earth much cooler than it was during the Hadean and allowing the formation of continents.
Usage examples of "archean".
Others divide the Precambrian into two eras, the very ancient Archean and the more recent Proterozoic.
The Archean, composed of gneiss and crystalline schists, and traversed by eruptive veins, extends over the greater part of the Eastern Rumelian plain, the Rilska Planina, Rhodope, and the adjacent ranges.