hadean eon造句

• The Jack Hills zircon led to something of a revolution in our understanding of the Hadean eon.
• According to first proposal, it precedes the Hadean eon and is the earliest eon in Earth's history as a planet.
• Alternatively it is defined as the first era of the Hadean eon, before the formation of the first crust on the Earth.
• Nevertheless, at least one notable scientific work has advocated using the lunar geological time scale to subdivide the Hadean eon of Earth's geologic time scale.
• The International Commission on Stratigraphy currently does not recognize the lower boundary of the era which has been provisionally placed at nor that of the preceding Hadean Eon.
• Earth records a similar history of impact melting in its zircons from the Hadean eon, 4.5-4.0 b . y . ago.
• :: I can't find a question, but the OP may find useful information on the cooling of the earth at History of the Earth and Hadean Eon.
• The presence of an ocean, first dating from the late Hadean, would suggest the start of life in the following Archean Eon rather than in the Hadean Eon depended on the presence of an ocean ..
• The Hadean Eon represents time before the reliable ( fossil ) record of life beginning on Earth; it began with the formation of the planet and ended at 4.0 billion years ago as defined by international convention.
• The zircons and various aspects of their geochemistry provide evidence for the existence of continental-type crust on the surface of the earth during the Hadean eon, contrasting with earlier ideas on the earliest phase of Earth's history.
• It is bracketed at the old end by the dates of the earliest Solar System material at 4.567 Ga, ( gigaannum : billion years ago ) and the age of the Earth at 4.54 Ga at the beginning of the informally recognized Hadean eon.
• The early Earth during the Hadean eon is believed by most scientists to have had a Venus-like atmosphere, with roughly 100 bar of CO 2 and a surface temperature of 230 癈, and possibly even sulfuric acid clouds, until about 4.0 billion years ago, by which time plate tectonics were in full force and together with the early water oceans, removed the CO 2 and sulfur from the atmosphere.
• The "'giant-impact hypothesis "', sometimes called the "'Big Splash "', or "'the Theia Impact "'suggests that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago, in the Hadean eon; about 20 to 100 million years after the solar system coalesced.