Search results
Results from the WOW.Com Content Network
Impacts from these comets could trigger a mass extinction of life on Earth. These disruptive encounters are estimated to occur an average of once every 45 million years. [28] There is a 1% chance every billion years that a star will pass within 100 AU of the Sun, potentially disrupting the Solar System. [29]
The estimated time until a gamma-ray burst, or massive, hyperenergetic supernova, occurs within 6,500 light-years of Earth; close enough for its rays to affect Earth's ozone layer and potentially trigger a mass extinction, assuming the hypothesis is correct that a previous such explosion triggered the Ordovician–Silurian extinction event ...
The scientific study of paleoclimatology began to take shape in the early 19th century, when discoveries about glaciations and natural changes in Earth's past climate helped to understand the greenhouse effect. It was only in the 20th century that paleoclimatology became a unified scientific field.
Pliocene–Pleistocene boundary extinction: 2 Ma: Possible causes include a supernova [7] [8] or the Eltanin impact [9] [10] Middle Miocene disruption: 14.5 Ma Climate change due to change of ocean circulation patterns. Milankovitch cycles may have also contributed [11] Paleogene: Eocene–Oligocene extinction event: 33.9 Ma
The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes. Researchers have identified five other major extinction events in Earth's history, with estimated losses below: [11] End Ordovician: 440 million years ago, 86% of all species lost, including graptolites
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
For premium support please call: 800-290-4726 more ways to reach us
Solidified lava flow in Hawaii Sedimentary layers in Badlands National Park, South Dakota Metamorphic rock, Nunavut, Canada. Geology (from Ancient Greek γῆ (gê) 'earth' and λoγία () 'study of, discourse') [1] [2] is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. [3]