A2 Earth and Climate Over Time Flashcards
Cratons
stable portions of the continental crust no longer tectonically active, often ancient and described as continental shields. Mostly crystalline basement rocks, they are thicker parts of the crust.
Great Oxygenation Event (GOE)
was the biologically induced appearance of oxygen in the Earth’s atmosphere around 2.3 billion years ago.
Snowball Earth
describes a condition in which the planet is either entirely frozen or is frozen to very low latitudes. The hypothesis has been resisted by some, on the grounds that there is no clear mechanism to reverse the condition.
Albedo
the fraction of solar energy (shortwave radiation) reflected from the Earth back into space. It is a measure of the reflectivity of the Earth’s surface. Ice, especially with snow on top of it, has a high albedo: most sunlight hitting the surface bounces back towards space.
Pannotia
a short-lived supercontinent that formed at the end of the Precambrian.
Gondwanaland
also called Gondwana; formed between 570 and 510 Ma ago. It included most of the southern land masses, including Antarctica, South America, Africa, Madagascar, and the Australian continent, as well as the Arabian Peninsula and India.
Laurasia
combines the names of Laurentia, the name given to the North American craton, and Eurasia. It contains most of the present northern hemisphere continents.
Variscan orogeny (or Hercynian)
is a mountain-building event caused by late Palaeozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea.
Anthropocene
the suggested name for the current geological epoch. The time during which human activity has been the dominant influence on climate and the environment. From the Greek anthropos meaning ‘human’.
Holocene
the present epoch, the last 11700 years. A relatively warm interglacial after the last major ‘ice age’. Sometimes (carelessly) referred to as recent.
