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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.
The mass of Earth's oceans is estimated to be 1.37 × 10 21 kg, which is 0.023% of the total mass of Earth, 6.0 × 10 24 kg. An additional 5.0 × 10 20 kg of water is estimated to exist in ice, lakes, rivers, groundwater, and atmospheric water vapor. [20] A significant amount of water is also stored in Earth's crust, mantle, and core.
Generally, the age is estimated based primarily upon the age of any mountains it dissects; the age of the sea or ocean to which it eventually outflows can be irrelevant; for example, several rivers of the east side of the Appalachian Mountains are thought to be older than the Atlantic Ocean into which they flow. If a river fully dissects a ...
There were two major oceans in the Carboniferous: the Panthalassa and Paleo-Tethys. Other minor oceans were shrinking and eventually closed the Rheic Ocean (closed by the assembly of South and North America), the small, shallow Ural Ocean (which was closed by the collision of Baltica , and Siberia continents, creating the Ural Mountains) and ...
The latter two are sub-divided into several eras as currently defined. In total, the Precambrian comprises some 85% of geological time from the formation of Earth to the time when creatures first developed exoskeletons (i.e., hard outer parts) and thereby left abundant fossil remains.
Mesopotamian cities became self-run civil governments. One of the cities within this civilization, Ur , was the first literate society in history. Eventually, they constructed irrigation systems to exploit the two rivers, transforming their dry land into an agriculturally productive area, allowing population growth throughout the cities and ...
The De Virga world map was made by Albertinus de Virga between 1411 and 1415. Albertin de Virga, a Venetian, is also known for a 1409 map of the Mediterranean, also made in Venice. The world map is circular, drawn on a piece of parchment 69.6 cm × 44 cm (27.4 in × 17.3 in). It consists of the map itself, about 44 cm (17 in) in diameter, and ...
The Clean Air Act is passed in the United States, with subsequent amendments in 1970, 1977 and 1990. 1974 World population reached 4 billion. [23] 1970s 2010s Deindustrialization occurs in the Midwest and then much of the United States, as manufacturing industries (and their pollution) move to China and other Asian countries. 1980