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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 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.
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 ...
While they were sailing west around the Southern tip of Africa, it was found that the Sun was to their right (the north). This is thought to have been a key trigger in the realization that the Earth is spherical, in the classical world. In the 4th century BC the Greek explorer Pytheas traveled through northeast Europe, and circled the British ...
Pomponius is unique among ancient geographers in that, after dividing the Earth into five zones, of which two only were habitable, he asserts the existence of antichthones, people inhabiting the southern temperate zone inaccessible to the folk of the northern temperate regions due to the unbearable heat of the intervening torrid belt.
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 ...
So to understand how we came to exist on planet Earth, we'll need to know how Earth managed to stay fit for life for billions of years. Earth has been habitable for billions of years ...
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