Geographical origins of ancient civilizations

(This is an unfinished knol)

Background:
- The first human civilizations originated at Tropic of Cancer.
- Most land area in tropic of cancer is desert or semi-desert area.
- There are three main types of plate boundaries, convergent, divergent and transform fault. It is interesting to note that,
+ Masopotamia originated along Euphrates-Tigris rivers flowing from mountain chains, created as a result of transform plate boundary.
+ Indus Civilizations originated along Indus-Ganges rivers, flowing from mountain chains, created as a result of convergent plate boundary.
+ Ancient Egyptian Civilization originated along Nile river, flowing from mountain chains as a result of divergent plate boundary.

Tropic of Cancer:
It is an imaginary line, runs around the globe at 23.5 degree of equator in northern hemisphere. In tropic of cancer, the sun is directly overhead at noon, on 21st June and 21 August. It is the hot and arid zone. The seasonal changes is slight year around. Why tropic of cancer is hot and dry with less seasonal change. Just a glance on the atmospheric currents makes clear everything.

Diagram Source: http://mynasadata.larc.nasa.gov/images/AtmosphCirc2.png
If you look at diagram above, the winds take the humdity of the tropics and carry them to northern temperate regions and middle equatorial regions and so cause raining in those regions. In simple words the winds from temperate and equatorial regions steal humidity of tropics and turn these regions into desert or semi-arid regions.

Geography of ancient civilizations:

It is not accidental that earliest human civilizations, Mesopotamia, Indus valley civilization and Egyptian Civilizations were emerged on the Tropic of Cancer. In the second phase the next two major civilizations, Chinese and earliest Greek ones appeared in the vicinity of Tropic of Cancer further north. In third phase, human spread southward towards equator but still kept distance from equator. Certainly there is a deep correlations with increasing abilities of human and choosing areas to inhabit.

Image Source:
https://qed.princeton.edu/getfile.php?f=Ancient_Civilizations_of_the_Old_World_3500_to_after_600_BCE.jpg

Image Source:http://blue.utb.edu/paullgj/geog3320/lectures/map_of_ancient_civilizations.gif

How Plate tectonics influenced origin of earliest human civilizations?
The current positions of continents, landscapes, water bodies on the continents and oceans are the result of the plate tectonic activities over 4.5 billion years. It is interesting to note how plate tectonics have influenced the evolution of human civilizations. If we look to tectonics of areas where earlies human civilizations emerged, we see a close correlation between rivers flowing out from moutain chains and direct sun in arid areas, with less precipitation or with seasonal precipitations. The Collision of Indian Plante with Eurasian Plate created Himalayan mountain chian which is the source of Indus river and river valley civilization. Similarly, the Collision of Arabian Plate with Eurasian Plate created the Zagros mountain chain, Makran Mountain Chains and also Eastern Anatolian transform fault. The Eastern Anatolian Transform fault is the source of Three river systems, Aras, Euphrates and Tigris. The south flowing Tigris and Euphrates river created Euphrates valley which is the cradle of human civilization. It is not only collisions that create large mountain chains and rivers to support human civilization but divergent of plates also create valleys and river systems to support human civilization. One classic example is that of Ancient Egyptian Civilization. East African Rift has created largest lake of African continent (Lake Victoria) and longest river system on the earth, the Nile river.

East Anatolian Transform Fault (Between Arabian Plate and Anatolian Block)

Image Source:http://neic.usgs.gov/neis/eq_depot/2003/eq_030501/neic_tgac_anaflt.gif

Image Source: http://neic.usgs.gov/neis/gifs/iran_plates.gif

Image Source: http://pubs.usgs.gov/gip/dynamic/graphics/FigS8-2.gif
Northward drift of Indian Plate and Collision of with Eurasian Plate created Himalayan mountain chians.

Image Source:
http://itac.glp.net/uganda_ptc/sst/unit%209/images/The%20Eastern%20Africa%20Rift%20Valley.gif

The East African Rift is a divergent Plate boundary which is dividing the African Plate and also creating a new ocean (Along Red Sea: Red Sea is expanding and Persian Gulf is closing). East African Rift is creating several Lakes, most notably is the largest lake of African continent (Lake Victoria) and the most important river system, Nile River.