Answer:
It's the 4th, as third is modified by the man.
Explanation:
- The Third atmosphere was a rearrangement of the plate tectonics and the evolution of atmosphere by the transferring of it to the oceanic basins. As the amount of oxygen in the atmosphere used to be more than 30% around 280 million years ago than the present.
- Rapid development of land plants and animals was caused due to this atmosphere and hence this atmosphere is now less than 21% and due to his influence or modification of man with his technological tools and techniques.
- The atmosphere is rapidly shrinking due to the greenhouse effect and global warming that is leading to the fifth atmosphere that may be like that of mars as devoid of gases and barren and dry with oceans running under the crust.
Central America is bordered by Mexico to the north, Colombia to the southeast, the Caribbean Sea to the east, and the Pacific Ocean to the west and south!!!!!!!!
Answer:
<u><em>River valley civilizations</em></u>
Explanation:
They were centred around various river valleys as their main source of livelihood and the flourished only due tiote river valley on which they were based. Like the harappan in Indus Valley, The yellow river (Huang He), the Mesopotamia around Tigris and Euphrates and the egyptian Nile.
Sand, rocks, and sediment could be carried(erosion) by wind and water
