Because they are not man made and are part of the earth's natural features caused by the the weathering and erosion of the earth.
        
             
        
        
        
Because the rock making up continental plates is generally lighter and less dense than oceanic rock, it is too light to get pulled under the earth and turned into magma. Instead, a collision between two continental plates crunches and folds the rock at the boundary, lifting it up and leading to the formation of mountains and mountain ranges. 
<span>At some convergent boundaries, an oceanic plate collides with a continental plate. Oceanic crust tends to be denser and thinner than continental crust, so the denser oceanic crust gets bent and pulled under, or subducted, beneath the lighter and thicker continental crust. This forms what is called a subduction zone.
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Answer: The speed of the earth as it travels around the sun is 67,000 m / ph (107,000 km / h).
Explanation:
The orbit around the sun forms an ellipse and it takes approximately 365.25 days to fully around the orbit, because of that on earth the seasons are experienced throughout the year, as the earth recedes or gets closer to the sun. In addition to the orbit around the sun, the earth rotates on its own axis in about 24 hours giving rise to day and night.
I hope this information can help you.
 
        
                    
             
        
        
        
They are based on Islam or Christianity