Answer:
gravity
Explanation:
streams erode dirt and rocks, transport the sediment, and redeposit it in new locations shaping the earths surface into a system of stream valleys. streams now flow downhill due to the force of gravity
Creole is a primary language
I think this would be the Great Wall of China!
although it's actually thought to be much, much longer: over 5000 miles long, if yoiu include natural defensive barriers used in it.
The code of Hammurabi was an important document in the evolution of laws