Iwill give brainlest! 20 points! need answer asap, .what can you assume about the layers in areas 2 and 4? (pic showed below)the layers were originally horizontal. the layers were deposited in a river bed. the layers formed from sand dunes. the layers formed in a marine environment. pls me!

The greatest gift the sumerians gave the world was the invention of writing. the sumerians were wealthy people. they needed some way to keep track of what they owned. they began drawing pictures. they used a reed as a pen. they drew on soft pieces of clay. the soft clay was then dried in the sun. the tablet became a permanent record. later, the sumerian drawings changed into wedge-shaped symbols. this kind of writing is called cuneiform. by putting symbols together, the sumerians could write entire sentences.