Finally, choose the best answer for why the mouth of the valley near the beach is flat (Segment C-D), while the streams above are steep and "V-shaped" (Segments A-B, B-C). Group of answer choices The streams further up the valley are steeper, and although they don't carry as much water, they have greater velocity and can erode more and larger material. The stream at the end of the valley near the beach is not as steep, so it slows and deposits stream material, filling the valley floor over time.. The stream near the beach are narrower, which means it can transport more water and erode the side walls faster, leading to a flattened valley. The streams up the valley have less velocity and thus less energy to transport material. The streams further up the valley are wider and carry more. Consequently, they carry more material from the landscape, eroding it away. The stream at the end of the valley near the beach is narrower and faster, so it can't carry as much, causing it to deposit the sediments and fill in the valley floor over time