Describe the evolution of an erosional floodplain from a mountain stream. Explain the processes that take placeto change the landscape.Your response should be at least 200 words in length. Selected Answer:Erosional floodplains start in a simple mountain stream, as the water over time starts eroding the land it flows across the valley floor starts widening. From a continuousside to side motion it eventually creates a v-shaped valley eroding the walls on each side. Once a stream cuts closer to the base level downward erosion becomes less dominant. The streams channel takes on a meandering pattern and more and more of its energy is directed side to side creating valley widening. In time the lateral erosion creates a broader flat valley floor. This is called a flood plain meaning when a river overflows its banks during a flood stage it inundates the floodplain. The flood plain will widen to a pointthat the stream is eroding the valley walls in afew places. In certain areas of the Mississippi River valley the distance from one wall to the other can exceed (100) miles. The Yellowstone River is another good example of an erosional floodplain, with a very well defend V-shape valley. Having both waterfalls and rapids the river is continuously downcutting into the bedrock in which the stream channel is cutting resistant beds. So, in conclusion the base process starts with mountain streams creating narrow v-shaped valleys, eroding down until the valley walls widen creating a well enveloped flood plain.