Rivers have three sections or courses: the upper course, middle course and lower course. The upper course of a river typically sees much erosion of bedrock in order to achieve the equilibrium mentioned above.
The upper course is also at the highest altitude as this is where the headwaters of the river originate. Rivers in the upper course erode down vertically which often creates a steep channel profile in what becomes the river valley.
The middle course sees a river at a slightly lower altitude than the upper course, but is still maintains a sense of trying to acquire equilibrium in flow and shape. The discharge and velocity of the river still allows the water to erode the banks and chart a course of least resistance through lateral erosion.
The lower course is unique as this is the stage in which a river has reached sea level. Here we find features not found in the middle and upper courses like floodplains and river deltas that have been formed by the sediment deposits of rocks and dirt gathered from upstream.
2. Sediment B quartz sand forms when rocks first break apart
Explanation:
Limestone is a carbonate rock that sedimentary in origin that is often made up of skeletal body parts of freshwater organisms such as corals, and mollusks, etc.
Major material of mineral calcite. That are different crystal forms of calcium carbonate CaCO3. It's colorless or white, also gray, yellow, green. And chemically dissolves to form an acid.
Calcite may form in substance to the response of organisms which result in sulfate dependent and when methane is oxidized. They have existed on earth primarily in forms of calcium carbonate in marine waters low magnesium calcite.