Rivers

• Upper course


  steep = water pushed downwards , onto the bed = vertical erosion
• middle course


  Flatter = water spreads sideways = lateral erosion
• Lower course 


  slows down = less energy = deposition
• 4 Types of erosion :
• Attrition - when sediment is carried along the riverbed, it will eventually hit larger rocks which causes smaller particles to become worn down into finer material.
• Abrasion - when sediment is carried by the river and collides with other objects, such as boulders, causing them to wear away over time.
• Hydraulic action - when fast flowing water hits an object it exerts pressure on that object, this can cause rocks to break apart or be moved.
• Solution - this type of erosion happens when soluble (dissolvable) rocks come into contact with acidic or alkaline water. The water then dissolves these rocks, removing them from their original location.
• Deposition - When a river slows down, its velocity decreases and the load becomes too heavy to carry any further. This results in the deposition of sediments on the floodplain.
• Hydraulic Action


  The pressure exerted by fast-flowing water on an object, causing it to break apart or move.
• Erosion


  The process of wearing away or removal of material from the Earth's surface by natural forces, such as wind, water, or ice.
• Attrition


  The wearing down of rocks through physical friction and abrasion, often caused by the transfer of energy from one rock to another.
• Abrasion


  A specific type of attrition where rocks are worn down through the rubbing and grinding of sediment particles against them.