1 Insertion â when a base is added to the sequence. 2  Deletion â when a base is deleted from the sequence.  Copy number variation (CNV) is a type of mutation where large chunks of DNA are inserted, repeated or lost. These regions of DNA can be between 10,000 and 5,000,000 bases long.
Wind deposition can result in dunes and loess deposits.
Sand dunes only form where the rate of beach deposition is greater than erosion (positive sediment budget). Sand Dunes on Flamborough Head. When the dried sand reaches the top of the beach it can be trapped by debris such as driftwood, dead seaweed or rocks and pebbles.idge and runnel systems are formed due to the interaction of tides, currents, sediments and the beach topography. They only form on beaches with a shallow gradient. They form as a simple drainage route for tides. Water flows in and out via the runnel.