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.
Physical features of the Sahara Desert. Some geographical features of the Sahara are sand dunes, dry valleys, salt flats, and several mountain ranges, some of which are volcanic. The Sahara has a number of physical features, including ergs, regs, hamadas, and oases. Ergs cover 20% of the Sahara.