Central Sahara, Libya
The Libyan Desert is considered to be the most arid part of the Sahara. Moisture is almost non existent and only a few oasis exist. This part of the Sahara is typically sand sheets and large sand dunes reaching up to 400ft in height. The desert is a mixture of sand, stony plains and rocky plateaus.
In North east to central Sahara the star dune makes up 23% of the desert. They dominate the Grand Erg Oriental in the Sahara, which covers the countries Algeria, Tunisia, and Libya. They from in response to multi-directional strong winds. In the Grand Erg they reach an enormous size and show a preferential positioning at the nodes of crossing trends formed from linear dunes. They are 2640 feet to 5280 feet around and they can reach heights of up to 500-800 feet. (The Exploratorium)
Star Dunes approximately 3000feet around.
Another type of dune that is found in the central Sahara is the Dome dune. These are oval or circular mounds. They are rare and occur a the far upward margins of sand seas. (usgs).