Hello satishgsk !.... nice work on these fabolous places around the world !... I live in Chile and I notice some posts about Driest place on Earth "Atacama Desert" (that in fact it is !).. and huge earthquake measured at Valdivia City (9.5 Richter) :-)
Any way, I'm writing to complain a post about the Highest San Dune on earth... I really don't know how it was measured the Isaouane-n-Tifernine in Algeria.... also , What is a "dune" anyway ?... I'm doing this question because I know a sand dune formation at Nazca - Perú called "CERRO BLANCO" that has 2000 meters altitude above sea level and the "base" of the sand is at 1200 meters above sea level, so the vertical "height" of the dune could be the difference = 800 meters !!!... but that isn't the important thing :-) .. because the real matter is that you can acctually do a 1300 meters continue ride on a sandboard !!!
Here goes a link about Cerro Blanco where you can check how big is this "dune" ?...