Grand Erg Oriental follow the wind's direction. There are other types of dunes, as well as "complex" dunes. Saharan winds are also known to clear an area of sand altogether, leaving bare rock (hamada) or gravel (reg). The "Grand Erg Oriental" is accessible overland by an Algerian road, which goes south from Constantine. It passes through the Aurès mountains, then salt lakes by the city of Biskra. Next the road skirts the western edge of the erg. After about 500 km. in all, it reaches the ancient oasis of Ourgla [Wargla]. Since late antiquity Wargla was a stop for the Saharan trade, being
What Love Is Made Of does best, albeit slightly more polished around the edges". He finally wrote that "the result is more than enough to keep our obsession rolling through yet another summer stretch". Sam Lansky from Idolator believed that the song had potential to become a "club hit" and named it the "biggest thing she’s recorded to date", while like other critics, highlighting Katy's vocals. Commercially, "What Love Is Made Of" fared well on European charts. It stayed two weeks at the UK Singles Chart, where it peaked at number 21. On its component chart, the UK Dance chart, its peak was higher, at