Overview
The Sahara is the largest hot desert in the world, covering approximately 9.2 million square kilometers across North Africa. It stretches from the Atlantic Ocean in the west to the Red Sea in the east, and from the Mediterranean Sea in the north to the Sahel savanna in the south. The desert spans parts of eleven countries.
Geography and Physical Features
Contrary to popular imagination, only about 20 percent of the Sahara consists of sand dunes, known as ergs. The remaining terrain includes vast gravel plains called regs, rocky plateaus called hamadas, mountains, salt flats, and dry valleys called wadis. The highest point is Emi Koussi in Chad, a volcanic peak rising to 3,415 meters.
Significance
The Sahara has been a barrier and a bridge between sub-Saharan Africa and the Mediterranean world for millennia. Trans-Saharan trade routes carried gold, salt, and other goods across the desert by camel caravan for over a thousand years, supporting wealthy empires such as Mali and Songhai. Rock art across the desert shows that it was once a much greener region.
Notable Facts
Temperatures in the Sahara can exceed 50 degrees Celsius during the day but plunge below freezing at night. The desert is roughly the size of the contiguous United States. Sahara sand is carried by winds across the Atlantic and helps fertilize the Amazon rainforest with mineral-rich dust deposits.