This map shows the chain of highlands and mountain ranges that University of Utah geologists Royhan and Nahid Gani dub "the Wall of Africa." Higher elevations are shown in reddish tones and lower ...

Now, millennia later, a "Great Green Wall" may rise in Africa to deter another ... Saharan sands by 2025 (explore an interactive Sahara map). Trees are almost always formidable foes against ...