Google Earth reveals hundreds of geoglyphs in the desert, possibly 9,000 years old. For almost a century, aerial photographers have been documenting mysterious, millennia-old structures built from low walls of stone in the rocky lava fields, known as harrat, in Syria, Jordan, and Saudi Arabia. This desert region, blistered with volcanic mounds, is nearly devoid of life. But seen from above, the barren ground is covered with massive, interlocking geoglyphs that take the form of abstract arrow shapes called "kites" and rough rectangles called "gates." University of Western Australia archaeologist David Kennedy became interested in the structures after discovering how...