When the Sahara Was a Seaway

HOW SCIENTIFIC EVIDENCE EXPOSED THE WATERY PAST OF THE DRIEST PLACE ON EARTH.

- Devin A. Reese

Encompassing much of northern Africa, the Sahara Desert is well known as a scorching hot, dry place. Early European explorers, lacking experience in these harsh conditions, had a harrowing time exploring the Sahara. All too frequently, they never returned from their expeditions.

But the Sahara was not always a dry place. Believe it or not, 100 million years ago, the Sahara hosted a wetland teeming with aquatic life: fishes, turtles, crocodiles, and sharks! And many of these animals were gigantic.

Traces of a Seaway

How do we know the Sahara was a seaway? The Tuareg people, who are native to the Sahara Desert, first found traces of the wetland in fossil shells. The first published descriptions came from European scientists. And in 1850, a team of explorers, originally led by geologist Adolf Overweg, brought back sandstone from the central Sahara. Sandstone rocks typically form when layers of sand build up in lakes, rivers, or oceans.

Later that century, the Frenchman François Élie Roudaire came across natural basins that fill up and become small, salty lakes after rainfall. He wondered whether these "chotts" in the northern Sahara in Algeria were remnants of a channel to the sea. Roudaire teamed up with Ferdinand de Lesseps, the man famous for building the Suez Canal, which connected the Mediterranean Sea with the Red Sea in 1869. The two men envisioned bringing water in from the Mediterranean Sea through a 120-mile-long canal to farm the Sahara.

Recruiting engineers and businessmen, they went forward with surveys for the project. What they hadn't anticipated was a ridge of hard limestone that cut right across the canal's path. De Lesseps tried to convince people that the canal was still a good idea, but he never got enough support for the project.