Diggers

The shaggy men of the Old Stone Age had their industrial centers too, and one of them was in central Tanganyika, Africa. Last week Anthropologist F. Clark Howell of the University of Chicago told about extracting thousands of stone tools from what was once a lake bed in the Southern Highlands. The site was discovered in 1951 by a Johannesburg school principal, but not much was done about it until last summer when Dr. Howell arrived with a small expedition (his wife and two graduate students) and hired 35 natives at $1.50 a week to dig.

At 5,800-ft. altitude a gully 60 ft. deep had cut through alternating layers of sandstone and clay. The clay was barren but the sandstone was stuffed with stone tools. Five thousand square feet of the highest sandstone layer yielded 117 stone cleavers, 157 axes, 48 scrapers, hundreds of other tools and weapons. In the three highest sandstone layers, the tools were all made of mylonite, a fine-grained igneous rock; the fourth layer contained tools of quartz, and among them were bones of strange animals: a giant hippopotamus, pigs 6 ft. tall, and a short-necked giraffe-like creature with antlers.

After digging for several months, Dr. Howell figured out why the ancient lake was so popular with ancient man. About 10,000 years ago, he thinks, Tanganyika had a capricious climate. During rainy periods, the lowland plains and valleys were good places to live. Animals preferred them to the hills, and ancient human hunters stayed near the animals. The upland lake was deep during rainy periods, and its bottom collected a layer of clay, but it had no attraction for man.

After hundreds of thousands of years of this, the climate grew drier. Tanganyika's lowlands turned arid. The upland lake shrank, but it did not disappear. Up from the hungry plains trooped the animals, and soon ancient men moved in with them. For centuries they lived on the beaches, chipped their razor-sharp weapons and fed on the animals. When the rains came again, animals and men trooped back to the plains. This alternation seems to have happened four times; then the lake went dry. The shaggy men, the giant hippos, the giant pigs and the antlered giraffes abandoned it forever.

In England the masterwork of Stone Age men is getting long-needed maintenance, using the most modern methods. In spite of clamor from indignant traditionalists, Britain's Ministry of Works intends to reerect one of the massive trilithons (three-stone arches) of prehistoric Stonehenge on Salisbury Plain. It fell in 1797 after staying upright for perhaps 3,000 years, and there are accurate drawings that show it unfallen. The ministry will not reerect other trilithons that fell in Roman times or earlier, but it sees nothing false about restoring Stonehenge to its 18th century condition.

Fearing the indignation of the British public if the ancient stones were damaged during restoration, the ministry is taking no chances. One stone, 4 ft. thick and weighing 45 tons, was known to have cracks, but no one knew whether they went deep enough to weaken the stone so it would break if lifted. To find out, the ministry called on Britain's atomic research station at Harwell. The scientists put 24 grams of sodium carbonate in a reactor and exposed it to neutrons until it became fiercely radioactive. They took it to Stonehenge by truck, put it in a rabbit-size burrow under the great stone and left it there for 36 hours while its gamma rays felt for cracks. If the cracks were really serious, they would show on photographic films placed on top of the stone.

The films showed nothing at all, indicating that the ancient stone was fairly sound. A lifting cradle was built around it and a powerful crane hoisted it gingerly out of the ground, doing in a few minutes the job that a tribe of skin-clad men had done with panting slowness 3,000 years ago.

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