This is the strategy of the archaeological campaign at Les Eyzies:

A horizontal latticework of pipes is constructed about ten feet above the ground to be excavated. Hanging plumb lines from this metal checkerboard, the archaeologist marks the ground off into orderly squares, two meters on a side. As objects are uncovered, he records their position relative to this grid system.

With the pipes in places, two parallel trenches are dug, about ten feet apart and three feet wide. These slices reveal the earth layers piled on top of one another, and the digging--a chore which falls on trained college and graduate students--proceeds horizontally from one trench to the other, one thin layer at a time. The digger usually pokes his way along with a large screw driver bent into a right angle. Occasionally he uses a spatula-like tool to skim off the dirt. As the work proceeds boards are placed down to prevent damage to the underlying stratum.

Keeping to one layer is fairly easy if its dirt has a distinctive color. Otherwise, the digger uses other criteria, for example the "feel" of the dirt-some layers are stickier or harder than others.

When an artifact appears, its position is measured. The object is then removed by hand--or, in the case of a fragile item, with a dental extractor--and tossed into a basket with three compartments: for bones, for flint, and for river stones and pebbles. The stones go to a geologist, the bones to a paleontologist, and the flint to an archaeologist. The pale botanist takes a sample of dirt from eastrata, which he centrifuges to recover the pollen grains of plants which grad around the rock shelter thousands years ago.

Two diggers work on each two-met square at a time; and it takes them to 40 hours to remove a cubic meter earth, depending on the wealth of are aeological material that is recovered.

Sub-Arctic Hunters

Up to now, the evidence that the scientists have brought to light document two Upper Palaeolithic hunting group who lived at the Abri Pataud a few thousands of years apart