ADOLF MORLOT: THE MEASURE OF QUATERNARY TIME

Around the shores of Lake Geneva in Switzerland are a succession of terraces, at levels of about 50, 100, and 150 feet, formed when the lake stood at higher levels. Where swift-running streams descend from the surrounding mountains into the lake, they form cone-shaped deltas as they rapidly deposit their burden of sediment in the still lake water.

In September 1856 the builders of the railroad along the south shore of Lake Geneva made a cutting through the elevated cone-shaped delta of La Tinière, a stream entering the lake at Villeneuve. Adolf Morlot, a young geologist at Lausanne, recognized the potential of the cutting to expose an historical record of the formation of the delta. Over the next several years he studied its sides intensively. At a depth of about four feet from the top, Morlot found a layer representing a former surface soil. It contained fragments of Roman pottery and a Roman medal, indicating that it dated from about the third century AD. At a depth of ten feet was another former soil layer, containing charcoal, bone fragments, and a fragment of Bronze-Age pottery. Morlot calculated that if four feet of sediment had accumulated in the delta since Roman times, the ten-foot Bronze-Age level must be about 3,800 years old. This was the first measure of the antiquity of the Bronze Age in Europe. Danish archaeologists had recognized the succession of Stone, Bronze, and Iron ages among their antiquities, but they had no means of determining their length in prehistoric times.

In 1857 Sir Charles Lyell met Morlot at Lausanne and was fascinated by his discoveries at La Tinière. Lyell encouraged Morlot to continue with his estimates. Continued deepening of the cutting at Villeneuve revealed a still lower Stone-Age surface which Morlot estimated to be 6,700 to 7,000 years old.

In 1861 Morlot calculated an age of 10,200 years for the modern cone of La Tinière, but behind and above it was an older cone, roughly ten times larger, about 100,000 years old. The modern cone had formed since the last glacial period, the older cone before it. Morlot recognized two successive glacial deposits alternating with alluvial sediments.