Birth of the Glacial Theory

James S. Aber
Emporia State University

Early Concepts of Glaciation

The glacial theory was developed in the early 1800s in the mountains of western Europe. Jean de Charpentier and Jens Esmark, as well as many other natural scientists, are credited with initial discoveries and development of the concept that glaciers had formerly expanded over larger areas. No single person invented the idea (Cunningham 1990).

In Scandinavia, Jens Esmark concluded in 1824 that glaciers had once been much larger and thicker, and had covered much of Norway and the adjacent sea floor. He attributed erratic boulders and moraines to glacial transportation and deposition. He also recognized that glaciers were powerful agents of erosion that had carved out the Norwegian fjords (Cunningham 1990).

View eastward along Sørfjorden, near Bergen, western Norway. Esmark was first to recognize the glacial origin of deep fjord valleys. Photo date 5/87, © J.S. Aber
Late winter view down the Aletsch Glacier in the Swiss Alps. This is the largest glacier in the Alps today. Note the two skiers (small dots) in lower portion of scene. Photo date 4/79, © J.S. Aber

In the early 1830s, Jean de Charpentier began to marshall the scientific evidence for former alpine glaciation. He observed moraines, striations, and erratics, as well as existing glaciers of the Swiss Alps, and presented his conclusions in a very persuasive manner (Teller 1983). His ideas initially met with much skepticism, but his work eventually became quite influential. During this time interval, scientists generally held two contradictory views about how to explain the past development of the Earth.

  1. Catastrophism -- Earth had suffered a series of great catastrophies, each of which completely reformed the surface of the Earth and caused extinction of all life. Totally new and fully developed forms of life appeared spontaneously during the period of stability that followed each catastrophy. The latest catastrophy was a great flood--the biblical deluge.

  2. Uniformitarianism -- Earth's features were gradually formed in a "uniform" manner by the same processes now in operation: erosion, sedimentation, volcanism, etc. Life had developed continuously by slow evolution. Cataclysms or catastrophies had not taken place.

One of those, who at first disbelieved de Charpentier, was Louis Agassiz, a famous Swiss zoologist. Through his own observations, Agassiz came to accept the concept of former alpine glaciation, and then carried the idea much further. In 1837 he proposed that vast sheets of ice had once covered much of the northern hemisphere. This was a radical suggestion, for at that time the modern ice sheets in Greenland and Antarctica were completely unknown. Agassiz was a highly energetic and controversial naturalist, speaker, and writer. He travelled widely and popularized the idea of a geologically recent ice age as the latest catastrophy in Earth history.

Agassiz undertook detailed studies of glacier movement in Switzerland in the 1840s, and he influenced James D. Forbes, a Scotch physicist, to begin similar glaciological research in the French Alps. Forbes established that glaciers move in part by internal "viscous" (plastic) deformation, in contrast to the more popular dilatation or regelation theories of the day (Cunningham 1990). Agassiz and Forbes were initially close friends, but they became bitter enemies over questions of priority and integrity in their glaciological discoveries.

By the mid-1800s, the glacial theory existed at three levels of acceptance.

  1. Alpine glaciers -- Modern glaciers in the Swiss Alps and Norway had once extended farther down their valleys than today = uniformitarian process, local events (Forbes).

  2. Mountain ice caps -- Glacier cover in the Swiss Alps and Norway had once been much thicker (or mountains higher) so that ice caps formed and spread into adjacent regions = extended uniformitarian process, regional events (Esmark and de Charpentier).

  3. Continental ice sheet -- Vast sheet of ice spread from the Arctic and covered all of Europe as far south as the Mediterranean (also in North America) = global catastrophy and biological extinctions (Agassiz).

The glacial theory was initially opposed by a sizeable number of natural scientists, who prefered to interpret landscape features as the results of a great biblical flood. Some glacial deposits in former marine areas do, in fact, contain fossil shellfish. During the next few decades, those who opposed the glacial theory were either converted or died. The effects of glacial erosion and deposition were observed widely in Europe, the British Isles, and in North America. By the end of the 19th century, the glacial theory had been refined and was firmly established.

Greenland Ice Sheet

During the 1800s, the Arctic region was the focus of intense scientific and commercial exploration activity, as various groups sought to find a "northwest passage" from Europe to Asia. Greenland was part of this picture, and coastal portions of the large island were visited by many expeditions. Access to the interior was blocked by glaciers and snow. Several attempts to penetrate inland using conventional techniques (horses and wagons) failed miserably. Knowledge of Greenland was so inadequate that some geographers thought the interior might be a lush, warm oasis!

The first expedition to cross the Greenland Ice Sheet was led by Fridtjof Nansen, a Norwegian, along with five companions. They succeeded in 1888, where others had earlier failed, by adapting winter travel techniques of the Lapps and Eskimoes. They used skis and snowshoes and pulled light-weight sleds with their equipment and supplies. Nansen's expedition proved conclusively that Greenland is covered by an ice sheet, and thereby confirmed Agassiz's daring proposal made half a century earlier. Another Norwegian explorer, Roald Amundsen, was the first person to reach the South Pole in 1911.

By the end of the 19th century, real opposition to the glacial theory was gone, and new evidence for multiple glaciations was beginning to emerge. Both in Europe and in North America four or more glacial periods separated by interglacial episodes were identified. So the ice ages took on a cyclic character, which is still the subject of much scientific research and debate. The global catastrophy of Agassiz was discarded in favor of the regional approach first put forth by Esmark and de Charpentier.

References


Return to Louis Agassiz.
GO 521 © J.S. Aber (2003).