January 3, 2011 | 3
"It has already been said, that no small part of the present work refers to the nature and phenomena of glaciers. It may be well, therefore, before proceeding to details, to explain a little the state of our present knowledge respecting these great ice-masses, which are objects of a kind to interest even those who know them only from description, whilst those who have actually witnessed their wonderfully striking and grand characteristics can hardly need an inducement to enter into some inquiry respecting their nature and origin."
James, D. Forbes (1900): "Travels Trough the Alps." [page 17]
Today glaciers are studied worldwide and monitored as climate proxies, and the recent measurements show that almost all of them are retreating fast. The story about glaciers, their influence on the landscape and their possible use to reconstruct and monitor climate is an intriguing one, with many triumphs, setbacks and changes of mind.
For centuries, if not even millennia, the high-altitude belts of mountain ranges were regions visited and travelled by man, however, they were also haunted and forbidding places. The glaciers, masses of ice enclosing peaks and extending their tongues into valleys, were considered the residence of mountain spirits, then during the medieval times the prison of damned souls (the Italian poet Dante Alighieri 1265-1321 imagined the centre of hell as a frozen wasteland) and the playground of demons, who from time to time send avalanches and debris flows into the valley.
Despite these myths there were some early insights of what glaciers actually really are made of. The Greek historian and geographer Strabo (63 BC – 23AD) describes a voyage trough the Alps during the reign of Augustus and mentions:
"…there is no protection against the large quantities of snow falling, and that form the most superficial layers of a glacier…. It’s a common knowledge that a glacier is composed by many different layers lying horizontally, as the snow when falling and accumulating becomes hard and crystallises…."
However the knowledge got lost, and was only rediscovered during the Renaissance. The Italian Leonardo da Vinci (1452-1519) is considered one of the greatest Renaissance-geniuses. He studied anatomy, biology and geology, however regarding the glaciers of the Alps his ideas were somehow confused, as he thought glaciers were formed by un-melted hail accumulating through the summer. But soon the study of nature experienced an incredible rise, and glaciers found place in various descriptions of travelling scholars.
Between 1538 and 1548 glaciers were labelled (even if not depicted) with the term "Gletscher" on topographic maps of Switzerland, and in 1574 the Swiss Theologian Josias Simler describes the Rhone-glacier in his travel account.
The first historic depiction of a glacier is considered the watercolour-paint of the Vernagtferner in the Ötztaler Alps from 1601. The Vernagtferner was a glacier that repeatedly dammed up the Rofen-lake (named after the Rofen-valley), which outbursts caused heavy damage and loss of property, particularly in the years 1600, 1678, 1680, 1773, 1845, 1847 and 1848.
In 1642 the Swiss editor Matthaeus Merian the Elder in his "Topographie Helvetiae, Rhaetiae et Valesiae" published various copper engravings of glaciers, and in 1706 Johann Heinrich Hottinger was interested to explain the motion of "the mountains of ice" in his "Descriptio Montium Glacialium Helveticorum."
The Swiss naturalist Johann Jakob Scheuchzer, visiting in the year 1705 the Rhône Glacier, published his observations of the "true nature of the springs of the river Rhône" in the opus "Itinera per Helvetiae alpinas regiones facta annis 1702-1711", and confirms the idea that glaciers are formed by the accumulation of snow and they move and flow.
Fig.1. The description of the Rhone glacier according to Scheuchzer´s "Itinera per Helvetiae alpinas regiones facta annis 1702-1711", the engraving shows the "false springs at the mountain Furca" (M, N, O – left and right of the picture) and the "true springs" (J, K, L) coming from the snout of the "great glacier" (A-F), surrounded by the "small glacier" (G, H) (photo by D. BRESSAN).
The increasing interest to study glaciers in the Alps is also encouraged by enthusiastic travel reports; in his "Voyage pittoresque aux glaciers" the A.C. Bordier of 1773 describes the Bosson glacier as a "huge marble ruins of a devastated city".
The Swiss naturalist Horace Benedict de Saussure (1740-1799) was fascinated by the mountains of his homeland and an enthusiastic climber. After 1760 he travelled more than 14 times trough the Alps (considering the possibilities in this time an extraordinary achievement) to explore valleys and mountains. In the years 1767 to 1779 the first volume of his "Voyages dans les Alpes" was published, where he collected his observations and theories about the visited glaciers. He recognized moraines and large boulders as the debris accumulated by the glacier and proposed to map them to determine the former extent of glaciers. Despite this exact statement, de Saussure failed to connect large boulders found in the foreland of the mountains to the glaciers of the Alps. He assumed that these rocks were transported on their recent locations by an immense flood. Such a flood seemed to explain why most of the boulders found scattered around the plains of Germany came in first place from the regions of Scandinavia, where the same rocks were found in outcrops. The flood-theory worked lesser to explain the rocks in the foreland of the Alps – to transport such boulders the flood had to reach 1000s of meters in height and cover entire mountains.
Despite these problems, the idea of a flood as the explanation for "glacial" deposits in Europe became largely accepted. It seemed also to fit the description of the biblical flood. Even Lyell and Darwin assumed that huge erratic boulders were transported by swimming ice drafts on top of a flood wave.
That glaciers could propagate far out of their valleys was however not an unusual idea for local inhabitants, who observed and experienced the growth and recess of glaciers. In academic circles this approach was a little more difficult.
A contest thought to demonstrate the former extension of Swiss glaciers initiated by the Swiss pastor Jakob Samuel Wyttenbach in 1781 (maybe inspired be the advance of the Alpine glacier in 1770) didn’t arise any interest:
"Could it be proven to ourselves on the available documentation that both by the progress of our ice mountains as by our misbehaviour once for pasture most suitable land is currently covered by ice…"
There were only careful speculations considering a former expansion of glacier: the geologists James Hutton (1726-1797) and his friend John Playfair (1748-1819) speculated about glaciations of the Northern hemisphere. In 1826 a publication by the Danish mineralogist and mountain climber Jens Esmark (1763-1839) was translated into English. In this paper Jesmark discussed the possibilities that glaciers were much greater in the past then today. J.D. Forbes and Robert Jameson (who were the geology professors of Charles Darwin at Edinburgh University – Darwin in his autobiography of 1876 remembers "The sole effect they produced on me was the determination never as long as I lived to read a book on Geology or in any way to study the science.") discussed glacial theories during their lectures. And even Buckland, who still in 1831 argued "northern region of the earth seems to have undergone successive changes from heat to cold", in 1837 was converted to Lyell’s uniformitarianism and considered that sudden changes, like an ice age and glacier expansion, simply don’t happen in geology.
In 1815 the Swiss Jean Pierre Perraudin, a chamois hunter in the Val de Bagnes, discussed with the engineer Ignatz Venetz his theory of former glaciers covering the entire valley. Impressed by such an idea Venetz begun to map geological features that made him recognize that not only the Val de Bagnes was once covered by ice, but even the entire Switzerland. Vernetz´s lecture at the assembly of the Swiss Association for Natural History in 1829 found little interest for his proposal: only Jean de Charpentier, director of the salt mine in the city of Bex (Western Switzerland), who 14 years earlier had meet Perraudin, got interested in this new theory.
Charpentier himself begun a detailed mapping project, and in 1834 presented before the Swiss Association the results of his investigations, but again the Ice Age theory arouse much criticism. One of the critics in the public was a former student of Charpentier, named Jean Louis Rodolphe Agassiz, a young, but respected palaeontologist by the establishment. Charpentier invited Agassiz to visit the city of Bex and surrounding mountains, to observe glaciers and test the theory of former glaciers covering valleys by own investigations.
In the year 1837 Agassiz held an enthusiastic lecture about glaciers, ice ages and ice shields, and in 1840 published a detailed study of modern glaciers, their deposits and their spurs in his "Etudes sur les glaciers."
Agassiz experienced the same scepticism as many other ice-age proponents before. His friend, the German geographer Alexander von Humboldt, wrote in a letter to Agassiz (2. December 1837):
"I think that you should concentrate your moral and also your pecuniary strength upon this beautiful work on fossil fishes …. In accepting considerable sums from England, you have, so to speak, contracted obligations to be met only by completing a work which will be at once a monument to your own glory and a landmark in the history of science …[ ]…No more ice, not much of echinoderms, plenty of fish…"
However Agassiz didn’t surrender to the criticism so easily, and decided to use his connections to the most important geologist of the time. Soon he could persuade William Buckland and later Charles Lyell, and after that most respected geologist got convinced, the rest, as always, was history:
"advice – never try & persuade ye world of a new theory – persuade 2 or 3 of ye tip top men – & ye rest will go with ye stream, as Dr B. did with Sir H. Davy and Dr. Wollaston in case of Kirkdale Cave"
Edward Jackson, about an advice given by his professor Buckland in 1832 (BOYLAN 1998)
Fig.2. Reconstruction of the glacier that filled the valley of St. Amarin (southern Vosges, France), probably the first tentative reconstruction of an ice age glacier – from COLLOMB (1847): "Preuves de l´existence d´anciens glaciers dans les vallées des Vosges." (Foto by D. BRESSAN).
Agassiz’ intense research on the Unteraar-glacier in Switzerland established the foundations of glaciology; he recorded the dimension of the glacier, his velocity and even ventured inside the glacier by passing trough a glacial mill.
Soon after, the measurements methods introduced by Agassiz were carried out on various glaciers of the Alps and repeated nearly every year.
Fig.3. The Hintereis-glacier (in the centre of the picture), Hochjoch-glacier (left) and the Kesselwand- glacier in the Austrian Alps, drawing by Schmetzer in 1891. The Hintereis-glacier is one of the glaciers with the longest active monitoring program, values about his length change reach back to 1848, since then the glacier lost 3km of his tongue. Original caption: "Aus den tiroler Alpen: Der Abschluß des Oetzthales mit dem Hochjochgletscher (links), dem Hintereisferner (in der Mitte) und dem Kesselwandferner (rechts oben). Nach der Natur gezeichnet von K. Schmetzer (1891)." (Foto by D. BRESSAN).
Fig.4. Glaciers of the Ötztaler Alps, at the border region of Italy-Austria, satellite image by NASA (WMS Global Mosaic, Landsat 7), and temperature rise (from 1760 to 2007) in the Alps and length loss of some of the glaciers depicted in the image in the period 1910-1990. The green line shows temperature variations at the meteorological station of Lake Schwarzsee (Sölden, 2.800m a.s.l., after PSENNER 2008), red is the mean value of summer, and blue mean value for winter measured for the entire Alps (after BÖHM 2008). The large glaciers, with their tongues extending in the valleys, showed the strongest retreat and degradation of the studied Austrian glaciers, up to 40m only in the years 2007-2008 (diagram by D. BRESSAN).
These records showed various fluctuations, but from 1850 onward a general trend of recession of glaciers in the Alps is observable. This trend has experienced a strong increase in the last 50 years, causing concern for the fast change in the landscape, the destabilisation of the rock walls once supported by the melting glaciers and the alteration of the discharge and hydrology of mountain ranges, not to mention the lost of aesthetic value of the “ruins of ice.”
BÖHM, R. (2009): Klimarekonstruktion der instrumentellen Periode – Probleme und Lösungen für den Großraum Alpen. Klimawandel in Österreich – Alpine space – man & environment, vol. 6: 145-164
BOYLAN, P.J. (1998): Lyell and the dilemma of Quaternary glaciation. Geological Society, London, Special Publications 143: 145-159.
KRÜGER, T. (2008): Die Entdeckung der Eiszeiten – Internationale Rezeption und Konsequenzen für das Verständnis der Klimageschichte. Wirtschafts-, Sozial- und Umweltgeschichte Bd., Schwabe Verlag: 619
PSENNER, R. (2008): Wasser aus den Alpen – Globaler Wandel – regionale Anpassung. Ist es der Sindtfluss? – Alpine space – man & environment, vol. 4: 25-30
ZRYD, A. (2008): Eine kleine Geschichte der Gletscher. Die Alpengletscher im Klimawandel. Haupt-Verlag, Bern: 140
About the Author: David Bressan is a freelance geologist based in the European Eastern Alps. He graduated with a project on Rock Glaciers dynamics and hydrology in the Ötztal-Alps, this phase left a special interest for quaternary deposits and modern glacial environments. Following the traces, studying old maps and reading historic reports on glaciers he became interested in the development of geomorphologic and geological concepts by naturalists and geologists trough time, so he combines curiosity, field trips and old depictions to blog about the History of Geology.
The views expressed are those of the author and are not necessarily those of Scientific American.