Gerard De Geer
Encyclopedia
Baron Gerard Jacob De Geer (1858-1943) was a Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...

 who made significant contributions to Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...

 geology, particularly geomorphology
Geomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...

 and geochronology
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

. De Geer is best known for his discovery of varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

s.

Early life and family

De Geer was born in Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, on October 2, 1858. His family, originally Dutch nobility who had emigrated to Sweden in the early seventeenth century, included prominent industrialists and politicians. Both De Geer's father (Louis De Geer) and older brother were Prime Minister of Sweden
Prime Minister of Sweden
The Prime Minister is the head of government in the Kingdom of Sweden. Before the creation of the office of a Prime Minister in 1876, Sweden did not have a head of government separate from its head of state, namely the King, in whom the executive authority was vested...

, and De Geer himself was a member of the Swedish Parliament
Parliament of Sweden
The Riksdag is the national legislative assembly of Sweden. The riksdag is a unicameral assembly with 349 members , who are elected on a proportional basis to serve fixed terms of four years...

 from 1900 to 1905.

De Geer's discovery of varves

De Geer graduated from Uppsala University
Uppsala University
Uppsala University is a research university in Uppsala, Sweden, and is the oldest university in Scandinavia, founded in 1477. It consistently ranks among the best universities in Northern Europe in international rankings and is generally considered one of the most prestigious institutions of...

 in 1879, after joining the Swedish Geological Survey the previous year, and began what was to be his life's work studying the late Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...

 deposits and landforms of southern Sweden. De Geer's early studies of raised beach
Raised beach
A raised beach, marine terrace, or perched coastline is an emergent coastal landform. Raised beaches and marine terraces are beaches or wave-cut platforms raised above the shore line by a relative fall in the sea level ....

es, used to reconstruct glacio-isostatic
Isostasy
Isostasy is a term used in geology to refer to the state of gravitational equilibrium between the earth's lithosphere and asthenosphere such that the tectonic plates "float" at an elevation which depends on their thickness and density. This concept is invoked to explain how different topographic...

 sea level changes, and his mapping of glacial moraine
Moraine
A moraine is any glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or it may have...

s to reconstruct the extent of the last Scandinavian ice sheet and its pattern of deglaciation (the particular type of moraine he studied is now referred to as De Geer moraine), were well-received. However, De Geer is most famous for discovering varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

s and pioneering their use in geochronology
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

.

During fieldwork in 1878, De Geer noticed that the appearance of laminated sediments deposited in glacial lakes at the margin of the retreating Scandinavian ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...

 at the end of the last ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

, closely resembled tree-rings
Dendrochronology
Dendrochronology or tree-ring dating is the scientific method of dating based on the analysis of patterns of tree-rings. Dendrochronology can date the time at which tree rings were formed, in many types of wood, to the exact calendar year...

. In his best known work Geochronologia Sueccia, published in 1940, De Geer wrote "From the obvious similarity with the regular, annual rings of the trees I got at once the impression that both ought to be annual deposits" (1940, p.13).

While this observation was not new, De Geer was the first geologist to exploit its potential application. De Geer called these annual sedimentary layers varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

s and throughout the 1880s further developed his theory, publishing a brief outline of his discovery in 1882, which he followed with a presentation to the Swedish Geological Society in 1884. It was not until 1910, at the International Geological Congress, that De Geer's pioneering work reached the wider international scientific community.

The 1910 International Geological Congress

In 1910, the eleventh International Geological Congress was held in Stockholm. In addition to presenting his research on varves, De Geer presided over the congress. De Geer began his paper "A geochronology of the last 12000 years" by writing "Geology is the history of the earth, but hitherto it has been a history without years." At the congress De Geer formally introduced the term varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

 defining it as any annual sedimentary layer, and also proposed that the term geochronology
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

 be restricted to varve dating, other existing techniques being less accurate and precise.

By then, observations of the stratigraphic
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

 relationship between varved sediment and recessional moraine
Moraine
A moraine is any glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or it may have...

s, and the correlation of varve sequences between geographically distant sites, added more compelling evidence to De Geer's essentially circumstantial speculation. The geological community accepted that it was unlikely that the couplets were unlikely to represent any period other than the year.

The Swedish Time Scale

In 1897 De Geer was appointed professor of geology at Stockholm University
Stockholm University
Stockholm University is a state university in Stockholm, Sweden. It has over 28,000 students at four faculties, making it one of the largest universities in Scandinavia. The institution is also frequently regarded as one of the top 100 universities in the world...

, and went on to become the university's president from 1902-1910. With the help of numerous students from both Stockholm and Uppsala, De Geer began to piece together short, but overlapping, varve sequences in south east Sweden to create a longer year-by-year chronology of glacial retreat for the Lateglacial period. The urban expansion of Stockholm provided perfect conditions for De Geer and his colleagues, who made good use of numerous exposures of laminated sediment in the many pits and cuttings that exposed the glacial lake sediments of the Baltic basin. Estuarine sediments exposed along the valley of the Angermanalven River, allowed De Geer to further extend the chronology into the early Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

.The resulting varve chronology was called the Swedish Time Scale, and geologists outside Sweden soon followed suit using varved sediments to build high-resolution chronologies of glacial retreat, most notably Matti Sauramo in Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

.

Global expeditions, teleconections, and controversy

De Geer firmly believed the main control on varve sedimentation was solar radiation acting on glacier meltwater production, and that consequently, varved sediments represented a "..gigantic, natural self-registering thermograph" (De Geer 1926) and varve curves (varve thickness plotted against varve number or year), which he often referred to as 'solar curves', a reliable proxy
Proxy (statistics)
In statistics, a proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained...

 for past changes in solar radiation. Ultimately, De Geer hoped his studies of varves would explain the fundamental cause of Ice Ages - "If the last glaciation everywhere should show to be synchronous and the origin of the last Ice Age thus to be of a general nature, the assumption of a cosmic cause would scarcely be avoidable."

In 1915 De Geer matched, or 'teleconnected', varve curves from Sweden to varve curves from Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

 and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

. This first attempt at long distance correlation marked the start of two decades travelling around the world by De Geer and his colleagues, searching out varve sequences for potential teleconnections. In 1920, De Geer travelled to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 with his wife and two assistants, Ernst Antevs, and Ragnar Liden. Antevs remained in North America at the end of the trip, where he worked on the North American varve chronology. Further trips included Erik Norin's visit to the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...

 (1924 - 1925), Erik Nilsson's visit to East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 (1927-28), and Carl Caldenius' visit to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 (1925-1929), and later New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 (1932-34).

However, by the mid 1930's De Geer's teleconnections had become the subject of increasing criticism from his former student Ernst Antevs. Antevs correctly argued that the teleconnections were bad science, and that De Geer's Trans-Atlantic correlations were inaccurate. De Geer felt his position was being caricatured and intentionally misunderstood by Antevs, but did little scientifically to rebuff the criticisms levelled at him.

In 1924 De Geer retired from teaching and became the founder-director of the Geochronological Institute at Stockholm University
Stockholm University
Stockholm University is a state university in Stockholm, Sweden. It has over 28,000 students at four faculties, making it one of the largest universities in Scandinavia. The institution is also frequently regarded as one of the top 100 universities in the world...

.

Geochronologia Suecica Principles

In 1940, De Geer published his longest and best know work Geochronologia Suecica Principles, in which he presented part of the Swedish Time Scale in detail, and expounded upon his theories and work regarding varves.

Almost immediately after the publication of Geochronologia Suecica Principles De Geer's Swedish Time Scale underwent the first of many revisions, as other geologists became involved in the study of varves and more sites were examined.

However, international interest in varves diminished. The bitter dispute between De Geer and Antevs, coupled with the advent of new dating techniques, most importantly radiocarbon dating
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...

, showed varves in a bad light.

De Geer died in Stockholm on July 24 1943. His wife, Ebba Hult De Geer, continued to publish his work, and add to it, into the 1950s.

Awards and recognition

De Geer's contributions to geology were recognised in the UK, where the Geological Society awarded De Geer the Wollaston Medal
Wollaston Medal
The Wollaston Medal is a scientific award for geology, the highest award granted by the Geological Society of London.The medal is named after William Hyde Wollaston, and was first awarded in 1831...

 in 1920, and the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

 elected De Geer a foreign member in 1930. The ancient DeGeer Sea in modern-day Maritime Canada was named in his honour.
The Swedish Antarctic Expedition
Swedish Antarctic Expedition
The Swedish Antarctic Expedition was led by Otto Nordenskjöld and Carl Anton Larsen.-Background:Otto Nordenskjöld, a Swedish geologist and geographer, organized and lead a scientific expedition of the Antarctic Peninsula...

 (1901-1904) named a glacier on South Georgia Island
South Georgia and the South Sandwich Islands
South Georgia and the South Sandwich Islands is a British overseas territory and overseas territory of the European Union in the southern Atlantic Ocean. It is a remote and inhospitable collection of islands, consisting of South Georgia and a chain of smaller islands, known as the South Sandwich...

 in the southern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 after De Geer. The British would later rename the glacier Harker Glacier
Harker Glacier
Harker Glacier is a tidewater glacier on South Georgia Island in the southern Atlantic Ocean. Harker glacier was first mapped by the Swedish Antarctic Expedition , and named De Geer Glacier, after Gerard De Geer , a Swedish geologist who specialized in geomorphology and geochronology...

 after a contemporary English
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 geologist, Alfred Harker.

De Geer from a modern perspective

De Geer's most significant contribution to Quaternary science was unquestionably the identification of varves, and his recognition of their potential in establishing annual chronologies of past climatic and environmental change. The Swedish Time Scale was the most precise and accurate geological timescale of its day, and it is still being improved and added to today. His insistence that varves represented quantifiable proxies for past climate has since been borne out to a degree, but the relationship between varve thickness and hydrometeorological conditions is not as simple as he presumed. Varves have recently experienced a renaissance as methods and techniques of study have improved, and varves are now regularly used to calibrate radiocarbon timescales.

In many ways, De Geer's concerns mirror that of modern Quaternary geologists and palaeoclimatologists, particularly his recognition of the need for high-resolution natural archives of past change, and the importance of testing whether global change is synchronous. De Geer's principle failing was his faith in teleconnections, where his findings were clearly influenced by his preconceptions. His belief that variations in solar radiation were the principal agent of all climate change has also since been shown to be incorrect. Nevertheless, De Geer asked all the right questions, and his errors can be attributed as much to over-enthusiasm and a single-minded passion, as they can to bad science.

Selected English language works

  • De Geer, G. (1912), A geochronology of the last 12000 years. Congr. Géol. Int. Stockholm 1910, C.R., 241-253.
  • De Geer, G. (1921), Correlation of late-glacial clay varves in North America with the Swedish timescale. Geol. Förhandl., Stockholm 43 70-73.
  • De Geer, G. (1926), On the solar curve as dating the Ice Age, the New York moraine and Niagara falls through the Swedish time scale. Geogr. Annaler. (Stockholm) 8 253-284.
  • De Geer, G. (1927), Late glacial clay varves in Argentina measured by Dr. Carl Caldenius, dated and connected with the solar curve through the Swedish time scale. Geogr. Annaler (Stockholm) 9 1-8.
  • De Geer, G. (1934), Geology and geochronology. Geogr. Annaler (Stockholm) 1 1-52.
  • De Geer, G. (1935a), Dating of the Ice Age in Scotland. Transactions of the Glasgow Geological Society, 19 335-339.
  • De Geer, G. (1935b), Dating of Late-Glacial clay varves in Scotland. Proceedings of the Royal Society of Edinburgh, 55 23-26.
  • De Geer, G. (1935), Teleconnections contra so-called telecorrelations. Geol. Fören. Förhandl. Bd 57. H.2. 341-346.
  • De Geer, G. (1940), Geochronologia Suecia Principles .K.Svenska Vetenskapsakad. Handl.

Biography

  • Spjeldnaes, N. (1972) pp.329–330 in Gillispie, C. C. (Ed.) Dictionary of Scientific Biography, American Council of Learned Societies, Charles's Scribner's Sons Publishers New York ISBN 0684101165.

External links

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