Gerard De Geer facts for kids
Quick facts for kids
Gerard De Geer
|
|
|---|---|
 |
|
| Born | 20 November 1858 |
| Died | 24 July 1943 (aged 84) Stockholm, Sweden
|
| Citizenship | Swedish |
| Alma mater | Uppsala University |
| Known for | Varve geochronology |
| Children | Sten De Geer |
| Awards | Vega Medal (1915) Björkénska priset (1917) Wollaston Medal (1920) |
| Scientific career | |
| Fields | Quaternary geology |
| Institutions | Stockholm University |
| Doctoral students | Ernst Antevs |
Baron Gerard Jacob De Geer (20 November 1858 – 24 July 1943) was a Swedish geologist. He made very important discoveries about the Earth's history, especially about the most recent ice ages. De Geer is most famous for his work on varves. Varves are special layers of sediment that form each year in lakes. In 1890, De Geer was the first to name the ancient Baltic lake "Ancylus Lake". He was also part of a long scientific discussion about this lake.
Contents
About Gerard De Geer
Gerard Jacob De Geer came from a well-known Swedish noble family. His family had moved to Sweden in the early 1600s. Many people in his family were important business owners and politicians. His father, Louis Gerhard De Geer, and older brother, Gerhard Louis De Geer, both served as the Prime Minister of Sweden. The Prime Minister is the head of the government in Sweden.
Gerard Jacob was born on October 2, 1858, in Stockholm. His father, Baron Louis Gerhard de Geer, was the first Minister of Justice in the Swedish government. His mother was Carolina de Geer. Gerard studied at primary school starting in 1869, and then at Stockholm gymnasium from 1873. In 1877, De Geer went to Uppsala University. He graduated in May 1879 with a Bachelor of Arts degree.
In 1878, De Geer started working for the Geological Survey of Sweden. This is a government group that studies the Earth's geology. At first, he worked as a freelancer, meaning he was paid for specific tasks. Then, in 1882, he became an assistant geologist, and by 1885, he was a full-time geologist. During this time, he began studying the landforms and deposits left behind by the last ice age in southern Sweden. In 1897, he left this job to become a professor of geology at Stockholm University.
In 1882, De Geer joined a Swedish trip to Spitsbergen. This was part of the first International Polar Year, a time when scientists from different countries studied the polar regions. This trip started his many years of research on the glaciers in the Svalbard area. He went on six trips to Svalbard in total (1882, 1896, 1899, 1901, 1908, and 1910).
Gerard de Geer taught geology at Stockholm University from 1897 to 1924. He also served as the university's leader, called a rector, from 1902 to 1910. After that, he was the vice-chancellor from 1911 to 1924. Besides his university work, De Geer was also a member of the Parliament of Sweden, which is like the country's main law-making body, from 1900 to 1905.
A big moment in De Geer's science career was becoming the president of the 10th International Geological Congress. This was a large meeting of geologists from around the world, held in Stockholm in 1910. He helped plan the meeting and then led the main committee. At the congress, he gave a very important speech called "A geochronology of the last 12000 years." He started by saying, "Geology is the history of the earth, but hitherto it has been a history without years."
At this meeting, De Geer officially introduced the word "varve". He said a varve is any layer of sediment that forms each year. He also suggested that the term "geochronology" should only be used for dating things using varves. Other methods were not as exact. Scientists saw that varves were connected to how glaciers melted and that varve patterns could be matched across different places. This showed that varves really did represent yearly deposits. Before the congress, De Geer also led a trip for 65 scientists from 14 countries. They explored the Dicksonfjorden in Spitsbergen.
De Geer's Discoveries
De Geer's early studies looked at old raised beaches. These are former beaches that are now higher than the sea. He used them to understand how the land rose after the heavy ice sheets melted. He also mapped moraines, which are piles of rocks and dirt left by glaciers. This helped him figure out how far the last Scandinavian ice sheet reached and how it melted. The special type of moraine he studied is now called a De Geer moraine.
However, De Geer is most famous for finding varves and being the first to use them to tell time in geology. This is called geochronology.
In 1878, while working in the field, De Geer noticed something interesting. He saw that the layered sediments in lakes near melting glaciers looked a lot like tree rings. In his most famous book, 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."
Other scientists had noticed this similarity before. But De Geer was the first geologist to see how useful this discovery could be. He called these yearly layers of sediment "varves." Throughout the 1880s, he kept working on his idea. He published a short summary of his discovery in 1882. Then, he gave a presentation to the Swedish Geological Society in 1884. It wasn't until the International Geological Congress in 1910 that De Geer's important work became known to scientists around the world.
The Swedish Time Scale
In 1897, De Geer became a professor of geology at Stockholm University. He later became the university's president from 1902 to 1910. With help from many students, De Geer started to connect shorter varve sequences in southeast Sweden. He put them together like puzzle pieces to create a very long, year-by-year timeline of how the glaciers melted during the Lateglacial period.
The city of Stockholm was growing, which was perfect for De Geer. Many construction sites dug into the ground, showing clear layers of lake sediments from the Baltic Sea basin. De Geer and his team used these sites to study the varves. They also found sediments along the Angermanalven River that allowed them to extend the timeline even further, into the early Holocene period. This varve timeline was called the Swedish Time Scale. Soon, geologists outside Sweden, like Matti Sauramo in Finland, started using varved sediments to build their own detailed timelines of glacial melting.
Geochronologia Suecica Principles
In 1940, De Geer published his longest and most famous book, Geochronologia Suecica Principles. In this book, he shared many details of the Swedish Time Scale. He also explained his ideas and work about varves.
Soon after the book came out, other geologists started studying varves. They found more sites, and the Swedish Time Scale was updated many times.
However, interest in varves around the world started to fade. There was a disagreement between De Geer and another scientist named Ernst Antevs. Also, new dating methods like radiocarbon dating became available. These new methods made varves seem less important for a while.
De Geer passed away 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 Honors
De Geer's important work in geology was recognized in the United Kingdom. The Geological Society gave him the Wollaston Medal in 1920. The Royal Society also made him a foreign member in 1930. An ancient sea in what is now Canada was named the DeGeer Sea in his honor.
The Swedish Antarctic Expedition (1901–1904) named a glacier on South Georgia Island after De Geer. This island is in the southern Atlantic Ocean. Later, the British renamed this glacier Harker Glacier after an English geologist named Alfred Harker.
The valley of De Geerdalen in Spitsbergen, Svalbard, is also named after him.
De Geer's Legacy
De Geer's biggest contribution to science was finding varves. He also realized how useful they could be for creating yearly timelines of past climate and environmental changes. The Swedish Time Scale was the most accurate geological timeline of its time. Scientists are still improving and adding to it today.
De Geer believed that the thickness of varves could tell us about past climate. This idea has been proven true to some extent. However, the connection between varve thickness and weather conditions is more complex than he first thought. Varves have become popular again recently. New methods and techniques have made them even more useful. Varves are now often used to check and improve radiocarbon dating timelines.
In many ways, De Geer's questions are similar to what modern geologists and palaeoclimatologists (scientists who study past climates) ask today. He understood the need for detailed records of past changes. He also knew it was important to see if global changes happened at the same time everywhere. De Geer's main mistake was believing too strongly in "teleconnections." This meant he thought his findings were always linked to his existing ideas. He also believed that changes in the sun's energy caused all climate change, which has since been shown to be incorrect. Still, De Geer asked the right questions. His errors were more due to his great excitement and passion than 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. (1940), Geochronologia Suecia Principles .K.Svenska Vetenskapsakad. Handl.
