Jakob Sederholm
Encyclopedia
Jakob Johannes Sederholm (1863–1934) was a Finnish
petrologist
most associated with his studies of migmatite
s.
Troubled by illness throughout his life, Sederholm originally chose to study geology
to allow him to work outdoors. After studying first in Helsinki
(where he was a student of Fredrik Johan Wiik
), then in Stockholm
and Heidelberg
, Sederholm returned to Finland to work for the Geological Survey of Finland
. In 1893 he assumed the role of director of this institution, a post he occupied until his death forty years later.
Working on local Precambrian
basement rock
s, Sederholm instigated a map-making
programme that, between 1899 and 1925, published many maps and descriptions of their geological history. Gneiss
es in the areas he studied (the so-called Baltic Shield
) were often of mixed composition, with layers of granitic
rock being interleaved
with metamorphic rock
. Sederholm termed these as migmatite
s, and viewed them as the product of the intrusion
of igneous
magma
into metamorphic rocks at depth.
During his career Sederholm received both the Murchison Medal
from the Geological Society of London
(1928) and the Penrose Medal
from the Geological Society of America
(also 1928). The mineral sederholmite is named in his honour.
Aside from his geological work, Sederholm was a member of the Diet of Finland
, and undertook missions from this to the League of Nations
. He was also a member and chairman (twice) of the Economic Society of Finland.
In the 1974 historical novel
Centennial
, James Michener
listed Sederholm among those scientists who made early estimates of the age of the Earth
. Sederholm's estimate was 40 million years.
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...
petrologist
Petrology
Petrology is the branch of geology that studies rocks, and the conditions in which rocks form....
most associated with his studies of migmatite
Migmatite
Migmatite is a rock at the frontier between igneous and metamorphic rocks. They can also be known as diatexite.Migmatites form under extreme temperature conditions during prograde metamorphism, where partial melting occurs in pre-existing rocks. Migmatites are not crystallized from a totally...
s.
Troubled by illness throughout his life, Sederholm originally chose to study geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
to allow him to work outdoors. After studying first in Helsinki
Helsinki
Helsinki is the capital and largest city in Finland. It is in the region of Uusimaa, located in southern Finland, on the shore of the Gulf of Finland, an arm of the Baltic Sea. The population of the city of Helsinki is , making it by far the most populous municipality in Finland. Helsinki is...
(where he was a student of Fredrik Johan Wiik
Fredrik Johan Wiik
Fredrik Johan Wiik, also known as F.J. Wiik was a Finnish geologist and mineralogist; in 1877, he was named the first professor of geology and mineralogy at the Imperial Alexander University of Finland , where his students included Jakob Sederholm...
), then 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...
and Heidelberg
Heidelberg
-Early history:Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907; with scientific dating, his remains were determined to be the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of...
, Sederholm returned to Finland to work for the Geological Survey of Finland
Geological survey
The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information....
. In 1893 he assumed the role of director of this institution, a post he occupied until his death forty years later.
Working on local Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
basement rock
Basement Rock
Basement or Basement Rock music was a sub-genre coined in 2006 in an article by music magazine TGR. This was first in relation to the existence of underground record label Criminal Records but more for the independent bands they represent. The roots of the sub-genre are noted to be as far back as...
s, Sederholm instigated a map-making
Cartography
Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively.The fundamental problems of traditional cartography are to:*Set the map's...
programme that, between 1899 and 1925, published many maps and descriptions of their geological history. Gneiss
Gneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...
es in the areas he studied (the so-called Baltic Shield
Baltic Shield
The Baltic Shield is located in Fennoscandia , northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton...
) were often of mixed composition, with layers of granitic
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
rock being interleaved
Interleaving
In computer science and telecommunication, interleaving is a way to arrange data in a non-contiguous way to increase performance.It is typically used:* In error-correction coding, particularly within data transmission, disk storage, and computer memory....
with metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
. Sederholm termed these as migmatite
Migmatite
Migmatite is a rock at the frontier between igneous and metamorphic rocks. They can also be known as diatexite.Migmatites form under extreme temperature conditions during prograde metamorphism, where partial melting occurs in pre-existing rocks. Migmatites are not crystallized from a totally...
s, and viewed them as the product of the intrusion
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
of igneous
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
into metamorphic rocks at depth.
During his career Sederholm received both the Murchison Medal
Murchison Medal
An award established by Roderick Murchison, who died in 1871. One of the closing public acts of Murchison’s life was the founding of a chair of geology and mineralogy in the University of Edinburgh. Under his will there was established the Murchison Medal and geological fund to be awarded annually...
from the Geological Society of London
Geological Society of London
The Geological Society of London is a learned society based in the United Kingdom with the aim of "investigating the mineral structure of the Earth"...
(1928) and the Penrose Medal
Penrose Medal
The Penrose Medal was created in 1927 by R.A.F. Penrose, Jr. as the top prize awarded by the Geological Society of America to those who advance the study of geoscience.-Award winners:* 2011 Paul F. Hoffman* 2010 Eric J. Essene* 2009 B. Clark Burchfiel...
from the Geological Society of America
Geological Society of America
The Geological Society of America is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in New York in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitchcock, John R. Proctor and Edward Orton and has been headquartered at 3300 Penrose...
(also 1928). The mineral sederholmite is named in his honour.
Aside from his geological work, Sederholm was a member of the Diet of Finland
Diet of Finland
The Diet of Finland , was the legislative assembly of the Grand Duchy of Finland from 1809 to 1906 and the recipient of the powers of the Swedish Riksdag of the Estates....
, and undertook missions from this to the League of Nations
League of Nations
The League of Nations was an intergovernmental organization founded as a result of the Paris Peace Conference that ended the First World War. It was the first permanent international organization whose principal mission was to maintain world peace...
. He was also a member and chairman (twice) of the Economic Society of Finland.
In the 1974 historical novel
Historical novel
According to Encyclopædia Britannica, a historical novel is-Development:An early example of historical prose fiction is Luó Guànzhōng's 14th century Romance of the Three Kingdoms, which covers one of the most important periods of Chinese history and left a lasting impact on Chinese culture.The...
Centennial
Centennial (novel)
Centennial is a novel by American author James A. Michener, published in 1974.Centennial traces the history of the plains of northeast Colorado from prehistory until the early 1970s. Geographic details about the fictional town of Centennial and its surroundings indicate that the region is in...
, James Michener
James A. Michener
James Albert Michener was an American author of more than 40 titles, the majority of which were sweeping sagas, covering the lives of many generations in particular geographic locales and incorporating historical facts into the stories...
listed Sederholm among those scientists who made early estimates of the age of the Earth
Age of the Earth
The age of the Earth is 4.54 billion years This age is based on evidence from radiometric age dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and lunar samples...
. Sederholm's estimate was 40 million years.
External links
- Biographical entry (Encyclopedia Britannica)
- Murchison Medal winners (Geological Society of London)
- Penrose Medal winners (Geological Society of America)
- Sederholmite mineral data (Mindat.orgMindat.orgMindat.org is a non-commercial online mineralogical database, claiming to be the largest mineral database and mineralogical reference website on the internet....
) - Sederholmite mineral data (WebMineral.com)