Johanna Alida Coetzee | |
---|---|
Born | [1] Johannesburg, South Africa [1] | 7 July 1921
Died | 28 April 2007 85) | (aged
Alma mater | University of the Witwatersrand (MSc) University of the Free State (DSc) |
Known for | fossil pollen analysis |
Scientific career | |
Fields | Palynology |
Institutions | University of the Witwatersrand University of Natal University of the Free State |
Thesis | Pollen analytical studies in east and southern Africa. (1964) |
Johanna Alida Coetzee (1921 - 2007) (also known as Joey Coetzee) was a researcher in the field of Palynology at the University of the Free State and a pioneer in the analysis of fossil pollen. [2] Her DSc thesis received worldwide recognition and praise from the eminent glacial geologist Richard Foster Flint and helped recognise the significance of temperature changes in controlling shifts in global and local vegetation zones. [1]
Coetzee was born in 1921 in Johannesburg and was educated at the Jeppe High School for Girls. She completed a master's degree in Botany at the University of the Witwatersrand. She performed some postgraduate work at the University of the Witwatersrand and the University of Natal before moving to the University of the Free State where she was appointed as an assistant botanist in the Department of Botany in 1946. [1] [2] Coetzee made several overseas journeys where she studied with various experts in the field of botany, including a three-month period with Gunnar Erdtman, the pioneer of palynology. [2]
In the late 1950s and 1960s Coetzee travelled with her mentor, Eduard Meine van Zinderen-Bakker, in search of lakes and swamps that would be suitable for fossil pollen analysis, including such places as Mount Kenya in east Africa and the Lesotho Highlands in southern Africa. [1]
Coetzee served on several committees connected with the studies of the Quaternary period and palynology and from 1978 to 1988, she served as the editor of the journal Palaeoecology of Africa. [1]
The highlight of her career was the completion of the 33 000 year BP pollen sequence from Sacred Lake on Mount Kenya. This work formed part of her DSc thesis, entitled Pollen analytical studies in east and southern Africa and was featured in volume 3 of Palaeoecology of Africa and the Surrounding Islands and Antarctica. [3] Her work helped to show that glacial episodes were not confined to the Northern Hemisphere. The accepted view at the time was that high humidity Pluvial phases in the east African region, which did not experience glaciation, coincided with glaciations of the higher latitude regions. [4] Coetzee's research, in conjunction with van Zinderen Bakker, helped change these views by recognising the significance of temperature changes in controlling shifts in vegetation zones. [1] [2] [5] [6]
Her research in the 1970s and 1980s helped establish the importance of temperature changes in the history of African vegetation during the Quaternary and that ice ages were not wetter there. [2] It also clarified the history of the South African fynbos biome by tracing the origins of diverse fynbos vegetation, identified by fossil pollen to be types of Palmae, Winteraceae, Casuarinaceae, Chloranthaceae, and Sarcolaenaceae amongst others in Cenozoic deposits. [1] [2] The research also showed that during the Neogene period global cooling and Antarctic glaciation drove the replacement of subtropical woodlands by fynbos. [1]
Coetzee became a senior lecturer in Botany at the University of the Free State [7] and was later appointed a professor of Botany. She retired from the University in 1988. [1]
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: CS1 maint: location missing publisher (link)On retiring from the Department of Botany at the University of the Free State in 1988, Coetzee moved to Somerset West, Western Cape. She died on 28 April 2007. [1]
The Pleistocene is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek πλεῖστος (pleîstos) 'most' and καινός 'new'.
Palynology is the study of microorganisms and microscopic fragments of mega-organisms that are composed of acid-resistant organic material and occur in sediments, sedimentary rocks, and even some metasedimentary rocks. Palynomorphs are the microscopic, acid-resistant organic remains and debris produced by a wide variety of plants, animals, and Protista that have existed since the late Proterozoic.
The Last Glacial Period (LGP), also known as the Last glacial cycle, occurred from the end of the Last Interglacial to the beginning of the Holocene, c. 115,000 – c. 11,700 years ago, and thus corresponds to most of the timespan of the Late Pleistocene.
Winteraceae is a primitive family of tropical trees and shrubs including 93 species in five genera. It is of particular interest because it is such a primitive angiosperm family, distantly related to Magnoliaceae, though it has a much more southern distribution. Plants in this family grow mostly in the southern hemisphere, and have been found in tropical to temperate climate regions of Malesia, Oceania, eastern Australia, New Zealand, Madagascar and the Neotropics, with most of the genera concentrated in Australasia and Malesia. The five genera, Takhtajania, Tasmannia, Drimys, Pseudowintera, and Zygogynum s.l. all have distinct geographic extant populations. Takhtajania includes a single species, T. perrieri, endemic only to Madagascar, Tasmannia has the largest distribution of genera in Winteraceae with species across the Philippines, Borneo, New Guinea, Eastern Australia, and Tasmannia, Drimys is found in the Neotropical realm, from southern Mexico to the subarctic forests of southern South America, Pseudowintera is found only in New Zealand, and Zygogynum has species in New Guinea and New Caledonia.
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The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period, was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent 26,000 and 20,000 years ago. Ice sheets covered much of Northern North America, Northern Europe, and Asia and profoundly affected Earth's climate by causing a major expansion of deserts, along with a large drop in sea levels.
The Bramertonian Stage is the name for an early Pleistocene biostratigraphic stage of geological history the British Isles. It precedes the Pre-Pastonian Stage. It derives its name from Bramerton Pits in Norfolk, where the deposits can be found on the surface. The exact timing of the beginning and end of the Bramertonian Stage is currently unknown. It is only known that it is equivalent to the Tiglian C1-4b Stage of Europe and early Pre-Illinoian Stage of North America. It lies somewhere in time between Marine Oxygen Isotope stages 65 to 95 and somewhere between 1.816 and 2.427 Ma. The Bramertonian is correlated with the Antian stage identified from pollen assemblages in the Ludham borehole.
Microcachrys tetragona, known as creeping pine or creeping strawberry pine, is a species of dioecious conifer belonging to the podocarp family (Podocarpaceae). It is the sole species of the genus Microcachrys. The plant is endemic to western Tasmania, where it is a low shrub growing to 1 m tall at high altitudes. Its leaves are scale-like, arranged in opposite decussate pairs, superficially resembling those of the unrelated Diselma archeri (Cupressaceae). It shares the common name Creeping pine with several other plants. Females produce tiny, red, edible berries in summer.
The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma and is ongoing. Although geologists describe this entire period up to the present as an "ice age", in popular culture this term usually refers to the most recent glacial period, or to the Pleistocene epoch in general. Since Earth still has polar ice sheets, geologists consider the Quaternary glaciation to be ongoing, though currently in an interglacial period.
Johannes Iversen was a Danish palaeoecologist and plant ecologist.
The Weichselian glaciation is the regional name for the Last Glacial Period in the northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet that spread out from the Scandinavian Mountains and extended as far as the east coast of Schleswig-Holstein, northern Poland and Northwest Russia. This glaciation is also known as the Weichselian ice age, Vistulian glaciation, Weichsel or, less commonly, the Weichsel glaciation, Weichselian cold period (Weichsel-Kaltzeit), Weichselian glacial (Weichsel-Glazial), Weichselian Stage or, rarely, the Weichselian complex (Weichsel-Komplex).
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Eduard Meine van Zinderen Bakker was a Dutch-born South African palynologist who made significant contributions to the fields of plant ecology, palynology and palaeo-ecology of Africa.
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Elizabeth Marchant Truswell is a former Chief Scientist at the Australian Geological Survey Organisation and is known for her application of recycled palynomorph distribution as an indicator of sub-ice geology.
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