The Gregory Rift ( Ufa la Gregori , in Swahili ) is the eastern branch of the East African Rift fracture system. The rift is being caused by the separation of the Somali Plate from the Nubian Plate , driven by a thermal plume . Although the term is sometimes used in the narrow sense of the Kenyan Rift , the larger definition of the Gregory Rift is the set of faults and grabens extending southward from the Gulf of Aden through Ethiopia and Kenya into Northern Tanzania , passing over the local uplifts of the Ethiopian and Kenyan domes. Ancient fossils of early hominins , the ancestors of humans, have been found in the southern part of the Gregory Rift.
36-644: The Gregory Rift is named in honour of the British geologist John Walter Gregory who explored the geology of the rift in 1892–93 and 1919. The Gregory Rift lies within the Mozambique belt , often considered to be the remains of an orogenic system similar to the Himalayas. This belt runs from Ethiopia through Kenya, Tanzania and Mozambique . The rift is widest at the northern end in the Afar region, narrowing to
72-475: A Political Factor . The lecture contained as its abstract: The three primary racial groups within the human species are the Caucasian, mongoloid and negroid. From analogy with cross-breeding in animals and plants, and from experience of human cross-breeding, it can be asserted that inter-marriage between members of the three groups produces inferior progeny. Hence racial segregation is to be recommended. However,
108-623: A few kilometers in northern Tanzania, then splaying out in the North Tanzania Divergence. The Gregory Rift has shoulders rising over 3,000 metres (9,800 ft) above sea level, 1,000 metres (3,300 ft) above the inner part of the graben. The Tanzanian portion includes Mount Kilimanjaro , the highest mountain in Africa, and the huge caldera of Ngorongoro In the Crater highlands This portion also contains Ol Doinyo Lengai ,
144-489: A series of parallel faults". The mineral gregoryite , first found in the Great Rift Valley, is named after him. Like many other intellectuals and writers during the 1920s, Gregory held Scientific Racist views based on Galtonism and the belief that opposition to cross-breeding in animals could be applied to miscegenation. In 1931, with Sir Arthur Keith, he delivered the annual Conway Hall lecture entitled Race as
180-582: Is about 80 kilometres (50 mi) wide and bordered on both margins by large, discontinuous normal faults that give rise to major tectonic escarpments separating the rift floor from the surrounding plateaus. These faults are now thought to be inactive at the northern rift valley termination, whereas to the south they are still tectonically and seismically active. The rift floor is cut by a series of smaller en echelon, right-stepping, rift basins of Quaternary to recent age. These basins are about 20 kilometres (12 mi) wide and 60 kilometres (37 mi) long. In
216-525: Is an interesting account of a journey to Mount Kenya and Lake Baringo made in 1892–3. Gregory was the first to mount a specifically scientific expedition to the mountain. He made some key observations about the geology which still stand. He made the first known attempt to climb the mountain, penetrating the montane forest zone and climbing past the Afro-alpine moorland to the glaciers, rocks and snow. The Gregory Glacier, of which little now remains, on
252-929: The Archives of the University of Glasgow (GUAS) . Main Ethiopian Rift The Great Rift Valley of Ethiopia , (or Main Ethiopian Rift or Ethiopian Rift Valley) is a branch of the East African Rift that runs through Ethiopia in a southwest direction from the Afar Triple Junction . In the past, it was seen as part of a " Great Rift Valley " that ran from Mozambique to Syria . Known for its scenery and diverse wildlife in Ethiopia specifically
288-670: The Miocene Period along the East African rift system. Rift initiation was asynchronous along the Ethiopian rift valley: deformation began around 18 million years ago at the south end, around 11 million years ago close to the Afar depression and probably around 6-8 million years ago in the central sector. The rift is extending in an ESE-WNW direction at about 5–7 millimetres (0.20–0.28 inches) annually. The Ethiopian rift valley
324-757: The geography and geology of Australia and East Africa. The Gregory Rift in the Great Rift Valley is named in his honour. Gregory was born in Bow, London , the only son of a John James Gregory, a wool merchant, and his wife Jane, née Lewis. Gregory was educated at Stepney Grammar School and at 15 became a clerk at wool sales in London. He later took evening classes at the Birkbeck Literary and Scientific Institution (now Birkbeck, University of London ). He matriculated in 1886, graduated BSc with first-class honours in 1891 and D. Sc. (London) in 1893. In 1887, he
360-715: The lithosphere may have thinned below the Gregory rift, although based on basalt geochemistry the lithosphere is at least 75 kilometres (47 mi) thick below the south of Kenya. The Gregory rift is oriented NS, and in the past the minimum horizontal tectonic stress direction was EW, the direction of extension. The alignment of rows of small vents , cones , domes and collapse pits in the Suswa , Silali and Kinangop Plateau regions support this theory. However, data from oil and gas exploration wells in Kenya, vents in volcanic shields to
396-617: The volcanic and earthquake centres of the Andes . The expedition, sponsored by the Royal Geographical Society in London, made the first geological traverse of the central Andes of Peru. His boat overturned and he was drowned in the Urubamba River in southern Peru on 2 June 1932. One of his companions on this expedition was the diplomat, artist and author Victor Coverley-Price who painted extensively whilst on
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#1732772795743432-433: The 1930s and collecting material that has led to the site being recognized as an important center of early hominin occupation. Volcanism and rifting started in Kenya in the northern region of Turkana between 40 and 35 million years ago and then spread north and south. To the south volcanism and rifting happened together, first in other parts of northern Kenya around 30 million years ago, then around 15 million years ago in
468-741: The Advancement of Science which met at Dunedin in January 1904. The Mount Lyell Mining Field, Tasmania , was published in 1905. This does not give a complete impression of Gregory's activities in Australia, for he was director of the Geological Survey of Victoria from 1901, in which year he was elected a fellow of the Royal Society , London, and he was able also to find time for university extension lecturing. In 1904, Gregory
504-513: The Afar depression up to 100 metres (330 ft) thick. The first well-known European geologist to explore the region was Joseph Thomson , a member of an expedition in 1879–1880 sponsored by the Royal Geographical Society of Britain. From his observations he deduced the existence of a great fault. Thomson returned in 1883, traveling through the rift valley in Kenya from Mount Longonot to Lake Baringo . Describing
540-580: The Ethiopian flood basalts. Rifting in Ethiopia began about 18 million years ago in the southwest and 11 million years ago in northern parts of the Main Ethiopian Rift as the opening of the Gregory rift caused the Afar Triple Junction to form. Volcanism from the Middle Pleistocene onward formed a chain of volcanoes along the floor of the rift throughout its length, dividing it into separate valleys. There are some indications that
576-666: The North side of the mountain, was named after him. Although he never saw this glacier he named the Lewis, Darwin, Heim, Forel and Tyndal Glaciers after eminent Victorian scientists. In 1896 he did excellent work as naturalist to Sir Martin Conway's expedition across Spitsbergen . His well-known memoir on glacial geology written in collaboration with Edmund J. Garwood belongs to this period. Gregory's polar and glaciological work led to his brief selection and service in 1900-1 as director of
612-681: The Rift Valley holds importance in the field of human evolution. It is recognized as an area for researching the stages of human development with crucial fossil findings such, as Lucy (Australopithecus afarensis) unearthed within its bounds. The Great Rift Valley lies between the Ethiopian Plateau to the north and the Somalia Plateau to the south. The rift developed as the Nubian and Somali plates began to separate during
648-568: The Society's vice president from 1920 to 1923 and won their Keith Prize for 1921–23. His students included John Vernon Harrison who was greatly impacted by Gregory. After his retirement in 1929, he was succeeded by Sir Edward Battersby Bailey (Glasgow chair in geology 1929–1937). He made several expeditions including one to Cyrenaica in North Africa in 1908, where he showed the same interest in archaeology as in his own subjects; another
684-466: The central Ethiopian plateau around 30 million years ago, long before rifting began. The first period of activity deposited flood basalts and rhyolites from 500 metres (1,600 ft) to 2,000 metres (6,600 ft) thick. Uplift of the Ethiopian plateau began around this time or soon after. Between 30 million and 10 million years ago synrift shield volcanoes deposited from 1,000 metres (3,300 ft) to 2,000 metres (6,600 ft) of additional material over
720-721: The central part of the Kenyan Rift , 12 million years ago in southern Kenya and 8 million years ago in northern Tanzania. When rifting reached the Tanzanian Craton , the rift split into the eastern Gregory Rift and the western Albertine Rift , which are separated by the 1,300 kilometres (810 mi) wide East African Plateau . Large shield volcanoes near the margins of the craton and in the adjacent Mozambique belt issued large volumes of basaltic to trachytic magmatism between five and one million years ago, with faulting around 1.2 million years ago. Volcanic activity started in
756-523: The civilian scientific staff of the Discovery Expedition . The expedition was in planning during this period, and had not yet set sail for Antarctica when Gregory was compelled to resign from his position upon learning that he was outranked by the expedition's commander, Robert Falcon Scott . The University of Melbourne had created new chair in geology and mineralogy created after the death of Frederick McCoy ; on 11 December 1899 Gregory
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#1732772795743792-622: The council could not promise any immediate improvement. In 1904 he accepted the chair of geology at Glasgow , and he was back in Great Britain in October of that year. Besides carrying out his professional work he had many other activities during his stay in Australia; during the summer of 1901–2 he had spent his vacation in Central Australia and made a journey around Lake Eyre . An account of this, The Dead Heart of Australia ,
828-546: The different races can still assist, and co-operate with, each other, in the interests of peace and harmony. Gregory married Audrey Chaplin, daughter of the Rev. Ayrton Chaplin, and had a son and a daughter. Leake, B. E. 2011. The Life and Work of Professor J. W. Gregory FRS (1864– 1932): Geologist, Writer and Explorer. Geological Society, London, Memoirs, 34., ISBN 1-86239-323-0 and ISBN 978-1-86239-323-3 The archives for John Walter Gregory are maintained by
864-525: The east of the rift at Huri Hills, Mount Marsabit and Nyambeni Hills and recent small cones at Suswa and east of the Silali caldera all indicate that the minimum horizontal stress direction has changed to NW-SE within the last half million years. John Walter Gregory John Walter Gregory , FRS , FRSE , FGS (27 January 1864 – 2 June 1932) was a British geologist and explorer, known principally for his work on glacial geology and on
900-589: The expedition. He was in Gregory's canoe and narrowly escaped death when it overturned and later wrote about the expedition in his own autobiography and for the Royal Geographical Society. He was president of the Geological Society of London from 1928 to 1930, and was awarded many scientific honours including the Bigsby Medal in 1905. Apart from his books he also wrote about 300 papers on geological geographical, and sociological subjects. Gregory
936-469: The general public, and as scientist, teacher, traveller, and man of letters, he had much influence on the knowledge of his time. The Gregory Rift in the Great Rift Valley is named in his honour. He visited central Kenya in 1893 and again in 1919 and his 1896 book The Great Rift Valley is considered a classic. He was the first to use the term "rift valley", which he defined as "a linear valley with parallel and almost vertical sides, which has fallen owing to
972-499: The northern part of the rift, extension within the valley is now thought to be mainly along these faulted and magmatically active segments. These segments are considered to be developing mid ocean ridge spreading centers. The Ethiopia Rift Valley lakes are the northernmost of the African Rift Valley Lakes. The Ethiopian Rift Valley lakes occupy the floor of the rift valley between the two highlands. Most of
1008-708: The term "rift valley", which he defined as "a linear valley with parallel and almost vertical sides, which has fallen owing to a series of parallel faults". In 1913 the German geologist Hans Reck made the first European study of the strata in the Olduvai Gorge to the west of the Crater Highlands. He brought a large collection of mammalian fossils back to Berlin. In 1928 Louis Leakey , the anthropologist, visited Berlin, where he saw that some of Reck's materials were artifacts . Leakey began exploring Olduvai in
1044-402: The valley around this lake he said: "Imagine if you can a trough or depression 3300 feet above sea level, and twenty miles broad, the mountains rising with very great abruptness on both sides to a height of 9000 feet". John Walter Gregory visited central Kenya in 1893 and again in 1919. His 1896 book The Great Rift Valley is considered a classic. Gregory was the first well-known European to use
1080-463: The world's only active carbonatite volcano. Lakes in the rift other than Lake Turkana are mostly small and shallow, some with fresh water but many being saline. The thickness of lake sediments is mostly unknown. In Lake Turkana they seem to be at most 4 kilometres (2.5 mi) thick, in the Baringo – Bogoria half-graben from 500 metres (1,600 ft) to 1,000 metres (3,300 ft) thick and in
1116-536: Was a modest man, sincere, with wide interests. A fast thinker who did an extraordinary amount of work, it is possible that as a geologist he sometimes generalised from insufficient data; his last work Dalradian Geology was adversely reviewed in the Geological Magazine . Nevertheless, he was one of the most prominent geologists of his period, widely recognised outside his own country. Most of his books could be read with interest by both people of science and
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1152-753: Was appointed an assistant in the geological department of the Natural History Museum , London. Gregory remained at the museum until 1900 and was responsible for a Catalogue of the Fossil Bryozoa in three volumes (1896, 1899 and 1909), and a monograph on the Jurassic Corals of Cutch (1900). He obtained leave at various times to travel in Europe, the West Indies , North America, and East Africa. The Great Rift Valley (1896),
1188-412: Was appointed professor of geology and began his duties in the following February. Gregory was less than five years in Australia but his influence lasted for many years after he left. He succeeded in doing a large amount of work, his teaching was most successful, and he was personally popular. But he came to the university when it was in great financial trouble, there was no laboratory worthy of the name, and
1224-474: Was awarded the chair in Geology at Glasgow University winning against Thomas James Jehu , Philip Lake and others. He occupied his chair at Glasgow for 25 years and obtained a great reputation both as a teacher and as an administrator. In 1905, he was elected a Fellow of the Royal Society of Edinburgh . His proposers were Sir John Graham Kerr , John Horne , Ben Peach , and Lionel Wordsworth . He served as
1260-483: Was published in 1906, dedicated to the geologists of Australia. He also published a popular book on The Foundation of British East Africa (1901), The Austral Geography (1902 and 1903), for school use, and The Geography of Victoria (1903). Another volume, The Climate of Australasia (1904), was expanded from his presidential address to the geographical section of the Australasian Association for
1296-682: Was to southern Angola in 1912. His journey to Tibet with his son is recorded in To the Alps of Chinese Tibet by J. W. and C. J. Gregory (1923). His other books on geology and geography include: He wrote books in other subjects as well, such as The Story of the Road (1931), and he dabbled in eugenics with The Menace of Colour (1925) and Human Migration and the Future (1928). In January 1932 Gregory went on an expedition to South America to explore and study
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