Great Rift Research Articles

An investigation of galactic structure in a region of Cygnus.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An investigation of galactic structure in a region of Cygnus. Annear, Paul Abstract This investigation was carried out with the ~-inch Burrell Schmidt-type telescope at the Warner and Swasey Observatory. It is a part of a general program dealing with the luminosity function in the plane of the galaxy in process at that observatory. The field investigated has its center about three degrees south of P Cygni, and includes parts of the Cygnus Cloud, Great Rift, and a prominent parabolic area of obscuration. It also includes part of an area where a well-known clustering of B stars exists. The spectral types and photographic magnitudes of all (1281) stars to 12.0 photographic magnitude were obtained within an area of 12.5 square degrees. Photo-red magnitudes were obtained for all stars of spectral type Ao and earlier (6o8), and for I I I stars of later spectral types. Star-counts were made to photographic magnitude 17.6 as an aid in determining absorption features over the plate. In spite of the fact that the region involves absorption which is definitely non-uniform, it was divided into two areas approximately homogeneous in absorption. In one area, which includes part of the Great Rift, the absorption begins at about 500 parsecs and increases rapidly to about two and one-half magnitudes at 1500 parsecs. In the other area, it increases more slowly to about two magnitudes at 3000 parsecs. Using these absorptions, a density analysis was made for various spectral groups in each area. The B-type stars show clustering tendencies at various distances, whereas the other spectral groups in general show a rapid decrease in density with increasing distance from the sun. A comparison with the standard luminosity function reveals an excess of luminous stars (M between -4 and $1) in this region, and a deficiency of less luminous stars (M between I and Y4), a result in agreement with conclusions reached in two other fields included in this general program. B urrell Observatory, Baldwin- Wallace College, Berea, Ohio. Publication: The Astronomical Journal Pub Date: 1949 DOI: 10.1086/106298 Bibcode: 1949AJ.....54R.181A full text sources ADS |

Education in British Central and South Africa

The Protectorates of Nyasaland and Northern Rhodesia are in the tropics, the Northernmost point of Nyasaland being 700 miles south of the equator. Nyasaland is a narrow strip 520 miles long and 50 to 100 miles wide adjoining Northern Rhodesia to the West. The trough of the Great Rift Valley runs through it, covered at its deepest part by the waters of Lake Nyasa. Along the lake shore and its outlet, the altitude falls to 120 feet above sea level, but most of the country is uplands and hills where the altitude reaches 8,000 to 10,000 feet. The country is agricultural and there is no mining industry. The main export crops are tobacco and cotton grown by African farmers and tea from European estates in the South. Cattle are kept in the North and an African dairy industry produces ghee. Most of Northern Rhodesia is on the central African plateau with an average elevation of 4,000 feet falling to 1,000 in the Zambezi and Luangwa valleys. Nearly the whole territory is covered with bush and scrub and soil fertility is low. Maize, tobacco, wheat and mixed vegetables are grown. There are tracts of sand, desert and marshland and over large areas tsetse fly prevents the keeping of cattle. The wealth of the country is in the copper mines. Southern Rhodesia lies on the plateau to the South of the Zambezi river. It is a country with a settled European farming population. Maize is the main crop grown by Africans. There is mineral wealth including gold and coal. Bechuanaland, Basutoland and Swaziland are inset in the Union of South Africa. Bechuanaland is in the high central basin of the Zambezi and Limpopo river systems, the average altitude being over 3,000 feet. To the East there are some hills but the rest of the territory is an undulating plain with great waterless areas save where bore holes and dams have been established. The livestock industry is the mainstay of the economic life of the country. Basutoland is a mountainous, well-watered territory with altitudes from 5,000 to 11,000 feet, and a climate with extremes of heat and cold. Cattle and sheep are raised and horses and donkeys are used for transport. The most important exports are wool, wheat, mohair and cattle. Swaziland is a hilly territory with altitudes ranging from 5,000 to 300 feet. About 75 per cent is used for grazing. An African dairy industry is developing. South West Africa is bordered by Bechuanaland to the East. Land on this plateau ranges from grazing and arable tracts to desert and bush. To; the West, the boundary is the Atlantic Ocean and along the shore there is. a belt of desert. There are some mining developments. Africans keep stock and practice a subsistence economy.

A New Genus of Hypocreales

In December 1939 Dr. Alfred E. Emerson of the Zoology Department of the University of Chicago, known for his work with termites, gave me for identification a fungus parasitic on termites. Two infected insects were collected on January 5, 1935, below Great Rift Wall, Lake Manyara, Tanganyika, Africa, by Dr. Harold Kirby of the department of Zoology of the University of California at Berkeley, California. These termites, as determined by Dr. Emerson, were dealated Macrotermies natalenlsis (Haviland) and were dead when found underneath a stone.

Explanatory note on the Block Diagram of the Great Rift Valley from Nakuru to Lake Magadi (Plate XIV)

This diagram was constructed during an examination of the Rift Valley region on behalf of the D'Arcy Exploration Company and the Anglo-Saxon Petroleum Company. The author is greatly indebted to these companies for permission to publish this work, and acknowledges with gratitude the assistance rendered during the examination by the Department of Mines, Kenya Colony. It is difficult to give an effective picture of the Great Rift Valley by contour maps, and in those that exist the topographer has tended rather to round off his contour lines in the conventional manner, so that, where in nature there exists bold ruggedness, there appears on the map only flowing curves. An attempt has been made in this projection to bring out the steepness of the fault scarps, and the colouring has been progressively deepened to show the increasing depth to which the plateau has been faulted down. Thus the plateau round Nairobi, lying on the Kapiti plains, is coloured lightly, and the depth of colour increases northward from Limuru along the Kainankop plateau, and then down to Naivasha. Yet Naivasha is at a greater height above sea-level than Nairobi, the sides and bottom of the Rift Valley having together been raised to the northward relative to sea-level. There is a considerable slope of the whole of the Rift Valley and its sides towards the south. Thus, Lake Magadi lies at the lowest point in the diagram, though the difference between the level of this lake and the sides of the valley is

The Nyasa-Shire Rift

IN an earlier volume of this Journal I gave a preliminary account of the Nyasaland section of the Great Rift Valley,1 and it may be of interest at this stage to review subsequent observations in this region and to trace their bearing on the views then expressed as to the age and development of the Nyasa-Shire rift, which forms a notable feature in the majestic scenery of this part of central Africa. These later observations refer chiefly to the northern end of the Nyasa rift, the neighbouring and almost parallel Luangwa valley lying to the west, and the region traversed by the Shire rift. The Nyasa-Shire rift, forming part of the Rift Zone of eastern Africa, extends throughout the length of Nyasaland from north to south. The floor of the Nyasa rift is in part occupied by Lake Nyasa, which stands at 1550 feet but is in places over 2200 feet deep, with the result that parts of the floor lie more than 700 feet below sea-level. The Shire rift is traversed throughout by the Shire River, which forms an intermittent outlet, now active, from Lake Nyasa to the Lower Zambezi. The Nyasa rift and the greater part of the Shire rift are bounded by a high plateau ranging mainly from 3000 to 4000 feet in height, and this plateau, which is regarded as of Miocene age, is surmounted by a number of other smaller plateaus that attain to elevations usually of 6000 to 7000 feet, but sometimes as much as 8000 feet.

Ancient Ruins in East Africa

AN archaeological reconnaissance with the view of further investigation has been made recently by Dr. L. S. B. Leakey on two sites in East Africa. Of these, one, the ruins of Gedi, an ancient city of considerable extent, sixty-five miles north of Mombasa, is already scheduled under the Ancient Monuments Preservation Ordinance; the other is the large assemblage of stone-built dwelling-places and tombs at Engaruka in the Great Rift Valley in Tanganyika, to which attention was directed as a new discovery in June last of Mr. T. E. Wetherell. The ruins at Gedi, though situated at no more than fifty yards from the Mombasa-Malindi road at their nearest point, are so obscured by a tangle of tropical vegetation as almost to escape notice. Trees of considerable size growing on or in the ruined structures afford some gauge of the antiquity of the ruins. According to Dr. Leakey's report (The Times, October 11) future investigation will reap a rich harvest. Town walls, buildings and tombs alike afford evidence of at least two, and possibly three, distinct periods of construction. The materials used consist of dressed blocks of coral, built up with a hard mortar and plastered to a smooth surface. In places, where the dressing is unplastered, as on the arches over doors and windows, it is extremely fine. It is Dr. Leakey's opinion that the ruins may be those of an Arab or Persian settlement of considerable antiquity, the first settlement possibly dating so far back as the beginning of the Christian era.

Traces of Ancient Changes of Climate in East Africa

T he investigation of the traces of ancient changes of climate which the present writer started in British East Africa in 1927-1928 was partly carried out on high mountains there, partly in the eastern branch of the Great Rift Valley in the neighbourhood of the Equator (NILSSON, 1932). Traces of former pluvial periods in British East Africa (abbreviated B. E. A. below) are abundant. The heavier precipitation of these periods gave rise to large glaciers, the extension of which are marked by huge moraines far down the slopes of the highest mountains, and in the areas between the mountains we find almost everywhere evidence of such periods in the numerous river beds and ancient lake basins, now wholly or partly dried up. Especially in the basins of the Rift Valley, the series of ancient lake sediments and beaches give a very good idea of the sequence of pluvial and interpluvial periods and their subepochs which have followed each other up to the present time. During my work in B. E. A. it gradually became clear to me that traces of pluvial and interpluvial periods must no doubt occur also in adjacent parts of Africa where the conditions for their development were favourable. It seemed to me that Abyssinia must be, from my point of wiew, a very promising country, though HUME and CRAIG (1911) and other geologists consider that Abyssinia, even during the pluvial periods, had a drier climate than it has to-day. .In July 1932 I went to Kenya Colony in order to complete my former observations in the Nakuru-Naivasha Basin and on Mount Kenya, but the main object of my expedition was to extend the field of investigation to Abyssinia. During the first half of 1933 I travelled by caravan from Addis-Abbaba to the Blue Nile, Lake Tana and the high mountains of Semien in the northernmost part of the Abyssinian Plateau. Afterwards I visited the Zwai-Shalla Basin in the Rift Valley and also Mount Kaka, the highest point of the Somaliland Plateau, situated at the NW. corner of the plateau. In Fig. I Mount Kaka lies just N. of A in the word Alutu, E. of Lake Zwai.

Societies and Academies

DUBLIN Royal Irish Academy, April 24. P. J. NOLAN: The influence of condensation nuclei and dust particles on atmospheric ionisation. Fair conformity with Wright's conclusion that dust particles play an important part in the equilibrium of atmospheric ionisation is obtained from a re-examination of previous work. A theoretical basis for the equilibrium equation q = ζnνZ is proposed. The combination coefficients of small ions with dust particles and with large ions are deduced. R. F. SCHARFF: The past wanderings in Europe of two African animals. The manner in which the hippopotamus and the bivalve mollusc Corbicula seem to have entered Europe from the south-east in late Pliocene times is described. They probably travelled along the great Rift Valley from Central Africa to Palestine when the Red Sea was still a river valley. The area of the Ægean Sea, while still unsubmerged, afforded an easy passage between Asia Minor and Greece and thus on to Italy and Malta. Their remains occur everywhere in Italy, France and Belgium, but the hippopotamus never crossed the Rhine. Eventually, in the early Pleistocene, both species passed into England, when it was part of the Continent. Special comment is made on the significance of the British distribution of both animals.

The Californian Earthquake

THE earthquake that occurred in southern California at 5.54 p.m. on March 10 (1.54 a.m., March 11, G.M.T.), though it was the cause of considerable loss of life and property, can scarcely be regarded as one of the great earthquakes of that State. The number of persons known to have lost their lives is 151, and it is estimated that 7,500 houses were destroyed or damaged, and that the value of the property lost was more than ten million pounds. Most of the places in which houses were injured lie within an area about sixty miles long, running in a south-easterly direction from near Los Angeles to beyond Santa Ana. The place that suffered most is Long Beach, a town on the coast about twenty miles south of Los Angeles. Here, 65 persons were killed and about a hundred wounded. The epicentre thus lies near the coast, possibly under, the ocean, so that the earthquake cannot be connected with the great San Andreas rift, which, in this part of California, runs about fifty miles inland. Since 1769, the Los Angeles district has frequently been visited by severe, though not disastrous, earthquakes. About ninety miles to the west lies Santa Barbara, part of which was seriously damaged by the earthquake of June 29, 1925.

John Walter Gregory, 1864 - 1932

John Walter Gregory was born in London on January 27, 1864, and received his early education at Stepney Grammar School. The son of a wool merchant, he embarked on a business career in the City of London, but at the same time continued his scientific studies and graduated in the University of London. His ambition to adopt a scientific career was attained in 1887 when he was successful in the competition for an Assistantship in the Geological Department of the British Museum (Natural History). Keenness for travel led to his undertaking expeditions, first (in 1891) to the Rockies and Great Basin of North America, and later to the West Indies. Already in his early years at the British Museum his capacity for work showed itself in Museum publications. He produced three volumes of the “ Catalogue of Fossil Bryozoa ” in 1896, 1899 and 1909, and published elsewhere the “ Jurassic Corals of Cutch ” in 1900, and a paper on Cainozoic Echinoids in the Proceedings of the Geologists’ Association. Meanwhile, he was lent by the Museum as Naturalist to a large expedition to British East Africa in 1892, sent out to explore the northern part of what is now Kenya Colony. After starting up the Tana River, the expedition was unfortunately wrecked by transport difficulties and dissensions, but Gregory (who never knew the meaning of “ a lost cause,” whether the expression was applied to an ill-fated expedition or an abandoned geological theory) reorganized the venture, notwithstanding that he was stricken with fever. With a party of 40 natives, himself the only white man, he conducted a private expedition up country, covering a distance of 1,650 miles in a little less than five months. He made observations on the ancient glaciers of Mt. Kenya and all but accomplished the first ascent of that mountain ; he studied the lava-fields and the tectonic features of the immense trough (which he termed the Great Rift Valley) and the neighbouring highlands. The results of this journey showed themselves in a never-flagging interest in Colonial policy and racial problems in Africa.

Scientific results of the Cambridge Expedition to the East African Lakes, 1930-1.-4. The waters of some East African Lakes in relation to their fauna and flora.

The lakes visited by the expedition are situated on the floor of the Great Rift Valley.

Geological Exploration of the Andes

PROF. J. W. GREGORY is leaving England on Jan. 4 with an expedition to investigate some little-known parts of the coastal Cordillera of southern Peru and their relations to the Andes and to the recent extension of South America into the Pacific. It is hoped to examine especially the structure of the part of the Peruvian coast that trends from northwest to south-east, and the geology of the desert belt between that coast and the western front of the Andes. A geological section is also to be prepared across the little-known belt between lea and the Urubamba valley. The earth-movements and volcanic epochs of the Andes appear to have significant correspondence in date with the main stages in the formation of the Great Rift valley that were discovered in its exploration by Prof. Gregory thirty-nine years ago. The expedition will descend from the Andean plateau down one of the head streams of the Amazon, and may return to England across Brazil. Miss McKinnon Wood will accompany the expedition especially to collect fossils. Mr. A. V. Coverley Price will join the expedition at Lima. The work will be helped during parts of the journey by Mr. M. A. Tarnaiecki and Señor Don Alberto Calderon.

A Classification of some Rhyolites, Trachytes, and Phonolites from part of Kenya Colony, with a Note on some Associated Basaltic Rocks

In spite of the importance of the volcanic region of the Great Rift Valley of East Africa, very little attention has been paid in the past to the detailed petrography of the rocks of Kenya Colony. Previous work on the subject may be summarized in a few sentences. August Rosiwal described the rocks collected by L. von Hohnel on Count Teleki's expedition in 1886–88 (1891, pp. 490–511). Descriptions of some of the lavas of Mount Kenya were given by J. W. Gregory (1900) in his account of the geology of that mountain, which he ascended in 1893, and G. T. Prior (1903) described the rocks collected by Gregory in other parts of the Colony on the same expedition, and specimens from a collection presented to the British Museum (Natural History) by Sir H. H. Johnston in 1901. This paper contained five analyses. H. B. Maufe (1908) gave an account of the field relations of the rocks which he collected in 1905 and 1906 along the line of the Uganda Railway and on several traverses from various points along it. He followed Prior's nomenclature fairly closely. A few specimens collected by G. Uhlig, also on the line of the Uganda Railway, were described by M. Goldschlag (1912), who gave four analyses. Miss A. T. Neilson (1921) gave a brief description of the rocks collected by J. W. Gregory in 1919. Finally, A. Lacroix (1923) gave a short summary of the work of these earlier authors and added four new analyses of

A New Ceratotrochus from the Upper Cretaceous of Portuguese East Africa

Three small simple corals were collected by Mr. F. P. Mennell from the Upper Cretaceous of the Cheringoma district, Portuguese East Africa. The area is of special geological interest as it includes the southern end of the Great Rift Valley and furnishes useful evidence as to the date of the formation of that valley. A coral from almost the same horizon has been figured by Schlosser, and, as it is clearly a different species, the horizon may be expected to yield a good fauna of simple corals.

Central African volcanoes in 1929

The existence in Central Africa of a group of volcanoes, some of which are active, has long been known. They lie in the Central African Rift Valley (the western branch of the Rift Valley as distinct from the Eastern or Great Rift Valley) in the region where Uganda, Belgian Congo, and former German East Africa come together. There are eight major volcanic piles named from east to west, Muhavura, Mgahinga, Sabinyo, Wissoke, Karissimbi, Mikeno, Namlagira, and Ninagongo, with a large number of other vents that are topographically less conspicuous (see Fig. 4 ) . The highest is Karissimbi (14,865 feet) and the lowest Namlagira (10,046 feet). The distance from east to west (Muhavura to Namlagira) is 33 miles. The area in which the volcanoes lie, whatever the true mechanics of its formation may be, has the appearance of a sunk‐land which is a lateral expansion of the Western Rift. (A. D. Combe in Ann. Rept. Geol. Survey Uganda for 1928, p. 14, calls this expansion the Bufumbira Bay, a very appropriate name. The mountains are usually known in German literature as the Virunga volcanoes, in English literature as the Mufumbira volcanoes, or again they may be referred to in either as the Lake Kivu volcanic area on account of their proximity to Lake Kivu.)

Bushveld Igneous Complex of the Transvaal

Research Article| September 30, 1928 Bushveld Igneous Complex of the Transvaal REGINALD A. DALY REGINALD A. DALY Search for other works by this author on: GSW Google Scholar Author and Article Information REGINALD A. DALY Publisher: Geological Society of America Received: 17 Nov 1927 First Online: 02 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 1928 Geological Society of America GSA Bulletin (1928) 39 (3): 703–768. https://doi.org/10.1130/GSAB-39-703 Article history Received: 17 Nov 1927 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation REGINALD A. DALY; Bushveld Igneous Complex of the Transvaal. GSA Bulletin 1928;; 39 (3): 703–768. doi: https://doi.org/10.1130/GSAB-39-703 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract IntroductionSince the time of the Cæsars “something new” has ever been coming “out of Africa.” Nowadays geologists are there finding novelties, impressive, even spectacular, and each one thought-provoking. The Great Rift and volcanoes of the east, the Atlas structures of the north, the igneous rocks of the west, the remarkable copper deposits of Katanga in the center, and in the south the Rhodesian “Great Dike,” the clear evidences of Carboniferous glaciation, the unexcelled display of dolerite sills, the unique Vredefort dome, the dominating gold and diamond mines, the recent demonstration of widespread platinum-bearing rocks—all these and many other newer discoveries in Africa are affecting the very foundations of general and economic geology. Not the least of the finds is the amazing body of igneous rocks called the Bushveld Complex, in the Transvaal. Molengraaff, Henderson, Kynaston, Mellor, Humphrey, Hall, Wagner, and du Toit have published the results of study . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Nyasaland Section of the Great Rift Valley

The Nyasaland Section of the Great Rift Valley

A Recent Visit to Gudru and Gojjam

SINCE I had the privilege of reading my first paper on the subject of Abyssinia before the Royal Geographical Society nearly four years ago, my wife and I have been able to make two further visits to that country, and to parts differing materially from each other, both geographically and racially. Our first visit in 1919-20 was confined to Shoa, and from Addis Ababa we undertook a number of short treks to different parts of that province, of which the population, though largely Abyssinian, is very much diluted by inter-marriage with the Shoan Galla and with conquered negroid races. The country itself is high, Addis Ababa being near the south? eastern extremity of the main Abyssinian plateau at an elevation of approximately 8000 feet, just below and to the south of the Intotto Mountains, which run to a height of about 11,000 feet. On our second trip in 1922-23 we travelled southward from Addis Ababa round Lake Zwai and in the Arusi country, keeping to the west of the Arusi Mountains. This country is lower, lying indeed partly within the Great Rift Valley between the Somali plateau and the Galla Highlands, Lake Zwai itself being at an elevation of about 5000 feet. The people here are Galla, different branches of this great race. The Arusi Galla Wylde brackets with the Masai as the two most warlike and savage tribes north of the equator in the eastern part of Africa; but we found them pleasant enough to deal with, though shy and wild. Our third trip, from which we have just returned, was through Gudru to the more purely Abyssinian country of Gojjam, lying north of the great southerly bend of the Blue Nile, between this river and Lake Tana. The difference in appearance between the races is strongly marked, both as regards features and colour, and traces of the three peoples from which the mixed population of Abyssinia derives its origin, i.e. the Semitic, Hamitic, and negroid, are clearly evident. Nor do the social and political conditions of the people of Shoa, Arusi, and Gojjam differ less widely, and any generalization as to the

The Structure of the Great Rift Valley

THE difference as to the faults between the figure in NATURE of October 6 and that in Prof. Emmons's book is that he copied the original section of 1916, whereas the figure in NATURE gives the modified section published by the Geological Survey of Egypt in its Petroleum Research Bulletin No. X. Dr. Hume's letter published in NATURE of January 12, 1924, confirms the later section. Mr. E. J. Way-land's summary of the recent progress in the investigation of the Rift Valley in the Uganda Protectorate is of great value, and he and his colleagues are to be congratulated on their interesting results. The fifth point he mentions agrees with the pivotal movements on east and west axes in the eastern branch of the Rift Valley in Kenya Colony. The results already announced indicate that Mr. Way-land's full report on the geology of the Rift Valley in the Uganda Protectorate will be a most important contribution to African geology.

The Structure of the Great Rift Valley

IN the issue of NATURE for October 6, 1923, which reached me at the end of the year, Prof. J. W. Gregory gives an admirable resume of our knowledge of the Great Rift Valley. May I, in this connexion, be afforded space in order to contribute a few remarks upon the subject?