Southwestern Direction Research Articles

Genesis of nickel laterites and bauxites in greece during the jurassic and cretaceous, and their relation to ultrabasic parent rocks

Nickel laterites and bauxites, including their proposed parent rocks from the Mesozoic of Greece, have been investigated by means of mineralogical and geochemical methods. The results are discussed in order to recognize the genetic sequence which comprises: pre-lateritic alteration and reworking of ophiolites and associated rocks, lateritic in-situ weathering, reworking and redeposition of the alteration products in an epicontinental transition environment, and post-depositional events affecting the mineralogical and geochemical properties. The ultramafic massifs of the Euboea and Locris area, i.e. the parent rocks of the NiFe deposits, are primarily harzburgites which represent the erosional outliers of a probable “complete” ophiolitic nappe that were transformed to a monomineralic lizarditite. Xenoliths of basic and sedimentary rocks are included in the serpentine matrix of the basal tectonic melange. Lateritic NiFe deposits resting as in-situ alterites on ophiolites or as mechanically reworked laterite detritus, either on serpentinite or karstified limestone, are mainly derived from serpentinites. The ore deposits in the Locris area have been affected by a strong supergene epigenetic overprint, mainly resulting in a downward Ni redistribution and enrichment. A continuous transition from karstic NiFe deposits towards bauxitic material in a southern direction is interpreted as sedimentary admixture of weathering products of different origin. The three bauxite horizons B 1, B 2 and B 3 and their satellite horizons are intercalated in epicontinental shallow-water limestones within an Upper Jurassic to Middle Cretaceous sequence. A karstic surface (unconformity) forms the substratum of these bauxite horizons. Similar to nickel laterites on karst, the detrital parent material was transported from a terrestrial hinterland by widely ramified river systems into a brackish lagoonal or marine environment from a northeastern to southwestern direction. Colloidal matter, fine muds and coarse material were deposited on a karst topography in mechanical traps by successive debris flows during cycles of emersion and marine regressions. Diagenesis resulted in (a) leaching of silica and iron under partly reducing conditions, and (b) recrystallization of iron minerals and neoformation of Al minerals, i.e. boehmite and/or diaspore. During tectonic subsidence and early marine transgression a strong supergene-epigenetic downward mobilization of Fe, Mn and associated elements took place. They were reprecipitated near the footwall in chemical traps. Bauxites of all horizons originate from serpentinites as well as from metamorphic and magmatic rocks. This is indicated by a high content of siderophile elements and lithic components. The sequences of regression and transgression and their erosional, sedimentary and geochemical processes are interpreted as cyclic events.

1930年および1976年前後の伊豆東方線の活動

The crustal upheaval amounting to 10cm for latest two years in the Izu peninsula, Japan, was detected by the Geographical Survey Institute in March, 1976. This upheaval developed afterward laterally to south-western direction from Ito to Shimofunabara through Hiyekawapass. The upheaval was associated with small and microearthquake activities whose epicenters are restricted within the upheaved region. In order to interpret this event, the author assumes slow fault movement at depth along the downward extension of thrust fault on the East-off-Izu tectonic line. The propagating fault movement at different depth and horizontal position can provide a model for migrating crustal movement.Preceding the 1976 crustal upheaval, the crustal upheaval of 1cm in 1971 at Oiso and of 2cm in 1972 at Manazuru occurred. Furthermore, the observed crustal upheaval associated with the 1974 Izu-hanto-oki earthquake can not be interpreted by the calculated crustal movement assuming the right-lateral strike slip faulting in Minami-izu and is rather suggestive for creep dislocation at depth. Therefore, we can presume a sequence of propagating crustal upheaval Oiso-Manazuru-Ito-Minami-izu.On the other hand, the 1923 Kanto earthquake was related mainly to the right lateral faulting along the Sagami fault and also to the faulting along northern part of the East-off-Izu tectonic line. After the 1923 event, there occurred the Ito earthquake swarm and the Kita-izu earthquake in 1930.The sequence of the Ito earthquake swarm and the crustal activities in 1930 are very similar to the one of the 1976 crustal upheaval and the microearthquake activities. For both crustal activities, large or moderate earthquake were associated during the course of rapid accerelating upheaval and small earthquakes were followed during subsequent crustal subsidences.Based on these facts, we can conclude that creep dislocation propagation were recurred around 1930 and 1976. These aseismic slip at depth along the East-off-Izu tectonic line will release some part of crustal strains that are stored on the northern boundary of the Philippine Sea Plate.

The Breeding of the Kestrel, Falco Tinnunculus L., in the Reclaimed Area Oostelijk Flevoland

The Breeding of the Kestrel, Falco Tinnunculus L., in the Reclaimed Area Oostelijk Flevoland

A contribution to the study of the evolution on Hesperis series Matronales CVĚL. emend. DVOŘÁK

AbstractThe Taxon Hesperis theophrasti BORB. subsp. sintenisii DVOŘÁK subsp. nov. is described. The migration of the species of Hesperis series Matronales took place in a western and southwestern direction from the development centre situated probably in the mountain‐ranges bordering northern Asia in the south. In the southwestern migration trent three parts can be distinguished: “The Balkan part of the southwestern migration trend”; “The Asia Minor‐Crimea‐Caucasus part of the southwestern migration trend”; “The central Asian part of the southwestern migration trend.”

Two New Subspecies of Antelope Ground Squirrels from Utah

Many kinds of mammals reach their distributional limits in Utah. This is especially true of rodents restricted to montane or desert habitats. The diverse topography has been instrumental in developing many isolated or semi-isolated populations that have subsequently evolved into recognizable kinds. The central mountain ranges, beginning in northern and northeastern Utah, extend in a southern and southwestern direction. These mountains separate the deserts of the Lake Bonneville Basin from those of the Colorado Drainages of southern, southeastern and eastern Utah. Correspondingly, the desert areas in which antelope ground squirrels occur are also separated. In eastern and southeastern Utah, the Green and Colorado rivers, and their tributaries, with their deeply entrenched canyons, are also barriers that restrict gene flow between populations of antelope ground squirrels. In attempting to re-evaluate the effects of river systems and mountain barriers on the evolution and subspeciation of antelope ground squirrels in Utah, two populations were found that were beyond the range of variation found in the already known subspecies. These are here described as new subspecies. Acknowledgements .—I wish to thank Dr. Stephen D. Durrant of the University of Utah for his supervision and helpful suggestions; the United States Public Health Service, Microbiological Institute for financial aid during the course of this study; the following persons and institutions for the loan of specimens: John Aldrich and Viola S. Schantz, U. S. National Museum, Washington D. C.; J. Kenneth Doutt and Caroline A. Heppenstall, Carnegie Museum, Pittsburgh, Pennsylvania; Seth B. Benson, Museum of Vertebrate Zoology, University of California, Berkeley, California; Vasco M. Tanner and C. Lynn Hayward, Brigham Young University, Provo, Utah; Howard Knight, Weber Junior College, Ogden, Utah. Methods .—Comparisons are of adult specimens unless otherwise indicated. Color comparisons are of summer pelage unless otherwise stated. Capitalized color terms are those of Ridgway (color …

Studes on the center of population in Japan. IV.

Using the population data for Heian period (about 800. w900 A.D.), 1750 and 1872, the gravity centers of population were computed, the result being as follows:The above result shows that the population center in 1750 fell in the. north-eastern direction of that in 1872. But the population data for 1750 were inacurate, mainly due to the fact that the large feudal clans in western Japan had reported their own population less than the real number. Hence the real population center in Tokugawa era must have situated more in south-western direction than the point indicated above as for 1750.

Studes on the center of population in Japan. II

Using the population data for Heian period (about 800. w900 A.D.), 1750 and 1872, the gravity centers of population were computed, the result being as follows:The above result shows that the population center in 1750 fell in the. north-eastern direction of that in 1872. But the population data for 1750 were inacurate, mainly due to the fact that the large feudal clans in western Japan had reported their own population less than the real number. Hence the real population center in Tokugawa era must have situated more in south-western direction than the point indicated above as for 1750.

Dr. Lenz on the Sahara

IN a paper which Dr. Oscar Lenz contributes to the Zeitschrift of the Berlin Geographical Society, he gives an authentic account of the results of his journey across the Sahara, from Tanger to Timbuktu, and thence to Senegambia. The real journey was begun at Marrakesh, at the northern foot of the Atlas Mountains, where Dr. Lenz laid in his stores of provisions and Changed his name and dress, travelling further under the disguise of a Turkish military surgeon. He crossed the Atlas and the Anti-Atlas in a south-western direction. The Atlas consists, first, of a series of low hills belonging to the Tertiary and Cretaceous formations, then of a wide plateau of red sandstone, probably Triassic, and of the chief range which consists of clay-slates with extensive iron ores. The pass of Bibauan is 1250 metres above the sea-level, and it is surrounded with peaks about 4000 metres high, whilst the Wad Sus Valley at its foot is but 150 metres above the sea. The Anti-Atlas consists of Palæozoic strata. On May 5, 1880, Dr. Lenz reached Tenduf, a small town founded some thirty years ago, and promising to acquire great importance as a station for caravans. The northern part of the Sahara is a plateau 400 metres high, consisting of horizontal Devonian strata which contain numerous fossils. On May 15 Dr. Lenz crossed the moving sand-dunes of Igidi, a wide tract where he observed the interesting phenomenon of musical sand, a sound like that of a trumpet being produced by the friction of the small grains of quartz. But amidst these moving dunes it is not uncommon to find some grazing-places for camels, as well as flocks of gazelles and antelopes. At El Eglab Dr. Lenz found granite and porphyry, and was fortunate enough to have rain. Thence the character of file desert becomes more varied, the route crossing sometimes sandy and sometimes stony tracts or sand-dunes, with several dry river-beds running east and west between them. On May 29 he reached the salt works of Taudeni, and visited the ruins of a very ancient town, where numerous stone implements have been found. Here he crossed a depression of the desert only 145 to 170 metres high, while the remainder of the desert usually reaches as much as 250 to 300 metres above the sea-level; and he remarks that throughout his journey he did not meet with depressions below the sea-level. The schemes for flooding the Sahara are therefore hopeless and misleading. The landscape remained the same until the wide Alfa fields, which extend north of Arauan. This little town is situated amidst sand-dunes devoid of vegetation, owing to the hot souihern winds. Four days later Dr. Lenz was in Timbuktu, whence he proceeded west to St. Louis. During his forty-three days' travel through the Sahara Dr. Lenz observed that the temperature was not excessive; it usually was from 34° to 36° Celsius, and only in the Igidi region it reached 45°. The wind blew mostly from north-west, and it was only south of Taudeni that the traveller experienced the hot south winds (edrash) of the desert. As to the theory of north-eastern tradewinds being the cause of the formation of the desert, Dr. Lenz remarks that he never observed such a wind, nor did his men; it must be stopped by the hilly tracts of the north. Another important remark of Dr. Lenz is what he makes with respect to the frequent description of the Sahara as a sea-bed. Of course it was under the sea, but during the Devonian, Cretaceous, and Tertiary periods; as to the sand which covers it now, it has o nothing to do with the sea: it is the product of destruction of sandstones by atmospheric agencies. Northern Africa was not always a desert, and the causes of its being so now must be sought for, not in geological, but in meteorological influences.

On the Geology of the Beaufort and Ebbw Vale District of the South Wales Coal-Field

In my former paper I endeavoured to describe the general appearance and characteristics of the limestone, millstone grit, and Pennant rocks of this coal-field, and shall now proceed to give a brief outline of the coal measures themselves and their fossil contents. As I stated before, the character of the coal is materially different in different parts of the basin; for instance, if a line be drawn from Merthyr to the sea in a south-western direction, it will divide the basin into two unequal portions, the eastern one containing bituminous coal, and the western the anthracite. I do not mean to say that there is an exact line of demarcation between the two kinds of coal, but merely that such a boundary will seem to show pretty well where the two qualities pass into one another. Curiously enough, too, in the western or anthracite portion the seams are anthracitic in the northern bassets, while the southern outcrops of the same veins are bituminous. The anthracite is now in very great demand; but, formerly, people would have nothing to do with it, and there was even a law passed to prevent its being burned in London, on account of its supposed noxious qualities, and the idea that it was detrimental to health. It differs from the bituminous coal principally in containing more carbon, less bituminous matter, and less ashes; and, as a consequence, is a much cleaner-burning coal. We may, however, dismiss the anthracite, as this portion of the field is destitute of it.

XI. Notice respecting the Geological Structure of the Vicinity of Dublin; with an Account of some rare Minerals found in Ireland.

The following observations are to be ascribed principally to the late Rev. Walter Stephens. I present them to the Geological Society in their present imperfect form, with the hope that they may attract the attention of mineralogists to the country in the vicinity of Dublin; for they are sufficient to shew that very interesting information may be expected from a correct examination of that district; which from its situation is easy of access, and presents many advantages to the observer. I shall subjoin to a brief statement respecting the geological structure of that country, an account of some minerals of not very common occurrence, recently found in Ireland. The city of Dublin is placed in a flat limestone country, at the distance of about five miles to the northward of a range of mountains, which form the verge of a mountainous district, extending from thence for more than thirty miles to the southward. Through this tract there passes in a south-western direction from the shore on the south side of Dublin bay, a broad body of granite, bounded on its eastern and western sides by incumbent rocks of great variety; the structure and relations of which, as well as of the granitic mass, are in many places very distinctly exhibited. Within this mountainous district, distinguished by the interesting and beautiful scenery which it presents, are found the copper mines of Cronebane and Ballymurtagh; * and the lead mines of Glenmalur; the veins of lead ore at Dalkey, and that near the