988 resultados para Rocky Mountain Basin


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Senior thesis written for Oceanography 445

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In this paper we study the modifications that occurred in some forest soil properties after a prescribed fire. The research focused on the alterations of soil pH, soil moisture and soil organic matter content during a two-year span, from 2008 to 2009. The study site is located in Anjos, Vieira do Minho municipality, a forest site that has suffered from recurrent wildfires for several decades. Furze (Ulex, sp.), broom (Cytisus, sp.), gorse (Chamaespartum tridentatum) and a very few disperse adult pine (Pinus sylvestris) are the predominant vegetation type in the study area. The average height of this shrub vegetation is around 1.5 m. The prescribed fire was conducted by the National Forestry Authority (AFN) in November 2008. Fuzzy Boolean Nets (FBN) were used to evaluate the alteration in soil parameters when compared with adjacent spots where: i) no fire occurrence was registered since 1998; ii) fire occurrence was registered in 2008; and iii) vegetation pruning by mechanical cut was done in Spring six months prior to the prescribed fire event. Results suggest that in the particular case of the studied site, Anjos, the observed soil properties alterations cannot be related with the prescribed fire.

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(l) The Pacific basin (Pacific area) may be regarded as moving eastwards like a double zip fastener relative to the continents and their respective plates (Pangaea area): opening in the East and closing in the West. This movement is tracked by a continuous mountain belt, the collision ages of which increase westwards. (2) The relative movements between the Pacific area and the Pangaea area in the W-E/E-W direction are generated by tidal forces (principle of hypocycloid gearing), whereby the lower mantle and the Pacific basin or area (Pacific crust = roof of the lower mantle?) rotate somewhat faster eastwards around the Earth's spin axis relative to the upper mantle/crust system with the continents and their respective plates (Pangaea area) (differential rotation). (3) These relative West to East/East to West displacements produce a perpetually existing sequence of distinct styles of opening and closing ocean basins, exemplified by the present East to West arrangement of ocean basins around the globe (Oceanic or Wilson Cycle: Rift/Red Sea style; Atlantic style; Mediterranean/Caribbean style as eastwards propagating tongue of the Pacific basin; Pacific style; Collision/Himalayas style). This sequence of ocean styles, of which the Pacific ocean is a part, moves eastwards with the lower mantle relative to the continents and the upper-mantle/crust of the Pangaea area. (4) Similarly, the collisional mountain belt extending westwards from the equator to the West of the Pacific and representing a chronological sequence of collision zones (sequential collisions) in the wake of the passing of the Pacific basin double zip fastener, may also be described as recording the history of oceans and their continental margins in the form of successive Wilson Cycles. (5) Every 200 to 250 m.y. the Pacific basin double zip fastener, the sequence of ocean styles of the Wilson Cycle and the eastwards growing collisional mountain belt in their wake complete one lap around the Earth. Two East drift lappings of 400 to 500 m.y. produce a two-lap collisional mountain belt spiral around a supercontinent in one hemisphere (North or South Pangaea). The Earth's history is subdivided into alternating North Pangaea growth/South Pangaea breakup eras and South Pangaea growth/North Pangaea breakup eras. Older North and South Pangaeas and their collisional mountain belt spirals may be reconstructed by rotating back the continents and orogenic fragments of a broken spiral (e.g. South Pangaea, Gondwana) to their previous Pangaea growth era orientations. In the resulting collisional mountain belt spiral, pieced together from orogenic segments and fragments, the collision ages have to increase successively towards the West. (6) With its current western margin orientated in a West-East direction North America must have collided during the Late Cretaceous Laramide orogeny with the northern margin of South America (Caribbean Andes) at the equator to the West of the Late Mesozoic Pacific. During post-Laramide times it must have rotated clockwise into its present orientation. The eastern margin of North America has never been attached to the western margin of North Africa but only to the western margin of Europe. (7) Due to migration eastwards of the sequence of ocean styles of the Wilson Cycle, relative to a distinct plate tectonic setting of an ocean, a continent or continental margin, a future or later evolutionary style at the Earth's surface is always depicted in a setting simultaneously developed further to the West and a past or earlier style in a setting simultaneously occurring further to the East. In consequence, ahigh probability exists that up to the Early Tertiary, Greenland (the ArabiaofSouth America?) occupied a plate tectonic setting which is comparable to the current setting of Arabia (the Greenland of Africa?). The Late Cretaceous/Early Tertiary Eureka collision zone (Eureka orogeny) at the northern margin of the Greenland Plate and on some of the Canadian Arctic Islands is comparable with the Middle to Late Tertiary Taurus-Bitlis-Zagros collision zone at the northern margin of the Arabian Plate.

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Correlation between facies associations (marine, estuarine and distal fluviatile environments) and disconformities, observed between Foz da Fonte (SW of Setúbal Peninsula) and Santa Iria da Azóia (NE of Lisbon) are presented. The precise definition of the marine-continental facies relationships improved very much the chronology of the depositional sequence boundaries. Tectonic and eustatic controls are discussed on the basis of subsidence rates variation.

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An earlier study revealed the strong phylogeographical structure of the lesser white-toothed shrew (Crocidura suaveolens group) within the northern Palaearctic. Here, we aim to reconstruct the colonization history of Mediterranean islands and to clarify the biogeography and phylogeographical relationships of the poorly documented Middle East region with the northern Palaearctic. We performed analyses on 998-bp-long haplotypes of the mitochondrial cytochrome b gene of 143 samples collected around the Mediterranean basin, including islands and the Middle East. The analyses suggest that the Cypriot shrew belongs to the rare group of relict insular Pleistocene mammal taxa that have survived to the present day. In contrast, the Cretan, Corsican and Menorcan populations were independently introduced from the Middle East during the Holocene. The phylogeographical structure of this temperate Palaearctic species within the Middle East appears to be complex and rich in diversity, probably reflecting fragmentation of the area by numerous mountain chains. Four deeply divergent clades of the C. suaveolens group occur in the area, meaning that a hypothetical contact zone remains to be located in central western Iran.

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In 1903, the eastern slope of Turtle Mountain (Alberta) was affected by a 30 M m3-rockslide named Frank Slide that resulted in more than 70 casualties. Assuming that the main discontinuity sets, including bedding, control part of the slope morphology, the structural features of Turtle Mountain were investigated using a digital elevation model (DEM). Using new landscape analysis techniques, we have identified three main joint and fault sets. These results are in agreement with those sets identified through field observations. Landscape analysis techniques, using a DEM, confirm and refine the most recent geology model of the Frank Slide. The rockslide was initiated along bedding and a fault at the base of the slope and propagated up slope by a regressive process following a surface composed of pre-existing discontinuities. The DEM analysis also permits the identification of important geological structures along the 1903 slide scar. Based on the so called Sloping Local Base Level (SLBL) an estimation was made of the present unstable volumes in the main scar delimited by the cracks, and around the south area of the scar (South Peak). The SLBL is a method permitting a geometric interpretation of the failure surface based on a DEM. Finally we propose a failure mechanism permitting the progressive failure of the rock mass that considers gentle dipping wedges (30°). The prisms or wedges defined by two discontinuity sets permit the creation of a failure surface by progressive failure. Such structures are more commonly observed in recent rockslides. This method is efficient and is recommended as a preliminary analysis prior to field investigation.

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The rock sequence of the Tertiary Beda Formation of S. W. concession 59 and 59F block in Sirte Basin of Libya has been subdivided into twelve platformal carbonate microfacies. These microfacies are dominated by muddy carbonates, such as skeletal mudstones, wackestones, and packstones with dolomites and anhydrite. Rock textures, faunal assemblages and sedimentary structures suggest shallow, clear, warm waters and low to moderate energy conditions within the depositional shelf environment. The Beda Formation represents a shallowing-upward sequence typical of lagoonal and tidal flat environments marked at the top by sabkha and brackish-water sediments. Microfossils include benthonic foraminifera, such as miliolids, Nummulites, - oerculina and other smaller benthonics, in addition to dasycladacean algae, ostracods, molluscs, echinoderms, bryozoans and charophytes. Fecal pellets and pelloids, along with the biotic allochems, contributed greatly to the composition of the various microfacies. Dolomite, where present, is finely crystalline and an early replacement product. Anhydrite occurs as nodular, chickenwire and massive textures indicating supratidal sabkha deposition. Compaction, micr it i zat ion , dolomit izat ion , recrystallization, cementation, and dissolution resulted in alteration and obliteration of primary sedimentary structures of the Beda Formation microfacies. The study area is located in the Gerad Trough which developed as a NE-SW trending extensional graben. The Gerad trough was characterized by deep-shallow water conditions throughout the deposition of the Beda Formation sediments. The study area is marked by several horsts and grabens; as a result of extent ional tectonism. The area was tectonically active throughout the Tertiary period. Primary porosity is intergranular and intragranular, and secondary processes are characterized by dissolution, intercrystalline, fracture and fenestral features. Diagenesis, through solution leaching and dolomitization, contributed greatly to porosity development. Reservoir traps of the Beda Formation are characterized by normal fault blocks and the general reservoir characteristics/properties appear to be facies controlled.

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The relationships among chick feeding, size and type of prey item, and foraging time away from the brood have not been well studied in seabirds. This study investigated spatial and temporal patterns of foraging and chick-provisioning among 23 radio-tagged male common terns nesting at Hamilton Harbour, Lake Ontario during 1991 and 1992. Telemetry data were collected concurrently with behavioural observations from an elevated blind. Terns fitted with transmitters did not differ from controls with respect to either brood attendance, patterns of chick mortality, species and size distributions of prey delivered to offspring, or chick-provisioning rates. There was a clear separation of parental roles: males were primarily responsible for feeding chicks while females allocated more time to brood attendance. The prey species most commonly delivered to chicks by adults were rainbow smelt (Osmerus mordax) and alewife (A/osa pseudoharengus), followed in importance by larval fish, emerald shiner (Notropis antherinoides), salmonids, and fathead minnows (Pimepha/es prome/as). The relative proportions of various fish speCies delivered to chicks by males differed over the course of each breeding season, and there was also much variability in species composition of prey between years. Sizes of prey delivered to chicks also differed between sampling periods. The modal size of fish brought to chicks during Peak 1991 was 1.5 bill lengths, while the majority of prey in Late 1991 were small larval fish. The reverse trend occurred in 1992 when small fish were delivered to chicks predominantly during the Peak nesting period. During periods when predominantly small fish were delivered to chicks, the foraging activity of radio-tagged males was concentrated within a two kilometer radius of the colony. The observed variation in prey composition and foraging locations during the study likely reflects temporal variation in the availability of prey in the vicinity of the colony. Males delivered fish to chicks at a constant rate, while females 4 increased their feeding frequency over the first six to ten brood days. The mean length of fish delivered to chicks by adults increased significantly with increasing chick age. As a group, within each nesting period, transmittered males either foraged predominantly in the same directional bearing (north during Peak 1991, south during Late 1992), or concentrated foraging activity in the immediate vicinity of the colony (Late 1991, Peak 1992). However, individual radio-tagged males exhibited unique and predictable foraging patterns, often favouring specific locations within these areas and differing in their secondary foraging patterns. Overall, the Lake Ontario shoreline between NCB Bay" (3.5 km south of colony) and the lift bridge canal (4 km north of colony) was the foraging area used most frequently by radiotagged males during the chick-rearing period. Foraging patterns of transmittered males at Windermere Basin are similar to patterns of peak-nesting common terns, but differ from those of late-nesters, at a nearby colony (Port Colborne, Lake Erie). Differences between the foraging patterns of late-nesting terns at these colonies likely reflect differences in annual patterns of fish availability between the two locations. No relationship was found between foraging proficiency of adults and survival of offspring. Stochastic factors, such as predation by black-crowned nightherons (Nycticorax nycticorax) and adverse weather conditions during the early stages of chick rearing, may be more important determinants of common tern breeding success than parental quality or fish availability.

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The description of the image reads "No. 65 - The great ice mountain and American Falls, Niagara".

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Iron Mountain Route Railway schedule: the great through line St. Louis, Arkansas and Texas to the Hot Springs of Arkansas.