The species compositions and densities of the littoral and pelagic zooplankton assemblages in Crater Lake were compared. The littoral and pelagic zooplankton assemblages of most lakes are typically different due to different habitat conditions in the two zones. The littoral zone of Crater Lake lacks many of the habitat characteristics, which distinguish a typical littoral zone from the pelagic zone. In fact, none of the water quality variables measured differed significantly between the littoral zone and epilimnion of the pelagic zone in Crater Lake. The littoral and pelagic zones of Crater Lake were sampled with twelve paired sites in August and again in September of 1995. For the purposes of this study, the littoral zone was defined as lakeward from the shoreline to the 10m depth contour. At each paired site the pelagic assemblage was sampled to a depth of 120m at the 200m depth contour. Despite the almost identical water quality between the pelagic and littoral zones of Crater Lake, lack of vascular macrophytes in the littoral zone, and well-mixed epilimnion, the littoral zooplankton assemblage differed from the pelagic assemblage in both species composition and density. Several ubiquitous zooplankton taxa dominated both the littoral and pelagic zooplankton assemblages, although the density of these taxa as well as the relative abundance of these taxa differed between zones. These ubiquitous species reached their maximum densities in the metalimnion of the pelagic zone at a depth range of 10 to 60 meters below the lake surface and were considered primarily pelagic. A shift in wind direction between sampling periods influenced the distribution of pelagic zooplankton taxa in the littoral zone. Twenty-four taxa were recorded in the littoral zone, and aside from infrequent exceptions, none of these taxa were found in the pelagic zooplankton assemblage. Most of the littoral taxa were primarily adapted to the benthic zone. / Graduation date: 1999

Thesis (Ph. D.)--Oregon State University, 1999. / Typescript (photocopy). Includes bibliographical references (leaves 118-132). Also available via the World Wide Web.

No description available.

Since the advent of the industrial revolution man has become increasingly detached from the idea of making and the processes associated with it. Today’s society is a consumer driven one dependant on machinery as a means to an end. This attitude has lead to industry becoming an exploitative entity that rapidly becomes obsolete due to the static nature of its program. A shift in mindset is required to create healthy environments that balance the acts of being and doing. At the Tswaing crater, the salt and soda reserves in the crater basin were mined and exploited until they were completely depleted. The factory ruins now stand alone as silent witnesses to the downfall of a doomed industry, consumed by nature and ravaged by time. Although the process has long vanished from memory, the scars of industry are still visible on the landscape, providing an opportunity for a new layer to be woven into the fabric of the site. To respect its history, a new, craft-orientated industrial intervention is incorporated within the existing ruins, which allows visitors to get acquainted with the process of making and allows workers to experience the ephemeral qualities of the site. The end goal is to encourage man to dwell within his surroundings blurring the line between being and doing. The intervention is a fabric dyeing workshop where sheets of fabric add a new layer of colour to the landscape. The fabric is sold to the public on site and training is also provided for the public to educate people about the craft of fabric dyeing. The new process works with the natural surroundings, not looking to exploit the resources as before, but instead looking to add value to people’s lives through learning and experience - and not simply creating an economically viable product. / Dissertation MArch(Prof)--University of Pretoria, 2012. / Architecture / MArch(Prof) / Unrestricted

Graduation date: 1992

This project documents my process of visual and hermeneutic enquiry centred on the Tswaing meteorite impact crater, north of Pretoria. In my visual investigation I attempt to apprehend the landscape through a cyclical process which involves walking within it, photographing it in 360° ‘visualisations’, editing the imagery and returning, often frustrated, to repeat both encounter and process. The cycle of reflection leads me to consider my circular process itself as a dialogical mode of interpretation and response to the primeval, circular landscape of the impact crater. Informed by Gadamer’s (1975) notion of a hermeneutic circle which extends interpretation and understanding, the reflexive process is extended and enriched through dialogue with the work of pertinent scientists, artists, poets and writers. Landscape is considered as an artefact of deep time, challenging entrenched traditions and notions while considering significant contemporary responses. The dissertation attempts to demonstrate the layered accretion of concept and meaning contained within the visual and theoretical components of the investigation

Mt. Ruapehu is one of the most lahar prone volcanoes in the world, having both a crater lake and six small glaciers upon its 2797 m summit. The major outlet for the crater lake, the Whangaehu Gorge, has hosted over 46 historic lahars. However, the low preservation of debris flow deposits, as a result of frequent remobilisation on steep slopes, allows for the detailed description of only 9 lahar events over the last 150 years. Field investigation, historic aerial photos, two airborne LiDAR surveys and direct measurements have been utilised to describe the sedimentology, geomorphology and distribution of historic lahar deposits in the first 11 km of the Whangaehu Gorge. Inundation maps have been created for 1945, 1953, 1975, September 1995, October 1995, March 2007 and September 2007. Grain size distribution, componentry and geomorphology of the 1861, 1975, September 1995, October 1995, 1999 and 2007 lahar deposits have been compared. The lahar deposits are massive, very poorly sorted, silty gravels that form a series of unconsolidated terraces. The limited sediment sources in the steep sided Whangaehu Gorge, including minor historic eruption products, results in significant recycling of lahar deposits. However, the deposits can be differentiated by proportions of lithological components and in some cases anthropogenic debris. The abundance of hydrothermally altered material reflects the role of Crater Lake in lahar formation, although, some of these materials (gypsum, sulphur and snow) are only temporary. Non-cohesive debris flows and occasional snow slurry lahars have been formed by a range of triggering mechanisms associated with and independent of eruptions. Lahars have been formed in the Whangaehu Valley as the result of ejected crater lake water and associated snow melt (1975, September 1995 and September 2007), as well as the progressive displacement of lake water as a result of lava dome growth (1945) and uplift of the lake floor (1968). Inter-eruption lahars occur as a result of Crater Lake outburst floods (1861, 1953 and March 2007) and remobilisation by precipitation and the collapse of tephra laden snow (October 1995 and 1999). The comparison of historic lahars also reflects the range of lahar magnitudes experienced historically on Ruapehu. The most recent Crater Lake outburst of March 2007, with a peak discharge of 1700-2500 m3/s is the second largest recorded lahar, behind only the eruption-generated lahar of April 1975 with a peak discharge of 5000-7500 m3/s. Lahar mitigation can subsequently be based on lahar generation and incorporation of the vast amounts of data collected before and after the 2007 outburst flood. Recent remobilisation and phreatic activity suggest the significant under-representation of small volume events like rain-generated and snow slurry lahars in the geologic record.

Thesis (Ph. D.)--Oregon State University, 1972. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

En nuestro medio desde hace aproximadamente una década se han ubicado varios posibles cráteres de origen meteorítico. Las restricciones existentes para su verificación en la prospección de estos sitios geológicos, la recolección de muestras y su posterior análisis, ha motivado este trabajo para suministrar un medio alternativo para este fin. En principio, el problema se enfrento mediante el estudio de ondas de choque de la forma tradicional, es decir mediante las ecuaciones de Rankine – Hugoniot pero aplicadas a un sólido; el resultado mostró que el terreno en un proceso violento y extremadamente rápido se comporta como un gas ideal. A la luz de este resultado, aplicamos un nuevo método: la autosimilaridad aprovechando que tanto Landau como Zel’dovich ya probaron su eficiencia en la dinámica de fluidos. Este método proporciono una relación fundamental para el trabajo que liga la profundidad del cráter transciende, la energía del proyectil y el tiempo característico de la formación del cráter. Sin embargo esta relación como se menciono depende de dos cantidades que son muy difíciles de medir experimentalmente: el tiempo de la explosión, considerando que ésta acaba con la formación del cráter transciende y la energía del meteorito para la cual necesitamos conocer ya sea la velocidad, tamaño, forma y/o densidad del objeto. La dificultad en encontrar alguno de dichos datos experimentales hace que se usen aproximaciones generalizadas para la determinación de la energía, se usó una tabla de datos elaborados de esta manera pero al mismo tiempo se buscó una fuente alternativa de datos de las mismas características. Los registros de detonaciones de pruebas nucleares realizadas por las potencias mundiales a lo largo de décadas nos proveyó de dicho banco de datos -a pesar de que uno de los parámetros requeridos, el diámetro, no fuera uno de los registrados en la mayoría de los casos-. Los datos obtenidos de explosiones tienen una evidente tendencia a ajustarse a una curva, comparándola con la curva ajustada a datos elaborados mediante aproximaciones generalizadas revelo que al aplicarles una corrección se ajustaban a una curva muy similar a la de las detonaciones nucleares. Por lo que conseguimos una relación entre la energía del impacto con el diámetro del cráter que genera resultados aceptables al ser calibrado mediante un parámetro de corrección y mediante el uso de datos de un cráter de referencia.

No description available.