The Gorda Escarpment (40.4° N and from 126° W to 124.7° W) is a topographic high which is the eastern portion of the Mendocino Transform Fault. The Vizcaino Block is the anomalously shallow portion of the Pacific plate immediately south of the Gorda Escarpment. Sediments of the Vizcaino Block record a history of uplift and subsidence for itself and the Gorda Escarpment. Previous work on the Mendocino Ridge (the bathymetric expression of the Mendocino Transform Fault west of 126° W, where there is little sediment overlying basement) indicated that the ridge had been above sea level at some time in the past (Krause et al., 1964; Fisk et al., 1993). Assuming that the two bathymetric features have undergone the same response to tectonic forces, this study aims to constrain the timing of uplift and subsidence for the Gorda Escarpment, Vizcaino Block, and Mendocino Ridge by using the geological record of sediments of the Vizcaino Block. ODP Site 1022 drilling penetrated 379 meters into the Vizcaino Block's sediments. Age and lithologic constraints from the recovered cores, along with in-situ sampling by ROV and gravity cores, were integrated with a network of 25 seismic reflection lines. From these it is evident that uplift of the Gorda Escarpment and Mendocino Ridge began before 6 Ma, and was at a maximum at 2.7 Ma. Ocean circulation was likely altered by the uplift of the Gorda Escarpment and Mendocino Ridge. In turn, the altered ocean circulation regime may have had an impact on the regional climate in the Pliocene. From 2.7 Ma until the present the Gorda Escarpment, the Vizcaino Block and the Mendocino Ridge have been subsiding. / Graduation date: 2003

Not available / text / text

Thesis (Ph.D.)--University of Melbourne, School of Earth Sciences, 2009. / Typescript. Includes bibliographical references (leaves 205-235)

The grasslands of South Africa, and especially the higher altitudinal grasslands, are under increasing human pressure. In this study a floristic-ecological account of the vegetation of the southernmost Drakensberg and its foothills is given. This is the first comprehensive botanical study undertaken in this floristically poorly known region. The study area is situated in the magisterial districts of Barkly-East, Elliot and Maclear between 30°40' and 31°35' S, and 27°25' and 28°35' E. In the study area afforestation is the greatest threat at lower altitudes, whereas at the higher altitudes overgrazing, trampling and invasion by exotic plant species impact negatively on the native vegetation. A brief review of the history and previous botanical exploration of the area, as well as the physical environment are given. Four main plant communities - the Maytenus undata- Rhus dentata woodland and forests communities, Harpechloafalx- Pycreus cooperi hygrophilous communities, Themeda triandra - Alloteropsis semialata high altitude communities and Alloteropsis semialata- Rendlia altera Afromontane grassland communities, with various sub-communities and variants are identified and described. An annotated check-list of the plant species collected in the study area and distribution maps of all the Drakensberg Alpine Region and local endemic species found in the study area are given. Twenty two local endemic species and 74 rare and threatened taxa were identified. During the study 1 991 species and infraspecific taxa of vascular plants were collected or listed. Most of the endemic species in the study area are located above 1 500m altitude. Due to the relatively low number of local endemic species (22) the study area can at best be considered as a weak centre of endemism. However, it is clearly linked with two other major centres of plant endemism, namely the Drakensberg Alpine Region (DAR) and Maputaland-Pondoland Region (MPR). Within the study area 194 DAR and 86 MPR endemic species were recorded. No local endemic species occur in the forest and wetland communities. Most of the rare and threatened species are found in open grassland which are the areas most suitable for afforestation. This causes a major conflict between the forestry industry and conservation agencies in the area. All grasslands situated at an altitude of above 1 600 m are floristically very diverse and adequate representative areas should be protected, especially the areas of Tentkop and Elands Heights. Soils here are highly erodible and forestry and trampling in these areas should therefore be avoided at all costs. The higher lying grasslands and, to a lesser extent, the lower lying grasslands are ecologically sensitive areas. This is particularly so where the underlying mother rock is basalt, which weathers into highly erodible soils. It is suggested that all areas above 1 600 m be declared "no-go" areas for afforestation. This is based on not only the number of endemic and rare species found in these areas, but also because of the floristic diversity and aesthetic value they hold for eco-tourism. All habitats are sensitive to some degree, but the most threatened areas are the higher lying and open grasslands. Areas that are generally unsuitable for afforestation include rocky outcrops, vleis, drainage lines and forests. Most of these areas are protected by law, albeit for reasons not to do with biodiversity or endangered species. AFRIKAANS : Die grasvelde van Suid-Afrika, en veral die hoërliggende grasvelde, is onder toenemende menslike druk. In hierdie ondersoek word 'n floristies-ekologiese weergawe gegee van die plantegroei van die mees suidelike Drakensberg-eskarp en voetheuwels. Hierdie is die eerste uitgebreide plantkundige ondersoek in dié gebied. Die studiegebied is geleë in die Barkly-Oos, Elliot en Maclear landdrosdistrikte tussen 30º40' en 31º35' S, en 27º25' en 28º35' 0. In die studiegebied is bosbou die grootste bedreiging in laerliggende gebiede, terwyl oorbeweiding, vertrapping en indringing van uitheemse plantspesies die grootste negatiewe impak op die inheemse plantegroei van die hoërliggende gebiede bet. 'n Kort historiese oorsig, die vernaamste vorige versamelaars in die gebied en 'n beskrywing van die fisiese omgewing word verskaf. Vier hoof plantgemeenskappe word onderskei - die Maytenus undata - Rhus dentata boomveld en woud gemeenskappe, Harpechloa falx - Pycreus cooperi vlei gemeenskappe, Themeda triandra - Allotercpsis semialata hoogliggende grasveld gemeenskappe en die Alloteropsis semialata - Rendlia altera Afromontaan grasveld gemeenskappe met verskeie sub-gemeenskappe en variante. 'n Spesielys van aile spesies wat tot nog toe in die studiegebied aangeteken is, asook verspreidingskaarte van alle Drakensberg Alpynse en lokale endemiese spesies wat in die studiegebied versamel is, word verskaf. Twee-en-twintig lokale endemiese spesies en 74 skaars en bedreigde spesies is vir dié gebied geïdentifiseer. Gedurende die ondersoek is 1 991 spesies en infraspesifieke vaatplanttaksa versamel of gelys. Die meeste van die endemiese spesies in die studiegebied word hoër as 1 500 m bo seevlak aangetref. As gevolg van die relatief lae getal endemiese spesies (22) in die studiegebied, kan hierdie streek slegs as 'n swak sentrum van endemisme beskou word. Die gebied vorm egter deel van beide die Drakensberg Alpynse Sentrum en die Maputaland-Pondoland Sentrum van endemisme. Vir die studiegebied is 194 Drakensberg Alpynse en 86 Maputaland-Pondoland endemiese spesies aangeteken. Geen lokale endemiese spesies word in die woud en vlei gemeenskappe aangetref nie. Die meeste van die skaars en bedreigde spesies is met oop grasvelde geassosieer. Laasgenoemde is ook die mees geskikte habitat vir bosbou. Dié feit is verantwoordelik vir die meeste konflik tussen die bosboubedryf en bewaringsgroepe. Grasvelde bokant 1 600 m het 'n hoë floristiese diversiteit en daadwerklike pogings behoort aangewend te word om dit te bewaar, veral in die Tentkop en Elands Heights gebiede. Gronde in hierdie gebiede is besonder maklik erodeerbaar. Bosbou en vertrapping deur vee behoort ten alle koste vermy te word. Die hoogliggende, en tot 'n mindere mate die laagliggende grasvelde is ekologies baie sensitief. Dit is veral die geval waar die onderliggende moedermateriaal basalt is, omdat laasgenoemde gesteente tot gronde met 'n hoë erosie-potensiaal verweer. Daar word voorstel dat geen bosbou in gebiede bo 'n hoogte van 1 600 m beoefen word nie. Hierdie voorstel word nie net gemaak op grond van die aantal endemiese, skaars en bedreigde spesies nie, maar ook met die oog op die voordele wat die estetiese landskap vir ekotoerisme mag inhou. Enige habitat is tot 'n sekere mate sensitief, maar in die studiegebied is die mees sensitiewe dele uit 'n plantkundige oogpunt is die hoërliggende oop grasvelde. Laerliggende gebiede wat nie vir bosbou geskik is nie sluit vlei gebiede, klip koppies en randjies, woude en dreinerings lyne in. Die meeste van hierdie gebiede word deur die wet beskerm, alhoewel nie noodwendig as gevolg van biodiversiteit of bedreigde spesies nie. / Dissertation (MSc)--University of Pretoria, 2013. / Plant Science / unrestricted

A review of the history of the nomenclature of the Medina Formation and of the previous studies of its members, particularly those studies dealing with the source of the Whirlpool sandstone. This is an attempt to show the direction of origin of the detrital materials of the Whirlpool sandstone by a study of the lateral variation of its grain size along the Niagara Escarpment. It is illustrated with maps and with photographs taken by the writer. / Thesis / Master of Science (MSc)

No abstract Provided. / Thesis / Bachelor of Arts (BA)

No abstract Provided / Thesis / Bachelor of Arts (BA)

The stability of the Niagara Escarpment is of critical importance to residents of Hamilton, Ontario as it bisects and divides the lower downtown core from upper residential and commercial areas. The frequency of large rockfalls and debris slides from the exposed escarpment face has resulted in reoccurring road closures that connect these two areas and has prompted the city to seek information on the processes affecting escarpment erosion and slope stability. The research reported here examines the relationship between tree and plant growth on bedrock stability by investigating relationships between species abundance and slope profile, and the potential movement of tree roots growing in rock fractures. The contributing factors of tree growth to physical weathering processes on highly fractured bedrock remain largely unknown; however, plants are suggested to play a key role in weathering processes in the critical zone. Bedrock structure and lithology influence the establishment of vegetation, and vegetation in turn exploits bedrock joints, fractures, and bedding planes, exacerbating physical and biomechanical weathering processes. In this study, vegetation characteristics observed on different parts of the escarpment face were documented and categorized into three distinct biophysical zones: upper and intermediary plateau, bedrock face, and sloping talus. Tree growth, with the potential to enhance bedrock disaggregation through the transfer of tree bole movement to roots exploiting bedrock fractures, was particularly prevalent on areas of sloping talus. To document the potential for bedrock disaggregation through tree bole movement, triaxial accelerometers were mounted on the boles of three different tree species growing along the escarpment in Hamilton. Sampled trees varied in geographic location to allow identification of the relationship between tree bole movement, wind speed, and dominant wind direction. Both deciduous and coniferous species were monitored to determine the impacts of canopy architecture on tree sway in response to wind. Monitoring took place over several days in the months of March, May, September, and November. Recorded tree bole movement (tilt) varied between deciduous and coniferous tree species; wind speed was strongly correlated to tilt of the coniferous tree, and wind direction was strongly correlated to tilt of the deciduous trees. Overall tree bole movement was strongly influenced by diurnal cycles of air movement and was greatest in the hours around mid-day. The outcomes of this research will form an integral component of an erosion-risk assessment study conducted, in part, for the City of Hamilton and will facilitate the design and development of vegetation management strategies for the Niagara Escarpment that may reduce erosion processes and potential damages to impacted citizens and businesses. / Thesis / Master of Science (MSc) / This research examines the impact of vegetation growth on erosion processes on the Niagara Escarpment in Hamilton, Ontario. The slope of the escarpment face exerts an important control on vegetation growth which in turn affects slope stability. Documentation of the dominant vegetation species at two research sites allows the identification of three distinct vegetation zones on the upper plateau, bedrock face, and sloping talus. The movement of tree trunks in response to air movement was also measured for several days in the months of March, May, October and November. Results show that the movement of two monitored deciduous trees was most strongly correlated to wind direction, while the movement of a coniferous tree was strongly correlated to changes in wind speed. All monitored trees were strongly influenced by daily cycles of air movement which were greatest around noon. This research identifies factors that influence both vegetation growth and slope stability on the Niagara Escarpment and may be used to develop effective erosion protection and mitigation strategies.

Master of Science - Science / The replacement of indigenous grasslands by commercial forestry plantations on the mountainous eastern escarpment of South Africa, has inevitably led to alteration of nutrient cycling. The overall objective of this study was to determine the nutrient status (soil, litter and foliar nutrient concentrations) of Pinus patula and Eucalyptus grandis plantations and adjacent grasslands. The 2, 13 and 30 year old P. patula plantations and adjacent Driekop grassland were located relatively high up on the escarpment (altitudes ranging between 950–1610 m) and were underlain by dolomite while the 2, 8 and 13 year old E. grandis plantations and adjacent Brooklands grassland were located lower down (altitudes ranging between 900–1100 m) and were underlain by granite. It was assumed that the nutrient status of the soil under the plantations and the adjacent grasslands were similar prior to afforestation. Samples were collected once in winter (August 2002) and once in summer (January 2003). Soil samples were collected to a depth of 20 cm and litter material, to a maximum depth of 20cm. Lower canopy foliar samples were collected within the lowermost metre of the canopies and upper canopy foliar samples were collected within the uppermost metre of the canopies. The data were analysed in the laboratory for various elements and soil physical parameters. The soil pH was lower under the P. patula (pH 4.8-5.2) and E. grandis plantations (pH 4.6-5.3) when compared with the soil under the adjacent grasslands (pH 5.3-5.6). The soil under the P. patula plantations had lower exchangeable base cation concentrations (204-300 mg kg-1) compared with the adjacent Driekop grassland (452-645 mg kg-1), while there were no clear trends when comparing the exchangeable basic cation concentrations in the E. grandis plantations and the adjacent Brooklands grassland. The soil aluminium saturation was similar between the plantations, ranging between 39.7 and 63.3% in the P. patula plantations and 27.4 and 75.6% in the E. grandis plantations. The grasslands had lower soil aluminium saturations, ranging between 17.7 and 35.7% in the Driekop grassland and 17.5 and 39.1% in the Brooklands grassland. Exudates from mycorrhizal associations chelate iv acidic cations, rendering plantations more tolerant of acidic soils. Soil total nitrogen, phosphorus and carbon in the plantations were similar to the adjacent grasslands. Higher nitrogen mineralisation rates in the P. patula plantations corresponded with higher litter and foliar total N concentrations relative to the adjacent Driekop grassland, while there were no clear trends when comparing rates of N mineralisation in the E. grandis plantations and the Brooklands grassland. The concentrations of foliar amino acids and protein were significantly higher (p<0.01) in the plantation foliage, when compared the grassland foliage. The amino acid arginine, occurred in higher proportions relative to other amino acids in plantation foliage, when compared with the relative proportions found in the grasslands. Relative to nitrogen, foliar ratios indicated that phosphorus and potassium were the most limiting nutrients for the plantations, which possibly resulted in N storage in the form of protein and amino acids. The soil and foliage were the more sensitive indicators of the nutrients status than litter. Differences in nutrients concentrations between the lower and upper canopies in both plantations were minor and no major trends were found. Therefore the sub division of lower and upper canopies is not recommended for further foliar nutrient analyses. Age related trends were unclear as a result of higher soil clay contents found in the 13 year old P. patula plantation and the 8 year old E. grandis plantation as well as the various silvicultural practices implemented. In terms of the relative impacts of P. patula and E. grandis plantations, the results of this study imply that the upper 20cm of soil was more impacted under the P. patula plantations than under the E. grandis plantations, in terms of reduced base cation and increased acid cation concentrations. The P. patula plantations are shallow rooters and thus the base cation status of the upper soil horizons may affect the sustainability of the P. patula plantations.

Since the earliest explorations of the Colorado Plateau, geologists have suspected that cliffs are retreating back laterally. Clarence Dutton envisioned “the beds thus dissolving edge wise until after the lapse of millions of centuries their terminal cliffs stand a hundred miles or more back from their original position” when he wrote about the landscape in 1882. While many geologic studies have determined how fast rivers cut down through the Plateau, only a few studies have calculated how quickly cliffs retreat laterally, and geologists have been arguing since the 1940’s what exactly drives cliffs to retreat in the first place. We study the Book Cliffs in central Utah, and in particular remnant landforms and deposits related to a 120,000-year history of erosion and deposition, which we date by optically stimulated luminescence methods. Our dataset shows that deposits along the Book Cliffs are preserved especially during times of climate instability, which suggests that escarpment retreat locally is driven by climatic disturbances. This disproves older hypotheses suggesting escarpments retreat in response to local factors regardless of shifts in climate, and it is consistent with the few other well-studied escarpment records globally. We also constrain the rates of cliff retreat via a new measurement approach and luminescence age control, showing that the Book Cliffs have retreated at 1-3 meters per thousand years while local toeslope drainages have incised at about 0.5 meters per thousand years, which confirms that cliffs of shallow-dipping, layered rock retreat laterally faster than streams lower the landscape vertically.