Volume 5, Number 1, 1971
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This collection contains all the articles from Volume 5, Number 1, 1971 of the Earth Science Journal.
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Item Coverpage and Contents(Journal Article, Waikato Geological Society, The University of Waikato, 1971) Waikato Geological SocietyCoverpage and Contents from Volume 5, Number 1, 1971 of Earth Science Journal.Item Pared-down landscapes in Antarctica(Journal Article, Waikato Geological Society, The University of Waikato, 1971) Cotton, C.A.; Wilson, A.T.The frigid-arid climate that now prevails in ice-free parts of Victoria Land, Antarctica, inhibits glacial erosion. If certain landscapes, more or less remote from the great troughs of outlet glaciers, have been glaciated in the past, as seems very probable, landforms that resulted from glaciation have been replaced by surfaces of different origin. A widespread landscape glaciation was probably contemporaneous with the excavation of large cirques which still survive in mountain summit areas. Replacement of glaciated landforms by others, in a general paring down of the land surface to forms of moderate relief, seems to have resulted from the process of gravity removal of debris from precipitous rock outcrops that were retreating because of disintegration by salt weathering and were eventually eliminated, in most cases, so that the landscape became a mosaic of smooth denudation slopes inclined at 33° to 350. In the Darwin Mountains ice-free area (80ºS) an advanced stage of such denudation with respect to a base level some 400 m above the present level of surrounding glaciers has produced some pyramidal landforms. Just above the present ice level, however, narrow Richter denudation slopes that border weathering rock faces are at only a juvenile stage of development. Thus the ice level appears to have stood alternately at about its present position and 400 m higher in Pleistocene interglacials and glacial ages respectively. The higher ice levels must have been due to extensions of the ice sheet seaward caused by groundings of the shelf ice during low glacio-eustatic stands of sea levelItem Soil crusting in Western Samoa. Part I - Some examples of crusting and methods of control(Journal Article, Waikato Geological Society, The University of Waikato, 1971) Reynolds, S.G.The problems and effects of soil crusting in Western Samoa are discussed. Illustrations of typical crust features include the glazed or 'frosted' surface of certain crusts, and dispersion mosaics. Surface mulches and fine wire mesh frames were investigated as control measures to dissipate the considerable kinetic energy of falling raindrops before they reach the soil surface. Soil crusting was much reduced by these control methods. Mulching increased the germination percentage of dwarf beans, and frames the germinating percentage of lettuce and cabbage over untreated plots; the yield of dwarf beans was increased by 80 per cent using a mulch of coconut fronds.Item Soil crusting in Western Samoa. Part II - Experimental investigation of factors influencing crust formation(Journal Article, Waikato Geological Society, The University of Waikato, 1971) Reynolds, S.G.The Alafua Penetrometer was used to measure relative differences in soil crust strength. Crust strength and thickness were shown to increase with increases in rainfall amount, drying time, droplet size, kinetic energy and soil clay and silt content. The investigations were designed to illustrate some of the factors influencing crust formation to a diploma level soil conservation class.Item Dynamic equilibrium in applied geomorphology: Two case studies(Journal Article, Waikato Geological Society, The University of Waikato, 1971) Douglas, IanEngineering works and agricultural activity which change the relationship between rainfall and river flow lead to modifications of river channels with attendant erosion and deposition problems. In the Swiss Jura Lakes area, the natural flooding of the River Aare became such an acute problem by the mid-nineteenth century that extensive engineering works were carried out to alleviate flooding. The land thus reclaimed became a valuable agricultural asset, but the fall of the water table following removal of the annual flood risk, led to a fall in the level of the land as peat was changed into humus. Renewed flooding occurred. The natural readjustment following the first series of flood alleviation works reproduced the original problem and a second series of engineering works has had to be undertaken to remedy the situation. On the Belgian coast, harbour construction and the spread of buildings over the sand dunes have resulted in severe beach erosion in the eastern seaside resorts. Extensive engineering works have had to be undertaken to restore the beach. These examples illustrate how man's challenges to nature are often recurrent phenomena, and how the alteration of one aspect of the physical environment may lead to a succession of readjustments. Each phase of engineering activity may be considered a break in natural equilibrium, and each period of natural erosion or deposition a trend towards a new equilibrium.