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In recent years, the study of rock glaciers has increased remarkably. Substantive progress has been made, particularly in understanding the formation of rock glaciers that have developed adjacent to existing or former valley or cirque glaciers, However, our understanding of valley-wall rock glaciers that are located at the base of talus slopes remains scant. Published work exhibits little consensus on the formation of valley-wall rock glaciers and several hypotheses remain under vigorous debate. The major objective of the research reported in this thesis has been to test the generality and feasibility of seven major models of valley-wall rock glacier formation using both empirical and theoretical evidence. The primary conclusion is that only one of these models, the segregation ice model, emerges as a general model of valley-wall rock glacier genesis. The model assumes that a thin layer or several thin layers of segregated ice are overlain by interstitially frozen sediments and an unfrozen mantle of coarse debris. A wide range of empirical and theoretical findings are shown to be consistent with the implications of the segregation ice model. Detailed observations on the morphology, sedimentology and distribution of active, inactive and relict valley-wall rock glaciers studied in Switzerland, northern Norway and Scotland provided a range of findings that support this model. Theoretical evidence was obtained by modelling a number of different density models that reflect different distribution of internal ice by applying a simple laminar flow equation to field measurements. Although only the segregation ice model appears to be valid at a general level, the possibility cannot be excluded of alternative modes of valley-wall rock glacier formation under particular circumstances. Snow avalanching, deformation of snowbank or matrix ice, and basal sliding under conditions of high hydrostatic pressure all constitute possible contributing mechanisms of formation and movement in particular cases.

A variety of moraine forms were deposited by glaciers during the Loch Lomond Stadial. Study of such moraines and related landforms provides a valuable source of data on patterns of landscape evolution and climatic change. This thesis presents detailed case-studies of moraines in geologically and topographically contrasting areas on the Island of Skye, Scotland. Geomorphological mapping, sedimentological analyses and mathematical modelling techniques were employed to determine the principal controls on moraine morphology, composition and distribution. Particular emphasis was placed on the provenance, transport and deposition of debris, and their spatial variation. The results were used to construct a summary model of glacial landform evolution, which relates different sediment-landform associations to spatial and temporal controls, particularly basin lithology and structure, topography, position of deposition and ice-margin activity. The initial stage of deglaciation in the study area was marked by a series of readvances and/or stillstands. During this stage, the lower-lying glaciers were more sensitive to climatic amelioration than the higher glaciers. The subsequent phase was characterised by more rapid deglaciation. Evidence for one instance of late-stage in situ glacier stagnation is described. The results indicate that landforms hitherto grouped as 'hummocky -moraine' formed by a variety of processes. Such moraines formed by (a) uneven deposition of supraglacially and/or -subglacially-derived debris at active ice margins, (b) deposition at the stagnant margins of otherwise active glaciers, and (c) deposition during uninterrupted glacier retreat or areal stagnation. Differentiation and analysis of so-called 'hummocky moraine' enables glacier behaviour, during the Lateglacial to be interpreted in great detail.

All the warm deserts of the world exhibit gypsum crusts in favourable localities, generally areas with a source of gypsum and less than 250 mm of rainfall annually. The features, comprising loose powdery or cemented crystalline accumulations of calcium sulphate dihydrate, are found at the surface or within the uppermost 10 m of regolith. Thicknesses vary from a few millimetres to several metres and purities range from about 15% to nearly 100% gypsum. A review of the literature on gypsum soils and crusts reveals that the classification of types requires both standardizing and simplifying. A preliminary classification of crusts into three types can be made on the basis of structural and stratigraphic characteristics of examples from southern Tunisia and the Central Namib Desert. The types consist of subaerial aqueous evaporites, two subsurface and three surface forms. Detailed physical and chemical analyses justify a broadly similar genetic classification though one subsurface form is believed to be a primary pedogenic type of which the surface forms represent relics at various stages of solutional deterioration. Examples of subaerial aqueous evaporites are all products of shallow-water sedimentation in seasonally flooded chotts and sabkhas. The non-pedogenic subsurface type, croûte de nappe, is produced by displacive crystallization at the surface of a fluctuating water table. Gypsum precipitation results from either evaporation or mixing of saline waters causing saturation with respect to gypsum. Surface gypsum crusts are subsurface illuvial accretions exposed by erosion of overlying material. The gypsum is derived from solution of surface aeolian, atmospheric, colluvial or alluvial deposits by meteoric waters which percolate into the upper soil zone replenishing the antecedent soil moisture deficit. Subsurface accumulation results from displacive crystallization at host sediment grain contacts when gypsum saturated soil moisture evaporates.

No description available.

Thesis (Ph.D.)--University of Washington. / Vita. Bibliography: L. 122-128.

Thesis (Ph. D. - Civil Engineering)--University of Arizona. / Includes bibliographical references (leaves 98-102).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 241-246).

Thesis (Ph.D.)--McMaster University (Canada), 1991. / Source: Dissertation Abstracts International, Volume: 54-02, Section: B, page: 0699.

Thesis (Ph.D.)--McMaster University (Canada), 1993. / Source: Dissertation Abstracts International, Volume: 56-01, Section: B, page: 0141. Adviser: R. G. Walker.