Abstract The development of the conceptual ground model (CGM) is a critical component of any desk study or ground engineering project planning process. A key task of the engineering geologist is to develop the CGM in order to predict the occurrence of known terrain units, elements and facets within a given landsystem, and to communicate the lateral and vertical variability of engineering rocks and soils found within that system. This chapter details the significant ground components of glacial and periglacial landsystems within a geomorphological framework describing the sediments, structures and landforms that could reasonably be expected to be encountered in these terrains. Examples are provided of both modern and relict glacial and periglacial landforms, their mode of formation and their field recognition. Glaciogenic and periglacial sediments are described both in terms of their sedimentological and formal engineering description. The chapter provides a suggested naming nomenclature for these sediments that can be used within a BS 5930 description. An extensive photoglossary is presented as a field aide memoir, enabling the engineering geologist to identify these features once on site.

Abstract 3.1. Introduction The formation and alteration of clay minerals and their accumulation as clay materials can occur by a very wide range of processes. In one way or another, however, most of these processes and the environments in which they operate involve the chemical actions and physical movement of water. As such, clay minerals can be considered the characteristic minerals of the Earth;s near surface hydrous environments, including that of weathering, sedimentation, diagenesis/low-grade metamorphism and hydrothermal alteration (Fig. 3.1 ). Simply defined, the weathering environment is that in which rocks and the minerals they contain are altered by processes determined by the atmosphere, hydrosphere and the biosphere. Soil formation, also known as pedogenesis, occurs in the weathering environment. The sedimentary environment is the zone in which, soil, weathered rock and mineral (and biogenic) materials are eroded, mixed and deposited as sediments by water, wind and ice. Diagenesis involves all those physical and chemical processes that occur between sedimentation and metamorphism, whilst hydrothermal alteration encompasses the interactions between heated water and rock. In this chapter, the origins of the various clay minerals that may occur in each of these environments are reviewed along with the processes that may lead to their accumulation and alteration, usually together with other components, to form clay materials. In many instances, clay materials are formed in one environment by the accumulation or alteration of clay minerals formed in others. Thus the geological history of a clay material, and consequently its properties and behaviour, may depend on many processes separated in both time and space.

Abstract Chalk flows are flow slides that develop under certain circumstances from falls in chalk slopes. They are characterized chiefly by the mobility of the debris, which can run out over near-horizontal surfaces for as much as five to six times the slope height. After a brief account of the stratigraphy and extent of the Upper Cretaceous exposures of northwest Europe, chalk flows are described in outline, classified, and set in context with other types of flow slides. The relevant morphological parameters are defined. The incidence of chalk flows on the coasts of northwest Europe is outlined. Such failures occur in England, to a small extent in Sussex but predominantly in southeast Kent, in France from just north of Cap de la Hève to Ault in Haute-Normandie, in Denmark at Møns Klint, and in north Germany at Jasmund, in the northeast of the Isle of Rügen. It is shown that these flows occur only in soft chalks of high porosity (>~40%), in cliffs higher than ~30 m. Their mobility is inferred to derive principally from high excess pore-water pressures generated by a process of impact collapse in the saturated or near-saturated metastable soft chalk as it impacts onto the shore platform. Where earlier saturated colluvium is present on this platform, its undrained loading by the falling debris probably also plays a role, as does the presence or absence of seawater. Desirable further research is outlined, and the hazards posed by chalk flows are described.

Abstract The purpose of this chapter is to provide a background to the properties of natural clay materials used in the construction industry and other applications (see Table 4.1 ). There is a frequent need to evaluate clay materials for civil engineering projects, which has led to a bias in this chapter towards a consideration of their geotechnical properties. The intention is to present this information, and also some data applicable to other applications, in a manner suitable for scientists and engineers with an interest in clay materials. Both fundamental material behaviour and derived parameters are described. This chapter considers the engineering behaviour of rock and soil materials that consist largely of clay mineral grains, together with minor amounts of other minerals. As discussed in Chapter 1 , the term clay may mean a material made of clay-sized grains (smaller than 2 µm or 0.002 mm) or of grains consisting of clay minerals (see Chapter 2 ). Grains smaller than 2 µm may be clay minerals or other materials such as finely ground quartz or rock flour. Clay mineral grains may be larger than 2 µm and they are often bound into silt-sized (0.002-0.06 mm) aggregates. The Chapter concentrates on the properties of the material relevant to the exploitation and uses of excavated or extracted clays and mudrocks, rather than those of soil and rock masses in the ground, which are outside the scope of this report. The behaviour of clays depends on their particle size distribution, mineralogy and moisture content. In terms of moisture content, it is convenient to identify three distinct ranges of liquid and plastic limits, as defined in Section 4.2.3 :