Abstract From time to time in its history, the Earth has suffered an 'Ice Age', when large parts of its land surface have been covered by glaciers and its ocean surface by sea ice. This has happened at least during the late Precambrian, the Ordovician and the Carboniferous. The earth is again in an Ice Age. It began to develop during a phase of global cooling at the Eocene-Oligocene boundary (35-40 Ma) and has intensified during the late Tertiary and Quaternary. Antarctica is the continent most susceptible to glaciation, and evidence of the first growth of the Antarctic ice sheet from the Middle Miocene (c. 14 Ma) is the first sign of severe cooling. Some stages in progressive cooling are: 2.4 Ma: the first icebergs dropped detritus in the North Atlantic; 2 Ma: the first Arctic marine microfaunas in the North Sea; 0.75-0.8 Ma: detritus dropped from icebergs and glacial tills in the Forth approaches, showing that Scottish-centred ice sheets extended into shallow waters; 0.55 Ma: the first time that a Scottish-centred ice sheet extended to the edge of the western continental shelf. The cooling of global climate has not however been smooth and gradual. It has shown complex patterns of variation on all timescales. The best continuous evidence of global climate change through the Late Tertiary and the whole of the Quaternary comes from low sedimentation rate cores from the deep ocean that preserve a record of changing oceanic water temperature in changing microfaunal assemblages ( Fig. 15.1 a)

Abstract In engineering terms, all materials deposited as a result of glacial and periglacial processes are transported soils. Many of these deposits have engineering characteristics that differ from those of water-lain sediments. In the UK, the most extensive glacial and periglacial deposits are tills. Previously, engineering geologists have classified them geotechnically as lodgement, melt-out, flow and deformation tills, or as variants of these. However, in this book tills have been reclassified as: subglacial traction till, glaciotectonite and supraglacial mass-flow diamicton/glaciogenic debris-flow deposits (see Chapter 4 , Sections 4.1 – 4.3 ). Because this classification is new, it is not possible to relate geotechnical properties and characteristics to the subdivisions of the new classification. Consequently, the domain/stratigraphic classification, recently developed by the British Geological Survey and others, has been used and their geotechnical properties and characteristics are discussed on this basis. The geotechnical properties and characteristics of the other main glacial and periglacial deposits are also discussed. For some of these (e.g. glaciolacustrine deposits, quick clays and loess), geohazards relating to the lithology and/or fabric of the deposit are discussed along with their properties. Other geohazards that do not relate to lithology and/or fabric are discussed separately as either local or regional geohazards. In some cases (e.g. glaciofluvial sands and gravels), the geotechnical properties and behaviour are similar to sediments deposited under different climatic conditions; these deposits are therefore not discussed at length. Similarly, some of the local geohazards that are found associated with glacial and periglacial deposits relate to current climatic conditions and are not discussed here. Examples include land-sliding and highly compressible organic soils (peats).