Downloaded from http://egsp.lyellcollection.org/ by guest on October 7, 2021 Chapter 1 Introduction to engineering geology and geomorphology of glaciated and periglaciated terrains C. J. Martin1*, A. L. Morley2 & J. S. Griffiths3 1BP Exploration Operating Company Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK 2Ove Arup & Partners Ltd, 13 Fitzroy Street, London W1T 4BQ, UK 3School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, UK *Correspondence: [email protected] Abstract: This chapter provides an introduction to the Engineering Group of the Geological Society of London (EGGS) Working Party book on the engineering geology and geomorphology of glaciated and periglaciated terrains. A summary of changes in the extent of glacial and periglacial conditions throughout the Quaternary to the present day is provided initially. The engineering difficulties associated with working in glaciated and periglaciated terrains are demonstrated through the inclusion of seven important case histories. The chapter then discusses the background to the Working Party, the scope and structure of the book, including abstracts of each chapter, before finally guiding the reader on how the book may be used at a site where glacial or periglacial conditions had formerly prevailed. In particular, the importance of updating the ground model at each stage of the project as an approach to risk management is emphasized. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. When the work of the geologist is finished and his final compre- their engineering geological characteristics and their geotech- hensive report written, the largest and most important chapter will nical properties. Appreciating the sedimentological inheri- be upon the latest and shortest of the geologic periods tance of glacial, periglacial and permafrost processes is Gilbert 1890, p. 1. therefore fundamental to any understanding of the engineer- ing geology and geotechnical behaviour of both soils and weathered bedrock in Great Britain and similar environments 1.1 Introduction overseas. It was for these reasons that the Engineering Group of the Geological Society of London (EGGS) established a At present, glaciers only cover about 10% of the Earth’s sur- Working Party to produce this state-of-the-art book on The face (Owen & Derbyshire 2005; Benn & Evans 2010). That is Engineering Geology and Geomorphology of Glaciated a total of over 15 million km2, with 99% found in the ice and Periglaciated Terrains. sheets of Antarctica and Greenland. However, over the past It must be acknowledged that the extent of contemporary 2.6 Ma of the Quaternary Period there have been multiple glacial and permafrost limits (Figs 1.1 and 1.2) has changed phases of spatially more extensive ice and permafrost around significantly since the 2005 summary paper by Owen & the globe (see Chapter 2). Even as recently as 18–24 ka at the Derbyshire (2005). The changing climate has reduced the Last Glacial Maximum this coverage was as high as 30% and, permanent ice coverage that has been replaced with newly during some earlier glacial advances, the ice coverage was exposed areas of permafrost/periglacial activity. There are even higher. The former and current global glacial extents also many reports of loss of permafrost affecting native com- are shown in Figure 1.1. Currently active periglacial condi- munities in Alaska and northern Canada (Sven Lukas, pers. tions occur in 25% of the world’s land area (French 2007) comm. 2016). It is anticipated that these changes will con- with permafrost (perennially frozen ground) underlying tinue in response to global climate change (ACIA 2005; 20%, mainly in the Northern Hemisphere (Walker 2005). IPCC 2014), which means that the extent of formerly glaci- The former and current global extents of periglacial influence ated and periglaciated terrains will continue to increase. The are shown in Figure 1.2. In most of NW Europe, Asia and driving mechanisms for present-day climate change are con- North America it is the legacy of these ice advances and sidered to be outside the scope of this book; here, the focus is retreats, along with the migration of periglacial and perma- on the engineering geology and geomorphology of glaciated frost conditions, that dominate the distribution of soils, and periglaciated terrain resulting from Quaternary stadials. Engineering Group Working Party (main contact for this chapter: C. J. Martin, BP Exploration Operating Company Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK, [email protected]) From: GRIFFITHS,J.S.&MARTIN, C. J. (eds) 2017. Engineering Geology and Geomorphology of Glaciated and Periglaciated Terrains – Engineering Group Working Party Report. Geological Society, London, Engineering Geology Special Publications, 28,1–30 https://doi.org/10.1144/EGSP28.1 © 2017 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://egsp.lyellcollection.org/ by guest on October 7, 2021 2 INTRODUCTION Fig. 1.1. Map showing approximate limits of Northern Hemisphere ice sheets at the present day and during the Last Glacial Maximum (LGM). Ice caps and smaller glaciers are omitted. Based on Hubbard et al. (2006), Andrews & Dyke (2013), Ehlers et al. (2013) and Hughes et al. (2016). As a general rule, engineering geologists and geotechnical and programme, and which can only be identified from a engineers are typically only concerned with the upper few detailed examination of soil samples. metres, or tens of metres, of ground that underlie a site of To demonstrate how it is critical to understand the nature interest. This is in contrast to hydrogeologists, mining geolo- and formation of glacial and periglacial terrain to overcome gists and petroleum geologists whose zone of interest is the engineering difficulties, a selection of seven case histories upper hundreds to thousands of metres of ground that host is presented in Section 1.2. These case histories are presented their resources. While it is important for engineering geolo- in order of age, starting in 1908, and demonstrate some of gists to understand the formative processes and resulting mate- the typical engineering problems that have been encountered rials and structures of the ‘deep geology’, it is generally the over the past 100+ years working in these materials. How- geological events of the Quaternary that have an overwhelm- ever, this is only a very small sample of the many examples ing influence on the characteristics of the near-surface rocks that can be found in the scientific literature (e.g. Kiersch and soils (Fookes 1990, 1997a, b), as illustrated in Figure 1.3. 1991). While Section 1.2 sets the historical context for the The extent of the dominant glacial and periglacial influ- work, Section 1.3 presents the background, aims and specific ence in the top few tens of metres means that many engineer- objectives of the Working Party. In Section 1.4 the scope of ing structures are located within these variable and complex this book is summarized and Section 1.5 provides the struc- soils and rocks. A glossary of ground conditions that could ture of this book, including the abstracts of Chapters 2–9. be encountered (Chapter 3) helps to confirm the variability Finally, Section 1.6 guides the reader on how the book may and complexity that might be seen during an engineering pro- be used at a site where glacial or periglacial conditions ject. This ranges from regional-scale structures found during have prevailed. In particular, the importance of updating the desk study and walkover to a micro-scale soil fabric that the ground model at each stage of the project as an approach can have a profound influence on construction safety, cost to risk management is described. Downloaded from http://egsp.lyellcollection.org/ by guest on October 7, 2021 INTRODUCTION 3 Fig. 1.2. Former and current Northern Hemisphere permafrost extents. 1.2 A history of engineering difficulties The case histories presented below are in chronological order and reflect the state of knowledge and understanding in formerly glaciated and by the geologists and engineers at the time of the projects. periglaciated terrain While the tunnel construction through a glacial over- deepened valley presented in Case History 1.1 at Lötschberg The engineering geological importance of former periglacial occurred over 100 years ago, it is a classic example of the and glacial conditions is illustrated by the following seven ability of a glacier to over-deepen a valley to such depths case histories of engineering failures that resulted from a not thought conceivable from the scientific knowledge at lack of appreciation at that time of the influence of periglacial that time; it was a case of an ‘unknown unknown’. Today’s and glacial processes on materials and landforms. These case updated landsystems approach to the understanding of histories have been selected to demonstrate the effect of such these terrains (Chapters 4 and 5) now contributes to more features on a wide range of national and global engineering robust ground models and therefore more carefully targeted projects including tunnels, dams, transport infrastructure, ground investigations based on the lessons learnt from this slope instability, building foundations and offshore structure case history. An example of these advances is presented foundations. Further case studies in Chapter 9 demonstrate later in this volume in Chapter 9. Case Study 9.2 (the occur- the successful application of the engineering geological and rence of subglacial channels that could have affected the geomorphological principles advocated in this book to suc- M18 motorway in Yorkshire, UK) illustrates an example cessfully solve challenging engineering problems. of the successful anticipation of buried valleys, albeit not to Downloaded from http://egsp.lyellcollection.org/ by guest on October 7, 2021 4 INTRODUCTION Fig. 1.3.