Excursion guide to the geology of the Isle of Skye

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This book is now out of print
From: Bell, B.R. and Harris, J.W. An excursion guide to the geology of the Isle of Skye : Geological Society of Glasgow, 1986. © 1986 B.R. Bell & J.W. Harris. All rights reserved. October 2022 note: A new edition of the guide is now available.

Chapter 1 Introduction

(A) History of research

(B) Geological synopsis

Chapter 2 Pre-Tertiary rocks

(A) Lewisian Gneiss

(B) Torridonian sedimentary rocks

(C) Moine schists

(D) Cambro-Ordovician sedimentary rocks

(E) Triassic sedimentary rocks

(F) Jurassic sedimentary rocks

(G) Cretaceous sedimentary rocks

(H) Pre-Tertiary minor intrusions

Chapter 3 Tertiary extrusive products

(A) Basal Tuffs

(B) Interbasaltic sedimentary rocks

(C) Interbasaltic laterites

(D) Plateau lavas

(E) Acid lavas

Chapter 4 The Cuillin Complex

(A) Introduction

(B) The Outer Marginal Gabbros and Eucrites

(C) The Border Group

(D) The Layered Peridotite Series (Sgurr Dubh Peridotites)

(E) The Outer Layered Allivalite Series

(F) The Outer Layered Eucrite Series

(G) The Outer Layered Gabbro Series

(H) The Druim nan Ramh Eucrite

(I) The Inner Layered Allivalite Series

(J) The Inner Layered Eucrite Series

(K) The Inner Layered Gabbro Series

(L) The Coire Uaigneich Granite

(M) Thermal effects of the Cuillin Complex

(N) The volcaniclastic pipes of the Cuillin Complex

Chapter 5 The Srath Na Creitheach Centre

(A) Introduction

(B) General field relationships

(C) The Meall Dearg Granite

(D) The Ruadh Stac Granite

(E) The contact between the Meall Dearg and Ruadh Stac granites

(F) The Meall Dearg Acid Breccias

(G) The Blaven Granite

(H) Shape and mechanism of intrusion of the granites

Chapter 6 The Western Red Hills Centre

(A) Introduction

(B) The Belig and Meall a' Mhaoil vent agglomerates and breccias

(C) The Marsco Summit Gabbro

(D) The Glamaig Granite

(E) The early northern granites of Maol na Gainmhich and Eas Mor

(F) The Beinn Dearg Mhor and Loch Ainort granites

(G) The early southern granite of Glen Sligachan and the Southern Porphyritic Granite

(H) The Marscoite Suite

(I) The Northern Porphyritic Felsite and the late northern granite of Meall Buidhe

(J) The late southern granite of Marsco

(K) Mechanisms of intrusion and volcanic processes

Chapter 7 The Eastern Red Hills Centre

(A) Introduction

(B) The Kilchrist Hybrid Ring-dyke

(C) The Beinn na Cro Gabbro

(D) The Broadford Gabbro

(E) The Glas Bheinn Mhor Granite

(F) The Outer Granite

(G) The Inner Granite

(H) The composite sills and dykes

(I) Thermal and metasomatic effects of the granites

Chapter 8 Pyroclastic rocks of The Central Complex

(A) Introduction

(B) The Srath na Creitheach Deposits: description

(C) The Srath na Creitheach Deposits: origin

(D) The Creagan Dubh and Kilchrist Deposits: description

(E) The Creagan Dubh and Kilchrist Deposits: origin

Chapter 9 The minor intrusions

(A) Introduction

(B) The regional dyke swarm and associated subswarms

(C) The compositions of the basic dykes of the regional swarm

(D) The cone-sheets of the Cuillin Complex

(E) The tholeiite sheets of the Western Cuillin Complex

(F) The Gars-bheinn ultrabasic sill

(G) The layered ultrabasic dyke of Stac Suisnish

(H) The basic sill complex of North Skye

(I) The ultrabasic (picritic) dykes and sills of Central Skye

(J) The ultrabasic (allivalitic) dykes of North Skye

(K) The trachyte dykes

(L) The augite-andesite dykes

(M) The pitchstone dykes

(N) The leidleite dyke of the Tungadal River

(O) The brecciated rhyolite and acid breccias of the Kilchrist Area

(P) Deformed Lower Tertiary dykes and sills

Chapter 10 Tectonic and stratigraphic evolution

(A) Introduction

(B) The Moine Thrust Zone

(C) The Sea of the Hebrides and Inner Hebrides sedimentary basins

(D) The Camasunary Fault

Chapter 11 Quaternary and Recent geology

(A) Introduction

(B) Glaciation and glacial deposits

(C) Raised beaches

(D) Landslips

(E) Screes and rockfalls

(F) Diatomite deposits

(G) Alluvium

(H) Peat

(I) Blown sand

Chapter 12 Origin of the magmas and the hydro-thermal systems associated with the Skye centre

(A) Introduction

(B) Mantle melting events and crustal contamination of magmas

(C) The parental magmas of the Cuillin Complex

(D) Generation of the acid magmas

(E) Magma-mixing

(F) Hydrothermal systems associated with the Skye Centre

(F) Hydrothermal systems associated with the Skye Centre

Introduction to excursions

List of excursions

Excursion 1 The area around Isleornsay

Excursion 2 The areas around Ord and Tarskavaig

Excursion 3 The Strathaird Peninsula

Excursion 4 Beinn an Dubhaich

Excursion 5 Kilchrist

Excursion 6 The area around the Old Manse at Kilchrist

Excursion 7 The Broadford area

Excursion 8 Creag Strollamus

Excursion 9 Strollamus to Torrin

Excursion 10 Camasunary Bay

Excursion 11 Loch Coruisk - Druim Hain

Excursion 12 Gleann Torra-mhichaig - Coire nam Bruadaran - Belig

Excursion 13 The Moll Coast

Excursion 14 The Allt Daraich section

Excursion 15 Marsco

Excursion 16 Glen Brittle and the Western Cuillin Hills

Excursion 17 The Portree area

Excursion 18 Bearreraig Bay - The Storr

Excursion 19 The Loch Cuithir diatomite deposits

Excursion 20 The Kilt Rock

Excursion 21 Kildorais to Staffin Bay coastal section and The Quirang

Excursion 22 West Trotternish

Appendix 1: Glossary of petrological names and terms

Appendix 2: Glossary of fossil names

Appendix 3: Glossary of place names and grid references

Foreword

The Isle of Skye has attracted geologists since the beginning of the Nineteenth Century. Within this comparatively small area many of the major geological units of Scotland are found. In this guide we have attempted to describe the geological history of the island. The accompanying excursions allow many of the important field relationships to be observed directly. In a few instances, however, supplementary information is provided in order that interpretations can be presented. In following the excursions additional observations will doubtless be made. We hope, therefore, that the guide will stimulate new interest in this classic area.

Acknowledgements

During the production of this guide two organisations have been most generous with facilities and funding. Britoil plc. provided cartographic facilities through Aileen Clark and Michael Cairns. The high quality of the maps and diagrams in this guide is the result of their skills. The Scottish Development Agency provided funds in order that the excursions to the guide could be prepared. This contribution allowed us to include more detailed information which we believe substantially improves the text. Dr Jain Allison of the University of Strathclyde gave much valuable information on the publishing of the guide, as well as advice on aspects of structural geology incorporated in the text. Dr John Hudson of the University of Leicester reviewed the section on the Mesozoic sedimentary rocks and helped with the stratigraphic sections within the excursions. On Skye, Mr David Lloyd of Broadford most generously made available to us his cottage and provided logistic support during our fieldwork. We thank the University of Strathclyde for the academic environment which enabled this guide to be written and for the use of its facilities to carry out the work involved. Finally, our thanks go to all who gave permission to reproduce maps and diagrams: their important contribution to the guide is acknowledged in the appropriate places in the text. Grid References in the text and on maps are from the Ordnance Survey and are reproduced by permission of the Controller of Her Majesty's Stationery Office.