CHAPTER 8 S IZE S ORTING D URING T RANSPORT AND D EPOSITION OF F INE S EDIMENTS :S ORTABLE S ILT AND F LOW S PEED I.N. McCave Department of Earth Sciences, University of Cambridge, Cambridge, UK Contents 8.1. Introduction 121 8.2. Size Analysis of Fine Sediments 123 8.2.1. Measurement of fine grain sizes 123 8.2.2. Size distributions of components 125 8.3. Unsorted Delivery to Deep Current Systems: Pelagic Flux and Down-Slope Transport 126 8.4. Controlling Factors for Input and Transport 127 8.4.1. Settling velocity of grains and aggregates, w s 127 8.4.2. Boundary-layer flow structure and turbulence 130 8.5. Sorting in Suspension Transport 131 8.6. Processes of Deposition from Turbulent Boundary Layers 132 8.6.1. Rate of deposition 132 8.6.2. Limiting shear stress for deposition t d 132 8.6.3. Sorting by selective deposition: cohesive versus sortable silt 134 8.6.4. Repeated sorting events under deep-sea storm conditions 135 8.7. Deposits from Currents 137 8.7.1. Spatial variability of sediment size over bedforms and drifts 137 8.8. Some Examples of Palaeoflow Inferred from Sortable-Silt records 140 8.8.1. Gardar Drift and Bermuda Rise at the penultimate glacial termination 140 8.8.2. Flow on the Iberian Margin over the last glacial cycle 141 Acknowledgements 142 8.1. I NTRODUCTION The transport and deposition of contourites, involving many cycles of erosion and deposition under intermittently strong deep-sea currents, produces fine sedi- ments that show some sorting. Palaeocurrent reconstruction with high temporal Developments in Sedimentology, Volume 60 Ó 2008 Elsevier B.V. ISSN 0070-4571, DOI: 10.1016/S0070-4571(08)00208-2 All rights reserved. 121