PORTABLE ANTIQUITIES SCHEME A GUIDE FOR RESEARCHERS This guide has been produced as part of the Leverhulme Trust funded project ‘The Portable Antiquities Scheme as a tool for archaeological research’. It builds upon a thesis funded by the University of Southampton and the ‘Arts and Humanities Research Council’ Dr Katherine Robbins August 2014 Front page images (not to scale): NMS-FB1B14 YORYM-8D1453 YORYM-691CA3 CONTENTS PURPOSE OF THE GUIDE .................................................................................................................................. 9 METAL DETECTING AND THE PAS ................................................................................................................... 11 THE GROWTH OF METAL DETECTING (1960 – 1980) ................................................................................................... 12 PORTABLE ANTIQUITIES LEGISLATION (1970 – 2010) .................................................................................................. 12 METAL DETECTOR USERS AND ARCHAEOLOGISTS .......................................................................................................... 13 METAL DETECTORISTS TODAY ................................................................................................................................... 13 SUMMARY OF KEY DEVELOPMENTS SINCE THE 1960S .................................................................................................. 15 UNDERSTANDING AMATEUR COLLECTION BIAS ............................................................................................. 23 THEORIES OF SAMPLING BIAS ................................................................................................................................... 23 STAGE 1: DEPOSITION – LOSS AND BURIAL ................................................................................................................. 26 STAGE 2: PRESERVATION ........................................................................................................................................ 27 STAGE 3: SURVIVAL ............................................................................................................................................... 29 STAGE 4: EXPOSURE .............................................................................................................................................. 29 STAGE 5: RECOVERY .............................................................................................................................................. 31 STAGE 6: REPORTING ............................................................................................................................................. 34 STAGE 7: RECORDING ............................................................................................................................................ 36 METHODS FOR EXPLORING BIAS IN THE PASD ............................................................................................... 37 MAPPING CONSTRAINTS ......................................................................................................................................... 38 History .......................................................................................................................................................... 38 Types of Constraints ..................................................................................................................................... 39 Grouping Constraints ................................................................................................................................... 47 Using Constraints Mapping .......................................................................................................................... 51 DENSITY AND DISTRIBUTION ANALYSES ....................................................................................................................... 52 Data fuzziness .............................................................................................................................................. 52 Density mapping .......................................................................................................................................... 55 Using KDE to examine PAS data ................................................................................................................... 57 LANDSCAPE ANALYSIS ............................................................................................................................................. 60 Landscape features ...................................................................................................................................... 60 THE PAS AND OTHER ARCHAEOLOGICAL DATASETS ...................................................................................................... 65 Site targeting ............................................................................................................................................... 67 Other archaeological datasets ..................................................................................................................... 67 PEOPLE AND THE PAS ............................................................................................................................................ 69 Exploring finder behaviour ........................................................................................................................... 69 Exploring recorder behaviour ....................................................................................................................... 74 APPROACHING AN ANALYSIS OF THE PASD ................................................................................................... 77 WHAT IS THE SURVEY AREA? .................................................................................................................................... 77 HOW ARE THE CHOICES OF COLLECTORS AFFECTING YOUR DATA? .................................................................................... 77 WHAT ‘REPORTING’ AND ‘RECORDING’ ISSUES ARE THERE? ............................................................................................ 77 BIBLIOGRAPHY ............................................................................................................................................... 79 CODE OF PRACTICE FOR RESPONSIBLE METAL-DETECTING IN ENGLAND & WALES ........................................ 87 BEFORE YOU GO METAL-DETECTING: ......................................................................................................................... 87 WHILE YOU ARE METAL-DETECTING: ......................................................................................................................... 87 AFTER YOU HAVE BEEN METAL-DETECTING: ................................................................................................................ 88 5 TABLE OF FIGURES Figure 1: Reasons for the non-reporting of finds .................................................................................. 35 Figure 2: The VASLE constraints base map (2009) ................................................................................ 38 Figure 3: A selection of potential ‘hard’ constraints ............................................................................. 47 Figure 4: Constrained land at a nationwide scale (using access land and SSSIs boundaries © Natural England, Forestry Commission and National Trust boundaries, and elevation data derived from OS Terrain 50) ............................................................................................................................................. 48 Figure 5: Section of the nationwide constraints map plotted against all PAS finds (correct to April 2013), illustrating the general accuracy of the constraints map ......................................................... 49 Figure 6: PAS finds (correct to April 2013) plotted against elevation (derived from OS Terrain 50 © Crown copyright 2013) ......................................................................................................................... 50 Figure 7: PAS finds (correct to April 2013) plotted against Forestry Commission and National Trust land ....................................................................................................................................................... 50 Figure 8: Comparing Roman PAS data to all other findspots (correct to April 2013) illustrating the links between clusters of finds from different periods ......................................................................... 53 Figure 9: (a) Random selection of ~100,000 PAS artefacts (b) (c) (d) findspots represented as NGR squares .................................................................................................................................................. 54 Figure 10: KDE map with kernel size = 20km ........................................................................................ 55 Figure 11: KDE map with kernel size = 10km ........................................................................................ 55 Figure 12: KDE map with kernel size = 5km .......................................................................................... 56 Figure 13: Trend surface, polynomial 4 ................................................................................................ 56 Figure 14: KDE map with