Archaeologia Islandica - 01.01.2002, Page 32

Archaeologia Islandica - 01.01.2002, Page 32
Timothy J. Horsley & Stephen J. Dockrill Skálholt reduce this thermoremanent input, allowing more subtle archaeologi- cal anomalies to be detected. An important discovery from this project concerns the data collection method for magnetometer surveys. Many of the surveys revealed an enhanced effect of 'bunching' produced when data is collected in the 'zig-zag' fashion, possi- bly exaggerated by the strong geological anomalies. The only solution is to under- take carry out gradiometer surveys in the 'parallel' fashion. Unfortunately this will increase the time taken to survey each grid, but will produce clearer results. It has been demonstrated that the most information of archaeological value was produced by the small-scale noise caused by individual rocks associated with structural remains. Being small anomalies, these are best identified at a higher resolution of surveying than might ordinarily be undertaken. Consequently it is advised that a high resolution of data collection, i.e. 0.5m x 0.25m, is employed for most effective and inform- ative results. Magnetic susceptibility Throughout this assessment it was possi- ble to collect only a limited number of soil samples for measurement of magnet- ic susceptibility at Bradford. The preliminary results imply that, despite very high natural background values (generally in the range 100 to 250 SI xl0"8m3kg‘’), archaeological sedi- ments associated with buming produce strong enhancements, with values above 400 SI xl0"8m3kg‘', and even as high as 1800 SI xl0"8mJkg"'(midden material from Neðri Ás). However, it is not known how effective this method would be for reconnaissance surveying, as in many areas aeolian deposits overlay the archaeology and the natural mixing processes in the soil might not be extreme enough to bring enhanced mate- rial to the surface. Instead, this technique might prove valuable by aiding the inter- pretation of deposits during excavation by distinguishing between samples with natural and anthropogenic enhancement. Detection of archaeological remains As a preliminary evaluation, it was nec- essary to target archaeological remains known from other sources to allow a proper and confident assessment of these techniques to be made. Surveys at a num- ber of sites, and over different remains make it possible to talk generically about certain feature-types. Many sites presented visible earth- works constructed of turf. As discussed earlier in this paper, a lack of good build- ing stone has meant that many structures and field boundaries are constructed of turf. Where geophysical surveys included such remains, they were shown to appear as low resistance anomalies. This might be surprising since such extant remains could be expected to be better drained and therefore possess a higher resistance. These results therefore seem to indicate that the turf is water retentive, and it might be possible to use this characteris- tic for the future prospection of now- buried turf remains. Buried stone walls have been detect- ed in earth resistance and magnetometer surveys, despite the intense geological 30
Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19
Page 20
Page 21
Page 22
Page 23
Page 24
Page 25
Page 26
Page 27
Page 28
Page 29
Page 30
Page 31
Page 32
Page 33
Page 34
Page 35
Page 36
Page 37
Page 38
Page 39
Page 40
Page 41
Page 42
Page 43
Page 44
Page 45
Page 46
Page 47
Page 48
Page 49
Page 50
Page 51
Page 52
Page 53
Page 54
Page 55
Page 56
Page 57
Page 58
Page 59
Page 60
Page 61
Page 62
Page 63
Page 64
Page 65
Page 66
Page 67
Page 68
Page 69
Page 70
Page 71
Page 72
Page 73
Page 74
Page 75
Page 76
Page 77
Page 78
Page 79
Page 80
Page 81
Page 82
Page 83
Page 84
Page 85
Page 86
Page 87
Page 88
Page 89
Page 90
Page 91
Page 92
Page 93
Page 94
Page 95
Page 96
Page 97
Page 98
Page 99
Page 100
Page 101
Page 102
Page 103
Page 104
Page 105
Page 106
Page 107
Page 108
Page 109
Page 110
Page 111
Page 112
Page 113
Page 114
Page 115
Page 116
Page 117
Page 118
Page 119
Page 120
Page 121
Page 122
Page 123
Page 124
Page 125
Page 126
Page 127
Page 128
Page 129
Page 130
Page 131
Page 132
Page 133
Page 134
Page 135
Page 136
Page 137
Page 138
Page 139
Page 140
Page 141
Page 142
Page 143
Page 144
Page 145
Page 146
Page 147
Page 148
Page 149
Page 150
Page 151
Page 152
Page 153
Page 154
Page 155
Page 156
Page 157
Page 158
Page 159
Page 160
Page 161
Page 162
Page 163
Page 164

x

Archaeologia Islandica

Direct Links

If you want to link to this newspaper/magazine, please use these links:

Link to this newspaper/magazine: Archaeologia Islandica
https://timarit.is/publication/1160

Link to this issue:

Link to this page:

Link to this article:

Please do not link directly to images or PDFs on Timarit.is as such URLs may change without warning. Please use the URLs provided above for linking to the website.