Table 1

Clay types and properties

SiteFormationFormation age and locationTypeCEC(mequiv per 100 g)Clay (%)Silt (%)Sand (%)foc (%)CO3 (%)
1Gault ClayEarly Cretaceous (Sussex)Silty mudstone23 ± 5445420.84.9
2Kimmeridge ClayLate Jurassic (Wiltshire)Bitumous shale31 ± 55132171114
2Kimmeridge ClayLate Jurassic (Wiltshire)Calcareous mudstone22 ± 75039114.112
19Kimmeridge ClayJurassic (Wiltshire)Mudstone28 ± 1563954.25.4
19Kimmeridge ClayJurassic (Wiltshire)Calcareous mudstone26 ± 2623622.129
3Oxford ClayMid-Jurassic (Oxon.)Sandy mudstone22 ± 21841411.212
4Lower LiasTriassic–Early Jurassic (Gloucs.)Calcareous mudstone30 ± 1435522.422
5Mercia MudstoneTriassic (Devon)Silty mudstone12 ± 31757260.53.6
6Mercia MudstoneTriassic (Somerset)Silty mudstone16 ± 52854181.65.2
6Mercia MudstoneTriassic (Somerset)Silty mudstone14 ± 24543120.414
6Mercia MudstoneTriassic (Somerset)Mudstones37 ± 1494560.24.5
6Mercia MudstoneTriassic (Somerset)Clayey siltstone13 ± 23357100.44.8
7Etruria Fm, Upper Coal MeasuresCarboniferous (Staffs.)Red marl11 ± 12756171.72.1
8Etruria Fm, Upper Coal MeasuresCarboniferous (Staffs.)Red marl8.9 ± 12934370.22.5
9Coal MeasuresCarboniferous (Derbyshire)Clayey siltstone23 ± 33150190.31.1
21Coal MeasuresCarboniferous (Lancs.)Ex situ colliery spoil10.417.632.217.54.64.85
10London ClayEocene (Essex)Silty clay23 ± 3613720.22.5
11London ClayEocene (Essex)Silty clay21 ± 2653500.72.3
12Ball Clay(Devon)Silty clay8.8 ± 3574120.40.4
12Ball Clay(Devon)Silty clay11 ± 4534520.30.0
20London ClayPalaeogene (Dorset)Sandy clayey siltstone11 ± 22456200.40.1
20London ClayPalaeogene (Dorset)Sandy clayey siltstone10 ± 22454220.30.9
13Upper Thanet SandsEocene (Essex)Sandy siltstone9 ± 0.11120691.216 ± 1
13Lower Thanet SandsEocene (Essex)Sandy mudstone15.8 ± 0.52735391.620 ± 4
14Boulder ClayGlacial (Lancs.)Silty mudstone21 ± 74344130.66.2
15Boulder ClayGlacial (Lancs.)Silty clay6.3 ± 12854180.82.5
21Boulder ClayGlacial (Lancs.)13.326.835.530.40.510.3
17Glacial TillGlacial (S'land)*Silty sandstone9.5 ± 12031490.34.4
2Glacial TillGlacial (Wilts.)Fine rock flour23 ± 54430260.66.2
13Alluvium, Thames EstuaryRecent (Essex)†Silty clay23 ± 24639152.10.3
18Alluvium, Severn EstuaryRecent (Gloucs.)Silty clay21 ± 2356230.47.6
18Alluvium, Severn EstuaryRecent (Gloucs.)Silt9 ± 11272160.65.2
18Alluvium, Severn EstuaryRecent (Gloucs.)Organic clay44 ± 4791742.910
  • foc, fraction of organic carbon. At Site 21, the ex situ colliery spoil was originally of Carboniferous age and was left on-site following mine closure. *Scotland (East Lothian); †correct usage.