Table 1.

Data on engineering character of heads developed over shales and slates in SW England

>SandSiltClay
Seaton downderry (East Cornwall)<70%17–20%<10%
PL10–20%
LL23–35%
Bulk density2120 kgm−3
Dry density1750 kgm−3
Wembury16%–80%5%–50%1%–10%
PL16%–28%
LL23%–38%
Prawle21%–80%9%–44%0.1%–10%
PL16%–20%
LL19%–30%