(836-5 to 840) interval chiefly a dirty clay silicious to (illegible?) claystone with one streak of dirty flint clay. (GC-166) Flint is fragmental - appears about half way between reworking while soft and reworking while hard. (565-4 to 571) interval chiefly silicious to silty semihard clay with considerable Fe and minor lump inclusions. specimen (GC 16.12) 16/12 shows contact of homogenous silicious semihard and overlying fragmental zone. * GC G11 is at base of fragmental zone + shows large fragments of silty claystone and/or fracture filling it down.