Spinosa - pulchellus Zone
Definition: From first appearance of Rugia spinosa to immediately below first appearance of Trigonosemus pulchellus (Johansen & Surlyk, 1990). There is a local acme in brachiopod density just below the middle part of the zone (Johansen & Surlyk, 1990).
Biostratigraphical correlation: The zone spans the junction of the B. lanceolata and B. occidentalis zones of the standard biozonal scheme.
Lithostratigraphical correlation: The zone equates with the middle and higher parts of the Sidestrand Chalk Member, the Trimmingham Sponge Beds Member and the Little Marl Point Member (Johansen & Surlyk, 1990).