Chadian age, younger than typical Waulsortian mounds. Below lower Visean unconformity.
Reef knolls.
Bryzoans are dominant macrofossils.
Fenestella, crinoids and stromatactis are common.
Grivanella and sponges locally abundant.

Including Crow Hill, Worsaw, Gerna, Sykes and
Twiston localities of ref. 2567