ludlow group

from The Century Dictionary.

• noun In geology, in England, a series of rocks, consisting chiefly of shales, with occasionally an intercalated belt of limestone, belonging to the Upper Silurian and lying above the Wenlock group, into which it graduates downward, and with whose fauna it has a large number of species in common.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Geol.) A subdivision of the British Upper Silurian lying below the Old Red Sandstone; -- so named from the Ludlow, in Western England. See the Chart of geology.