uriconian

from The Century Dictionary.

• noun The name given by some English geologists to a series of volcanic rocks, of which the Wrekin, in Shropshire, England, is chiefly made up, and which is supposed to occupy a position very near the bottom of the fossiliferous series. The name is from the Roman station Uriconium, the site of the present village of Wroxeter, in Shropshire.