五峰阶(Wufengian Stage)位于石口阶之上,曾用于中国上奥陶统顶部的一个阶,大致与欧洲的阿什极尔阶相当。五峰阶自下而上含有六个笔石带:①Pleurograptus lui带;②Dicellograptus szechuanensis带;③Tangyagraptus typicus带;④Diceratograptus mirus带;⑤Paraorthograptus typicus带和⑥Diplograptus bohemicus带。后人厘定为五个化石带,自下而上为:①Dicellograptus complexus带,②Tangyagraptus typicus带,③Paraorthograptus Diceratograptus mirus带,④Diplograptus bohemicus带,⑤Hirnantia Kinnella带。笔石相广泛分布于南方、西北等地区。五峰阶一名源自湖北五峰渔洋关。现已停止使用。[1]