Cenozoic volcanic rocks in Fildes Peninsula can be divided into four lithological members, i.e., Jasper Hill Member (Eb), Agate Beach Member (Em), Fossil Hill Member (Eh) and Block Hill Member (Ey).

• 菲尔德斯半岛出露一套第三纪岛孤火山岩；包括高铝玄武岩、玄武安山岩、及少量安山岩与英安岩；从早到晚可划分为碧玉山段、玛瑙滩段、化石山段和岩块山段四个岩性段.