The base of Artifact Ridge is covered with glacial, talus and landslide deposits. The oldest exposed rocks are of Mesozoic or Paleozoic age and are overlain by Miocenealkali basalt flows of the Raspberry Formation. The Raspberry rocks are overlain by quenched, hydrothermally altered and highly fractured Miocene trachybasalt which comprise the lower subaqueous facies of the Little Iskut Formation. Overlying these rocks are Miocene trachybasaltic lava flows and flow breccia comprising the upper subaerial facies of the Little Iskut Formation.[4]
The Little Iskut rocks are overlain by Miocene comendite or trachyte lava flows and domes of the Armadillo Formation which are in turn overlain by Pliocene alkali basalt of the Kounugu Member of the Nido Formation. The youngest and uppermost rocks comprising Artifact Ridge are Pliocene alkali basalt flows of the Kitsu Member of the Spectrum Formation which are interbedded with fluvial gravel and paleosols.[4]