An alternative explanation for the distinct composition of the Avalon-type assemblage is that it was a terrestrial assemblage of volcaniclastic coastal soils near a continental volcanic arc. This view is based on geochemical studies of the substrates of Mistaken Point fossils and associated matrix supported tuffs and volcanic bombs that could only form on land. Some of these fossils such as "Fractofusus" and "Charniodiscus" were found in strata that Retallack interprets to be red well drained paleosols of coastal plains, but others such as "Aspidella" were found in strata that Retallack interprets to be intertidal paleosols.