 Ancient studies have had stratigraphic exposure to sections, are easier to work on, have more and better exposures and have an existing relationship to resources.Some geologists would restrict the term subaqueous pyroclastic flow deposits to volcaniclastic units that show characteristics of emplacement in a hot state deposited underwater—however, this cannot always be done because of the subsequent process of alteration/diagenesis such as active hot springs and associated hydrothermal alteration.Deposits from pyroclastic flows that interact with water and are transformed into water-supported mass flows are called subaqueous pyroclastic debris flow deposits by some geologists.