A redefinition of waste: Deconstructing shell and fish mound formation among coastal groups of southern Brazil

• Shellmound formation goes beyond secondary discard of daily refuse.
• Sediments in shellmounds show complex depositional history.
• Transport of midden material was the recurrent action behind mound formation.
• Off-site habitation sites buried by modern sediments, demanding new survey methods.
• Geoarchaeological approach necessary to decipher site composition and history.

The prehistory of the southern coast of Brazil (Santa Catarina state) is materialized in the present landscape by numerous large-scale shellmounds, shellmounds with a sandy core, and fishmounds. A geoarchaeological approach was applied to understand the sequence and diversity of human actions involved in the settlement of the area as expressed in the multiple mounded structures, dated from the early Holocene to shortly before the arrival of the first colonizers. A detailed account of the composition and history of four stratified shellmounds, two shellmounds with a sandy core, and two fishmounds is given using a standard method for intra and inter site comparisons. The method combines the macroscopic evaluation of the profiles with off-site sampling, provenance of the organic matter in the sediments, and micro-scale identification of components, their alteration, and arrangement. Substantial implications result from this analysis related to the identification of recurrent behaviors in shellmound formation and growth, prehistoric alteration and destruction of habitation sites, development of a built environment, and continuity in mound building as an expression of group identity. Shellmounds and fishmounds show a complex pre-depositional history that denies the traditional view of them as secondary deposits of food remains.