This volume will draw the attention of everyone interested in the fascinating diversity of

ancient ecosystems such as reefs and shell accumulations in the Palaeozoic, whose

difficulty of study rests primarily on its multidisciplinary position crossing numerous

geological disciplines. Their facies characterization is, like many other biosedimentary

structures, a process that requires the acquisition and integration of a wide and multiscale

diversity of observations, which include field (global geometries), sample (fabrics),

and thin-section (textures) scales.

One of the messages of this collection of papers is the wide diversity of sedimentary

geometries and facies displayed by Palaeozoic reefs, shell accumulations, and transitional

composite deposits. We have touched on some of the major issues at this stage of development

in the field: the major climatic, environmental and evolutionary factors that

controlled the Palaeozoic development of shell accumulations and reefs.