7. Biogenic Structures

The presence of life, in its multifarious aspects, has an important bearing on both the origin and the modification of sediments. The ways that life and sediments interact are highly diversified, and the same is true for the morphology and the scale of their products. It is obviously impossible to illustrate them all, and a selection is necessary. Moreover, a sedimentologist cannot describe and understand structures related to life or biological processes (biogenic structures ) without the help of other experts (biologists, ecologists, paleontologists).

In this chapter, some structures are presented that exemplify relatively common categories  of biological activity related to sedimentation and, above all, provide useful and often valuable information on sedimentary processes, mechanisms, and environments. Among biogenic structures, in other terms, sedimentological indicators  will be emphasized.

I will start with so-called constructive  features, which contribute to sediment accumulation in some way or the other. After that, I will examine destructive  and biodeformative  structures, resulting from organic activities that disturb the sediment and obliterate, in part or entirely, its depositional structures.