Bioturbation in the context of "Ecosystem engineer"

In geology, fissility is the ability or tendency of a rock to split along flat planes of weakness (“parting surfaces”). These planes of weakness are oriented parallel to stratification in sedimentary rocks. Fissility is differentiated from scaly fabric in hand sample by the parting surfaces’ continuously parallel orientations to each other and to stratification. Fissility is distinguished from scaly fabric in thin section by the well-developed orientation of platy minerals such as mica. Fissility is the result of sedimentary or metamorphic processes.

Planes of weakness are developed in sedimentary rocks such as shale or mudstone by clay particles aligning during compaction. Planes of weakness are developed in metamorphic rocks by the recrystallization and growth of micaceous minerals. A rock's fissility can be degraded in numerous ways during the geologic process, including clay particles flocculating into a random fabric before compaction, bioturbation during compaction, and weathering during and after uplift. The effect of bioturbation has been documented well in shale cores sampled: past variable critical depths where burrowing organisms can no longer survive, shale fissility will become more pervasive and better defined.

The Formation of Vegetable Mould Through the Action of Worms, with Observations on their Habits (sometimes shortened to Worms) is an 1881 book by Charles Darwin on earthworms. It was his last scientific book, and was published shortly before his death (see Darwin from Insectivorous Plants to Worms). Exploring earthworm behaviour and ecology, it continued the theme common throughout his work that gradual changes over long periods of time can lead to large and sometimes surprising consequences. It was the first significant work on soil bioturbation, although that term was not used by Darwin (it first appeared in the soil and geomorphic literature one hundred years later).