Composition and origin of stromatactis‐bearing mud‐mounds (Upper Devonian, Frasnian), southern Rocky Mountains, western Canada

Geologists recognize a myriad of post-depositional agents, which invariably influence and alter any sediment as soon as it is deposited. Some of these agents are physical (e.g., oscillating waves, transportive currents and compaction phenomena); some are chemical (e.g., oxygen diffusion, mineral dissolution and cementation); and some are biological (e.g., sediment reworking by animals and plants).

In many cases, the effects of biological agents in the sediment overshadow those of physical and chemical agents in producing recognizable features, such as textures, fabrics and sedimentary structures, that aid geologists in their attempts to understand the history of a sedimentary rock. It is very important for sedimentary geologists to recognize and understand primary textures, diagenetic fabrics and physical sedimentary structures; it is equally important for them to recognize and understand biogenic textures, biogenic fabrics and biogenic sedimentary structures.

The study of post-depositional biological effects on sedimentary deposits is known as “ichnology” (from the Greek iknos, meaning “trace or track”, and logos, meaning “word or study”). The field encompasses those aspects of organism-substrate interrelationships that focus on how plants and animals leave a record of their activity in the sediment. Whether it be a trilobite that makes a footprint, a dinosaur that digs a nest, or a dense population of shrimp that thoroughly churns the sea-floor, its record in the rock is something to interest and excite the ichnologist.

Ichnology is truly an interdisciplinary subject, involving important elements of paleontology, paleoecology, sedimentology, stratigraphy and even geochemistry. The subject has a history of inquiry extending