Darwin would be proud: Bioturbation, dynamic denudation, and the power of theory in science

Abstract

While the development of a stratigraphic-archaeological record is usually given to specific geologic processes such as alluvial, colluvial, and eolian deposition, recent research strongly suggests that the formation of the archaeological record in these sandy areas [open-air upland soils] is attributed to a dynamic system of bioturbation and gravity (J.L. Michie, 1983: 23).Charles Darwin's worm book influenced many early researchers who, following his lead, demonstrated how soil biota mechanically generate new strata and soil horizons, as well as blur or destroy them. Such early observations on biomechanical processes failed to find visibility in our models of landscape evolution for several reasons, chief of which are (1) except for ichnology, an Earth sciences tradition of adopting frameworks where biomechanical processes are absent and (2) a lapse of over 100 years after Darwin before a genetic language backed by supporting theory appeared that could showcase the importance of such processes. Examples of influential Earth science frameworks in which biomechanical processes are absent are the V.V. Dokuchaev-USDA-H. Jenny soil formational (five factors) paradigm, W.M. Davis' geographical cycle, the W. Penck-L.C. King-R.V. Ruhe backwasting-pedimentation concept, the stratigraphic Law of Superposition, and other traditional approaches to archaeology, geomorphology, and pedology. Examples of recent genetic language that serve to ameliorate the problem are soil thickness concepts, biomantle, bioturbation, faunalturbation, floralturbation, and pedoturbation. Examples of recent supporting theory that incorporate biomechanical processes are soil evolution, biomantle evolution, dynamic pedogenesis, and the dynamic denudation framework advocated here. Dynamic denudation is a unified synthesis that elevates bioturbation to parity levels with other major archaeogenic, geomorphogenic, and pedogenic processes. The general framework and its principal elements are summarized and simulated by diagrams and augmented by photographs taken in disparate parts of the world. The model has useful explanatory and predictive value in archaeology, geomorphology, pedology, and other surficial process research. ᭧

What is bioturbation? The need for a precise definition for fauna in aquatic sciences

“…This central topic of his last book (Darwin 1881) is the foundation of what we now consider as bioturbation, yet he did not specifically use the term. In the years to come, a number of researchers were encouraged by Darwin's new research, which resulted in several publications on how fauna and flora affect soil and sediment textures (see review by Johnson 2002). Some of these late 19th century scientists described their fascination of the large-scale consequences of the relatively modest action of small animals.…”

“…It was used in pedology to describe biological processes by animals and plants that physically disrupt soil horizons and alter soil properties (e.g. Blum & Ganssen 1972, see also review by Johnson 2002). Thus, terrestrial plants can affect soils in a manner analogous to animal burrow construction by establishing root structures that can disrupt soil horizons and break up bedrock.…”

“…Biomixing can be either of a local na ture, where frequent displacement of individual particles occurs randomly over very short distances (Boudreau 1986a), or of a non-local nature, with particles moving over longer distances in dis- crete steps (Boudreau & Imboden 1987, Meysman et al 2003) ( Table 1). Depending on their mode of reworking, animals can be categorized as biodiffusors, upward conveyors, downward conveyors and regenerators (Boudreau 1986a,b, Gardner et al 1987, François et al 1997, 2002. Because of reworking, or ganic matter and microorganisms are displaced (biomixed) within the sediment matrix.…”

Reinterpretation of an archaeological pebble culture from the Middle Mekong River valley, Cambodia

“…However, other outcrops lack these vertical fabrics. Similar stone concentrations identified at archaeological sites have been attributed to bioturbation, particularly by burrowing fauna (Johnson, 2002). It is possible that the Upper Sand (Figure 3) at Sre Sbov represents a "biomantle" and that the PisolitesRich Conglomerate is the result of biological reworking of water-laid deposits.…”

The role of armadillos in the movement of archaeological materials: An experimental approach

“…However, research on the topic by many authors has shown that more often than expected, archaeological materials have the tendency of not staying where they were deposited (e.g., Bordes, 1972;Cahen and Moeyersons, 1977;Siiriä inen, 1977;Moeyersons, 1978;Rolfsen, 1980;Villa, 1982aVilla, , 1982b. Among the many variables responsible for displacement of artifacts is the action of burrowing animals such as ants, termites, earthworms, and rodents (Stein, 1983;Bocek, 1986;Johnson, 1990Johnson, , 1993Johnson, , 2002Pierce, 1992;Araujo, 1995;Balek, 2002;Van Nest, 2002). There is, however, one animal that despite its regional VOL.…”