Summary
Highlights
Building on previous discussions about geo-archeology and physiogeography, this lecture focuses on site-specific formation processes. It introduces key terminology, starting with 'taphonomy,' a term coined by a Russian paleontologist, meaning 'the law of burial.' Originally referring to the fossilization of organic matter, in archaeology, it signifies the balance between preservation and decay, encompassing various factors that affect artifacts and sites.
Taphonomy involves a duality of forces. Physical forces are external natural elements like humidity, rain, wind, sun, snow, freeze-thaw cycles, gravity, fire (not human-caused), and water transport. Biological forces include animal scavenging, trampling, insect activity, bacterial degradation, plant growth, and human activities like purposeful interment or disinterment. Additionally, intrinsic factors are the inherent properties of an object (size, shape, material) influencing its preservation potential, while extrinsic factors are external processes (weathering, scavenging) whose impact depends on the item's intrinsic qualities.
While most archaeological sites preserve only inorganic remains, rare conditions allow for exceptional preservation of organic materials. Waterlogged or peat bog environments, whether subtropical or temperate, are particularly favorable. Examples include shipwrecks like the Mary Rose, which provided insights into Tudor history, and the Somerset Levels in England, where prehistoric wooden trackways (like the 6,000-year-old Sweet Track) were preserved in peat. Danish bogs have also yielded remarkably preserved artifacts and even complete human remains, such as the 2,000-year-old Tollund Man, whose last meal and cause of death could be determined.
Arid and frozen environments also offer unique preservation opportunities. Lovelock Cave in Nevada, an extremely dry environment, preserved delicate organic artifacts like 2,000-year-old duck decoys made from tule reeds, moccasins, and baskets. The Ozette site in Washington, covered by a mudslide, created an anaerobic environment that perfectly preserved cedar longhouses and their contents, providing a detailed look into the Makah Indian past. Ötzi the Iceman, found in the Alps, is a famous example of preservation in a frozen environment, offering extensive data on European prehistory, his life, and death.
The Santa Clara County Medical Center Historical Cemetery provides a complex case of preservation. Excavations revealed highly variable preservation due to the interaction of redwood coffins (acidic), sand, and clay soils. In some areas, bone was well-preserved, but organic materials like textiles were absent. In others, organic materials like clothing and hair survived, but bone had disintegrated due to the acidic environment created by the collapsing redwood. This highlights the inter-site specific nature of formation processes.
Sudden natural events like volcanic eruptions can lead to remarkable preservation. Sites like Pompeii and Herculaneum, buried by Mount Vesuvius, are well-known, but Ceren in El Salvador, a Mayan village buried by ash in 580 A.D., offers an equally complete snapshot of daily life, including houses, fields, and artifacts. Other natural processes affecting site formation include floral turbation (tree roots disturbing artifacts), faunal turbation (animals burrowing and moving artifacts), cryoturbation (freeze-thaw cycles moving soil and artifacts), and graviturbation (gravity moving artifacts down slopes).