The last million years have seen the emergence of Homo sapiens, of the complex social fabrics that we call civilization, and of large-scale societies that expect and, to an extent, require some measure of climatic predictability or stability. Intensive food-production began within the most recent major warming cycle in the present ice age (the Holocene epoch); it has supported an unprecedented population expansion in our species. This population expansion has occurred mainly since the end of the “Little Ice Age” in the nineteenth century, in a time of warming and relatively stable climate (Grove 1988). The rate of population growth has steepened dramatically since industrialization, which occurred massively within the early to middle twentieth century, a period of unusually stable climate. Recent droughts and crop losses in Africa, and disastrous rains and flooding elsewhere, force us to realize how precariously balanced we are in depending upon intensive food-production in a world that may be fundamentally inimical to our present ways of doing things. Modern climates are neither typical nor normal in the perspective of world prehistory. Recent instabilities may presage major change.

Climate, as a statistical generalization about temperature and precipitation, varies from place to place, time to time and, especially, with the time duration and the size of spatial unit summed. Climatic statements should be understood as statements about the average and range of weather conditions at a place and time of specified scales.

Even metaphysical time is measured by means of geophysical processes. Ages calculated from measurements of processes such as radioactivity and magnetic-field variations have gained such prominence in archaeology that they threaten to eclipse the more fundamental stratigraphic method. Their claims to accuracy, however, have proven unreliable. It is essential that archaeologists understand the weaknesses as well as the strengths of these esoteric chronometric methods. The application of sound, careful stratigraphic methods of observation and recording in the field can help control for the grosser errors of radiometric and magnetic dating methods by calling attention to discrepancies that require special attention and interpretation.

CHRONOMETRY BASED ON RADIOACTIVE DECAY

Elemental atoms may have one or more unstable isotopic forms with different atomic weights, subject to loss of alpha (α) or beta (β) particles by spontaneous emission. A radioactive isotope has a characteristic half-life, the time during which half of all the radioactivity will be spent. The rate at which various materials emit particles, therefore, can be used to estimate the passage of time from a defined beginning point. Counting apparatus counts particle emissions; over a short span of time average emission rates can be recalculated as portions of half-lives. The emission of beta particles by radioactive carbon, and of alpha particles by uranium and its radioactive “daughter” products in decay series, are the basis of several chronometric methods that have redefined the reach and potential of the historical geosciences and archaeology.

The case study in Part III summarized five different explanations for the mid-Holocene European elm decline and found all either inadequate or inconclusive. Climatic deterioration, soils depletion, human exploitation of the species, human competition for the tree's habitat, and disease were all shown to be inadequate to comprehend the evidence. The hypothesis invoking climatic deterioration to explain the widespread loss of elms from the temperate forests was poorly supported on several counts, as was the hypothesis of soils depletion. The diversity of habitats, elm species, soils, and topography across the prehistoric elm range in central and western Europe undermines the appropriateness of both these hypotheses as explanations. Looking for single causal explanations for the behavior of complex systems is fruitless (Chapter 2).

Decline in elm pollen began in southeastern Europe early in the sixth millennium b.p., even as the Holocene spread of elms reached its maximum distribution (Huntley and Birks 1983: 412). The decline was time-transgressive westward until around 5000 b.p., when it spread rapidly to its northern limits (Fig. a). The near-coincidence with evidence for the initiation of farming in northern Europe long supported speculation that the elms were killed by pastoralists and farmers establishing agricultural landscapes.

Climate – the mean and range of temperature and precipitation prevailing over a defined area of the globe – is complex in its causation and expression. Reconstructing climate, the effort to describe and measure climates of the past, must necessarily be a complex and technical undertaking. Climates leave only indirect, proxy evidence of their past states and conditions. The reconstruction of past climates, therefore, requires accumulation of indirect and partial evidence from many diverse sources, which must be carefully evaluated and compared. Archaeology and archaeologists contribute important sets and classes of data to the undertaking, but the task of reconstructing climate is not archaeological. It requires the integration of data from many sources by means of concepts and techniques that are themselves interdisciplinary.

The reconstruction of ancient climates involves specification of the distributions and amplitudes of temperature and precipitation in space and time. Once an exercise in inspired analogy, paleoclimatic study entered a dynamic phase in the 1970s, when the Earth's orbital and axial variations were demonstrated to be fundamental forcing factors for large-scale climatic states (Chapter 3). With basic mechanisms identified, paleoclimatology has been a lively research frontier since the 1980s. No survey such as this can be either complete or current. This chapter is an introduction for archaeologists, who may then explore further in the specialist literature.

This volume is about synergy. It was born in my dissatisfaction with so much of environmental archaeology that focused on the application of single techniques to isolated data classes, and with the early prevailing notion of “environment” as background or stage set for human actions. As any thespian knows, the stage set is not passive; it constrains, and sometimes even inspires, particular actions and responses.

While teaching courses in environmental archaeology, I sensed the possibilities for integration based on the concept of environment as context for human actions – not an original insight. The essays that comprise the chapters of this volume explore the possibilities for interpretation of human contexts from non-artifactual, and some limited artifactual, finds. Only when I included the larger universe of off-site paleoenvironmental data at several scales did the integration begin to look feasible and powerful. In doing so I realized, as Aldo Leopold did long before, that humans are environments for other humans, for all living things, and for the physical world which they inhabit.

Detailed consideration of human environments is justified for what it tells about the conditions of life in which human choices and decisions are made. It does not entail deterministic interpretations, and no environmental determinism appears herein. Environmental effects upon human communities are mediated through technology and cognition, the specifically human means of adaptation. These impose upon the study of human adaptations certain constraints of scale which are foreign to many of the environmental sciences, so that archaeologists cannot simply shop passively for concepts, methods, and data appropriate to the study of the human past.

The Classical lands of the Mediterranean present the thoughtful observer with the paradox of the homelands of great early civilizations in landscapes now characterized by limited and discontinuous arable soils, bare rocky hillsides, and silted harbors. Already in late Classical times writers speculated about the destruction of formerly richer landscapes by abusive land-use practices. Early environmentalists used the Mediterranean case as a moral lesson, threatening similar impoverishment to heedless peoples elsewhere (e.g., Marsh 1965). This view of things is necessarily based on the assumption that the damage had been done during classical times and that later populations simply endured the burden of their poor inheritance, which doomed them to economic marginality in the modern world.

By the decade of the 1960s, informed observers had noticed that the massive alluvial deposits in circum-Mediterranean valleys contained Roman and younger sherds, and that in some instances they buried Classical and Byzantine sites (e.g., Judson 1963). These observations particularly impressed Claudio Vita-Finzi, who inspected valley fills around the Mediterranean and published in 1969 a monograph on his investigations.

Vita-Finzi observed two major episodes of Mediterranean valley fills, which he called the “Older” and “Younger” Fills. The older and more massive was very rocky in places, was typically a deep red color, and had been deeply incised by stream-cutting before the deposition of the Younger Fill that was “nested” within it.

The truly dynamic components of the biosphere are members of the Animal Kingdom, most of whom are capable of motion and intentional behavior. Behavior (e.g., feeding, competition, migration, cooperation) immensely complicates environmental modeling by reducing predictability in system states. Here, the emphasis is on describing and interpreting the faunal components of past ecosystems, including humans, as a basis for understanding paleoecology.

Paleoenvironmental reconstruction has been important in paleontology for a very long time, beginning two centuries ago in the fossiliferous Paleolithic caves of Europe. However, interest in paleoenvironmental reconstruction from archaeological faunas did not travel intact across the Atlantic (Grayson 1981). The best American work in the genre has been done by paleontologists, whether or not working for archaeologists (e.g., Graham, Guilday, Guthrie, Klippel, Parmalee). The problem in America seems to derive from the fact that few paleontologists are interested in Holocene faunas, while neoecologistswork in a timeless dimension that assumes the validity for ancient times of actualistic study in present conditions. Consequently, the development of critical theory for paleoenvironmental reconstruction from archaeological faunas in the Americas has been delayed, to the detriment of research designs and excavation strategies. Archaeozoology with an environmental emphasis is more at home in the rest of the world than in the western hemisphere, where autecological studies are in short supply and zooarchaeological emphases on human behavior dominate the archaeological literature.

Admittedly, there are stringent limitations to the applicability of archaeological data for paleoenvironmental work with fauna, as indicated below.

Decades ago, b.p. (before 1950), dating Bronze Age sites in the eastern Aegean seemed direct and reliable, given artifactual cross-ties with the astronomically calibrated Egyptian king lists that served as calendars. For instance, the association of Late Minoan IA ceramics in a Greek tomb with Egyptian scarabs provided a terminus ante quem age estimate for the ceramic style at ca. 1500 b.c., a nice round, memorable date. Ceramics of LMIA style were buried when the Thera volcano erupted on Santorini island, north of Crete, and 1500 b.c. was proposed as the date of the event (Marinatos 1939). The scale of the eruption, devastating to the town of Akrotiri, led archaeologists to try to relate it to catastrophic fires and building destruction elsewhere in the Aegean. When radiocarbon dating became available, scholars wanted to use that method to refine the dating of the eruption and test its synchroneity with destructive events nearby. The result of those efforts, and applications of additional dating methods, has been a vast, expanding, contentious literature that remains inconclusive. Why?

In the decade of the 1970s, charred organic samples from the Akrotiri excavations were sent to the radiocarbon laboratory at the University of Pennsylvania, a respected research facility. The immediate results supported the traditional age, but tree-ring calibration produced dates implying an age greater than 1600 b.c. (Fishman et al. 1977). Efforts to explain the results focused at first on contamination by ancient carbon in volcanic gases venting nearby (Weinstein and Michael 1978).

Human beings perceive environmental change mainly as change in the state (qualitative character or structure) or condition (quantitative composition or amount) of nearby communities of living organisms, or of the weather. For example, a change of state for living communities might be gains or losses in the diversity of plants or animals represented; a change in condition might be an increase or decrease in the numbers of plants and animals. For the weather, a switch fromwinter rains to predominantly summer rains in mid-latitudes would constitute a change in state, whereas a marked decrease in precipitation over a month or more would be a change in condition. We notice such changes, because they violate our expectations that things vary little from year to year. Our experience and observations of the environment are at the local scale and are mediated by language and opportunity, so that each of us has a slightly different idea of things. Because of thewaysweperceive environmental change, our “commonsense” leads us to seek the causes of change wherewe perceive it – among living communities and in the weather systems. Recent research in geophysics and climatology has demonstrated that this approach is oversimplified and misleading.

Every surface on which humans lay foot or artifact is a potential archaeological site, requiring only that subsequent processes not dislodge and transport the surficial deposits. Of course, disturbance of surficial sediments of every kind is the normal case. This vulnerability ensures that archaeological sites are neither ubiquitous nor permanent.

The focus of this chapter is on sediments and soils as matrices of archaeological sites, at local and micro-scales. We occasionally lift our eyes to regional-scale phenomena, as in considering the information potentials of widespread deposits of loess or volcanic ash, but we pay no attention here to the mega- and macro-scales of phenomena or to regional-scale interpretations.

MESSAGES IN THE MATRIX

Sedimentological analyses are undertaken to learn about the sources, transportation agents, depositional and transformational history of the materials comprising deposits (Chapter 11). Although archaeologists typically treat that information as background, environmental archaeology must begin with the environments in which materials, whether cultural or natural sedimentary particles, were brought to a site, deposited, and affected by postdepositional processes including pedogenesis and diagenesis. The enclosing matrix is the fundamental source of information about all the processes essential to understanding the context of human behavior at a site. Not all evidence is visible, and not all is extractable by techniques currently known. However, for sites lacking written evidence the matrix is the only source of non-artifactual information; for sites with written histories, the matrix will variously confirm, expand, or contradict elements of that record.