Landscape and climate change

Landscape change can range from the patter of tiny raindrops and the shuffling of beetles and rodents on hillslopes, to major slope failures that generate colossal debris flows, to cratering of the earth's surface caused by the impact of meteorites (Allen, 2005: 961). The scale of these examples encapsulates processes of change that range from uniformitarianism to catastrophism. Archaeologists have generally tended to discuss change in a gradualistic or uniformitarian way. It is increasingly recognized, however, that various types of discontinuity occur in environmental change, and identifying these discontinuities is critical to understanding their impacts on landscapes and their potential human impacts. Allen (2005) notes that physical landscapes are a result of two interacting systems: an internal system driven by tectonic fluxes of rock and an external system dominated by climate. Landscapes are perturbed by both these internal and external mechanisms at a range of temporal and spatial scales. In studying past landscapes archaeologists must be conscious of the fact that landscapes can change in response to a range of internal and external factors and at a number of time scales. This is demonstrated in this chapter by reference to climate change. Three periods of change—the Younger Dryas, the 8.2 cal ka event, and the Medieval Warm Period/Little Ice Age—of different magnitude and extent are described, and their implications for landscape modification are considered