C 1460 Chronological Systems, Establishment of the archaeological material. One clear observable difference is that in the areas that had not been Chronological Systems, Romanized, the official acceptance of Christian- Establishment of ity took place at a later stage, demonstrating the significance of the infiltration phase for this Michael J. O’Brien process. Overall archaeological evidence is cru- Department of Anthropology, University of cial for the study of Christianization as it provides Missouri, Columbia, MO, USA insight into the pagan peoples that are being converted, as well as numerous groups of people at different levels of the new Christian Introduction societies. On a more individual level, great dif- ferences are naturally found between the different Today’s student of archaeology might find it dif- geographical areas, and future research is likely ficult to imagine an era when modern chronomet- further to emphasize the variability in the pro- ric dating methods – radiocarbon and cesses of Christianization and Christian practices luminescence, for example – were unavailable. across Europe. How, the student might ask, were archaeologists working, say, in the first half of the twentieth century able to place objects and sites in proper chronological sequence? Given the important Cross-References roles that chronometric methods play in modern archaeology, together with the precision they ▶ Burial Excavation, Anglo-Saxon seem to impart, it is little wonder that today’s ▶ Churchyard Archaeology student might view earlier efforts to establish ▶ France: Medieval Archaeology temporal control as rather crude and outdated. ▶ Scandinavia and the Baltic Sea Region: Such a view, however, overlooks the fact that Medieval Archaeology early archaeologists devised a battery of clever methods to determine the ages of archaeological phenomena with considerable precision. This kind of chronological control is often referred to Further Reading as relative dating. BLAIR, J. 2005. The church in Anglo-Saxon society. Oxford: Oxford University Press. Definition CARVER, M. 2003. The cross goes north: processes of conversion in northern Europe, AD 300-1300. Woodbridge: York Medieval Press. Relative dating is defined as the production of HALSALL, G. 2010. Cemeteries and society in Merovingian a sequence of events for which no fixed or calen- Gaul: selected studies in history and archaeology, drical dates exist. Instead of knowing that 1992-2009. Leiden: Brill. a certain kind of pottery was made between, MORRIS, R. 1997. Churches in the landscape. London: Phoenix Giant. say, CE 200 and CE 400 and that another kind NILSSON, B. 1996. Kristnandet i Sverige. Gamla ka¨llor och was made between CE 500 and CE 600, all we nya perspektiv [The Christianization in Sweden: old know is that the latter kind is of more recent sources and new perspectives], Volume 5. Projektet origin than the former. The latter kind could Sveriges kristnande. Uppsala: Lunne bo¨cker. SEMPLE, S. 2013. Perceptions of the prehistoric in Anglo- postdate the earlier one by several hundred Saxon England. Ritual, religion and rulership. Oxford: years or by a thousand years, but we do not Oxford University Press. know this. All we know is that it is more recent. STIEGEMANN, C. & M. WEMHOFF. 1999. 799 - Kunst und Similarly, we might know, perhaps through his- Kultur der Karolingerzeit. Karl der Grosse und Papst Leo III in Paderborn. Katalog der Ausstellung torical evidence, the terminal calendrical date of Paderborn 1999. Mainz: von Zabern. manufacture and use of the later kind of pottery, Chronological Systems, Establishment of 1461 C but we might not know when on a calendrical scale that kind of pottery was first made and thus when it began replacing the earlier kind. In con- trast, absolute-dating methods – sometimes referred to as chronometric methods – yield the amount of time, within the limits of sampling error, that elapsed between each pair of events C as well as a calendrical date indicating when each White event occurred and perhaps each event’s duration Time as well. Black Absolute-dating methods thus provide more than a simple chronological sequence, but they in no sense render relative-dating methods obso- Red lete. There are situations where the latter are Older Younger preferable, especially when large areal chronolo- gies are desired. Relative-dating methods are Pottery Types inexpensive, as opposed to methods, such as radiocarbon, which may cost as much as $1,000 Chronological Systems, Establishment of, Fig. 1 Diagram showing temporal alignment of three per sample. Unfortunately, few modern archaeol- hypothetical pottery types from latest (black) to earliest ogists have more than a passing acquaintance (white) (From O’Brien & Lyman 1999) with the origins of relative-dating methods and as a result have by-passed some of the most innovative work ever undertaken in archaeology. of a type, its growth in popularity, and its decline That research is as relevant today as it was and eventual disappearance. Any type that passes a century ago. the test is referred to as a historical type, the gold standard of relative-dating methods. Historical Background Key Issues Numerous methods for working out relative chro- nological orderings have been devised in archae- Stratigraphic Excavation ology, one of which, stratigraphic excavation, Stratigraphic excavation is defined as removing had its roots in geological observations of the artifacts and sediments from vertically discrete eighteenth century. Stratigraphic excavation is three-dimensional units of deposition (strata) and perhaps the best known of the various relative- keeping those artifacts in sets based on their dis- dating methods used by prehistorians, no doubt tinct vertical recovery proveniences for the pur- because the majority of the archaeological record pose of measuring time (Lyman & O’Brien has a geological mode of occurrence (O’Brien & 1999). Vertical boundaries of spatial units from Lyman 1999). There are also two other methods – which artifacts are collected can be based on seriation and cross dating – that likewise deserve geological criteria, such as sediment texture, or attention. All of them, however, depend on arti- on metric criteria, such as elevation. Stratigraphic fact types, especially those that pass the excavation is based on the commonsense historical-significance test. This means that assumption that in a sedimentary column, strata a type comprises specimens that were made dur- stacked one on another represent the passage of ing a single, relatively short interval of time and time. More specifically, the assumption is that that the frequency distribution through time of strata at the bottom of a column were deposited the specimens approximates a unimodal curve before those above. This is known as the law of (Fig. 1). Such a curve reflects the introduction superposition. Unfortunately, archaeologists C 1462 Chronological Systems, Establishment of often fail to realize that depositional history does the Devonshire Coast, the excavation of Brixham not necessarily represent the age of the sediments Cave of England by prominent British geologists themselves. This includes objects in those sedi- and paleontologists in 1858 focused explicitly on ments. Although artifacts in one stratum were stratigraphic context. deposited before those in a higher stratum, it In North America, stratigraphic excavation cannot be assumed that artifacts in the lower became an art form during the second decade of stratum are older than those in the higher stratum. the twentieth century through the efforts of two It could be the case, for example, that artifacts prehistorians working in New Mexico, Nels from one period were eroded from one locality Nelson of the American Museum of Natural His- and deposited downslope on top of artifacts from tory in New York and Alfred V. Kidder of the a later period. Robert S. Peabody Museum in Andover, Massa- Thus, superposition is an indirect dating tech- chusetts. Nelson started working at San Cristobal, nique when applied to artifacts within strata. It is an abandoned pueblo in the Galisteo Basin south indirect because the ages of the artifacts are of Santa Fe, New Mexico, to test a suspected inferred from their vertical positions relative to local sequence of pottery types. In his report, one another. Another way of saying this is that the Nelson (1916) stated that by the beginning of target event is the age of an artifact’s creation the 1914 field season he suspected he knew the whereas the dated event is the age of the deposi- chronological order of five types of pottery, two tional event. The work of the archaeologist, like of which exhibited painted designs and three of that of the geologist, is to analyze the superposed which contained glazed designs. One of the sediments and to determine when strata were painted types was suspected of being the earliest deposited as well as when the sediments were of the five because it occurred primarily on small formed. Archaeologists are interested in cultur- pre-Puebloan sites. The other painted type was ally derived sediments – artifacts – but they real- known to be the latest of the five types because it ize that the artifacts usually occur within occurred in abundance on sites historically noncultural (natural) sediments. The nature of documented as postdating the Pueblo Revolt of the latter often is an important source of informa- 1680. Nelson viewed one of the three glazed tion relative to the nature of the former. types as being from the early historical