Archaeology must come to grips with the basic philosophical problems of science. With this premise in mind, we welcome the recent article on explanation by Fritz and Plog (1970) and offer a review and critique of it with the following points: (1) The D-N model of explanation is not the exclusive explanatory system in science and is in fact subject to extensive discussion and criticism in several areas of science; (2) archaeologists have not employed laws commonly in the past but rather deductive reasoning based on assumed premises; (3) the use of laws in explanation may reduce archaeology to a science of historical exemplification; (4) the research design presented by Fritz and Plog may be modified to include concern for hypothesis formulation, variable identification in the archaeological context, and the interplay of hypotheses and data throughout excavation and analysis; (5) the Meehan system paradigm explanatory model is presented as an alternative to the D-N model; (6) what archaeologists try to explain is relevant to the nature of the explanation.

The standard typology of Owasco pottery from New York State is examined. This typology is ostensibly based on Krieger's definition of a type as a consistently recurring combination of attributes. The application of statistical techniques suggested by Spaulding, Sackett, and others as appropriate to the discovery of such types revealed that the standard Owasco typology does not exist in Krieger's terms. This typology, however, has been a reliable spatial and temporal indicator for many years. The real, underlying logic and foundations for this typology were therefore sought through a careful inspection of the actual type definitions. This made it clear that the definition and recognition of these pottery types depend on 2 important but unstated principles, the existence of a hierarchy of importance among attributes and the shifting of defining criteria from type to type. Krieger's definition of a type is thus seen to be inappropriate here and a type is recognized to be defined by proceeding through a hierarchical, "tree-type" series of decisions. Statistical procedures appropriate to discovering types according to this definition are developed, and their application to the Owasco material is seen to come close to duplicating the original typology. Such a tree-type structure based on the 2 principles just outlined closely resembles cultural classifications elicited by ethnologists. It is suggested therefore that the attribute association or "Spaulding" approach and the currently popular techniques of numerical taxonomy will not work for establishing space-time reflective types, not because the techniques are not well developed, but because the basic concept or definition of such a type on which they are based is inappropriate.

The total variability in archaeological material derives from at least 4 different sources: technological, functional, stylistic, and random variation. Different attributes may be needed to quantify each aspect of the total variability, and the particular attributes that the archaeologist singles out for analysis will determine, to a large extent, the utility and validity of any subsequent typology. At present, there is relatively little theory to aid in the selection of the attributes most appropriate for a particular archaeological problem. In the analysis of prehistoric flake stone tools, the technology of flake production falls largely within the realm of the natural sciences; thus, technological variability is perhaps that aspect of the total variability for which suitable theory may be most readily developed.

Flake production can be divided into 2 distinct processes, percussion flaking and pressure flaking, on the basis of the duration of the applied force. The fracture processes involved in these 2 types of flake production are sufficiently different to warrant a separate treatment of each. Attention is focused specifically on percussion flaking because this process appears to have been the predominant mode of flake production throughout most of human prehistory and, at present, it remains poorly understood.

It is found that a percussion flake is detached from a core largely by a process known as spalling, the fracture produced by the reflection of a stress wave at the free surface of the core adjacent to the striking platform. The thickness of a flake is a function largely of 4 impact parameters and 2 constants of the material: the shape, intensity, and wavelength of the stress wave emanating from the point of impact, the angle of incidence of the stress wave on the free face of the core, the critical impact strength of the material in tension, and an elastic property of the material. Other attributes of flake size such as the length, width, area, weight, and volume are also influenced by these parameters. Several other factors affecting the size of a flake are discussed, and areas where further research is needed are outlined. It is concluded that the various attributes of flake size are highly and predictably interrelated.

Current emphasis on the definition of areal variation within the Fremont culture requires a re-examination of existing hypotheses of Fremont origins. The evidently very early appearance of regional variation suggests that Fremont crystallized out of a partial unification of several already differentiated Archaic (Desert culture) variants. This crystallization occurred at least partially as a result of adoption by Archaic groups of a horticultural complex of ultimately Mexican origin. Many of the characteristics which bind the Fremont regional patterns into a broader Fremont culture are elements of this horticultural complex, although the earlier Archaic variants presumably also shared basic similarities which contributed to the general unity of the later Fremont culture. Earlier hypotheses of Fremont origins are evaluated from this viewpoint. This is a revised version of a paper delivered in the Fremont Culture Symposium, 35th annual meeting of the Society for American Archaeology, April 30-May 2, 1970, Mexico City, D. F., Mexico.

Settlement pattern research was introduced to Peruvian archaeology by Gordon R. Willey 2 decades ago. A critical review of this pioneering work points up a basic problem in the structure of analysis. The problem is generated by the use of a simple site taxonomy that is insensitive to the range of human activities that went on at different settlements. Examination of the subsequent course of settlement pattern research shows that this fundamental problem has not been recognized or dealt with in a constructive manner. The small site methodology is introduced as one possible means of treating sites in terms of the different activity patterns they housed.

Archaeological finds from the Leavenworth and Sully sites in South Dakota have served to revive interest in the use of native-made glass beads by the Arikara and neighboring tribes of the Upper Missouri region. Although the distribution of these objects and the techniques involved in their manufacture are known, little has been said concerning their function. Ethnographic data suggests that one type of native-made bead, the sub-triangular pendant, was a forelock ornament employed in a ceremony known as the Blue Bead rite. Associations of native-made pendants with skulls from the Leavenworth site would tend to support this hypothesis.

Cultivated plants are sometimes considered good indicators of cultural contact because the same plant cannot be invented independently in distinct regions. Some crops no doubt did spread from a single center, but other, more complex, histories have also to be considered. In some groups different species were domesticated in different areas, so before the archaeological record can be interpreted, it is important that the specimens be securely identified to species. Other crops have differentiated further under cultivation so that distinct races are characteristic of different parts of the total area. Another possibility is independent domestication of the same crop in different areas. If this is demonstrated, then presence of this crop in sites in these areas does not constitute evidence of contact. Only after these possibilities have been eliminated may presence of the same crop in different cultures suggest contact between them.

Archival source materials and colonial period maps have been employed to reconstruct the settlement pattern characteristic of the chinampa districts of the Aztec capital, Tenochtitlan. The evidence includes detailed descriptions of a number of individual residential sites and chinampa holdings, which can be drawn to scale on street maps of the modern city. Genealogies and census data have been employed to determine the average size and social composition of typical urban households. Rough estimates of the economic value of urban chinampa holdings in relation to individual households, and to the urban population as a whole, indicate much higher levels of non-agricultural economic specialization, and a more complete dependence of the city on agrarian support areas outside the city than previously supposed.

The Izabal zone is a physiographic region located near the southeastern frontier of the southern Maya lowlands. Its environment is compared with that of northeast Peten, a second region of the same culture area. Prehistoric settlement patterns of the 2 regions are compared and differences in distribution of settlements, estimated population densities and types of settlements are noted. These differences are related to various environmental and cultural factors.

Most studies of trade in the Maya area of Mesoamerica have been descriptive examinations of exchanged objects and have relied heavily on ethnohistoric sources. This paper, on the other hand, relies mainly on archaeological data and offers several hypotheses about the socio-political significance of intra- and inter-community exchange systems.

It is proposed that in the relatively uniform environment of the Maya Lowlands, subsistence arti-facts and goods were generally exchanged within communities while prestige artifacts were exchanged between communities. This hypothesized situation is contrasted with the environmentally differentiated Mexican Highlands where subsistence items were traded widely. Following the theoretical leads of M. Coe, Webb, and Fried, we offer the hypothesis that prior to the introduction of foreign influences, the lack of differential access to basic resources among the ranked social groups of the Maya Lowlands did not stimulate the development of the state in this area.

Current interest among anthropologists in population size as a major independent variable makes it likely that attempts will be made to estimate the size of populations resident at various prehistoric sites at particular points in time in Mesoamerica. Such estimates are likely to depend on some notion of the average number of people resident in a single house. The problem of arriving at such a statistic is illustrated for the Classic Maya site of Tikal, Guatemala. A consideration of demographic data from Tikal and modern Yucatán Maya communities, as well as information on household composition in sixteenth century Yucatán are reviewed which suggests that it is best to assume that each individual dwelling within a prehistoric household group at Tikal was inhabited by an average of 5 people. This requires some slight modification of previously published population estimates for Tikal and Mayapan, which relied on a base figure of 5.6 people per house.

Haviland's assertion that cognatic kinship organization is typical of Late Classic Maya is examined and matrilineal and double descent alternatives suggested. Lineages are suggested as represented in small residential groups at Tikal rather than clans.

A sample of North Cameroon Fulani pottery for which median ages of types are known is used to show that the frequencies of types in the archaeological record are in part a function of their respective life spans. This is of some significance in interassemblage comparisons.