A detailed and critical review of the literature pertaining to Maya Blue led to the conclusion that the presence of indigo as an integral component of the pigment has not, as yet, been established by acceptable scientific criteria. A Maya Blue was prepared from indigo and attapulgite which had all the observed properties of the authentic pigment. Although the experiments performed in the present study can hardly be called scientific proof of the composition of the prehistoric material, they strongly suggest that the colorant was indigo, at least in one type of Maya Blue.

The strong emphasis usually placed upon the identification of attapulgite as the base mineral of Maya Blue seems to be an exercise in the use of identification equipment. The question of whether attapulgite, a clay of variable composition and available from widely separated sources, is the base of Maya Blue is immaterial. It appears that any clay containing palygorskite, sepiolite, montmorillonite, or possibly other minerals free of plate-like crystal structures can be converted to a Maya Blue pigment with all the observed chemical and physical properties of the authentic material.

The present experimental work and some reported observations regarding variations in shade and color of Maya Blue specimens suggest there may be more than one pigment so designated and that a blue mont-morillonite is one of the alternatives to an indigo-colored clay for post-firing decoration of pottery and mural painting.

The technical studies which form the basis for some of the conclusions reached will be found in the appendix to this report.

Although archaeomagnetic dating seems straightforward in principle, there are practical limitations which are not generally understood. Unlike rate-dependent processes such as isotopic dating, archaeomagnetic dating requires the construction of a master record of geomagnetic secular variation. Error is inherent in such a master curve due to statistical uncertainties regarding both the magnetic directions and ages of the samples used to create the curve. The master curve itself is thus best represented as a ribbon rather than a line. Features being dated have their own error of measurement of magnetic direction, and deriving a date involves an interpretation based on the relation between the oval of confidence for the unknown and the ribbon representing the master curve. Thus a practical precision limit for archaeomagnetic dating is about ± 20 years under optimal circumstances, but the limit will generally be higher. Our pilot study revealed no major discrepancies between our work and the curves of DuBois (1975).

The conventional carbon-14 method relies on the accurate measurement of a beta-ray decay rate to determine the age of the sample. The new method instead uses an ultrasensitive mass spectrometer to count the individual carbon-14 atoms in a sample. The advantages of this approach are many. The problem of cosmic ray background does not arise. Shorter counting times on samples 1,000 times smaller will be possible. One result will be the production of more accurate age determinations. The new method will permit a great expansion in the types of archaeological materials that can be dated because only milligram samples will be required. Research on the design of a dedicated carbon-14 atom counting machine is presently in progress.

From 1973 to 1974, investigations were carried out at a series of Initial Period and Early Horizon sites known as the Caballo Muerto complex, located in the Moche Valley on the North Coast of Peru. One site, Huaca de los Reyes, contains numerous adobe friezes that are noted both for their wide variety and early date. The amount of labor investment and the degree of architectural planning of the site strongly imply ranked societal divisions of the people responsible for its construction. Differential frieze distribution also supports this contention.

Age-at-death data on over 2,000 burials from two pueblo sites in New Mexico are subjected to demographic analysis. Prior studies are reviewed to illustrate deficiencies and qualifications in the data base and the analytical method. The skeletal assemblage is subdivided into seven samples by chronological phase, and life tables are constructed. Aspects such as mortality and life expectancy are then examined for each phase and a diachronic model of demographic structure is developed for Pecos Indians between A.D. 1150 and 1700.

Many archaeologists have ignored the complexities of preservation treatments and have proceeded alone, often with unsatisfactory results. Now that new legislation can provide conservation funding, archaeologists involved in federally funded research should have little reason to ignore professional standards in the areas of conservation, preservation, and collection interpretation and maintenance. Specific advantages of professional conservation input for the archaeologist are cited with reference to a case study in Maine.

Outwash from very heavy rains on the eastern slopes of the Southern California Peninsular Ranges in September of 1976, caused by tropical storm "Kathleen," cut an almost vertical cliff on the north bank of the Yuha Pinto Wash, just north of the international border in Imperial Valley. Some 80 Paleolithic flaked stone tools and utilized flakes were discovered solidly in place just above the base of the cut, overlain by alluvial, aeolian, and riverine deposits over 21 m thick. Three specimens of bone were recovered: one in place and associated with the artifacts but fragmentary and not identifiable as human, and two surface finds at the base of the exposure that were identified as human bone, but which had been washed out by the flood and were not positively relatable to the artifact level. Time of deposition of the artifacts is considered to be more than 50,000 B.P. by some unknown amount, based on pedological and geomorphic observations and radiocarbon dating of related features.

One shortcoming of the archaeological study of prehistoric societies is a failure to pursue the behavioral correlates of social distinctions. This paper shows, through a study of Middle Woodland mortuary populations, that analysis of degenerative joint disease is a productive approach to investigating status-linked behavior in archaeological populations.

The literature to 1979 on North American Indian rock art has been analyzed. It was found to be characterized by a high degree of dispersion, an erratic growth pattern before 1950 followed by an exponential mode of growth thereafter, and a low proportion of multiple-author works. The growth in literary output over the years was largely attributable to an increase in the number of authors, whereas the article/author ratio changed only slightly with time. The proportion of works dealing with general topics rose from 16.4% before 1970 to 41.6% thereafter while the proportion of site reports decreased accordingly. Although all rock art regions participated in the numerical growth of the literature over the decades, their relative proportions varied with time. The Southwest, the Great Plains, and the Eastern Woodland had the greatest number of works with regional emphasis; these three regions accounted for more than 50% of the total literary output. As an instrument of scientific information exchange, the rock art literature in North America appears to be in a comparatively early stage of development and maturation, a feature it shares with the communication system in the social sciences in general.

The dating of Casas Grandes is re-evaluated, and new relevant dates for southwestern New Mexico are presented. It is suggested that Casas Grandes dates from ca. A.D. 1150-A.D. 1300. This would make the site's florescence postdate the Bonito phase of Chaco Canyon and the Mimbres phase. Furthermore, it appears that Casas Grandes did not overlap the Civano phase of the Hohokam.

Gravel, bone, carbonized seeds, and charcoal recovered from a 2,000 year old cereal pit were successfully separated by chemical flotation. Specific gravities of each material were determined experimentally, and then for each pair of materials to be separated (e.g., bone from gravel, seeds from charcoal), a solution with a specific gravity intermediate between those of the two materials was used for flotation. Optimal sample sizes and possible sources of error are discussed, as are criteria for selection of solutions. A procedure for evaluating the effect of solutions and flotation practices on test seeds is also presented.

Forty-two obsidian artifacts from the Chantuto Zone, Chiapas, Mexico, have been analyzed by neutron activation analysis, and fifteen artifacts were reanalyzed using X-ray fluorescence spectrometry. These artifacts date to the Chantuto phase (3000-2000 B.C.), late in the Archaic period, and to a later period or periods. These analyses have made it possible to compare the two methods of analysis and also have made it possible to assign an obsidian source to each artifact. It has been shown that the majority of the obsidian originated from Tajumulco, with smaller amounts coming from El Chayal during the Chantuto phase and from El Chayal, San Martin Jilotepeque, and Pachuca during the late period.

Recent research within the Quiche Basin of Highland Guatemala has revealed at least 117 sites with remains suggestive of Paleoindian and Archaic periods of occupation. Partly because these artifacts are predominantly of a gray, fine-grained basalt rather than obsidian, we have been able to rapidly recognize surface indications of these occupations. Tentative settlement patterns for these time periods are discussed. These patterns-particularly the Archaic pattern-suggest that early human occupation may have been somewhat different in the Quiche Basin from patterns defined for other areas of Mesoamerica. This may be due to the environmental conditions of the areas involved.

The process of evaluating archaeological significance is dynamic and constantly changing. Factors affecting the significance evaluation process are considered, and an example of how the evaluation of significance at a central Texas rockshelter has changed over the last thirty years is offered.

Excavations conducted since Chomko's initial discovery in 1974 of Cucurbita pepo seeds have clarified their stratigraphic and radiometric context as well as delineated an earlier archaeological unit, the Squash and Gourd Zone, where a second cucurbit, Lagenaria siceraria, was found. The two units are Late Archaic with dates (weighted averages of radiocarbon assays) of 4257 ± 39 and 3928 ± 41 radiocarbon years B.P., respectively, and are beneath stratigraphically superior Late Archaic and Woodland units also containing cucurbits. A comparison of the early Cucurbita pepo with others from later contexts demonstrates an increasing size with time and morphology similar between the early seeds and the historic cultivar "Mandan." Nutritional value of the cucurbits, both cultigens, may have been comparable to that of other wild plant foods consumed. In any event, the cucurbits are artifacts of regional exchange mechanisms operating some 4000 years ago; the most plausible mechanism being down-the-line exchange.

A large sample of Gallinazo cobs from Huaca Prieta is classified using a set of five variables. Some types of Gallinazo maize recovered there seem to have been new to the Peruvian North Coast; some types of the preceding Salinar phase are not known from this site. Further changes occur in the Chicama-Viru area when Moche influence appears. In several ways Gallinazo maize seems more related to maize occurring today further north and east than to modern highland or coastal maize to the southeast.

The authors of this response believe that problem-oriented significance for archaeological sites can be accommodated within the existing National Register criterion. In addition, the authors feel that closer relationships between the archaeological community, federal agencies, and the State Historic Preservation Officers will result in the preservation of archaeological sites.

Excavation of the workshop of an ancient rhyolite quarry yielded three classes of artifacts. One class consists of worn and broken tools made of exotic stones. It is argued that these tools represent a "curated" assemblage and one that is highly revealing of the duration and distance of population movements.