Inscriptions at Piedras Negras are shown to form a pattern of discrete sets of records, each inscribed on a group of consecutive monuments beginning with a stela depicting the “ascension motif.” The earliest date in a series, identified by the upended frog glyph and called an “initial date” precedes the first dedicatory date by a number of years, falling within the span of an earlier series. A date in the first dedicatory hotun of each set is marked by a “toothache glyph” and is called the “inaugural date.” The intervals between these dates are such that no single series exceeds the span of a reasonable lifetime, and it is suggested that the initial date represents something in the nature of a birth or name day of a ruler who accedes to power on the inaugural date, and that each set of monuments records the history of a reign. The representations on monuments are interpreted as portraits of rulers and their families. Initial and inaugural dates at other sites are identified by their respective glyphs, but no articulated series of reigns has been found outside of Piedras Negras.

The variations of the upended frog and toothache glyphs suggest that they are essentially verbal action glyphs. Other action glyphs are correlated with motifs on Yaxchilan lintels, where they follow close upon date notations. Groups of glyphs following the action glyph are identified as appellatives, and are found to contain feminine head prefixes when they refer to robed or skirted figures of women. It is suggested that “ben-ich” katun notations occurring with appellatives of rulers are to be counted from their initial dates. Lunar and determinant meanings ascribed to dates are shown to have no relation to action glyphs accompanying them, and the historical approach is recommended as being more consistent with observed glyphic patterns.

A freshly exposed surface of obsidian will take up water from the atmosphere to form a hydrated surface layer. This layer has a different density and refractive index than does the remainder of the obsidian. Using special techniques, a thin section of the obsidian cut at right angles to the surface can be prepared. When examined under the microscope the hydrated layer is visible and its thickness can be measured. Photomicrographs of such thin sections are shown. Factors that determine the rate of hydration were considered. Using artifacts from archaeological sites of known age, the influence of temperature, relative humidity, chemical composition of the obsidian, burning and erosion of the obsidian on the rates of hydration was determined. Temperature and chemical composition are the main factors controlling the rate of hydration. Obsidian hydrates more rapidly at a higher temperature, and thus progresses at a faster rate in tropical than in arctic climates. Rhyolitic obsidian hydrates more slowly than does trachytic obsidian. Using archaeological data from various parts of the world, several tentative hydration rates were determined for tropical, temperate, and arctic climates. The method in its present state of development is especially suited to determine relative chronologies in layered sequences of artifacts from a single site, or region. It is also useful for detecting fake artifacts. Future work to refine the method is suggested.

Dating archaeological sites, cultures or phases by the obsidian method is still experimental, but shows promise provided the archaeologists understand the present limitations. Two categories of factors cause possible dating errors: the technical or geological aspect discussed by Friedman and Smith, and the archaeological context. For the establishment of valid rates of hydration and for the archaeological evaluation of the method, preferred samples are those datable by independent means, such as radiocarbon, dendrochronology, historical records, rates of refuse accumulation, contemporary calendars, or correlated positively with complexes or seriated sequences that are so dated. A few samples used in the preliminary part of the study do not meet these rigid standards and make the method look poorer than it is, but a table contains the raw data on all specimens tested to date. The principal source of potential error at our present state of knowledge is the frequency with which artifacts of older manufacture were re-used by a younger (more recent) culture. Evaluations of the data presented in the table and most of the results are discussed by geographical area. For the tropical region where the annual temperature range is minimal and where large obsidian samples from village refuse are available, the hydration rate appears to be a fairly accurate method of dating. Lack of conformity of obsidian dates with archaeological dates for the Maya region and the Southwest, however, emphasizes the need for further research using larger series of artifacts and for a continued examination of technical factors. Objects of modern manufacture can be identified with little difficulty, offering a simple means of detecting fakes or copies.

Settlement patterns are described for each phase of the sedentary agricultural occupation of the area from Pine Lawn phase (200 B.C.-A.D. 500) through Tularosa phase (A.D. 1100-1250), when the area was abandoned. Through time domestic structures changed from rounded to rectangular, from semi-subterranean to surface, and decreased in size. Earlier villages tended to be on higher, more defensible locations while later ones were lower, closer to water and arable land. Villages were generally random in plan, and great kivas, the only ceremonial structures identified in the area, appear to have served more than one village. From the settlement pattern data it is possible to construct a population curve for the area which may be partially explained in terms of botanical and climatological as well as cultural factors. Pine Lawn Valley Mogollon may have had some multi-village social organization which in later times may have united the entire valley. In this respect the Mogollon may have been intermediate between the well-integrated, segmented Anasazi communities in the plateau and the more politically structured Hohokam communities in the desert.

An archaeological sequence for the Sinaloa coastal strip of western Mexico had previously been developed by Sauer and Brand, Isabel Kelly, and Gordon Ekholm. Investigations carried out by Southern Illinois University and associates from 1952 to 1958 in Durango, across the Sierra Madre Occidental to the east of Sinaloa, have established an independent archaeological sequence. The presence of trade pottery and other artifacts from Sinaloa in the Durango sites makes possible an independent check of the Sinaloa sequence. This cross correlation essentially confirms the basic Sinaloa sequence of (early to late) Chametla, Aztatlan, and Culiacan periods, but indicates that there is some overlap between these major horizons and that the Aztatlan period is actually divisible into three more or less sequent phases: an early Lolandis phase, an intermediate Acaponeta phase, and a terminal Guasave phase. Re-examination of the Sinaloa sequence confirms and expands these conclusions, resulting in this revision of the archaeological sequence for Sinaloa. For consistency, a revised terminology for the various phases is also presented.

The archaeological sequence in the San Juan Islands is known best from two phases: the Marpole phase which occurs within the first millennium B.C., and the San Juan phase which lasts from at least A.D. 1300 to historic times. More difficult to place culturally and chronologically are: (1) the previously excavated bluff areas of Cattle Point which contain components similar to Whalen I and II and would thus occupy the time period between about 500 B.C. and A.D. 400; and (2) the Argyle Lagoon site which, though early, cannot be related definitely to other components because of insufficient excavation. Culture change is shown by increasing maritime adaptation through time and by the gradual replacement of the chipped stone industry by one using abrading and polishing techniques as the result of influence from the Old World.

In a review of MacNeish"s Preliminary Archaeological Investigations in the Sierra de Tamaulipas, Mexico, Taylor claims that the sequence of phases is built largely on the evidence from Diablo Cave and that the method of analysis is based on the premise that one congery of artifacts equals one phase. MacNeish rejects these claims by reviewing the way in which he used single components and stratigraphically unmixed deposits from several sites to work out the phase sequence.

Mesoamerican masons have used an extract from the bark of such trees as the chucum, chacte, chacah, and jabin in the preparation of lime plaster since prehistoric times, reportedly to increase the workability or strength of the lime and to reduce cracking in the plaster. Experiments involving the use of plasters prepared with these high tannin-content extracts show that the extracts have an effect on the properties of lime plater probably by stabilizing the system during drying.

The site of Pueblo Viejo extends knowledge of Ronquin-style ceramics farther east along the Orinoco than hitherto reported and provides new information on Ronquin settlement of the south bank of the Orinoco River. Laja de Manapiri adds another prehistoric settlement to the relatively thick cluster in the Caicara-Parmana area. Both sites contain Late Ronquin ceramics in a variety of forms including vessels, adornos, and figurines. Early Ronquin material is found at Laja de Manapire and is probably present at Pueblo Viejo. The Middle Orinoco is important archaeologically because of the possibility that the Ronquin styles link the Antillean area and northern Venezuela with the Guianas and the Upper Orinoco-Amazon region.

Alma Neck Banded has long been considered to be a component of Mogollon 1 and Mogollon 2 horizons. Present evidence indicates, however, that this pottery type is a horizon marker for Mogollon 3 when it does not occur in the same context with Three Circle Neck Corrugated and Mangas Black-on-white of Mogollon 4. Apparently Alma Neck Banded first appeared in the southwestern United States between A.D. 600 and 700 and continued to be made until about 950. It is still difficult to determine the order of temporal priority between Alma Neck Banded and Kana-a Gray.

Stone slabs recently discovered in the region near Tejupilco in the State of Mexico are sculptured in a simple, low-relief, bold, geometric style unlike known Mesoamerican styles but with striking parallels in the Peruvian Andes.

On the basis of present methods of identification of corn pollen, 30% of the pollen collected from maize plants grown under a wide range of environments was misclassified as Tripsacum and teosinte. The results show that the characters used to describe corn pollen are too variable to permit reliable identification of fossil pollen as corn.

Pottery life-expectancy has important archaeological implications for such problems as population sizes and duration of occupancy of sites. Specific data are here given from four contemporary Mexican village households on durability of several kinds of ware. The most important factors determining life-expectancy appear to be basic strength of the ware, functions of different types of vessels, handling practices, relative costs, and kinds of breakage. It may be inferred that similar factors determine life-expectancy in many contemporary and archaeological communities.

The validity of the association of extinct faunal remains with the artifact assemblage of the Sulphur Spring horizon of the Cochise culture has recently been questioned. Charred bones, bone articulation, the stratigraphic position of some of the bones above the culture bearing layer, and the frequency of association are cited as convincing evidence that the people of the Sulphur Spring horizon knew and hunted animals now extinct.