Chemical and microscopic examination of the material from successive floors of Mound A, Las Flores, Tampico, indicates that each building unit consisted of a lime-aggregate forming a monolithic mass, with subsequent plastering, essentially as at Comalcalco, Tabasco.

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.

Examples of the rebuilding of a boulder structure by Navajo and of a cliff dwelling by uranium prospectors, both buildings in Pueblo III sites in the lower San Juan River drainage, illustrate the difficulty of establishing universally valid, diagnostic house types.

Chemical and microscopic examination of building materials from Uxmal, Kabah, Sayil, and Labná demonstrate the presence of all the building elements previously identified at Comalcalco, Las Flores, and Palenque: mortar, plaster, stucco, wash coat, and lime-aggregate. The building elements at these Puuc sites differ from those at Comalcalco and Las Flores in the use of non-marine sources of lime, greater strength, and generally smoother composition. They differ from the Palenque building elements in the lack of multi-laminate structure and the absence of very smooth and highly worked outer surfaces. It is possible that some form of lime other than that obtained by burning limestone was used. An inclusion of gypsum found at Uxmal is the only such component identified at any of the Mesoamerican sites studied so far.

Several sherds from western Kansas, probably associated with Upper Republican or Woodland material, are from vessels made by coiling, in contrast to the “noncoiled” or “lump-modeled” technique usually considered characteristic of Plains pottery.

An obsidian fluted point was found on the slope of a gorge near San Rafael, just west of Guatemala City. The point probably washed from hills on the thick beds of volcanics through which the gorge is cut. This would confirm previous beliefs that the paleo-Indian occupation of the area post-dates the volcanics. The San Rafael point resembles the fluted points from Costa Rica and Durango, Mexico, and Clovis forms from the eastern United States. Thus, paleo-Indian influences from the north into Middle America may have been of predominately eastern rather than western origins.

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.

Flints which were formed during different geological periods and which can be confused with Alibates flint occur in widely separated localities in west Texas and eastern New Mexico.

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 claims of antiquity and authenticity made for the Manuscrito pictorico de la Cultura Maya sobre piel de mamifero are false. It contains many elements and scenes copied from a variety of sources, Mixtec, Aztec, Teotihuacan, as well as Maya. Numerals are used in meaningless fashion; many copied items are obviously misunderstood.

The lowest levels of the Simonsen site produced projectile points, scrapers, and knives in association with Bison occidentalis. The level is dated by radiocarbon at 6471 B.C. ± 520 years. The triangular, side-notched, and concave-based Simonsen point resembles points from the Turin and Hill sites in Iowa and the Logan Creek site in Nebraska. The close resemblances between the collections from the Simonsen site and the Logan Creek site, which is also radiocarbon dated, provide a basis for dating the essentially similar preceramic material from the Turin and Hill sites.

A layer of shells covered by a mixed aeolian and alluvial deposit was exposed by a road cut in a tributary of the Columbia River. Three occupation levels contained few stone tools, including burins and large knives in the lowest level. A contracting-stem point in the middle level places the site in the Frenchman Springs III phase, 4th to 11th centuries A.D. The latest level reflects increasing aridity; the streams became intermittent and the population moved to the main river.

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.

The demands of salvage archaeology in the Missouri Basin have directed attention to those culture complexes concentrated along streams. Two previously undescribed and unusual vessels from North Dakota suggest the presence there of Woodland cultures not recognized in the riverine regions.

The geological study of rocks is oriented toward examining the nature of the rock by means of chemical analyses and by examination with the petrographic microscope. The problem of the archaeologist is one of identification for which the stereoscopic or binocular microscope is best suited. About 20 criteria have been used in identifying with a binocular microscope flints from archaeological sites in Oklahoma as part of a program to trace the sources for the several kinds of flint used in tool making.