A Basket Maker III pithouse excavated in 1959 provides a cluster of tree-ring dates which terminate at A.D. 608. Features in the structure are typical of pithouses from the same time period in the area, with a northsouth orientation and a large southern antechamber having an inclined entranceway. Atypical features include a low bench encircling the main room and the presence of small adobe pellets at the bottom of each of the four post holes.

Seven charcoal tree-ring specimens from Site 1060 yielded dates with the range A.D. 544-608. It is concluded that outside A.D. 608 most nearly represents the time of construction of the pithouse.

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This, the first of five articles, gives the dates from specimens collected by the Navajo Land Claim Field Research teams. All specimens came from the Northern Sector of the Navajo Land Claim area. Out of a total of 237 specimens worked, 145 of them were dated and are listed here. Several specimens from each area were measured and plotted with modern cores from the area. The indices for each area are given, as well as the average indices for the Northern Sector.

Presented in this article are the dates of specimens collected from the Western Sector of the Navajo Land Claim. Of the 1283 specimens processed, 482 were dated. This is a dating percentage of 38 percent. All but one of these dated specimens were Pinus edulis Englm. The Western Sector has been divided into four areas; from west to east they are (1) Havasu Canyon, (2) Navajo Mountain, (3) Lower Little Colorado, and (4) Chinle. Indices for all areas except the Chinle are presented.

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Tree -ring characteristics are studied within and among stems of four Pinus ponderosa Laws. located at several semiarid sites in northern Arizona. Analyses are made of changes associated with certain physiological, height, and age gradients within the tree. Rings are grouped into twenty or forty-year intervals, are classified in four different arrangements, and the characteristics for the intervals are averaged and plotted to represent the gradients within the tree stem. Tree-rings are widest near the base and central portions of the stem. Ring width decreases with increasing age of the cambium, with increasing height within the young stem, with decreasing terminal growth, and with increasing environmental stress. Double (false or intra-annual) rings occur most frequently in the wide rings near the base and in the younger portions of the stem, or in the upper stem and branches of older trees. The frequency of rings which are locally absent (partial rings) is inversely related to ring width, and directly related to the potentiality for water stress conditions in the site or within the tree. Correlations among the year-to-year ring-width patterns throughout the tree generally increase with increasing tree age and frequency of water stress. They are high within the lower and central bole portions of older trees, but in the upper stem, in lateral branches, and in trees on the most extreme sites correlations among ring-width patterns are somewhat lower. Relative variability in widths of adjacent rings increases with decreasing ring width, increasing age, increasing height in the stem, and increasing environmental stress. First order serial correlation is frequently highest in older trees on semiarid sites. Many of these changes in ring characteristics within the tree are attributed to specific gradients or changes in auxin, food, and water supplies. A wide sampling of annual rings from the base of many semiarid site trees appears more appropriate for evaluating past fluctuations in climatic factors than an intensive sampling of rings at several heights in only a few trees.

Data derived from specimens received from the Southern Sector, Navajo Land Claim, are presented. This Sector includes East Central Arizona and West Central New Mexico. Of the 797 specimens worked, 299 yielded dates.