Aravaipa Creek is one of the few, small, permanent desert streams in Arizona. It has diverse fish and invertebrate faunas but the invertebrates are not well-known. I collected benthic and 24 hr. drift samples there during 1980-1981 and found 31 taxa. The most abundant species were Baetis insignificans and Choroterpes inornata (Ephemeroptera), which exhibited the nocturnal drift periodicity characteristic of drifting invertebrates studied elsewhere. In the laboratory, observations of the drifting behaviors of five species of mayflies were made in 5 and 10 cm/s current speeds. These provided evidence that drifting insects are not necessarily swept away by the current (accidental drift), but are probably exhibiting a specific behavior triggered by local conditions such as lack of cover or food (active drift). I also tested the relationship between drift rates and the presence and absence of food (periphyton) using B. insignificans and C. inornata. With both species, the number of insects drifting increased significantly when periphyton was not present; therefore lack of food may be an important cause of drift. The sizes of the nymphs used in these experiments were determined; I found that drifters were either similar in size to non-drifters (C. inornata), or that drifters were larger than nymphs that did not drift (B. insignificans). These results suggest that direct competition by size does not play a role in determining which individuals drift. Drifting appears to be a dispersal mechanism for benthic invertebrates; it maintains the numbers and distribution of the benthos according to the rapidly changing distribution of their food resources which occurs in streams. This process fits some recent models of population regulation by dispersal.

If the products of individual craftsmen can be identified, patterns of organization, specialization, and exchange may be traceable. Following a description of Grasshopper Pueblo's lithic technology, experimental and archaeological data on individual knappers are combined to examine projectile point manufacture. At Grasshopper, points in burials formed sets, consistent and distinctive in form and in flake scar patterning. The sets appeared to be the work of different knappers. Major distinguishing attributes of sets were identified using discriminant analysis. Both attributes of form, which are partly under conscious control, and unconsciously varied attributes of flake scar patterning distinguished sets. The individualistic nature of variation in these attributes was tested using sets of replicated points by five modern knappers. The similarity in the behavior of the attributes supported the hypothesis that the burial sets can be attributed to different knappers. In addition to the burial sets, another burial with 128 points, and two rooms with point manufacturing debris were examined. It appeared that more than ten knappers had contributed to the one burial, and the two rooms represented different workshop situations. In Room 28 almost all the lithic material came from point manufacture, and the points were similar and probably made by one knapper. Room 246 had a variety of points, plus many other lithic items, and is best interpreted as a communal room where a number of men pursued craft activities. Point sets, workshops, and other information indicate that at Grasshopper many knappers were producing lithic tools at only a low level of specialization. Grasshopper's lithic crafts were probably similar in their organization to crafts in the historic Pueblos, with no centralization of production or distribution. Until we have more detailed information on other crafts, reconstructions of the prehistoric Pueblos as highly organized and specialized centers for production and distribution should be received with caution. Studies of individual variation are difficult and time-consuming, but even less sensitive artifacts such as stone tools show individual differences. If individual craftsmen can be traced, it is sometimes possible to see how they cooperated, specialized, and participated in the economic and social life of their communities.

The elevated Kaibab plateau in northern Arizona has an area of 88 0 square miles and lies adjacent to the Grand Canyon of the Colorado river. It is composed of a sequence of lithified Paleozoic rocks that are approximately 4000 feet thick and consist of marine sediments that contain very little permeability. The ground water system of the plateau has two principal components: 1) circulation through unfractured stratified rocks that range up to a few tens of miles wide and 2) fault controlled drains. In unfractured zones, most of the ground water circulation takes place in the upper 900 feet of the section. The water drains laterally through these rocks toward fault zones or seep faces along the canyon walls. Approximately 40 percent of the plateau surface (330 square miles) drains to canyon seeps. Fault zones provide laterally and vertically continuous large capacity conduits through the plateau. These function as drains for the ground water system as well as floodways for storm pulses that enter the faults directly from the surface. Fracturing has controlled the development of extensive karst networks in limestones that lie near the base of the Paleozoic section. These systems drain to 10 groups of karst springs that discharge an average of approximately 100 cubic feet of water per second. The karst springs drain approximately 60 percent of the plateau surface (550 square miles). The springs in Tapeats amphitheater on the west side of the plateau discharge from the extensive West Kaibab fault zone and account for approximately 70 percent of the measurable water leaving the plateau. This group of three springs drains about 40 percent of the plateau surface (380 square miles). Development of ground water supplies does not appear to be economically tenable in the unfractured portions of the plateau because the permeabilities of the rocks are very small and the depth to the small quantities of available water exceed 500 feet. Production from the large fault controlled drainage networks is equally unattractive. Although the occurrence of water is certain, the large supplies are more than 2800 feet below the land surface and exist in finite channels along the fault zones. These would be difficult to penetrate with conventional drilling methods.

"Final report to National Park Service, Contract PX 8601-7-0106"

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The presidial system was the focus for Spanish and Mexican military operations in northern New Spain. The Spanish established these garrisons to provide their settlers and missionaries protection from hostile indigenous tribes opposing expansion into their territories. Between 1692 and 1776, presidios were established on the Sonoran frontier at Fronteras, Terrenate, Horcasitas, Santa Cruz, Altar, Tubac, Bavispe, Bacoachi, and Tucson. The Spanish and Mexican governments never completely solved the problem of adequately supplying the Sonoran presidios with men and materials to achieve dominance over the native populations. These conditions left the presidios and civilian population exposed to attack and harrassment by hostile Indians. Examination of the major events concerning the presidios from 1790 to 1835, including the Apache pacification policies, establishment of "Indian" presidios, the Mexican war for independence, transfer from Spanish to Mexican control, and the study of presidial personnel, reveals how the presidio functioned as a major frontier institution.