Archaeology Magazine - July/August 1984 - 25

the cardinal direction in which the
next station is located. The calculator then automatically computes
the northing and easting of the next
station and awaits the entry of the
reading for that station. This procedure is repeated until a reading
has been taken on each point on the
grid, or until the calculator indicates that its memory is full. The
data are then printed out on the
printer, stored on a micro-cassette
tape, or transferred directly to the
HP-85A microcomputer.
As with the cartography data,
the proton-magnetometer
data are
stored in files that can be retrieved
by the microcomputer. Geometries
wrote a program that performs
several mathematical and statistical
operations on the data. This program has been modified to accept
data from the HP-41CV calculator
as well as from the Model 856 protonmagnetometer readings, and to
convert the data into the same
format used by the cartography
programs. The data can then be
manipulated and depicted in the
same fashion as the cartographic
data, using the same programs.
These strategies make protonmagnetometer work much more costeffective. The process for generating
contour maps on the microcomputer from proton-magnetometer
readings is quite similar to that used
in surface mapping techniques and
uses the same hardware and software. These field techniques allow
more than 3,200 readings to be
collected each day, and the contour
maps can be ready in a few hours.
A proton-magnetometer
survey led
to the location of a large Hohokam
pit house. The orientation and structure of this pit house were identified by the proton-magnetometer
survey and the entrance to the pit
house was also defined by the map
of the proton-magnetometer
readings. Excavation of the pit house
is currently underway and, given the
mild southern Arizona winters,
fieldwork can continue uninterrupted into the early summer.
The proton-magnetometer
and cartography programs developed by our staff for the HP-41CV
require the extended functions and
extended memory modules offered
by Hewlett-Packard for the programmable calculator. These modules
plug into the HP-41CV to enhance its
operation and to allow more readings to be stored. However, these

Uncovering
Hohokam's

the
Past

Driving north out of TUcsonon Route 89, the highway follows the base of
the Catalina Mountains. A Pleistocene terrace is sharply dissected by several canyons emerging from the foothills of the mountains. Rooney Ranch lies
on the first terrace above a minor tributary of the Canada del Oro wash,
itself a tributary of the Santa Cruz River, the major drainage of the TYicson
Basin. The floodplain below would have provided rich soil for crops, an
important consideration for the prehistoric inhabitants of the site who probably
grew corn, beans, squash, and a variety of other crops.
lb the south and east of the site rise the peaks of the Catalinas, the
slopes of which support a wide variety of plant and animal life that would
have been important items in the diet of the site's inhabitants. Today, these
mountains are one of the last retreats of the bighorn sheep, an animal
known to have been hunted in prehistory. In fact, the charred jawbone of a
bighorn was found on the floor of one of the structures excavated at
Rooney Ranch.
The Rooney Ranch site itself has been the location of Pima Community
College's field school for the past three years. Access to the property and
initial funding for fieldwork were provided by the Estes Corporation, a developer based in TUcson.The site was occupied sometime around a.D. 10ÖÖ
by the Hohokam, who appeared in the Tticson Basin several centuries after
the birth of Christ. Exactly where the Hohokam originated is still a matter
of some debate among Southwestern archaeologists.
Traditionally, the Hohokam were thought to have migrated from Mesoamerica into the Phoenix Basin at around 300 B.c. Using the Phoenix
Basin as a "core" area, the Hohokam were believed to have then colonizedmuch
of the rest of the deserts of southern Arizona. Currently this model is
undergoing some revision.
Many Hohokam archaeologists now believe that this "colonization"
represents not a movement of people so much as a movement of ideas.
In this scenario, the appearance of the Hohokam in the Hicson Basin does
not signify an organized movement of people into the Basin; rather, it
simply reflects the local population adopting Hohokam traits such as irrigation, agriculture and pottery.
The Hohokam presence in the TtocsonBasin is accompanied by the first
appearance of permanent agricultural communities in the Basin. Not
surprisingly, considering their agricultural orientation, most of the early
Hohokam villages are located near the floodplains of major drainages.
In succeeding periods, as population grew and agricultural technology became increasingly sophisticated, Hohokam farming villages spread to
include secondary drainages and "bajada" areas, slopes coming off the mountains, It was during this period of growth and expansion that the site of
Rooney Ranch was first settled.
Rooney Ranch was occupied for a period of no longer than 150 years.
This inference is based on the presence of decorated ceramics that date
to a single phase in the Tbcson Basin chronology (Rincon phase, ca. a.D.
900-1100).In actuality, the site was probably occupied for a much shorter
period of time because the ceramics stylistically date to late in the Rincon
phase. Most of the artifacts represent fairly typical domestic trash, including
an abundance of pottery sherds and lithics. In addition, a single copper bell,
known to have been traded north from Mesoamerica, was also found.
Relatively few copper bells have been found in the Southwest from this
period, and the presence of one at Rooney Ranch raises questions about
the site's role in the larger picture of regional trade networks. The presence
of shell jewelry (known to have come from the Gulf of California) and a
turquoise pendant further supports the idea that the inhabitants of Rooney
Ranch were in frequent contact with groups ranging over long distances.
The site appears to have been occupied during a major transitional
period (pre-Classic to Classic period) in Hohokam prehistory, a period in which
we see a massive restructuring of Hohokam society. The major focus of
archaeological research at Rooney Ranch- aided by computer technologycenters around attempting to better understand this transition- ZX&
and D. C.

1984
July/August

Archaeology Magazine - July/August 1984

Table of Contents for the Digital Edition of Archaeology Magazine - July/August 1984