By Mark D. Mitchell

Four lines of evidence can be used to estimate the period and duration of occupation of the Porter area. These include a series of tree-ring dates; an analysis of associated pottery types; site stratigraphy and feature fill sequences; and data on feature construction, remodeling and abandonment. Chronological interpretations derived from these data can be compared to those developed for nearby sites, as well as to general trends in the occupational history of the region. A more complete discussion of Mesa Verde temporal periods, ceramic types, and changes in architecture types and style can be found in the section that defines the concepts and terms used in these reports.

Tree-ring Dating

Ten tree-ring dates from five proveniences are available for the Porter area (Table 1). Eight dates from three of these proveniences probably relate to the late Pueblo II occupation of the site, while one date is associated with an intermediate component context and one is associated with an early Pueblo III context. Except for the post from Room 22, all of the samples come from fill contexts; the precise relationship between the dates obtained and particular construction episodes is therefore not known. All but one of the samples produced non-cutting dates.

The single cutting date—A.D. 1052—comes from a ramada or post and adobe structure assigned to the intermediate component. However, it is all but certain that this post was re-used, because the stratigraphic position of the structure indicates that it had to have been constructed during the twelfth century. The remaining tree-ring dates only provide general temporal limits on the occupation of the Porter area.

Construction of the masonry roomblock could not have been completed prior to A.D. 1114, because Storage Pit 16 could not have been filled prior to that time and it is overlain by one of the last rooms to be added to the roomblock. However, because SP 16 is clearly an element of the late Pueblo II occupation it is also probable that none of the masonry roomblock was built prior to A.D. 1114.

The dates from EU113 and from beneath the floor of Room 1 indicate that late Pueblo II occupational debris continued to be deposited at least until A.D. 1103. If the Kiva E date came from a construction timber, then it might indicate that the kiva was constructed after A.D. 1194. However, the sample almost certainly derives from discarded charcoal and therefore simply indicates that the kiva was abandoned sometime after A.D. 1194. This in turn suggests that it was probably constructed during the last half of the twelfth century.

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Ceramic Cross-dating

Ceramic analysis provides the best evidence for reconstructing the occupational history of the Porter area. The results of preliminary studies conducted by Wheat and his students, coupled with a recent assessment of whole vessels and sherd assemblages from selected contexts, can be compared to well-dated assemblages from the Mesa Verde region to provide a general chronological framework for the occupation of the site (Lipe and Varien 1999aLipe, William D. and Mark D. Varien
1999a Pueblo II (A.D. 900-1150). In Colorado Prehistory: A Context for Southern Colorado Drainage Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 242-289. Colorado Council of Professional Archaeologists, Denver., 1999bLipe, William D. and Mark D. Varien
1999b Pueblo III (A.D. 1150-1300). In Colorado Prehistory: A Context for Southern Colorado Drainage Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 290-352. Colorado Council of Professional Archaeologists, Denver.; Ortman 2003Ortman, Scott G.
2003 Artifacts. In The Archaeology of Yellow Jacket Pueblo (Site 5MT5): Excavations at a Large Community Center in Southwestern Colorado [HTML Title]. Available: http://www.crowcanyon.org/yellowjacket. Date of use: December 17, 2004.; Wilson and Blinman 1991Wilson, C. Dean and Eric Blinman
1991 Ceramic Types of the Mesa Verde Region. Handout prepared for the Ceramic Workshop, Annual Meeting of the Colorado Council of Professional Archaeologists, Boulder, Colorado.).

Because artifacts were not collected systematically during the excavation of 5MT1, the proportions of different ceramic types in the University of Colorado's collection may not be an unambiguous reflection of types that were originally deposited at the site. However, if a bias is present in the ceramic collections it is very likely to be systematic. Beginning in the late Pueblo II period, decorated vessels tended to be better made through time, with thicker, more robust walls and lips. Other things being equal, more recent vessels will tend to break into larger sherds (Ortman 2003Ortman, Scott G.
2003 Artifacts. In The Archaeology of Yellow Jacket Pueblo (Site 5MT5): Excavations at a Large Community Center in Southwestern Colorado [HTML Title]. Available: http://www.crowcanyon.org/yellowjacket. Date of use: December 17, 2004.). More recent vessels also tend to be more highly decorated: a greater proportion of their total decorative field is used, and the designs tend to be better made and more intricate. All of these factors increase the probability than a sherd will be collected, leading to an over-representation of more recent vessels. If the Porter area assemblage is biased, it is likely that it will appear to be more recent that it in fact is.

The decorated pottery associated with the earliest occupation of the Porter area consists primarily of Mancos Black-on-white vessels, along with lesser numbers of McElmo Black-on-white vessels. A very small number of Cortez Black-on-white vessels also are present. Mesa Verde Black-on-white vessels are absent. These proportions suggest that the early component at Porter dates to the period between A.D. 1060 and A.D. 1140 (Lipe and Varien 1999aLipe, William D. and Mark D. Varien
1999a Pueblo II (A.D. 900-1150). In Colorado Prehistory: A Context for Southern Colorado Drainage Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 242-289. Colorado Council of Professional Archaeologists, Denver.; Ortman 2003Ortman, Scott G.
2003 Artifacts. In The Archaeology of Yellow Jacket Pueblo (Site 5MT5): Excavations at a Large Community Center in Southwestern Colorado [HTML Title]. Available: http://www.crowcanyon.org/yellowjacket. Date of use: December 17, 2004.; Wilson and Blinman 1991Wilson, C. Dean and Eric Blinman
1991 Ceramic Types of the Mesa Verde Region. Handout prepared for the Ceramic Workshop, Annual Meeting of the Colorado Council of Professional Archaeologists, Boulder, Colorado.).

The latest occupation is associated almost exclusively with Mesa Verde Black-on-white vessels, and therefore probably took place sometime between A.D. 1225 and 1280. However, most of the late masonry surface rooms, as well as Kivas B and E, are associated with a complex mix of vessel types that includes some Mancos Black-on-white vessels, some McElmo Black-on-white and some vessels exhibiting "transitional" attributes. A few Mesa Verde vessels also are present. Thus, most of the later occupation probably dates to the second half of the twelfth century, from A.D. 1140 to A.D. 1180, or perhaps as late as A.D. 1225 (Lipe and Varien 1999bLipe, William D. and Mark D. Varien
1999b Pueblo III (A.D. 1150-1300). In Colorado Prehistory: A Context for Southern Colorado Drainage Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 290-352. Colorado Council of Professional Archaeologists, Denver.; Ortman 2003Ortman, Scott G.
2003 Artifacts. In The Archaeology of Yellow Jacket Pueblo (Site 5MT5): Excavations at a Large Community Center in Southwestern Colorado [HTML Title]. Available: http://www.crowcanyon.org/yellowjacket. Date of use: December 17, 2004.; Wilson and Blinman 1991Wilson, C. Dean and Eric Blinman
1991 Ceramic Types of the Mesa Verde Region. Handout prepared for the Ceramic Workshop, Annual Meeting of the Colorado Council of Professional Archaeologists, Boulder, Colorado.).

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Stratigraphic Relationships, Construction Sequences and Abandonment

While tree-ring dates and ceramic analysis can be used to determine the period during which a site was occupied, estimates of the duration and continuity of that occupation require an analysis of construction sequences and the stratigraphic relationships among features. Extensive superpositioning indicates that the Porter area was occupied for an extended period; however, several lines of evidence suggest that the occupation may not have been continuous. These data indicate that three, or perhaps four, distinct components can be identified, separated by two or more periods during which the site was either abandoned or occupied by a small number of people.

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Late Pueblo II Component

The earliest occupation is represented by an open cluster of at least two kivas, eight semi-subterranean rooms, eight large storage pits, and a series of post alignments. A large number of small pits and isolated postholes also are associated with this earliest component (Plan Map of Porter Pueblo II Component - pdf format (190kb)). A second group of structures and features, including one kiva, two subterranean rooms, and three large storage features, slightly post-date this initial occupation, but are clearly associated with it, based on their architectural style and associated ceramics. Kiva A was probably the first to be built, followed successively by Kiva C1 and Kiva D. Each of these primary habitation structures is associated with a variety of dedicated storage features and subterranean workspaces. Few of these structures were remodeled and for those that were the modifications were minor, suggesting that the initial occupation of the Porter area was about three times as long as the use-life of these early kivas, or approximately 37.5 to 75 years total (Wilshusen 2002:108Wilshusen, Richard H.
2002 Estimating Population in the Central Mesa Verde Region. In Seeking the Center Place: Archaeology and Ancient Communities in the Mesa Verde Region, edited by Mark D. Varien and Richard H. Wilshusen, pp. 101-120. University of Utah Press, Salt Lake City.).

Generally, positive stratigraphic evidence for an occupational hiatus—in the form of truncated strata, deflated surfaces, or aeolian deposits—is limited. However, the best evidence for such a break in the occupation of the Porter area can be found in the fill sequence of Kiva D, the last of the early kivas to be built. There, an accumulation of aeolian sand suggests that the site may have been abandoned for a short period, some time during the first half of the twelfth century. The existence of a brief hiatus might help to explain the dramatic architectural differences that distinguish the site's earliest and latest occupations.

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Intermediate Component

Plan Map of Porter Intermediate Component. (pdf format)

The subsequent occupation is relatively ephemeral and consists of a small number of structures and features that post-date the earliest occupation of the Porter area, but pre-date the construction of the overlying masonry pueblo (Plan Map of Porter Intermediate Component)]. Most of these features are concentrated in the southeastern quarter of the site, and they include two masonry surface rooms (Rooms 21 and 23, one possible post and adobe structure, several post alignments and a cluster of pits and shallow basins. Their architectural characteristics are distinct from either the earliest or the latest occupations of the site, but it is not clear whether these intermediate features represent a separate and perhaps ephemeral occupation, or whether they merely represent the first phase of the most recent occupation. If distinct, they may indicate that the site was used on a temporary or seasonal basis. In either case, the duration of the intermediate component is likely to have been short.

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Pueblo III Component

The most recent occupation of the Porter area comprises a masonry roomblock, three kivas, and an unroofed masonry enclosure (Plan Map of Porter Pueblo III Component - pdf format (175kb)). Only some of these structures were contemporaneous. The roomblock took shape during a series of construction events and only some of the rooms were occupied when the Porter area was abandoned. Only one, or perhaps two, of the kivas were occupied concurrently. Distinctive ceramic associations and structure abandonment modes indicate that this occupation can be broken into two relatively distinct components. The first is more extensive and includes most of the masonry roomblock and Kivas B and E. The second is much less extensive and includes Kiva C2 and a restricted portion of the roomblock.

Kiva C2 was clearly the last pitstructure occupied in the Porter area. It is associated with late Pueblo III pottery. When it was abandoned at least 14 large, late black-on-white vessels, often with striking or unusual designs, were intentionally broken on the floor of the kiva. The ventilator shaft was plugged with groundstone tools and slabs. No domestic debris is present in the fill of Kiva C2.

Indirect evidence suggests that Kiva B may have been the earliest of the Pueblo III kivas. The earliest masonry surface structures (Rooms 4, 6 and 7) lie directly north of Kiva B. Rooms 21 and 23 of the intermediate component lie immediately to the east and may also be associated with Kiva B.

Based on a late twelfth century non-cutting tree-ring date, it is probable that Kiva E was built after Kiva B. Pottery in the fill of Kiva E consists primarily of McElmo Black-on-white sherds, while most of the pottery in the upper fill of Kiva B (in the stone enclosure) consists of Mancos Black-on-white sherds. However, it is possible that the "early" fill of Kiva B may simply result from its proximity to the late Pueblo II deposits that underlie the southern end of the masonry roomblock and may have eroded into the abandoned kiva.

Ceramic evidence suggests that Kiva E is only slightly older than Kiva C2. However, the overall assemblage differences between the early Pueblo III portions of the roomblock and Kiva C2 suggest that there may have been a short hiatus between them.

The lack of extensive kiva remodeling indicates that the combined Pueblo III occupation of the site may have lasted as long as three structure use-lives, or 60 to 120 years (Wilshusen 2002Wilshusen, Richard H.
2002 Estimating Population in the Central Mesa Verde Region. In Seeking the Center Place: Archaeology and Ancient Communities in the Mesa Verde Region, edited by Mark D. Varien and Richard H. Wilshusen, pp. 101-120. University of Utah Press, Salt Lake City.). Evidence for extensive remodeling of the masonry roomblock suggests that many of the rooms were used in conjunction with more than one of the kivas.

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Generalized Stratigraphic Section

During five seasons of excavation a variety of designations were applied to the stratigraphic units observed in the Porter area. In some cases, similar names were used to designate different depositional units, while in others different names were used for the same unit. The following reconstruction is based primarily on the correlations developed by Frank Eddy in his various field notes from1966.

Four more-or-less discrete sediment packages can be recognized in the stratigraphy of the Porter area. The lowest of these is described as "native clay," and consists of undisturbed sediment. It is not clear whether this unit includes all of the pre-village pedogenic horizons, but a comparison of the Porter component stratigraphic sequence with nearby soil profiles suggests that the pre-village A horizon was not substantially removed by village construction activities. At Porter, undisturbed caliche underlies the "native clay" surface at a depth of 1.3 to 1.6 meters. The Porter area is located on soils of the Witt series, which form in silty calcareous loess on slopes ranging from one to 12 percent (Leonhardy and Clay 1985Leonhardy, Frank L. and Vickie L. Clay
1985 Soils. In Dolores Archaeological Program: Studies in Environmental Archaeology, compiled by Kenneth L. Petersen, Vickie L. Clay, Meredith H. Matthews, and Sarah W. Neusius, pp. 139-153. Bureau of Reclamation, Engineering and Research Center, Denver.). Pedogenic carbonates accumulate at depths ranging from 1.0 to 1.5 meters in these soils. The correspondence between these depths suggests that the "native clay" surface observed during excavation approximates the pre-village ground surface.

The overlying sediment, typically but not exclusively referred to as "Layer D," consists of sandy clay containing varying amounts of fine charcoal and sparse to moderately abundant artifacts. In some cases, Layer D clearly fills pit features which originate at the pre-village ground surface. However, due to its broad distribution, it is also possible that some portions of Layer D represent either the top of the pre-village A horizon, into which artifacts and charcoal have been trampled, or redeposited A horizon sediment resulting from the construction of kivas, mealing rooms and storage pits. The thickness of Layer D is variable, but averages 10 to 15 centimeters. The stratum thins away from the roomblock, where it may be indistinguishable from the pre-village A horizon. The artifact content of Layer D is frequently quite sparse, especially at some distance from the center of the site; the overlying Layer B can generally be distinguished from Layer D by its higher artifact and charcoal content.

Layer C consists of a discontinuous, secondary deposit of caliche that thins in all directions away from the approximate center of the roomblock. Because most of the semi-subterranean pitrooms at the site did not penetrate the pre-village caliche stratum, the majority of this material derives from kiva construction. In some places Layer C is a relatively homogenous carbonate deposit that is combined with minor amounts of silt and trash. In other places the carbonate content of Layer C is much lower and it is likely that it represents a secondary deposit resulting from the excavation of later pit features or the collapse of buildings that were partially constructed from mortar that incorporated caliche derived from kiva excavations.

The thickness of Layer C varies, but is not generally more than 10 centimeters. Excavations near the center of the roomblock demonstrated that Layer C represents more than one construction episode. Where underlying Layer D is relatively thin, Layer C was probably deposited during the construction of the earliest Pueblo II kivas. Where underlying Layer D is thicker or where its artifact content is higher, Layer C probably marks the construction of later Pueblo III kivas. However, because Layer C is discontinuous and varies in thickness and content, it cannot be used as a consistent temporal marker.

Layer B subsumes a set of related deposits that overlie both Layer C and Layer D. Most of these consist of mixed domestic debris, but true midden deposits, construction debris, roof fall, and post-abandonment room fill are also included. Where Layer C is not present, Layer B rests directly on Layer D and is distinguished from it by differences in color, compaction, or charcoal content. Caliche in varying concentrations is also present in Layer B; however, it generally occurs in the form of small nodules or films and probably represents pedogenic carbonates that began to form after the abandonment of the site. Layer B varies in thickness, but is generally at least 20 centimeters thick. The frequency of artifacts associated with this sediment package varies from relatively sparse to abundant, generally as a function of distance from the roomblock. In general, artifacts and charcoal are more abundant in Layer B than in Layers A, C, or D.

The uppermost sediment package comprises the modern A horizon that is developing in post-occupation aeolian silt and sand. Recent organic material is evident throughout this layer, including rootlets and other plant parts. West of the roomblock, and perhaps to the east as well, the site has been plowed and there Layer A corresponds to the plow zone. The artifact density of Layer A is generally sparse, and is primarily a function of post-occupation disturbances.

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Chronological Assessment

These data indicate that the occupation of the Porter area can be broken into three or perhaps four components. The chronology of these components is summarized in Table 2. The earliest occupation dates to the late Pueblo II period, between about A.D. 1060 and A.D. 1140. This initial occupation may have lasted for two or three generations. During this time Kivas A, C1 and D were built.

It is likely that the late Pueblo II occupation was followed by a short hiatus, during which the site was largely or wholly abandoned. The duration of this hiatus is not known. The subsequent reoccupation of the site appears to have been relatively ephemeral, but it is not clear whether this intermediate component represents a distinct occupation, or whether it merely represents the initial phase of Pueblo III construction.

The early Pueblo III occupation at the site took place some time between A.D. 1140 and A.D. 1180, or perhaps as late as A.D. 1225, and may have lasted one or two generations. During this time Kivas B and E were constructed. This early Pueblo III occupation may have been followed by a short hiatus, but the evidence for such a break is circumstantial and is based primarily on the lack of extensive late Pueblo III trash deposits.

The last occupation of the Porter area dates to the late Pueblo III period, between A.D. 1225 and A.D. 1280. This component appears to be largely confined to Kiva C2. Unlike any of the prior uses of the Porter area, the abandonment of Kiva C2 was marked by ritual closure of the structure.

The initial occupation of the Porter area corresponds to a population "rebound" that began in the middle of the eleventh century in the central Mesa Verde region (Lipe and Varien 1999aLipe, William D. and Mark D. Varien
1999a Pueblo II (A.D. 900-1150). In Colorado Prehistory: A Context for Southern Colorado Drainage Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 242-289. Colorado Council of Professional Archaeologists, Denver.). It also corresponds to the founding of Yellow Jacket Pueblo (5MT5), located approximately 500 meters northeast of 5MT1.

The architectural trends evident in the Porter area are similar to those found at contemporaneous sites elsewhere in the central Mesa Verde region. While masonry construction is common during the eleventh century on the Mesa Verde itself, elsewhere late Pueblo II sites frequently include subterranean rooms of various sizes, masonry or post and adobe surface rooms, and kivas with a variety of architectural features. The architectural variability of the Porter area structures is easily subsumed within broader regional trends (e.g., Hampson, Merewether, and Robinson 2002Hampson, James G., Josephine A. Merewether, and Christine K. Robinson
2002 5MT9873: A Pueblo II Habitation Site, In The Puebloan Occupation of the Ute Mountain Piedmont, Vol. 2: Single Component Basketmaker III and Middle Pueblo II Habitation Sites, edited by Christine K. Robinson, pp. 7.1-7.39. Soil Systems Publications in Archaeology Vol. 22, no. 2. Phoenix, Arizona.; Kuckelman 1988cKuckelman, Kristin A.
1988c Excavations at Dobbins Stockade (Site 5MT8827), a Pueblo II Habitation. In Archaeological Investigations on South Canal, compiled by K.A. Kuckelman and J.N. Morris, pp. 373-403. Four Corners Archaeological Project Report 11. Complete Archaeological Service Associates, Cortez, Colorado.; Morris 1991Morris, James N.
1991 Archaeological Excavations on the Hovenweep Laterals. Four Corners Archaeological Project Report 16. Complete Archaeological Service Associates, Cortez, Colorado.; Stirniman 2003Stirniman, Paul J.
2003 5MT9924: A Late Pueblo II to Early Pueblo III Habitation Site. In The Puebloan Occupation of the Ute Mountain Peidmont [sic], Vol. 3: Late Pueblo II to Early Pueblo III and Late Pueblo III Habitation Sites, in pp.2.1-2.134, edited by Brian R. Billman and Christine K. Robinson. Soil Systems Publications in Archaeology No. 22. Phoenix, Arizona.).

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