- Management Summary
- Research Design & Time Line
- Environment & Native American Culture
- GIS Design
- Archaeological Database
- Archaeological & Environmental Variables
- Model Development & Evaluation
- Model Results & Interpretation
- Project Applications
- Model Enhancements
- Model Implementation
- Landscape Suitability Models
- Summary & Recommendations
- Archaeological Predictive Modeling: An Overview
- GIS Standards & Procedures
- Archaeology Field Survey Standards, Procedures & Rationale
- Archaeology Field Survey Results
- Geomorphology Survey Profiles, Sections, & Lists
- Building a Macrophysical Climate Model for the State of Minnesota
- Correspondence of Support for Mn/Model
- List of Figures
- List of Tables
Summary and Recommendations
By G. Joseph Hudak, Allyson Brooks, Curtis M. Hudak, Elizabeth Hobbs, Edwin R. Hajic, and Craig M. Johnson
With the advent of the new 36CFR800 regulations implementing Section 106 of the National Historic Preservation Act of 1966 (as amended) Mn/Model is even more essential as an environmental, cultural resource and transportation planning tool. The new regulations focus on tribal consultation and the integration of the National Environmental Policy Act (NEPA) with the Section 106 process. The regulations also highlight the importance of public participation and emphasize the primary role of the Agency in the Section 106 process. Mn/Model's data layers and subsequent models, derived from the data, provide the ease of visual and tabular information in one format for the purposes of environmental analysis as well as transportation and land use planning. These layers and models are also a means of providing information visually to the State Historic Preservation Office (SHPO), Tribal Historic Preservation Office (THPO), Tribal Councils, and the general public. The datasets and models can be used to explain analyses and subsequent decisions when there are competing resources. By providing visual and tabular data in one format the Agency is able to expedite the consultation process with the SHPO/THPO and tribal governments.
Mn/Model was completed through a process of inclusion by having representatives from a variety of state and federal agencies as well as tribal preservation staff on a steering committee. This gave the primary users ownership in the methodology used to construct the model. The steering committee process was also employed to discuss the data used to derive the site probability and survey models and the subsequent implementation model.
Initial use of Mn/Model, both to determine if inventories are needed and to determine inventory methodology, have been very successful. Where Agency and SHPO archaeologists were previously compelled to rely on their own intuitive reasoning, Mn/Model has provided scientifically testable and justifiable information for decision-making purposes. Mn/Model assists the consultation process by becoming a focus point of discussion, in essence becoming a baseline for the cultural resource analysis process. Its GIS based platform allows it to be a dynamic, rather than static tool, meaning that both the cultural and environmental data layers and its predictive capabilities will only become more refined as it is used and maintained.
Mn/Model is a Geographic Information Systems (GIS)-based statistically-derived model that predicts the most likely location of archaeological sites across Minnesota. The concept behind an archaeological predictive model is the correlation of environmental variables with the locations of known archaeological sites and locational information on where archaeological sites are not found. The underlying assumption is that human behavior is non-random, and therefore past settlements and activity areas are dispersed in predictive patterns across the landscape, primarily near life-sustaining resources. This assumption means that Mn/Model cannot only assume correlations between known site locations and present day environment data, but must also reconstruct prehistoric landscapes. While suitable data were not yet available to develop statewide landscape models, the geomorphological component of Mn/Model examined the potential of deeply buried landscapes across seven river valleys, one ancient glacial lake, and six "upland" areas within a framework of models of landscape evolution (Chapter 12).
Until recently, Minnesota archaeological managers, contractors and researchers have generally identified archaeological sites that occur on or near the ground surface in their research and planning but failed to consider those that might have been buried or eroded due to geomorphic post-occupational factors. Instead, it is common in most reports and cultural resource management investigations to assume that the post-occupational geomorphological factors were dealt with as a constant. Environmental factors were, more often than not, only considered to affect cultural adaptivity. Mn/Model, through its geomorphological paleolandscape component, incorporates the third and fourth dimensions of time and buried Holocene landscapes/surfaces for areas with higher probabilities for buried cultural resources. This alone is a unique aspect of Mn/Model that has not been previously accomplished by other modeling efforts on this scale.
Mn/Model produced other innovations as well. To our knowledge, this was the first attempt to model the distribution of surveyed places in addition to that of archaeological sites. This survey probability model (Section 8.6.3) provides a vivid illustration of survey bias. When combined with the site probability model, it allows us to identify portions of the landscape that lack archaeological information.
Mn/Model is also the first high-resolution GIS-based model attempted for such a large land area. The challenge of modeling at this scale were met by the development of standards and procedures to insure consistent results throughout the state. These are discussed in this report and are being documented in greater detail in a technical manual that is in preparation. MnDOT's attention to documenting Mn/Model will insure both that the project can survive staffing changes and that other organizations can learn from or even adopt Mn/Model methods for their own modeling projects.
MnDOT assembled an interdisciplinary team of researchers that included geographers, archaeologists, geomorphologists, statisticians, and paleo-climatologists for the Mn/Model project. The combined research activities of this team have enhanced our knowledge of the last several thousand years. While project members in all of the participating disciplines have benefited immensely, archaeologists were forced to reevaluate protocols, standards, and techniques employed in site modeling, as well as accurate site recording and evaluation. In our opinion, this alone will prove to be most valuable to the future archaeological researcher.
Prior to the development of Mn/Model, MnDOT cultural resource managers had no means of assessing where archaeological survey efforts should be focused. More often than not, exhaustive inventory surveys were conducted because of limited knowledge of the project area. Surveys were often conducted within environments that had little to no potential to contain cultural remains. Survey designs and agency decisions were based on the use of "biased" expert system or intuitive models. Mn/Model is now used to assist MnDOT during all phases of project planning and review. During the scoping and pre-design phase it helps planners determine which areas could be the most costly for MnDOT in terms of having the highest potential for containing archaeological sites. The model also allows MnDOT cultural resource staff, the State Archaeologist (OSA), and the SHPO/THPO to determine project Areas of Potential Effects (APE) and survey needs and requirements. With the implementation of Mn/Model, surveys will be greatly focused, and therefore, expedited. Sharing this scientifically testable process programmatically between agencies will streamline project reviews without sacrificing good science. Further, if a member of the general public questions the need for a survey, MnDOT, OSA, and the SHPO/THPO will be able to show that their decisions were based on a scientifically-based model.
The most important aspect of Mn/Model in terms of long term cultural resource management is that it is not person specific. Agency staff can change through time without affecting Mn/Model’s performance. Mn/Model will only be enhanced as more projects are completed and new data are included. Staff cannot affect the outcome of Mn/Model; only the quality of the data entered into the model will affect its ability to perform satisfactorily.
Mn/Model has developed a planning approach to predicting surface archaeological sites and the ability to identify deeply buried landscapes suitable for containing archaeological materials. This has presented a number of challenges.
Mn/Model has made explicit the spatial biases in past archaeological surveys. The next challenge for archaeologists is to use this information to extend our knowledge of previously unsurveyed landscapes without neglecting areas predicted as having high or medium site potential. Some survey in low probability areas will also be required to adequately test Mn/Model. Otherwise, the model becomes a self-fulfilling prophecy. This will require efficient and effective field survey designs based on the survey implementation model. Mn/Model's high resolution and statewide coverage facilitates the testing of the site location model on a large-scale. Such testing cannot be easily done with intuitive or expert models because of the need for precisely delimiting areas of differing archaeological potential over broad areas.
Buried archaeological sites, especially older ones, do not necessarily occur in easily predictable landscape situations. They tend to be exceptional and restricted to environments that are not usually identified in a less than complete reconstruction of the paleolandscape. This validates the use of a geoarchaeological, or landscape (hillslope)-evolution, model such as the one set up within Mn/Model. Mn/Model clearly has established that many broad-scaled archaeological endeavors should not be undertaken without a comprehensive understanding of the geomorphic framework and implications it has for the interpretation of the prehistoric cultural record. Moreover, since older archaeological sites may occur on deeply buried landscapes, they are testable only on a limited basis by remote sensing, coring, or backhoe trenching. Mn/Model has forced the archaeological profession to review protocols for exploring landscapes that have rarely been explored in a statistically valid manner in the past.
The Mn/Model GIS provides a strong base for future enhancements. These include building GIS applications that access and interpret the Mn/Model GIS data, improving and adding to the GIS data, and refining the Mn/Model modeling process to make it easier for MnDOT to use in the future.
In fact, enhancements to Mn/Model began even before the release of Mn/Model itself. The first funded enhancement was a prototype cost path analysis application for cultural resources and other environmental issues that are a factor in the NEPA process. The cost path analysis allows MnDOT pre-design engineers, archaeologists, and wetlands specialists to compare alternative corridor alignments. The application generates an optimum alignment based upon the calculation of the least costly or disruptive path given the costs being modeled. It also estimates and compare the costs of alignments entered by the user. The intent is to provide an advisory tool for environmental, land use, and transportation planners. Factors included in this decision-making process include the potential for archaeological, wetland, and other environmental impacts. This prototype has been implemented for only three counties. It can be extended in the future by acquiring the necessary data. If MnDOT decides to adopt this application, it could later be expanded by adding data and functionality to address other MnDOT needs, such as investment management, environmental justice (e.g. demographics, social analysis), traffic counts, pavement management, accident data, or endangered species.
While Mn/Model was being developed in the UNIX environment, MnDOT changed its standard GIS platform to Windows NT. So that MnDOT can continue updating data and models, the ARC/INFO AMLs and S-Plus scripts developed for the project were translated so that they run in the NT, rather than UNIX, versions of the respective software packages. In the process, AMLs were combined, edited, and generally made more efficient. New AMLs were written to perform maintenance and updating activities.
A formal process model and database design are being developed and should be completed by summer, 2002. These were never part of the original scope, and both the process and database developed over the course of the project. The result was rather complex. For MnDOT staff and consultants to replicate and improve the process in the future, they will need a formal model of the original process with which to work. Moreover, developing the process model will help pinpoint inefficiencies and aid the development of better procedures. A formal database model can likewise result in a more compact and systematic database that is better adaptable to other projects. Both will make any future modeling more efficient. They will be accompanied by a detailed User Manual to facilitate knowledge transfer between the original team and future modelers.
With a process model, database design, and NT macros as a foundation, it will be possible to more completely automate and integrate many of the Mn/Model functions. This automation and integration will improve the efficiency and accuracy of future modeling efforts, and make it easier for future users (MnDOT staff or consultants) to learn the procedures. It will not be possible, however, to develop one easy application that runs the process from start to finish. There will always be many points where user intervention is required to make expert decisions regarding the quality and nature of the intermediate results obtained.
Both the archaeological predictive models produced by Mn/Model and the results of any future analyses or applications will be improved by keeping the Mn/Model GIS data current. Already, the digital elevation models (DEMs) have been updated by replacing the 1:250,000 scale data used in some locations with the newer 1:24,000 scale data that were not available when Mn/Model was developed. Banded DEMs were also replaced. These data are critical to the quality of the models and are also important for planning applications. Moreover, with the digital geomorphology data now available, environmental data for Mn/Model will be at a scale of 1:100,000 or better, the only exception being Marschner's (1974) vegetation map.
Accurate and frequently updated archaeological data are important for planners to estimate cultural resource impacts and costs. SHPO now provides MnDOT with their archaeological site inventory on a regular basis. MnDOT has performed extensive spatial quality control on the data. Large numbers of site coordinate errors have been identified. These are being corrected and new procedures for locating sites within the GIS will be adopted. If funding permits, this may include digitizing site boundaries. Correcting archaeological site coordinates should have a significant effect on the models, by eliminating a large random component to the database. Digitizing site boundaries, by increasing the number of 30 meter cells known to be occupied by archaeological sites, will effectively increasing the number of "site present" locations available for analysis. This should put the modeling efforts on a stronger statistical foundation and improve model precision.
From a planning perspective, efforts should be made to enhance Mn/Model in areas where major improvements to the State’s transportation network are planned. One of these statewide initiatives is the replacement of the state's aging bridge system. Bridge replacements, with their associated approach realignments and often deep excavations for piers, abutments, and channel relocations, are historically more expensive when cultural resources are encountered within project construction limits. This is generally true because they usually include deeply buried remains, complex geomorphological landscape situations, and often older cultural material deemed more significant in terms of Research Design development and implementation.
As previously stated, it is important to understand landscape or hillslope evolution before undertaking many large scale programs. Mn/Model's ability to support bridge projects would be greatly enhanced with 1:24,000 scale (or better) geomorphic coverage of additional river valleys and streams. Mn/Model work to date has focused on valleys of large, high order rivers. Intermediate and low order (small) streams may or may not have patterns of aggradation or erosion similar to the larger river valleys, but in either case, they will certainly be related to the records of the higher order streams. Similarly, the record of the lowest order streams can be related to the type and durations of dominant geomorphic processes affecting hillslopes. Eventually, the entire stream network of the state can be integrated into several models covering the largest drainage basins (e.g. Mississippi River, Red River), based on integrated models of depositional subsystems, from drainage divides through small streams to major rivers. Stream order would be a relatively simple addition to the overall effectiveness of Mn/Model since the landform sediment assemblage mapping codes are already set up to handle stream orders. Upland drainages also need closer scrutiny to establish the contemporary differences in sedimentation and erosion between upland drainage ways and major valleys.
Biomantles, colluvial mantles, and human-modified landscapes also promise to be rewarding if evaluated relative to their impacts on cultural deposits. This could be undertaken as part of other enhancement studies. The presence or absence of biomantles, and their distribution relative to hillslope component, age, and physiographic region of the state could provide insight on the interpretation of the integrity and ‘significance’ of both buried and surface prehistoric cultural material. Site integrity is a major issue in Section 106 projects and the understanding of biomantles might lead to widespread re-thinking of how prehistoric archaeological sites, particularly the ubiquitous light lithic scatter, are evaluated for ‘significance’.
Another significant enhancement would be the systematic research of the effects of shoreline (including past and present wetlands) processes on cultural deposits - water elevation changes of the Holocene, and history of terrace and shoreline development within the many different temporal and spatial ecosystems and physiographic regions. In addition, the identification of smaller exposed lakebeds should also be a priority, as large numbers of Minnesota lakes have been drained for agriculture.
In conclusion, Mn/Model is an active, ongoing project. Better archaeological predictive models can and will be developed on the basis of better data and further refinement of the modeling procedures. These can be organized at four levels of effort.
- At the first level, new models developed using existing procedures and improved elevation and archaeological data will undoubtedly be better than the originals, at least in some parts of the state. A redefinition of what constitutes a steep slope would help eliminate many areas too steep to survey or very unlikely to contain cultural resources. This would require a minimal level of effort because no additional programming would be required.
- At the second level, new data or new classifications of existing data can be added to improve the models. The DNR 1:100,000 scale geomorphology data and the Mn/Model 1:24,000 scale geomorphology data, for example, were not completed in time to be used in Phase 3 statistical modeling. These are now ready to contribute to model results. Previously unused National Wetlands Inventory point and line data could be added to increase information about wetland distributions. The National Wetlands Inventory classification used for modeling could also be refined to increase the number of classes from four (wetlands, rivers, lakes, and uplands) to include additional features such as flats, bars, rocky shores, streambeds, and even distinctions between the shallow (near shore) and deep parts of lakes. This would require additional programming to call the new or reclassified data for use in the modeling procedures.
- At the third level, new procedures can be developed. For example, models could potentially be improved by a better understanding of the expected density of archaeological resources throughout the state. However, first a model of site density must be developed that incorporates information about the density of archaeological sites based on valid, probabilistic sampling of the landscape. A priori probabilities of finding sites in various zones of archaeological potential based on existing Mn/Model surveys and new probabilistic ones would provide an idea of the relative occurrence of sites across the landscape. This model could then be incorporated into the development of the archaeological predictive model. Likewise, prehistoric landscape models based on geomorphologic and other data could be developed. Even if these models indicate no more than former surface hydrology, their use for deriving variables should greatly help the prediction of older archaeological sites, Such enhancements would require a high level of effort, because they would require the development and programming of new modeling procedures.
- At the fourth level, additional information in the archaeological database can be used to further our understanding of the distribution of archaeological sites across the landscape. Although Mn/Model takes numerous biophysical variables into consideration in model construction, it does not consider social factors. Despite the fact that social factors are difficult to incorporate into model building, due to the need to establish contemporaneity between sites, concepts like central place settlements (ceremonial centers, trade centers, large base camps) can be used without tight chronological controls. Model construction can also incorporate various indicators of site activity that may prove useful in model interpretation. For example, the dichotomy between sites containing pottery and those that do not appears to tap into a basic difference in the way sites are distributed over the landscape, as the results of Mn/Model and other modeling efforts suggest. This in turn seems to be related to the degree of sedentism reflected in these sites, although temporal differences may be involved to a lesser degree. Other indicators could be relied on that make distinctions between the amount of activity (i.e. variety and intensity) reflected at sites. These distinctions are useful in making decisions about the significance of sites and whether they are eligible for listing on the National Register of Historic Places. If modeling could incorporate this information, it would go one step beyond a model based solely on site presence or absence.
Even without these enhancements, Mn/Model has met and exceeded its original goals. The primary objective of Mn/Model as a planning tool was to develop a product that would allow cultural resource managers to make scientifically based decisions that could then be tested in the field. A secondary product of Mn/Model is the ability of the system to function as an environmental planning tool for the purposes of NEPA. It permits cultural resource managers and environmental planners a means of assessing a project's impacts to a variety of resources. Finally, the development of Mn/Model brought together a variety of agencies and tribal preservation staff working in coordination towards a common goal. The end result of the endeavor is greater communication between agencies, an expedited consultation process, and a scientific basis for Section 106 and NEPA analysis.
Marschner, F. J.
1974 The Original Vegetation of Minnesota. Compiled from U.S. General Land Office Survey
notes. North Central Forest Experiment Station, Forest Service, U.S. Department of Agriculture.
The Mn/Model Final Report (Phases 1-3) is available on CD-ROM. Copies may be requested by visiting the contact page.
Mn/Model was financed by the Minnesota Department of Transportation using funds set aside by the Federal Highway Administration's Intermodal Surface Transportation Efficiency Act.
The Mn/Model process and the predictive models it produced are copyrighted by the Minnesota Department of Transportation (MnDOT), 2000. They may not be used without MnDOT's Consent.