Archaeological Prospection of the Hatfield Site, a Monongahela

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Archaeological Prospection of the Hatfield Site, a Monongahela Tradition Village in

Washington County, Pennsylvania

Jason Espino, Seth Van Dam, Ashley Brown, and Marion Smeltzer

Report completed for fulfillment of Specialized Methods in Archaeology: Archaeological

Geophysics (Anth 584) course requirements.

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ACKNOWLEDGEMENTS

This project could not have been completed without the generosity of the Anthropology

Department at Indiana University of Pennsylvania (IUP). The department provided the

geophysical and spatial equipment necessary for the survey as well as transportation to and from

Indiana, Pennsylvania. Equally generous were the Mansfield family for allowing access to the

property on which the Hatfield site is located. They are thanked for their hospitality, patience,

and all-around interest in the project. Dr. Beverly Chiarulli of IUP is thanked for her guidance,

suggestions, comments, and technical support throughout every step of the process, from data

collection to report preparation. We are especially grateful for her availability at a moment’s

notice to trouble-shoot problems that invariably arose during the project. Amanda Snyder and

Andrea Boon are thanked for rearranging their busy schedules to lend a hand in data collection.

Likewise, Allegheny Chapter of the Society for Pennsylvania Archaeology members Nina

Larsen, Bob Leidig, Don McGuirk, Ben Scharff, and Don Tanner volunteered their time and

aided in data collection. Any errors found herein are the sole responsibility of the authors.

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TABLE OF CONTENTS

Acknowledgments i

Table of Contents ii

List of Figures iv

List of Tables iv

Abstract v

Introduction 1

Archaeological Prospection Theory 1

Magnetometry 2

Ground-Penetrating Radar 2

Archaeological Prospection of Prehistoric North America 3

Circular Villages of the Monongahela Tradition 6

A Brief Background of The Hatfield Site 10

Research Objectives 13

Methods 13

Survey Parameters 13

Magnetometry Survey 16

Magnetic Susceptibility 16

Magnetic Gradient 16

Ground-Penetrating Radar Survey 17

Data Integration 19

Results 19

Magnetometry Survey 20

Magnetic Susceptibility 20

Magnetic Gradient 21

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Ground-Penetrating Radar Survey 24

Interpretations 26

Conclusions 30

References Cited 31

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LIST OF FIGURES

Figure 1. General Location of the Hatfield Site 7

Figure 2. Typical Monongahela Tradition Village 9

Figure 3. Typical Monongahela Tradition Dwelling 9

Figure 4. Topographic Setting of the Hatfield Site 11

Figure 5. Stratigraphic Profile of the Hatfield Site 12

Figure 6. View of Grid 2, facing East 15

Figure 7. View of Grid 3, facing North 15

Figure 8. Seth Van Dam conducting Magnetic Gradiometry Survey in Grid 2 18

Figure 9. Amanda Snyder and Nina Larsen Performing GPR Survey in Grid 2 18

Figure 10. Results of the Magnetic Susceptibility Survey 21

Figure 11. Results of the Magnetic Gradient Survey in Grid 2 23

Figure 12. Results of the Magnetic Gradient Survey in Grid 3 23

Figure 13. Results of GPR Survey in Grid 2 25

Figure 14. Results of the Magnetic Gradient and GPR Surveys in Grid 2 27

Figure 15. Results of the Archaeological Prospection of the Hatfield Site 29

LIST OF FIGURES

Table 1. Spatial Information for Grid 2 and Grid 3 14

Table 2. Magnetic Susceptibility Anomaly Attributes 21

Table 3. Magnetic Gradient Anomaly Attributes 24

Table 4. GPR Anomaly Attributes 26

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ABSTRACT

An archaeological prospection survey was undertaken at the Hatfield site in November of

2011. The survey utilized magnetometry and ground-penetrating radar techniques to identify

subsurface anomalies that may represent cultural features. In total, 28 anomalies were identified

through magnetic susceptibility, magnetic gradient, and ground-penetrating radar methods.

Several of the anomalies resulted from modern activities at the site, including agricultural

plowing and excavations by the Allegheny Chapter. However, at least 10 of the anomalies

possibly represent prehistoric cultural remain of the Middle Monongahela component of the

Hatfield site. These anomalies comprise two pit features, six dwellings, and a house ring zone.

The size and arrangement of dwellings as well as the spatial layout of the house ring is consistent

with typical Monongahela Tradition villages. If the anomalies indeed represent a section of a

village, the Middle Monongahela village at the Hatfield site would encompass an estimated area

of 1.7 to 2.27 acres. In addition, a composite anomaly south of the Middle Monongahela

component may represent a second village at the site that covers an area of 0.25 acres.

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INTRODUCTION

The following report describes an archaeological prospection survey undertaken at the

Hatfield site (36WH678) for fulfillment of course requirements in Specialized Methods in

Archaeology: Archaeological Geophysics (Anth 584). Specifically, it attempts to address the

nature of the subsurface archaeological record at the site through the use of geophysical methods,

including magnetometry and ground-penetrating radar (GPR). The field component of the

survey was undertaken during five non-sequential days in November of 2011 while data

processing, graphic design, and report production were completed in November and December

of 2011.

The Hatfield site was selected due to the senior author’s participation in ongoing

excavations there as part of public outreach efforts by the Allegheny Chapter of the Society for

Pennsylvania Archaeology. Given that, as Bercel and Espino (2010) point out, one of the

primary purposes of excavations at the Hatfield site was to garner public interest in the

archaeology of southwestern Pennsylvania through hands-on experience, the chapter decided to

excavate the site by hand. The chapter felt that there were a number of benefits to the slower-

paced excavations. First, it allows for the supervision and education of inexperienced

fieldworkers. Second, volunteers can be involved in most aspects of the fieldwork. Third, since

sites such as Hatfield are among the most complex sites to excavate, there is ample time to

properly document the findings without being overwhelmed. Finally, a smaller portion of the

site is impacted, thus preserving large areas for future research.

Conversely, one of the drawbacks of the chapter’s excavation procedures is that there is

limited opportunity to excavate large areas and expose settlement pattern information, including

the presence of a palisade, the layout of domestic structures, and the organization of activity

areas. As a result, archaeological prospection, also referred to as archaeological geophysics, was

proposed as a method to better define the subsurface record at the site and help identify

settlement patterns that would only be recognizable through extensive and expensive

excavations.

Archaeological Prospection Theory

The following section provides a general discussion of geophysical theory as it relates to

magnetometry and GPR.

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Magnetometry. Magnetic methods are based upon localized disruptions in the earth’s

magnetic field (Hargrave 1999:12). Magnetic surveys measure the variation of the magnetic

fields of the earth and the effects of near-surface features that may be overlain upon it. In

archaeological applications, the surveys map the contrasting values of buried anthropogenic

activities generally characterized through magnetic susceptibility of geological features and

ferrous materials. Once the average magnetic susceptibility for an area is established, the

magnetic gradient acts as a filter to reduce the effects of background geological magnetic fields

and daily effects caused by the interaction between the magnetic fields of the Earth and its

atmosphere, allowing anthropogenic activity areas to be viewed as anomalies (Campana 2009).

Magnetic gradiometry is a passive detection method that measures the sum of remnant and all

forms of induced magnetism at a location, whether forms are natural or anthropogenic (Kvamme

and Ahler 2007:455-546). The range of the spatial frequencies in the collected data depends on

the depth of subsurface features, the susceptibility contrast between features and their

surroundings, and the height of the measuring instrument above the surface (Scollar 1990:490).

Ground-penetrating Radar (GPR). The foundations of GPR lie in electromagnetic (EM)

theory that is based upon the relationship of a material’s response to EM fields. GPR survey

method involves the transmission of high-frequency electromagnetic radar pulses into the ground

and measures the time that elapses between each transmission, reflection off a buried

discontinuity, and the reception back to the radar antenna at the surface (Conyers and Goodman

1997:23). The frequency of the radar wave transmitted controls the depth to which radar energy

can penetrate and the amount of definition that can be expected in the subsurface (Conyers and

Goodman 1997). Once the reflected signal is detected by the receiving antenna at the ground

surface within close proximity to the transmitter, this reflected signal can then be compared to

the original signal. The magnitude or amplitude, phase (negative or positive), and frequency of

the received signal offers additional information as to the nature of the materials below the

surface (Heimmer 1992:37). The software of the GPR unit has equations of macroscopic (or

average behavior) descriptions of how different electron, atoms, and molecules respond en masse

to the application of the EM field. These fluctuations from the macroscopic properties stand out

from the average macroscopic state (Jol 2009).

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Archaeological Prospection of Prehistoric North America, a Brief Overview

The use of geophysical testing at archaeological sites in the United States was first

pioneered in 1946 by Richard J. C. Atkinson with the use of electrical resistivity (Scollar et al.

1990). Over the past 70 years, archaeologists have increasingly employed classical geophysical

methods to successfully enhance many cultural resource investigations (Heimmer 1992,

Weymouth, 1986). Not until recently however, has the use of geophysical testing become a

more standard survey technique. When employed, they provide non-destructive methods to

access information contained within significant sites. There are many different types of

geophysical methods for testing archaeological sites. These include ground penetrating radar

(GPR), magnetometry, electrical resistivity, magnetic susceptibility, and profiling to name a few.

Improved geophysical instruments and application methods, as well as new innovations in data

processing, have allowed for the study and measurement of earth-related physical contrasts with

extreme precision (Heimmer 1992). As a benefit of these advancements, minute or small

subsurface contrasts attributable to both historic and prehistoric site remains have a greater

chance of being detected using high resolution geophysical techniques without being destroyed

(Heimmer 1992). The following is a review of several cases in which archaeologists

successfully used geophysical testing methods to identify aspects of an archaeological site that

otherwise may have required full excavations. In each one of these cases, similar equipment was

used as in the archaeological prospection of the Hatfield site. By studying the results of these

cases, and how the data was processed, better interpretations of the Hatfield data can be offered.

Near-surface geophysical surveys were conducted at three locations at the Poverty Point

site (16WC5), Louisiana in 2001 (Britt et.al. 2002). Over the past 100 years, a number of

archaeological excavations have been carried out at Poverty Point, but none provided a clear

understanding of the nature, distribution, and density of archaeological features such as pits,

hearths, postholes, and other structural remains (Britt et.al. 2002). Due to this lack of

information, the geophysical survey was designed to emphasize high data density in three target

areas instead of covering large tracts of land at the site. The intention of the survey was to

collect data in a manner that would permit the detection of relatively small, very low contrast

subsurface features (Britt et. al. 2002). Mound E, West Sector and the Southwest Sector (rings

1-5) were selected as the target areas.

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Methods employed during the survey included magnetic field gradiometry, electrical

resistivity, electro-magnetic in-phase/conductivity, and GPR. The following systems and

parameters were used: Geoscan Research FM-36 gradiometer with two fluxgate sensors;

Geoscan Research RM-15 resistence meter equipped with an MPX15 multiplexor and a PA5

Probe array; Geonics Ltd. EM-38 terrain conductivity meter; and a Sensor & Software, Inc.

Noggins GPR system with 250 and 1000 MHz antennas. All resistivity and gradiometer survey

data was processed using Geoplot 3.0 software and exported into Surfer 7.0 to produce image

maps. The GPR data was processed using GPR Slice, but was considered unusable due to a high

clay soil content that obscured the detection of anomalies. Furthermore, datasets recovered from

Mound E were considered unreliable due to the proximity of modern field road, the incidence of

recent metal artifacts, and the presence of an overhead electrical power transmission line (Britt

et. al. 2002).

Geophysical surveys at both the West and Southwest Sectors (rings 1-5) of the site did

however produce interesting and usable results. In the West Sector, geophysical surveys

indicated magnetic variability in the composition of the sediments, such as would be seen in

compositional differences between sands and clays. The results lent support to Jon Gibson’s

position that Crowley’s clay, which is exposed along Bayou Macon, was consistently mined and

used for construction by the people at Poverty Point (Britt et. al 2002). In addition, numerous

anomalies were detected in the West and the Southwest Sectors, respectively, and are suggestive

of midden deposits. Several targets were identified for exploration, though no work has been

conducted to investigate these anomalies.

In 2003, geophysical surveys were conducted at four prehistoric and historic fortified

earthlodge settlements located in the Middle Missouri River Basin of North and South Dakota

(Kvamme 2003). The surveys were conducted to provide interpretive details that could bolster

information provided to tourists for the then upcoming bicentennial of the Lewis and Clark

expedition. The surveys included large scale magnetic gradiometry and electrical resistivity

along with the use of soil conductivity measurements and GPR. The following systems and

parameters were used: Geoscan Research FM-36 fluxgate gradiometer with 4-8 samples per

meter in 0.5-1 m traverses; Geoscan Research RM-15 resistence meter in four parallel twin

configuration with 0.5 m probe separation; Geonics Ltd. EM-38 electromagnetic conductivity

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quadrature phase data in vertical dipole mode with 1 x 0.5 m sampling; and GSSI SIR-2000 with

a 400 MHz antenna with 0.5 m traverse interval (Kvamme 2003).

The magnetic surveys proved to be the most consistent in providing subsurface details of

the village sites. At every site surveyed, the magnetic surveys revealed the presence of

fortifications, houses, hearths, and other features, such as storage and trash pits. Electrical

resistivity and GPR proved unsuccessful in defining subsurface anomalies. At one of the

villages, the Whistling Elk site, electrical resistivity, soil conductivity, and magnetometry were

successful in identifying an outer fortification ditch with five evenly-spaced bastions and 67

anomalies that represent houses (Kvamme 2003). The magnetometry survey further defined 34

of these houses as being burned, including what is known as the “Big House.” Ground-truthing

revealed that the “Big House” had indeed been burned. These results suggest that the Whistling

Elk prehistoric village had been sacked by another prehistoric group. At the historic village of

Mitu’tahaktos, the magnetic survey revealed household differences in the distribution of iron

artifacts, suggesting potential social and economic differentiation at the site (Kvamme 2003).

In November of 2008, geophysical investigations were conducted at the Late Prehistoric,

Monongahela Tradition Dividing Ridge site (36WM477) located in Westmoreland County,

Pennsylvania (Johnson 2008). Two methods were used for this investigation, magnetometry and

electrical resistance (Johnson 2008). For the purpose of this review, only the magnetometry

survey will be discussed since an electrical conductivity survey was not preformed at the

Hatfield site. The objective of the investigation at Dividing Ridge was to use geophysical

methods to map prehistoric features present at the site (Johnson 2008). The magnetometer

survey was conducted using a Geometrics G-858 Cesium magnetometer. Readings were taken at

a rate of 10 per second resulting in approximately 10 measurements for every meter (Johnson

2008). All magnetic data was collected along profile lines with a constant one-meter line

separation. All data maps were then produced using Surfer software.

The effect of recent human modification to the landscape can be seen in the data by the

presence of linear anomalies representing plow furrows. Even though the landscape had been

previously disturbed, numerous curvilinear magnetic features were observable in the maps. The

longest observable magnetic feature forms a large semi-circle at the western edge of the surveyed

area. Johnson (2008) interpreted this large feature as the palisade wall that once surrounded the

Dividing Ridge village site. Apart from this large palisade feature, numerous circular anomalies

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measuring 8 to 12 m in diameter were identified. They are interpreted as possible houses based

on their size and distribution (Johnson 2008). Other anomalies were identified in the data, and

they may represent hearth, pit, or midden features. Although no ground-truthing of the

anomalies at the Dividing Ridge site have been conducted, the survey shows promise in

providing data related to settlement patterns at a Monongahela Tradition village.

The last example discusses a successful attempt in identifying subsurface archaeological

remains through GPR in an area with an abundance of clay soils, and it is offered because

subsoils at the Hatfield site have high clay content. Clay soils often will yield poor GPR results;

this is mostly due to clay having a high electrical conductivity. The survey was conducted at the

Riverfront Village, a prehistoric Mississippian site along the Savannah River in South Carolina

(Weaver 2006).

A GSSI SIR-3000 system with a 400 MHz antenna was used to collect data, and it was

processed to produce profiles in 3 ns slices. Processing revealed linear and circular features

within the 21-24 ns slice, which converted to depths of 40-45 cm below the ground surface. This

level laid below flood deposits that contained clayey soils. Anomalies that were identified were

interpreted as a palisade of the Mississippian village (Weaver 2006). Subsequent archaeological

excavations exposed a linear palisade 10 cm beneath the clay horizon. The reflection profiles

created in this area were so ambiguous that no usable interpretations could be made from them.

Even though this reflection data appeared ambiguous, the amplitude maps that were constructed

from all the combined reflection profiles provided useful data and maps.

Circular Villages of the Monongahela Tradition

The Hatfield site is a large, multi-component archaeological site located approximately

30 km (18.9 mi) south of Pittsburgh in North Strabane Township, Washington County,

Pennsylvania. One of the principal components represents a Late Prehistoric, Monongahela

Tradition village that was occupied during the Middle Monongahela period. The Monongahela

Tradition is an archaeological term used to define the people that inhabited the lower portion of

the Upper Ohio River Valley during the Late Prehistoric period, or between circa A.D. 1050 and

A.D. 1635. This region encompasses much of southwestern Pennsylvania and contiguous

portions of Maryland, Ohio, and West Virginia. Following Johnson’s (2001) chronology, the

Early Monongahela period dates to between A.D. 1050/1100 to A.D. 1250, the Middle

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Figure 1. General Location of the Hatfield Site

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Monongahela period dates between A.D. 1250 to A.D. 1580, and the Late Monongahela period

dates between A.D.1580 and A.D. 1635.

Villages are the most archaeologically visible Monongahela Tradition settlement. Of

over 400 Monongahela sites or components in which function has been determined, 74 percent

of these are identified as villages (Johnson 2001:68-69), and most are situated in upland settings

(Hasenstab and Johnson 2001; Johnson et al. 1989:1-9). Typical Monongahela villages consisted

of an outer fence or palisade with a concentric ring of houses surrounding an open area in the

center of the village that is commonly referred to as a plaza (Figure 2) (Johnson et al. 1989). At

some villages, especially during the Middle and Late Monongahela periods, there are more than

one palisade and more than one ring of houses. Palisades were usually constructed out of large

wooden posts, and often, a trench was excavated adjacent to the palisade. Soil from the trench

was added to the base of the palisade to provide structural support for the posts, especially at

villages that sat on shallow soils where bedrock precluded their deep placement. Within the

house ring, or domestic zone, a variety of features are typically found. They include domestic

structures, unattached storage facilities, fire pits, smudge pits, refuse pits, and burials, to name a

few. Plazas are usually devoid of domestic activity, perhaps because they were treated as

communal and/or ritual space. Some villages show evidence that a large hearth and/or central

post once stood at the center of the village (Means 2007).

Monongahela houses were usually circular or oval (Johnson et al. 1989:12-13), ranging

between three and ten meters in diameter. The interior of a typical house consisted of a central

hearth, support posts, and little else (Figure 3). Occasionally, burials are found underneath house

floors, but these are almost exclusively of young children or infants. It is estimated that

Monongahela houses may have been occupied by seven or eight individuals (Means 2006).

During the Middle Monongahela period, some of these domestic structures began to have pear or

horseshoe-shaped storage facilities attached to them (Hart 1995:46). With access through the

interior of the house, these appendages were used to store surplus agricultural goods among other

things. Over time, the number of houses with appendages increased (Hart et al. 2005:352), as

did the number of appendages that appear on households.

Later in time, specialized structures that may have complex social implications appear at

Monongahela villages, and mostly within plazas or near the center of the village (Anderson

2002). One such structure is referred to as a petal house because of its distinctive lay-out.

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Figure 2. Typical Monongahela Tradition Village (Courtesy of the PHMC)

Figure 3. Typical Monongahela Tradition Dwelling (George 1997)

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Occurring within at least three Late Monongahela period villages, petal houses exhibit multiple

appendages, from as few as 11 to as many as 24 (Anderson 2002:123-124). Interpretations of

these structures have ranged from communal storage, to sweat baths or council houses, to

communal ritual space (Anderson 2002:125; Hart 1995:50; Herbstritt 1984, 2003:31). The other

type of specialized structure is recognized because of its mortuary function. Known as charnel

houses, these structures were used primarily for the burial of adults (Anderson 2002:125-127).

They are identified at four terminal Middle Monongahela and Late Monongahela villages, with

two of these possibly representing early progenitors of the type (Johnson 2001:73). These

structures suggest that certain individuals were treated, at least in death, differently than other

members of the village (Anderson 2002:127).

A Brief Background of the Hatfield Site

The Hatfield site is situated on a long peninsular hill spur oriented north to south at an

elevation of 360 m above sea level (Figure 4). This hill spur is flanked by springs on both the

eastern and western sides as it gently slopes down to a small unnamed tributary of Little

Chartiers Creek at its southern tip. Little Chartiers Creek joins the larger Chartiers Creek about

seven km northeast of the site. Chartiers Creek is a north-flowing, major tributary of the Ohio

River that is more or less paralleled by the Monongahela River to the east and a portion of

Raccoon Creek to the west. Cross-cutting Allegheny and Washington Counties, the stream

drains approximately an area of 446 square-kilometers (277 square-miles). The headwaters of

the creek originate just south of the City of Washington in south-central Washington County.

The creek empties about 50 km (31 miles) from its origin into the Ohio River near the Borough

of McKees Rocks, just upriver from Pittsburgh.

The site is situated within the Pittsburgh Low Plateau Section of the Appalachian

Plateaus Physiographic Province, which is characterized by narrow summits, narrow stream

bottoms, and steep linear valley slopes. This highly dissected terrain results from the erosion of

flat lying bedrock that belongs to the Pennsylvanian aged Washington Formation, and is

composed of cyclic sequences of sandstone, shale, limestone, and coal (Wagner et al. 1975). The

base of the Washington Formation is defined by the Washington coal. Overlying the coal are

three limestone beds (lower, middle, and upper) that are readily identifiable on many hilltops

across Washington County. The weathering of these various beds provides the parent material

from which the soils on the Hatfield site have formed. Soils

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Figure 4. Topographic Setting of the Hatfield Site

underlying the site are mapped as Guernsey silt loam on 3 to 8% slopes (NRCS 2007a), and are

excellent for growing staple crops such as corn and wheat (NRCS 2007b).

A geomorphologic study of the site revealed that a pronounced plow zone with a depth

ranging between 23 and 26 cm (9.06-10.24 in) was clearly shown by the unusually dark humic

soils of the Ap horizon (Figure 5) (Fritz and Valko 2007). It is possible that midden deposits

resulting from prehistoric occupation of the site have enhanced the darkness of the Ap horizon.

Based on the auger probes, the artifact density within the plow zone was relatively high, with

two artifacts recovered per 1.2 liters of soil. The bottom of the Ap horizon is sharply contrasted

against the lighter and more yellow Bt horizons. Formation of these Bt horizons is the result of

in situ weathering of bedrock over thousands of years. It was determined that artifacts were

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unlikely to be found within the Bt horizons except where human features, bioturbation, or any

other types of disturbances have intruded into the Bt horizons.

Figure 5. Stratigraphic Profile of the Hatfield Site

In total, seven features, over 150 postmolds, and more than 20,000 artifacts have been

documented by the Allegheny Chapter’s excavations (Bercel and Espino 2010). The field work

has exposed a 40 m2

(430.56 ft2) area of contiguous units arranged more or less linearly along the

eastern section of the village. Features include two refuse pits, two fire pits, two post-enclosed

storage pits, and a burial, all of which are found within the domestic zone, or house ring, of

typical Monongahela villages. However, the limited areal extent of the excavations has

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precluded any positive identification of domestic structures and other large-scale village features.

A fragment of hickory nut (Caryan sp.) from Feature 2, a refuse pit, produced an Accelerator

Mass Spectrometry (AMS) radiocarbon date of 545±15 radiocarbon years before the present

(rcybp) (ISGS-A1409; Bercel and Espino 2010). This date has a one sigma calibration of A.D.

1399-1419 and a two-sigma calibration of A.D. 1326-1425.

Research Objectives

Due to the limited extent of the Allegheny Chapter’s excavation, little can be said of the

settlement patterns at the Hatfield site. Therefore, the primary objective of the archaeological

prospection survey is to identify subsurface anthropogenic features that may help develop

interpretations about the spatial structure of the village. Similarly, the project is intended to

identify areas of archaeological interest as the Allegheny Chapter continues research at the site.

Prior to the survey, a number of research questions were developed to help guide data

collection: (1) Can overall boundaries at the Monongahela component be defined using

geophysical methods?; (2) Does the village contain a defensive stockade and associated trench?;

and (3) Can the domestic zone of the village be identified, and if so, can activity areas and

domestic structures be identified and measured? Delineating the spatial extent of the village

within the surveyed area is integral to understanding settlement patterns. With better-defined

boundaries, the size of the village may be extrapolated onto the neighboring property, and with

an extrapolated size, estimates of the number of houses and overall population size can be

developed. Similarly, identifying the stockade will help to more accurately define the aerial

extent of the village. Finally, identifying and interpreting anomalies within the domestic zone

may reveal patterns associated with the organization of the village, i.e. whether there are one or

two rings of houses, clustering of houses, and areas of specialized activities.

METHODS

The following section describes the data collection and processing methods and systems

used during the archaeological prospection of the Hatfield site.

Survey Parameters

Archaeological prospection of the Hatfield site commenced with the establishment of a

large grid (Grid 1) across the eastern section of the hill spur on which the site is situated. The

purpose of this grid was to provide an area to systematically collect magnetic susceptibility data

over most of the site. A shapefile of points spaced five meters apart was created using

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AUTOCAD 2004 and ESRI’s ArcGIS v. 10.0, the shapefile was then uploaded into a Trimble

TSC2 data collector through the use of Trimble’s GPS Path Finder Office 3.0 for field use. Grid

1 measured 35 x 265 m (114.83 x 869.42 ft) for an area of 9,275 m2 (2.29 acres).

Subsequently, two areas were selected for magnetic gradient and GPR sweeps based on

their proximity to the Allegheny Chapter’s excavations where cultural features had been

identified. The survey areas were established through spatial control points belonging to the

chapter’s existing localized excavation grid. The excavation grid originally had been created and

aligned to magnetic north using a Berger transit (Fritz and Valko 2007). For the purpose of the

geophysical survey and future work at the site, the excavation grid was updated with a Nikon

DTM-520 (with 3” angle accuracy, +/- [3mm+2ppm]) and a Trimble TSC2 Data Collector (256

MB), thereby establishing sub-millimeter accuracy for regions within the site. Once the

excavation grid was updated, the two geophysical survey grids (Grid 2 and Grid 3) were

established, and the corners of each grid were located using a Trimble R8 GNSS Global

Positioning Systems (GPS) unit (horizontal accuracy 3mm+0.4ppm RMS, vertical accuracy

3.5mm + 0.4ppm RMS). This process established real world coordinates for the project area

using the Universal Transverse Mercator (UTM) projection and a World Geodetic System

(WGS) 1984 datum. Grid 2 measured 20 x 30 m (65.62 x 98.43 ft) (Figure 6) while Grid 3

measured 10 x 40 m (32.82 x 131.23 ft) (Figure 7). Table 1 contains spatial information for both

these grids.

Table 1. Spatial Information for Grid 2 and Grid 3

Point #'s Desc Local Northing/Easting UTM Zone 19N Coordinates

Grid 2 Northing Easting Elevation

1004 NW 1010N,1000E 4452264.024 570877.515 321.778

1005 SW 990N,1000E 4452244.447 570881.254 321.015

1006 SE 990N,1030E 4452250.032 570910.756 317.619

1007 NE 1010N,1030E 4452269.679 570907.024 318.06

Grid 3

1010 NW 990N,1002E 4452244.788 570883.224 320.927

1011 NE 990N,1012E 4452246.66 570893.069 319.815

1012 SE 950N,1012E 4452207.376 570900.438 318.896

1013 SW 950N,1002E 4452205.494 570890.679 320.044

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Figure 6. View of Grid 2, facing east

Figure 7. View of Grid 3, facing north.

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Magnetometry Survey

As noted earlier, magnetic surveys measure the variation of the magnetic fields of the

earth and the effects of near-surface features that may be overlain upon it. In archaeological

applications, the surveys map the contrasting values of buried anthropogenic activities generally

characterized through magnetic susceptibility of geological features and ferrous materials. Once

the average magnetic susceptibility for an area is established, the magnetic gradient acts as a

filter to reduce the effects of background geological magnetic fields and daily effects caused by

the interaction between the magnetic fields of the Earth and its atmosphere, allowing

anthropogenic activity areas to be viewed as anomalies (Campana 2009).

Magnetic Susceptibility. The magnetic susceptibility survey was conducted in Grid 1 on

November 13 and 15, 2011. It employed a MS2F probe with a 15mm diameter tip that

penetrates to a depth of 15-20 mm (Bartington OM0408, Issue 42). The Trimble TSC2 data

collector was used to locate 417 pre-designated grid points where measurements were taken.

Probe readings were recorded in the field and transferred into a Microsoft Excel file containing

spatial information for each point. The Excel file was used to create a grid file in Golden

software’s Surfer 9, where processing and spatial analyses were conducted. The grid file was

converted into a contour map of the dataset. It should be noted that Surfer 9 created a contour

map that extrapolated a larger surface area than what was actually collected in the field, possibly

because the data points were collected on a grid oriented to magnetic north and therefore tilted

from the true north layout used by Surfer. In other words, large areas that were not surveyed

were given values based on statistical extrapolations from known points. The farther away the

extrapolated surface was from known points, the less accurate it appeared.

Magnetic Gradient. A magnetic gradient survey was conducted within Grids 2 and 3 on

November 13, 2011 through the use of a FM 256 Fluxgate Gradiometer data processing unit

(Figure 8). Specifications for the equipment include sensor separation of 500mm, operation field

range of +/- 100nT, analogue ranges of +/- 5, 10, 20, 40, 80, 160, 320, 640 nT, digital ranges of

+/- 20000, 2000, & 200 nT, digital display resolution of 10, 1, 0.1 nT and a response time of 20,

40, 120 mS (GeoScan Research 2005). Data from Grid 2 was collected at a sampling interval of

25 cm (9.84 in) along 50 cm (19.69 in) spaced transects traveling along the east-west axis. Data

from Grid 3 was collected at a sampling interval of 12.5 cm (4.92) along 50 cm (19.69 in) spaced

17

transects traveling along the north-south axis. Both grids were collected in a zigzag fashion

(Clay 2006).

Data analysis was completed with Geoplot software produced by Geoscan Research. The

following steps were followed in the processing of data from Grid 2: (1) clipping of seven areas

of extremely low reading, (2) Zero Mean Traverse, (3) De-stagger of the grid, (4) Interpolation

of Y & X axis – Sin X/X, x2, and (5) Low Pass Filter, X=1,Y=1, Weight: Uniform. Grid 3 was

processed as follows: (1) Clipping of four areas of extremely low readings and two areas of

extremely high readings, (2) Despike of the entire grid, (3) Zero Mean Traverse, (4) Interpolation

of Y & X axis– Sin X/X, x2, and (5) Low Pass Filter, X=1,Y=1, Weight: Uniform. Anomalies

that are identified will be classified according to magnetic gradient codes developed by Burks

(2009).

Ground-penetrating Radar Survey (GPR)

The foundations of GPR lie in electromagnetic (EM) theory, which is based upon the

relationship of a material’s response to EM fields. For GPR, the electrical and magnetic

properties are of importance. The software of the GPR unit has equations of macroscopic (or

average behavior) descriptions of how different electron, atoms, and molecules respond en masse

to the application of the EM field. These fluctuations from the macroscopic properties stand out

from the average macroscopic state (Jol 2009).

This survey was conducted using a GSSI SIR-3000 GPR model with a 400 MHz antenna.

It can penetrate into the ground to a depth of 0-4 meters (0-12 feet) (Figure 9). The equipment

specifications include Scan Rate Examples of 8 bit 220 scans per second at 256 samples per

scan, 16 bit 120 scans per second at 512 samples per scan, a Number of Samples per Scan of

256, 512, 1024, 2048, 4096, or 8192, Time Range of 0-8,000 nanoseconds full scale, user-

selectable, a Gain of Manual or Automatic, 1-5 gain points (-20 to +80 dB), Vertical Filters:

Low Pass and High Pass IIR and FIR, and Horizontal filters: Stacking, Background Removal

(GSSI 2009).

The GPR survey within both grids was conducted via north-to-south zigzag sweeps

spaced at 25 cm (9.14 in) intervals along the Y-axis (Conyers 2004). Datasets were collected

along parallel transects separated by 25 cm (9.84 in) intervals (Conyers 2004). The collection of

the data in Grid 2 occurred over two nonconsecutive days (November 5 and 8, 2011). Transect

18

Figure 8. Seth Van Dam conducting Magnetic gradiometry survey in Grid 2

Figure 9. Amanda Snyder and Nina Larsen doing GPR survey of Grid 2

19

0.0-17.25 m were collected on the first day and transects 17.5-30.0 m were collected on the

second day. The collection of the data from Grid 3 occurred on November 13, 2011.

GPR Slice v7.0 was used to process the datasets from both grids (GPR Slice 2011).

Settings for Grid 2 included the number of samples per scan as 512 with a sample start of 58 and

a sample end of 512. Twenty slices were created with sample thickness of 4.4 ns and a sample 0

ns of 58. Since the datasets were gathered on separate days, the combined dataset’s slices

required a mosaic correction of increased batch gains to make the two dataset represent equal

reflective values. Once corrected, the slices were further processed through a 3x3 Low Pass

Filter. Settings for Grid 3 included the number of samples per scan as 512 with a sample start of

64 and a sample end of 512. Twenty slices were created with sample thickness of 4.39 ns and a

sample 0 ns of 64. The dataset’s slices were further processed through a 3x3 Low Pass Filter.

Data Integration

Once the data from the magnetic susceptibility, magnetic gradient, and GPR were

processed and analyzed, the results were integrated into a Geographic Information System (GIS)

via ArcGIS v10.0. The datasets were combined by georeferencing select Joint Photographic

Experts Group (jpeg) files and layering them with varying transparencies in order to locate

anomalies that are represented in all three geophysical datasets. Shapefiles of the Allegheny

Chapter’s excavations were also combined to provide contrasting views of real-world cultural

features and geophysical anomalies that may represent areas of anthropogenic activities (Bercel

and Espino 2010).

RESULTS

Integration of the datasets into a geographic information system allowed for a layered

visualization of the data that greatly enhanced the interpretation of the results. Both the

magnetometry and GPR survey data strongly suggests that these particular archaeological

prospection methods are very effective in defining subsurface anomalies that may represent

cultural zones and smaller cultural features. Both methods provide complimentary results that,

together, begin to shed light on the settlement patterns and village organization of the Hatfield

site. In total, 28 anomalies were identified through archaeological prospection. Anomalies are

labeled sequentially according to grid number. Grid 1 contained eight anomalies labeled G1-1

through G1-8, Grid 2 contained 14 anomalies labeled G2-1 through G2-14, and Grid 3 contained

six anomalies labeled G3-1 through G3-6. The results of the surveys are described below.

20

Magnetometry Survey

Magnetic Susceptibility (Figure 10). The magnetic susceptibility portion of survey

proved highly efficient in collecting data from a large area in a relatively short time.

Measurements were recorded at 417 points spaced at five meter intervals within Grid 1. As

mentioned earlier in the Methods section, Surfer 9 created a contour map representing a larger

surface area than what was actually collected. In interpreting features, special care was taken to

not give too much weight to possible anomalies in the areas if the map that were extrapolated.

Initially, the magnetic susceptibility data revealed an arcing pattern (G1-1) trending east-

to-west that was dominated by relatively low magnetic values ranging between -10 to 60 nT.

The portion of the anomaly that was recorded during the survey measured 80 to 90 m north-south

and 55-65 m e-w. The ellipsoid has an extrapolated area ranging between 6,908 and 9,185

square-meters (1.71-2.27 acres). There was an area of higher magnetic value that peaked near 90

nT adjacent to the arc. When this area was examined, it became apparent that measurements

were affected by the Allegheny Chapter’s staging area, where screens, wheel burrows, shovels,

and other metal objects are stored. Since the resulting peak may have obscured true anomalies,

seven data points in that portion of Grid 1 were removed from the analysis and a modified

contour map was created. The modified contour map retained the arcing pattern of low magnetic

values seen in the earlier version. However, new anomalies appeared that indeed were masked

by the high magnetic values associated with the staging area. These anomalies (G1-3, 4, 5, 6,

and 7) appeared as small circular areas of higher values that ranged between 50 and 70 nT. They

measured between 5.7 and 29.4 square-meters (61.3-316.5 square-feet).

An interesting area of anomalies (G1-7) was identified approximately 90 m (295.28 ft)

south-southeast of the Allegheny Chapter’s excavations. Similar to the pattern noted above, the

anomalies consist of a ring of low to moderate magnetic values (50-80 nT) accentuated by

smaller areas of higher values (up to 110 nT). The center of the ring displayed relatively low

magnetism (-10-40 nT). The area encompassed by these anomalies measures approximately

1,107 square-meters (0.25 acres). Finally, large areas (G1-2) of high magnetic value were

measured in the southern portion of Grid 1. Values here peaked at 170 nT. The cause of these

anomalies is uncertain, though they are unlikely to represent archaeological remains since this

21

Figure 10. Results of the Magnetic Susceptibility Survey

portion of the grid is steeply sloped. The definitions and details of anomalies identified during

the magnetic susceptibility survey are available in Table 2.

Table 2. Magnetic Susceptibility Anomaly Attributes

Grid 1 Northing Easting Readings/Areas Comments

G1-1 N/A N/A 60nT, -10nT Probable House Ring

G1-2 4452129mN 570945.9mE 147nT Unknown magnetic Anomaly

G1-3 4452293mN 570879.9mE 55nT, 13.74sq m Probable Domestic Structures




G1-8 4452173mN 570907.2mE 50-110 nT, 1.107 sq m Possible Second Village Site

. Magnetic Gradient (Figures 11 and 12). Map surfaces covered in full, grid-length linear

features oriented north-to-south is immediately apparent from the magnetic gradient data. These

linear features are present in both grids, and are consistent with agricultural plow scars. The

presence and similar orientation of plow scars have been noted during excavations of the

22

Hatfield site (Bercel and Espino 2010). Additional agricultural disturbances are seen in Grid 3,

where a series of mixed positive and negative readings were recorded along the western edge of

the grid. Likewise, a series of mono-polar positive and mono-polar negative anomalies are

aligned linearly along the 1010E transect of Grid 3. Four of these are mono-polar positive

anomalies while the fifth one is a mono-polar negative anomaly. The sources of both sets of

anomalies are likely agricultural furrows noticed during data collection. In addition, two

anomalies in Grid 2 were influenced by recent activity at the site. One is a large mono-polar

negative anomaly located around the existing excavation trench, and likely caused by a large

number of 25.4 cm (10 in) iron spikes demarcating the corners of excavation units. The other

represents a multi-polar complex anomaly whose source is a 30.5 cm (12 in) iron spike at the

location of one the excavation’s spatial control points. Efforts to buffer these areas by a distance

of a meter in all directions were insufficient in reducing the magnetic noise caused by the ferrous

metal.

Despite these modern disturbances, the magnetic gradient survey proved relatively

effective in revealing a number of subsurface anomalies within Grid 2. In total, nine magnetic

anomalies were identified. None of the anomalies produced readings higher than 40 nT,

suggesting an overall lack of historic iron in the survey grid (Burks 2009). Three (G2-3, 6, and

8) of the observable anomalies are classified as mono-polar positive and two (G2-4 and 7) as

dipolar simple. Mono-polar positive and dipolar simple anomalies are typically classified as

undefined feature types due to difficulties in discerning their true polar nature, i.e. mono-polar

positive or only a portion of a dipolar simple anomaly (Burks 2009). Prehistoric features that

may produce these types of anomalies include pits as well as some hearths and earth ovens. One

large positive anomaly (G2-9) was detected near the southwestern edge of the grid. Initially, this

anomaly was observed as three monopoles, or a multi-monopositive anomaly, though by the end

of data processing, the anomalies blended into one mass. Though rare to detect, such anomalies

represent clusters of positive mono-poles arranged in linear or arcing patterns likely representing

postmolds (Burks 2009). Finally, one anomaly (G2-2) was identified as a dipolar complex

anomaly due to the presence of three negative peaks surrounding a large positive peak. This type

of anomaly is often associated with burned areas or prehistoric structure floors (Burks 2009).

The definitions and details of anomalies identified during the magnetic gradient survey are

available in Table 3.

23

Figure 11. Results of the Magnetic Gradient Survey in Grid 2

Figure 12. Results of the Magnetic Gradient Survey in Grid 3

24

Table 3. Magnetic Gradient Anomaly Attributes

Anomaly Northing Easting Readings (High,Low) Comments

G2-1 1005 1005 Dummy Caused by 10" spikes from previous excavation grid

G2-2 1008.875 1018 20.78nT, -7.33nT Dipolar Complex - Probable Hearth

G2-3 1009.625 1023.06 5.52nT, 1.89nT Mono-Polar Positive

G2-4 1007.375 1029.81 16.96nT, -9.21nT Dipolar Simple

G2-5 1000 1020 Dummy Caused by a 1" Rebar set as a local datum point

G2-6 996.125 1006.43 4.97nT, -0.28nT Mono-Polar Positive

G2-7 994.375 1010.43 10.70nT, -11.16nT Dipolar Simple – Probable Pit Feature


G2-9 991.375 1005.06 19.52nT, -0.43nT Multi-Monopolar Positive

G3-1 970 1022 18.46nT, -15.54nT Caused by agrilcultural furrows




G3-5 963.125 1010.59 2.08nT, -12.38nT Mono-Polar Negative


Ground-penetrating Radar Survey (Figures 13 and 14)

Six anomalies were identified during the GPR survey of Grid 2 and none were recognized

completely in Grid 3. This includes an area (G2-10) of high reflection in the northwest section

of Grid 2 where test units had been excavated by the Allegheny Chapter. A small anomaly (G2-

15) of high reflection values is located at 1000N 1020E. This anomaly was caused by an

existing spatial control point for the chapter excavations. Another high reflection anomaly (G2-

12) is situated on the western edge of the grid south of the chapter’s excavation area. The cause

of this anomaly is uncertain.

Two anomalies that produced similar moderate reflection values are also present in Grid

2. One (G2-13) is circular in shape located in the south-central portion of the grid with its center

point located at 995N 1020E. This anomaly has an area of approximately 78.50 m2 (844.97 ft

2)

and reflective values ranging between 0.25 to 1 ns. The location of this anomaly corresponds to

the location of anomaly G1-5 identified during the magnetic susceptibility survey. The second

anomaly (G2-11) has a roughly circular shape with an area of 63.59 m2 (684.48 ft

2). It is located

due north of G2-13 near the northern edge of the grid, with its center point located at 1007N

1020E. It appears as if the anomaly extends northwards beyond the survey area. The anomaly

has reflective values that range between 0 and 1 ns. While the boundaries of this anomaly were

not as well defined, it contains a few more areas of high reflection than G2-13. Interestingly, the

25

Figure 13. Results of GPR Survey in Grid 2

Dipolar Complex anomaly identified during the magnetic gradient survey is located near the

center of G2-11. Both G2-11 and G2-13 were identified in the same slice, and their parabolas

occurred at similar depths of 28-36 cm (11.02-14.17 in) below the antenna. While zero time was

not calculated, and therefore the exact depth of the anomalies is uncertain, this range of depth

encompasses the plowzone-subsurface interface at this portion of the site (Bercel and Espino

2010). A third anomaly (G2-14) is identified as a partial arc of mainly low reflection values (0-

0.75 ns). It is located along the southern edge of the grid at 990N 1009.5E and extends slightly

into Grid 3. The definitions and details of anomalies identified during the GPR survey are

available in Table 4.

26

Table 4. GPR Anomaly Attributes

Anomaly Northing Easting Readings Comments

G2-10 1008 1000.5 0.5-1 ns Previous Excavation Trench

G2-11 1007 1020 1.0-0.0ns Probable Dwelling Feature

G2-12 995 1001 0-1 ns Unknown Anomaly

G2-13 995 1020 0.25-1 ns Probable Dwelling Feature

G2-14 990 1009.5 0-0.75 ns Possible Dwelling Feature

G2-15 1000 1020 N/A Datum Spike

INTERPRETATIONS

The results of the archaeological prospection of the Hatfield site offer tantalizing clues as

to the nature of its subsurface archaeological deposits. It should be noted, however, that the

results remain highly hypothetical until they can be verified through excavations. To understand

what the results may mean, this discussion will begin with the small scale datasets recovered in

Grid 2 through magnetic gradient and GPR surveys and end with the large scale Grid 1 magnetic

susceptibility data.

The incidence of a dipolar complex anomaly (G2-2) identified by the magnetic gradient

survey within the boundaries of a roughly circular anomaly (G-2-11) recorded during the GPR

survey suggests that the geophysical techniques possibly identified a domestic structure (Figure

14). Hearth features often produce dipolar complex anomalies (Burks 2009), and its location

suggests that it may represent a central hearth within the domestic structure. The second circular

anomaly (G2-13) identified through GPR may also represent a domestic structure. This anomaly

appears better defined, and it is located four meters due south of the other possible structure. It

should be noted that the sizes of these anomalies (63.59 m2 [684.48 ft

2] for G2-11 and 78.5 m

2

[844.97 ft2 for G2-13) exceed the higher end of Monongahela mean dwelling size range in the

Somerset Plateau, where spatial analyses of Monongahela villages has been undertaken more

systematically (Means 2006). However, large houses in excess of 65 m2 (699.65 ft

2) have been

recorded at the McJunkin (36AL17), Portman (36AL40), and Household (36WM61) sites (Buker

1993; George 1978, and George et al. 1990), including a maximum of 83.3 m2 (896.63 ft

2) at

McJunkin. Moreover, plow disturbance of materials with high reflective values at Hatfield may

be accentuating their actual size.

Interestingly, the location of G2-13 corresponds to anomaly G1-5 measured by the

magnetic susceptibility survey. In analyzing the magnetic susceptibility data, the location of the

possible structure and central hearth (G2-11 and G2-5, respectively) returned low magnetic

27

Figure 14. Results of the Magnetic Gradient and GPR Surveys in Grid 2 (note: GPR layer has a

60% transparency)

28

values during the susceptibility survey. This situation seemed at odds with the magnetic

gradient survey since the latter measured high magnetism associated with the central

hearth/dipolar complex feature/anomaly. Closer examination of the magnetic susceptibility data

points showed that none of the points were recorded within the possible structure. The anomaly,

as it was identified by the magnetic gradient and GPR, fell within the gaps of the magnetic

susceptibility grid. Based on the G2-13 and G1-5 correlation, the arcing pattern of anomalies

(G1-3 through G1-7) also identified through magnetic susceptibility are inferred to represent

domestic structures as well. As noted earlier, these anomalies displayed similar magnetic

signatures and sizes.

The results of the survey suggest that six possible dwellings were identified through

archaeological prospection of the Hatfield site (Figure 15). These structures are aligned in an

arc, and they fall within a larger arcing pattern of low magnetic values. This pattern is

suggestive of the typical house ring of Monongahela villages (Means 2007). The geophysical

data provides rough boundaries for the Middle Monongahela component, but unfortunately the

survey failed in identifying the palisade. North to south, the village has a possible diameter

between 80 and 90 meters. The eastern boundary of the site falls within 35 to 45 meters of the

site’s datum. However, the east to west diameter is uncertain since the west boundary is outside

of the surveyed area. An extrapolation of the house ring into the un-surveyed portion of the

Hatfield site suggests that the ellipsoid village covers an area of between 6,908 and 9,185 m2

(1.71-2.27 acres). Though Monongahela village sizes vary greatly, the size of the Hatfield

Middle Monongahela village component is consistent with the range of Monongahela village

sizes (Hart et al. 2005). Villages that approximate the size of Hatfield include Ashmore Farm

(36WH675), Saddle (46MR95), McJunkin (36AL17), Campbell Farm (36FA26), Peck 2-2

(36SO8), and Foley Farm (36GR52). Even larger villages include Sony (36WM151), Johnston

(36IN2), Fort Hill 2 (36SO2), and Hughes Farm (46OH9).

Finally, it was mentioned during the results of the magnetic susceptibility survey that a

smaller arcing pattern that mimics the pattern described above was identified about 90 m (295.28

ft) south of the Allegheny Chapter’s excavation area. Identified as G1-7, this composite anomaly

has a size of 1,011.7 m2 (0.25 acres). Surface-collected artifacts from the Hatfield site include a

number of ceramics attributed to the Early Monongahela period (William C. Johnson, personal

communication 2009). The provenience of these artifacts in relation to the areas currently being

29

Figure 15. Results of the Archaeological Prospection of the Hatfield Site

30

excavated is uncertain, but no Early Monongahela period ceramics have been identified during

the course of the fieldwork (Bercel and Espino 2010). Anomaly G1-7 may represent a smaller

and older village at the site. A similar situation occurs at the Consol site (36WM100), where a

small, circular Early Monongahela village is situated a short distance from the much larger

Middle and Late Monongahela village component. However, since no excavations have taken

place at that portion of the Hatfield site, there is little evidence suggesting that cultural remains

may be found at that location. The above is only offered as an interesting pattern that is worth

investigating.

CONCLUSIONS

An archaeological prospection survey was undertaken at the Hatfield site in November of

2011. The survey utilized magnetometry and ground-penetrating radar techniques to identify

subsurface anomalies that may represent cultural features. In total, 28 anomalies were identified

through magnetic susceptibility, magnetic gradient, and ground-penetrating radar methods.

Several of the anomalies resulted from modern activities at the site, including agricultural

plowing and excavations by the Allegheny Chapter. However, at least 10 of the anomalies

possibly represent prehistoric cultural remains of the Middle Monongahela component of the

Hatfield site. These anomalies comprise two pit features, six dwellings, and a house ring zone.

The size and arrangement of dwellings as well as the spatial layout of the house ring is consistent

with typical Monongahela Tradition villages. If the anomalies indeed represent a section of a

village, the Middle Monongahela village at the Hatfield site would encompass an estimated area

of 1.7 to 2.27 acres. In addition, a composite anomaly 90 m (295.28 ft) south of the Middle

Monongahela component may represent a second village at the site that covers an area of 0.25

acres.

The application of geophysical techniques at archaeological sites is still in its infancy,

and they should not be used, by any means, as the final word of an investigation. Through their

continued excavations at the Hatfield site, the Allegheny Chapter will attempt to verify the

findings of the archaeological prospection of the Hatfield site. Only then could the results be

properly used to discuss the nature of subsurface archaeological deposits and intra-site settlement

patterns at the site. Nevertheless, the results of the archaeological prospection at the Hatfield site

offer solid data through which future excavations can be directed to begin to understand the

31

organization of this occupation and the social and cultural factors that influenced the formation

and use of space within this Middle Monongahela village.

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Documents

Archaeological Prospection of the Hatfield Site, a Monongahela