geoarchaeology at gilman falls: an archaic quarry and manufacturing site in central maine, u.s.a

Geoarchaeology: An International Journal, Vol. 16, No. 6, 633–665 (2001)� 2001 John Wiley & Sons, Inc.

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Geoarchaeology at Gilman Falls: An

Archaic Quarry and Manufacturing Site

in Central Maine, U.S.A.

David Sanger,1 Alice R. Kelley,2 and Henry N. Berry IV3

1Department of Anthropology and Institute for Quaternary and Climate

Studies, University of Maine, Orono, Maine 04469-57732Department of Geological Sciences, University of Maine, Orono, Maine 04469-

57903Maine Geological Survey, Augusta, Maine 04333

Interdisciplinary investigations at the Milford Reservoir, central Maine, resulted in excavationand analysis of a Middle Archaic quarry and manufacturing site at Gilman Falls, dated tobetween 7300 and 6300 yr B.P. Lithological analysis indicates that the majority of the artifactscame from very local outcrops, providing low-grade metamorphic rocks. Native Americansused a specialized technique to reduce the granofels and other rocks to long rods, artifactscommonly placed in local cemeteries. The Gilman Falls site was largely abandoned once theseartifacts were no longer in vogue. Therefore, access to particular bedrock outcrops seems tohave played an important role in site selection. Gilman Falls and other early to middle Ho-locene sites are preserved where bedrock sill dams ponded water that deposited fine sand.Early site sedimentation history is paralleled by a drainage change in the headwaters of thePenobscot River. Evidence for lower mid-Holocene lake levels and a period of higher tem-peratures and lower precipitation may correlate with the sedimentation history.� 2001 JohnWiley & Sons, Inc.

INTRODUCTION

The study of how humans interact with their physical surroundings has a longhistory in the field of archaeology (Trigger, 1989). Such studies should accomplishmore than catalogue cultural and noncultural phenomena, but, rather, they shouldattempt to integrate these phenomena to help explain human behavior. We under-took the current research to help elucidate the rationale for human occupation atGilman Falls Island, a small, bedrock controlled island in central Maine, north-eastern U.S.A., between about 7300 yr B.P. and 6300 yr B.P. (all ages are in uncal-ibrated radiocarbon years ago).Starting with the twin axioms that people do not settle at random on the land-

scape and that geological processes are continual, we approach the analysis of anysite with the following geoarchaeological model in mind:

1. People made decisions about site locations based on their perceived needsand site adequacy for fulfillment of those needs.

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2. Previous and current geological events and processes created the physicalsetting and affected its desirability for human utilization.

3. Site excavation followed by analysis of its matrix and artifacts (including eco-facts) may reflect cultural activities and use of immediate surroundings.

4. Occupation and post-occupation geological processes and cultural events in-fluence and alter the archaeological record, which then affects interpretation(Schiffer,1987).

In short, the history of cultural events at any particular locus must be viewed asan integration of cultural tradition, needs and physical surroundings.Our research is part of a 10-year program of site survey, testing, excavation, and

analysis in the Milford Reservoir area (Figure 1) (Sanger, 1996). Paleoenvironmen-tal studies have included a local pollen diagram (Almquist-Jacobson and Sanger,1995), a history of local wetland (peat land) development during the Holocene(Almquist-Jacobson and Sanger, 1999), and a reconstruction of water levels in anearby kettle-hole lake (Almquist et al., 2001). Bedrock and surficial geologic stud-ies have been integrated into this research. Alice Kelley conducted the stratigraphicdescriptions and the sedimentological analysis. Henry Berry conducted the bed-rock studies correlating bedrock and lithic artifacts. Project director David Sangersupervised the archaeological excavations and analysis.

PROJECT HISTORY

The Bangor Hydro-Electric Company, a local power producer, engaged the Uni-versity of Maine to conduct a mandated cultural history examination of MilfordReservoir, an impoundment created by dams on the Penobscot and Stillwater rivers(Figure 1). The study area lies within the traditional territory of the PenobscotIndian Nation (Speck, 1940). Prior to the current project, the general area hadreceived some archaeological attention: most notably, research at the Hirundo(Sanger et al., 1977) and Young sites (Borstel, 1982) located 15 km upstream fromGilman Falls on Pushaw Stream. However, until the recent research required byrelicensing the reservoir, the region lacked a detailed, systematic site survey. As aresult, more than 100 new prehistoric site locations were added to the inventory.Based on criteria established in the State of Maine Plan (Spiess, 1990), four pre-historic sites were selected for intensive investigation, including Gilman Falls.

FIELD METHODS

Between 1990 and 1992, excavations at the Gilman Falls site—so-named becauseof its location at a bedrock-controlled waterfall (Figure 2)—removed nearly 160m3 of sediment, to an average depth of over 1 m. Excavation focused on the northend of the island, that which currently is being impacted by erosion. Several sep-arate areas were excavated (Figures 3 and 4). A 7-m-long trench, designed for theanalysis of the cultural and natural stratigraphy, linked two of the blocks. Followingan initial hand dug trench, excavation of 50 by 50 cm units into a standing wallpermitted removal of deposits by stratigraphic units, or horizons. Within each unit,

AN ARCHAIC QUARRY AND MANUFACTURING SITE IN CENTRAL MAINE, U.S.A.

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Figure 1. Central Maine and locations mentioned in text.

10 cm arbitrary levels gave additional vertical control. The approach providedmorecontrol than the traditional top-down excavation strategy often employed in theregion. A total station transit and on-site computer enabled “piece-plotting” of spec-imens and cultural features. Zone 3 excavations produced over 600 lithic tools and40 cultural features. The latter were recognized by associations of artifact concen-trations and charcoal, or charcoal in a hearthlike setting. No remains of habitationswere uncovered. Excavated sediments were screened through 6 mm and 3 mmhardware cloth, often using a water spray. Feature fill was subjected to flotationand/or water washing through 1 mm mesh for recovery of small finds, including

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Figure 2. Gilman Falls Island (center) and the dam built on bedrock. Pushaw Stream enters from theleft into the Stillwater River. View is to the east.

bones and seeds. Sediment samples were collected systematically in columns oras “grab” samples.

RESULTS

Analysis of artifact assemblages and stratigraphic settings indicated three cul-tural zones (sensu Gasche and Tunca, 1983), defined as culturally significant as-sociations of artifacts and features within geological strata. Zone 1, the most recentand most ephemeral, encompasses the Ceramic (Woodland) period (ca. 3000 yrB.P. to the Contact [European] period—ca. 350 yr B.P.); Zone 2 represents portionsof the Late Archaic period (ca. 6000 yr B.P. to 3000 yr B.P.); and Zone 3 is a MiddleArchaic assemblage (ca. 7500 yr B.P. to 6000 yr B.P.). The latter, which constitutesby far the most intensive period of occupation at Gilman Falls, is radiocarbon datedby seven assays to between ca. 7700 yr B.P. and ca. 6000 yr B.P.(Table I). Zone 3is the focus of this paper.The Zone 3 lithic assemblage consists of more than 600 lithic tools, or artifacts,

plus approximately 30,000 pieces (76 kilos) of debitage. For the purposes of thispaper, we define lithic tools and artifacts as finished implements, or those thatshow evidence of having been formed. Debitage constitutes unused pieces createdin the manufacturing process. The assemblage is unusual in that it contains no



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Figure 3. Map of Gilman Falls Island locating excavation areas and bedrock outcrops. Numbers referto locations mentioned in the text and in Table II.

chipped biface projectiles made from fine-grained lithics, such as chert, or anytechnological indications of such an industry, based on detailed analysis of thedebitage. Instead, the emphasis is on the use of various low-grade metamorphicrocks. A unique percussion process formed many of the artifacts; pecking andgrinding subsequent to flaking completed the process.The Zone 3 assemblage is attributable to the Gulf of Maine Archaic [technolog-

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Figure 4. Gilman Falls site and block excavation near completion. Excavation has been taken to bed-rock. Note presence of culturally derived cobbles in sediment.

ical] tradition defined by Robinson (1992). The tradition refers to a number of earlyto middle Holocene sites around the western edge of the Gulf of Maine that featurethe use of quartz for scraping tools, and a deemphasis or even absence of chippedstone bifaces.The sedimentary history of Gilman Falls indicates a stratigraphic sequence pro-

duced by a series of flood events. Interspersed with the flood deposits are remnantsof buried soils that represent soil development made possible by periods of reducedflood events and sedimentation and increased vegetative cover. Zone 3 is one suchperiod of relative stability that lasted for more than a millennium. After this time(ca. 6000 yr B.P.), rapid accumulation of sediments began anew. This accumulationof flood deposits provides a stratigraphic separation between the cultural zones.In addition, fluvial deposition helps to preserve the integrity of cultural zones in aregion where it is not unusual to find much of the Holocene archaeological recordcompressed into a thin deflated zone (e.g., the nearby Hirundo site [Sanger et al.,1977]). Discovery and interpretation of the preserved fluvial deposits became amajor research focus once we realized that we could anticipate finding relativelyintact early and middle Holocene occupation components contained in these sed-iments (Petersen, 1991; Petersen et al., 1986; Petersen and Putnam, 1992; Putnam,1994; Robinson et al., 1992; Sanger et al., 1992).



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Table I. Radiocarbon (uncalibrated) ages from Gilman Falls.

Sample No. 14C Years Stratum Cultural Zone

A-7042 3590 � 150 IIb Zone 1/2A-7041 4140 � 130 III UnassignedB-38499 4160 � 70 III Zone 2A-7043 4180 � 80 IIa UnassignedA-7044 4425 � 125 III UnassignedA-7045 5950 � 165 III Zone 2/3A-7046 6290 � 160 III Zone 3A-6696 6840 � 50 III Zone 3A-7151 6920 � 250 III Zone 3A-6697 6380 � 65 III Zone 3A-6698 7285 � 80 III Zone 3A-7049 7670 � 240 III Zone 3

GEOMORPHIC SETTING

The Gilman Falls site is located on the north end of the island at the confluenceof the Stillwater River and Pushaw Stream, and 10 km above the confluence of theStillwater and Penobscot River (Figures 1 and 2). The island is adjacent to theupstream portion of Gilman Falls, a series of rapids and waterfalls.Gilman Falls is one of a 25-km-long series of rapids and waterfalls on the Pe-

nobscot and Stillwater Rivers that extends from Bangor to Old Town. These rapidsare formed by resistant bedrock ridges that trend across the valley, perpendicularto the flow of the river. Upstream (north) from the site, a 30 km portion of thePenobscot River is characterized by a broad floodplain, many low islands and bars,and limited bedrock outcrops. Examination of aerial photographs of the regionshows numerous meander scars and prograding point bars, indicating a changingpattern of erosion and deposition through time.

GEOLOGY OF STUDY AREA

Regional Bedrock Setting

The bedrock of central Maine is dominated by a thick sequence of variably meta-morphosed and deformed Silurian marine clastic rocks. In the Gilman Falls area,granofels, phyllite, and slate predominate, assigned regionally to the VassalboroFormation (Osberg et al., 1985) and locally to the Kenduskeag Unit (Griffin, 1976a,1976b). The Kenduskeag Unit is a turbidite deposit with highly variable rock types(Griffin and Lindsley-Griffin, 1974) distinguished by color, grain size, composition,bedding thickness, and sedimentary structures. Several rock types are irregularlyinterbedded through the unit. There are no bedrock sources of plutonic or volcanicrocks in the region.In the Gilman Falls region, the metamorphic grade is in the chlorite zone, be-

coming gradually lower toward northern and eastern Maine, and substantiallyhigher toward the west and south. The combination of rock type and low meta-

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morphic grade imposes technological constraints on tool-making techniques, be-cause techniques appropriate for reducing cryptocrystalline rocks that flake withconcoidal fractures cannot be employed successfully with low-grade metamorphicrocks.

Surficial Geology

Formation and preservation of the Gilman Falls site is tied to the complex Qua-ternary geologic history of the region. During the Wisconsinan glaciation, the Lau-rentide Ice Sheet extended across Maine and northeastern North America, reachingits maximum extent by 20,000–18,000 yr B.P. (Denton and Hughes, 1981). In thearea surrounding Gilman Falls, clay-rich till, produced by the glacial erosion of theregion’s fine-grained bedrock, commonly overlies glacially polished and striatedbedrock (Thompson and Borns, 1985).By 14,000 yr B.P. the margin of the receding ice sheet had reached the eastern

Maine coast (Dorion et al., 2001). Contemporaneous with the retreat of the icesheet from the region, the isostatically depressed land surface was inundated byan invasion of marine waters that lasted until approximately 12,500 yr B.P. (Dorionet al., 2001). Thick, fine-grained, glaciomarine deposits blanket the older glacialdeposits in the area (Bloom, 1960). Subaqueous outwash fans and glaciomarinedeltas are commonly associated with eskers in this region (Thompson and Borns,1985). Glaciofluvial deposits are present primarily as eskers located in stream val-leys. A large, well-developed esker is located 0.5 km west of the site (Thompsonand Borns, 1985).Large-scale isostatic adjustment following the ice sheet recession led to regres-

sion of marine water and the development of the present-day Penobscot drainagepattern. The early postglacial river system was influenced by high volumes of meltwater combined with a steep initial gradient created by a sea-level, low-stand of 60m below present at approximately 10,500 yr B.P (Belknap et al., 1987; Kelley et al.,2000). The extent of the river valley’s excavation was controlled by ultimate baselevel, as well as the resistance of bedrock and glacial deposits to erosion. In someportions of the central and lower Penobscot Valley, the river occupied earlier, pre-Wisconsinan drainage channels, while in other areas, the drainage was deranged(Calkin, 1960; Kelley et al., 1988). This pattern of river development resulted in abroad, deep, well-defined channel in portions of the river valley, and numerousrapids and falls in other areas, such as Gilman Falls.More localized isostatic changes also affected the Penobscot River system. Mi-

gration of a postglacial forebulge through the region, prior to 9000 yr B.P., causeddifferential tilting of the land surface (Balco et al., 1998). This may have led to theformation of extensive lakes and changes in local drainage networks in the centralPenobscot Valley, a low relief area (Kelley and Sanger, 2001). In the headwatersregion of the Penobscot River, isostatic changes caused a reorientation of Moose-head Lake, shifting the outlet away from the Penobscot drainage to that of theKennebec River (Figure 1). This resulted in reducing the size of the Penobscot



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drainage basin by approximately 12% and increasing that of the Kennebec by about22% (calculated on the basis of drainage basin area; data from USGS, 2000; U.S.Army Corps of Engineers, 1990; Nace 1970).Downcutting progressed as the river responded to a rapidly falling sea level, and

fluvial activity eroded glacial and postglacial deposits. After removing overlyingsediments, the river encountered the numerous erosion-resistant bedrock sills thattrend across the valley in the central portion of the Penobscot Valley. These ledgesformed local base levels and isolated portions of the river from the effects of chang-ing relative sea level. Once the bedrock sills were encountered, the depositionalcharacteristics of the river were altered. Sedimentation of fine-grained materialoccurred when floodwaters were ponded behind the bedrock sills, particularly inareas where tributary streams entered the river, such as the junction of PushawStream and the Stillwater River (Figure 1). In these locations, water could flow intothe river or back up into the stream channel, depending on the amount of streamdischarge. This situation created areas that favored the deposition of fine-grainedsediments, forming thick accumulations, such as those seen in the Gilman Fallssite. Not only did this process serve to form the Gilman Falls site, it has also servedto preserve the site, by adding layers without significant erosion of older strata.After European colonization of the region, dams were constructed at the site of

many rapids and waterfalls, representing the most drastic geologic change in thedrainage since the Early Holocene. An early 19th century map of the Gilman Fallsregion (Treat, 1820) shows the island occupied by the Gilman Falls site existedprior to dam construction. However, the island’s original shape and distance fromadjacent riverbanks are poorly illustrated. Construction of the dam at Gilman Fallsand elsewhere created impoundments that raised water levels and held water forlog drives or power generation, altering the natural, seasonal flow of water. As aresult, archaeological sites located along the shores of such head ponds are cur-rently experiencing erosion during high water and from ice scour during the springfreshet.

Bedrock Geology of Gilman Falls Island

In order to compare artifact lithology with local bedrock types, a more detailedinventory of specific bedrock types was necessary. A geologic map of Gilman FallsIsland is shown in Figure 3. Preserved sedimentary structures indicate stratigraphicrelationships that become younger towards the southeast. It is difficult to recon-struct stratigraphic relationships in more detail, however, because of incompletebedrock exposure and the scale of lithologic variation. Furthermore, some layersare internally disrupted, suggesting that the rock types probably do not occur inlayers of uniform thickness. Accordingly, the map (Figure 3) shows only the dis-tribution of observed rock types and does not predict what rock types may occurbeneath the sediment cover. Near the excavation site, bedrock is covered by up to2 m of Quaternary sediment.The common rock types comprise various proportions of granofels, phyllite, and

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Figure 5. Section of broken granofels rod fragment illustrating parallelogram geometry resulting fromcleavage. Long dimension is 3 cm.

quartzite in thin to medium beds. All consist of low-grade metamorphic rock, butrelict primary sedimentary structures are widely preserved. Soft sediment defor-mation features, such as disharmonic folds and chaotic sedimentary breccia zones,are developed in phyllite-rich rock types. Hard-rock deformation features, such ascleavage and folds, are superimposed on all rock types. The cleavage dips steeplytoward the west, intersecting bedding at an angle of 40–90�, and commonly be-tween 55� and 60�. Where the spacing of cleavage and bedding planes is appropriate,the rock may break into long, thin fragments with parallelogram-shaped cross-sections (Figure 5).Outcrops at the northern edge of the island (Figure 3, location 13) and on the

adjacent mainland shore to the west consist of tan-weathering, slightly calcareous,quartz-rich granofels in beds less than 2 cm thick. In addition, the mainland out-crops locally contain subordinate phyllite interbeds. The more deeply eroded bed-rock surface at the excavation site may be due to a higher proportion of interlay-ered phyllite there, in contrast to the more resistant granofels-rich outcrops to thewest. Other outcrops consisting dominantly of granofels are exposed in the south-central part of the island (Figure 3, location 6) and on the west-central side of theisland.



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A distinctive, red-weathering, thinly bedded quartzite is exposed in several out-crops in the middle of the island (Figure 3, location 7). This unit exhibits delicatecross-laminae (� 5 mm thick) and cut-and-fill structures, as well as splitting alonglayers into thin sheets. Locally, an axial plane fracture cleavage is strongly devel-oped at a high angle to bedding, causing the rock to break into splinters. A secondvariety of quartzite, exposed on the southeast side of the island, occurs in thickbeds (up to 85 cm) interbedded with smooth, gray slate 1–2 cm in thickness (Figure3).Medium gray to dark blue-gray phyllite dominates the large bedrock exposure at

the south end of the island (Figure 3, location 12). Minor amounts of muscovite-chlorite-quartz granofels and quartz-rich granofels are present in beds up to 20 cmthick. In most places, the phyllite is laminated or thinly bedded, which, combinedwith a strong penetrative cleavage, causes the rock to break and crumble into smallfragments. This would not be a preferred tool-making material and could be easilybroken if transported.

LITHOLOGIC CLASSIFICATION OF ARTIFACTS

Purpose and Methodology

Many artifacts recovered at the site consist of varieties of phyllite, granofels, andslate, all low-grade metamorphic rock types grossly similar to the local bedrock.Because rock type alone is not very distinctive here, a detailed lithologic study ofthe specimens was undertaken to evaluate the degree of similarity between theartifacts and the exposed bedrock on Gilman Falls Island. This comparison helpsus understand the human choices of materials that were made at the site.Six hundred twelve (612) artifacts recovered from the Gilman Falls site were

examined under 12� to 25� magnification and assigned to lithologic groups ac-cording to an array of features such as layering, foliation, mineralogy, and mineraltexture. Approximately 5% of the specimens were so deeply weathered or so fine-grained that classification was difficult by visual inspection. These specimens weretentatively assigned to a category, but with the uncertainty of assignment indicatedby a query (?) in the following text and tables.No classification scheme was assumed. Initially, each specimen was described

in detail on its own merits. After approximately 100 artifacts had been describedindividually, a preliminary classification scheme was devised on the basis of com-mon or distinguishing characteristics. As the study progressed, certain groupingsproved to be either too broad or too specific for the purpose of the study, and theoriginal categories were modified. The classification scheme was finalized after theentire collection had been examined. The collection was then reviewed to insureaccurate groupings. For each of the categories identified as similar to local bedrock,a petrographic thin section was cut from a representative specimen to allow char-acterization of mineral textures and fabric at high magnification. This scheme em-phasizes the similarity of specimens within groups rather than boundaries between

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groups. It is important to understand that this procedure resulted in a classificationscheme that is particular to this collection. For a collection with different propor-tions of rock types, certain categories would be subdivided differently.

Summary of Lithologic Categories

The specimens are classified on the basis of lithology, with those aspects affect-ing tool-making potential given particular attention. Important aspects of the fivemajor categories are described below. Subcategories, indicated by letter designa-tions, were developed within each major category based on more subtle aspects.Details of each subcategory are described in Table II.Category 1 (404�8[?] specimens) is composed of low-grade metamorphic rocks

similar or identical to the bedrock at Gilman Falls Island. This category contains amajority of the specimens in the collection and has been subdivided in greaterdetail than the other major categories. It consists of phyllite, granofels, and quartz-ite and represents rocks metamorphosed in the lower greenschist facies (chloritegrade). Category 1 is subdivided primarily on the basis of grain size and mineralcontent with additional consideration of color on weathered and fresh surfaces,bedding thickness, internal bedding style, and foliation quality.Category 2 (88�9[?] specimens) contains all the igneous rocks of the collection.

They are subdivided on the basis of grain size, composition, and the presence orabsence of phenocrysts.Category 3 (39�5[?] specimens) is made up of metamorphic rocks not known

to be present at Gilman Falls Island. Rocks in this category are subdivided on thebasis of mineralogy and texture.Category 4 (42�7[?] specimens) comprises sedimentary and weakly metamor-

phosed sedimentary rocks, as judged on the basis of hand sample identification.Most of the rocks in category 4 are interpreted to be sedimentary rocks becausethey lack metamorphic textures or deformational features. Metamorphicmuscovitewas not observed in category 4 rocks.Category 5 (9�1[?] specimens) consists of a special group of specimens of

unknown type. All ten samples in this category appear to be of the same rock type,probably metamorphic, but are difficult to classify without further tests.

COMPARISON OF ARTIFACTS WITH LOCAL BEDROCK

Criteria used in comparing artifacts with local bedrock include mineralogy, grainsize, metamorphic mineral assemblage, color on fresh and weathered surfaces,bedding style and thickness, soft-sediment deformational features, cleavage, folds,fractures, and veins. Clearly, some of these characteristics vary within the localbedrock, so a certain range of lithologic possibilities may be considered likely.Other features, such as metamorphic grade, may be used to identify specimens thatare lithologically incompatible with known local bedrock types. On this basis, onlythe rocks from Category 1 are deemed likely to have come from a local bedrocksource.



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Table II. Description of artifact lithologic categories.

Category Lithologic Description

Number ofIdentifiedSamples

CATEGORY 1 LOW GRADE METAMORPHIC ROCKS SIMILAR OR IDENTICAL TOBEDROCK AT GILMAN FALLS ISLAND

404 � 8?

1A Quartz-rich granofels—Light gray, massive, weakly foliated, medium- tofine-grained. Dominated by equigranular quartz grains, small propor-tion of muscovite (�15%). Uniform gray color, weathers to dullbrown. Samples are not deeply weathered. Specimens typically have atabular shape.

60 � 1?

1B Quartz-rich granofels or phyllite with prominent vitreous quartz

grains—Light gray to medium bluish gray, massive, foliated, medium-grained. This category is distinguished from 1A and 1C by the pres-ence of prominent vitreous quartz grains which are dark gray, bluishgray, light smoky-gray, or clear. They occur as equant, subrounded de-trital grains 0.5–1.0 mm across, slightly coarser-grained than the restof the rock. They comprise about 5–20% of the rock, and stand out inrelief on weathered surfaces.

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1C Quartz-muscovite-chlorite granofels and/or phyllite—Medium to darkgray, massive to thinly bedded, moderately to strongly foliated, me-dium- to fine-grained. Mineralogically, the rocks in category 1C fall be-tween the quartz-rich extreme of category 1A and the quartz-poor ex-treme of 1E. These rocks contain a significant proportion ofmuscovite and chlorite. These samples split readily into layers, follow-ing foliation directions. The phyllite included in this category is darkgray with fine quartz grains. It is less friable than the phyllite of cate-gory 1E due to higher quartz content.

80 � 4?

D Thinly bedded quartzite—Red to pink weathering, light gray to white,laminated and cross-laminated. The diagnostic feature is the beddingstyle. The rock consists mainly of thin quartzite layers, typically 1 to 3mm in thickness. Thin partings, less than 0.5 mm thick, of silvery-gray,muscovite-rich phyllite are present between some of the quartzite lay-ers. The thin, curved layers of quartzite split easily along the phyllitepartings like layers of an onion. In many specimens the layers are de-formed by open folds. Brittle fractures, some of which are mineralizedwith quartz, cut across bedding at a large angle, typically 60–90�.

41 � 1?

1E Chlorite-muscovite-quartz phyllite—Dark gray, thinly bedded to lami-nated, strongly cleaved, friable, fine-grained. The diagnostic propertyof specimens in this category is the dark purplish-gray or greenish-gray silky sheen on foliation surfaces. The rocks are soft, and readilyshed small, thin flakes. Deformational features such as folds, crenula-tion cleavage, and minor faults are common.

16

1F Red or yellow-weathering quartz-rich granofels—Light gray, massive,moderately well-foliated, medium grained. Distinguished from cate-gory 1A by the distinctive pale yellow to pale red-brown weatheringcolors. Coloring on smooth, weathered surfaces is commonly patchyor mottled. Muscovite comprises 10 to 30% of the rock in streaky foliainterleaved with quartz grains. Individual round quartz grains areprominent where they are bounded by muscovite.

16 � 1?

(Continued)

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Table II. (Continued)



1G Foliated quartz-muscovite granofels and phyllite—Pinkish-brown towhitish gray-weathering with a dull or chalky luster, thinly bedded,strongly foliated, medium-grained. Specimens in this category arecharacterized by thinly interlayered light gray quartz-rich granofelsand silver-gray phyllite, with granofels more abundant than phyllite inmost cases. The rock contains a closely-spaced fracture cleavage.Bedding and cleavage commonly intersect at 50–60�.

159 � 1?

CATEGORY 2 INGENOUS ROCKS NOT PRESENT AT OUTCROPS IN GILMAN FALLSISLAND REGION

88 � 9

2A Granite—Includes several varieties of granite: yellow-weathering, white,hornblende granite (#4958); pink, coarse-grained biotite-hornblende-perthite granite (#6051); white, medium-grained biotite granite (#289);red-weathering biotite-muscovite-tourmaline granite.

6 � 3?

2B Gabbro—Medium- to coarse-grained, dark colored, non-foliated rockswith crystals of plagioclase and/or amphibole.

3 � 1?

2C Basalt or diabase—Fine-grained, rusty-brown weathering, nonfoliatedblack rocks with relatively high specific gravity.

2 � 2?

2D Felsite, porphyritic—Light gray, light green, greenish-gray, or dark grayfelsite with euhedral to subhedral phenocrysts of quartz, or quartz andfeldspar. Weathered surfaces are chalky white to yellow-white, lesscommonly pink to red, and rarely purple. Quartz phenocrysts are vit-reous, light gray to clear, with hexagonal or square cross-sections andsome prismatic terminations. Feldspar phenocrysts have pseudorec-tangular cross sections.

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2E Felsite, aphanitic—Medium to light gray or light greenish-gray, andweathering to a chalky white, yellowish-white, or pale orange color. Afew specimens have very fine-grained gray quartz grains.

19 � 3?

CATEGORY 3 METAMORPHIC ROCKS NOT KNOWN TO BE PRESENT AT GILMANFALLS ISLAND

39 � 5?

3A Greenstone or amphibolite—One green, chlorite-rich hornblende-epi-dote greenstone (#6141); and one weakly foliated amphibolite withrelict gabbro texture, mantled pink and white feldspar, and chlorite-rimmed hornblende (#1464).

2 � 1?

3B Hornfels—Medium to dark gray, fine-grained, non-foliated to weakly fo-liated. Massive to thick-bedded, thought to be metamorphosed sedi-mentary rocks. Biotite porphyroblasts occur in randomly orientedplates 0.4–1.0 mm across.

4 � 2?

(Continued)



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3C Gneiss—Yellow-brown weathering, strongly foliated, mylonitic gneiss.Feldspar grains are deformed, with recrystallized tails parallel to thefoliation. The rock also contains virtreous, translucent gray quartzgrains up to 0.5 mm.

1

3D Quartz—Monocrystalline or polycrystalline aggregates. Most specimensare milky white quartz typical of quartz veins in metamorphic rocks.Four exceptional specimens (#310, #1858, #4987, #6161) are pieces ofclear, pure quartz, of the kind normally restricted to pegmatites orvugs.

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3E Meta-felsite—Light gray, foliated, medium-grained. The distinctive rocksof this category are characterized by megacrysts (0.4–1.0 mm in diam-eter) of vitreous, gray to clear quartz and white feldspar set in agroundmass of muscovite (or sericite) and chlorite.

5 � 1?

3F Quartz-biotite-feldspar granofels—Brown-weathering, weakly tostrongly foliated, medium- to fine-grained, equigranular. Mineralogi-cally similar to granite, but richer in biotite, and more even-grained.Muscovite present in some samples. Weathered rock crumbles readily.

4 � 1?

CATEGORY 4 SEDIMENTARY ROCKS 42 � 7?

4A Sandstone—Red, yellow, or gray. Light-colored, quartz-rich sandstoneswith low specific gravity. Most samples are layered. The rocks aresoft, may have surface scratches, and grains are commonly plucked.Common accessory detrital minerals include muscovite and feldspar.Biotite and hematite are present in some specimens.

15 � 5?

4B Chert—One specimen of medium-gray to slightly brownish gray withfossil fragments (#13). One specimen of pale, slightly bluish green, ho-mogeneous chert (#1613).

2

4C Green siltstone or slate—Light green to grayish-green, massive toweakly foliated, fine-grained. Several samples have thin streaks thatmay represent compositional layering of sedimentary origin. Two simi-lar specimens (#184 and #4660) have a weak foliation which may beslaty cleavage. Few broken edges exist for examination of fissility orcleavage.

5

4D Gray siltstone or slate—Light gray, dark gray, silvery gray and greenishgray, massive to weakly foliated, fine-grained. Texturally similar tocategory 4C, differing primarily by color. The weak parting andslightly reflective luster of most samples suggest that they are argilla-ceous siltstone or metamorphosed siltstones, rather than siliceousshales. The foliation present is interpreted to represent primary sedi-mentary structure. Few broken edges exist for examination of fissilityor cleavage.

12 � 1?

4E Lithic or arkosic graywacke—Light gray, medium grained, foliated,quartz-rich. Generally poorly sorted, quartz-rich sandstones with sub-angular clasts of white feldspar, lithic fragments, and detrital musco-vite. A yellow-brown weathering color is common.

6 � 1?

(Continued)

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4F Red siltstone—One dark maroon, homogenous rock with small, white,oval spots (#86). One brick red, massive siltstone with fine quartzgrains (#3739).

2

CATEGORY 5 ROCKS OF UNCERTAIN ORIGIN 9 � 1?

5A Unknown—Dark gray, massive, weakly foliated, quartzo-feldspathiccrystalline rock. Due to equigranular, holocrystalline texture, therocks are tentatively identified as metamorphic, but the protolith isunknown.

9 � 1?

The five major numbered categories are subdivided into minor categories, signified by a letter. Thefollowing descriptions emphasize the characteristics that were used to assign a specimen to a category.The specimens within eachminor category share certain characteristics, but are not necessarily identicalto each other. Therefore, the descriptions below apply to the category as a whole, and individual spec-imens may not display all the characteristics listed for the category. The number of identified samplesincludes both those samples identified with confidence, and those grouped with the category as the bestmatch, but with less assurance. These latter samples are followed by a question mark.

Most artifacts of local bedrock types (Category 1) can be matched with specificoutcrops on Gilman Falls Island. Certain artifacts of quartz-rich granofels (Category1A) are mineralogically and texturally identical to an outcrop on the east side ofthe island (Figure 3, location 4). Some artifacts of quartz-muscovite-chlorite gran-ofels and phyllite (Category 1C) are similar to rock types exposed in the south-central and southwestern parts of the island (Figure 3, locations 6 and 9). A thinlybedded quartzite is the most distinctive rock type in the collection (assigned toCategory 1D), which is identical to bedrock in the west-central part of the island(location 7 and neighboring outcrops). Chlorite-muscovite-quartz phyllites (Cate-gory 1E) match the large bedrock exposures at the south end of the island, in thevicinity of location 12. Artifacts of interbedded foliated quartz-muscovite granofelsand phyllite (Category 1G) include variable proportions of phyllite, similar to therange of lithology found at the northwestern part of the island (location 13 andoutcrops to the west). The majority of specimens in this category are very similarto an outcrop on the riverbank about 60 m west of the north end of the island. Aprominent feature of many specimens from this category is a bedding-cleavageangle of 50–60� producing long, flat-sided fragments with parallelogram-shapedcross-sections.Although for two of the seven groups within Category 1 (1B and 1F), specific

lithologically identical bedrock outcrops have not been identified at Gilman FallsIsland, the differences between artifacts in these two groups and the observed localbedrock types are not significant. Specimens from these two categories are similarto bedrock of the island in metamorphic mineralogy, texture, and grain size and



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are distinguished only because of minor constituents of vitreous quartz grains.Ludman and Griffin (1974) report that sandstones of the Kenduskeag unit com-monly contain vitreous quartz granules like those of Category 1B, indicating suchrocks are probably available within a short distance of the island.The collection includes a variety of igneous rock types (assigned to Category 2),

but no igneous rocks are present in the bedrock exposed near the site. While it ispossible that small, unknown bodies of granite, gabbro, or diabase (2A, 2B, or 2C)may be present in the region, the nearest known intrusive bodies are several tensof kilometers to the north and west. Volcanic rocks (2C, 2D, and 2E) are absentfrom the Silurian stratigraphic sequence that underlies the Gilman Falls area. It is,therefore, unlikely that igneous rocks (Category 2) are from a local bedrock source.A group of metamorphic rocks, including amphibolite, schist, gneiss, and others

(included in Categories 3A, 3B, 3C, and 3F), indicate metamorphism at biotite orhigher grade. Therefore, they could not have come from bedrock in the GilmanFalls region, which only attained chlorite grade (lower than biotite). Specimens ofmilky white quartz (in Category 3D) might have come from veins in metamorphicrocks near the site but could also be from elsewhere, for this rock type is widelydistributed throughout the region. The four specimens of clear quartz (in Category3D) do not match any quartz found in the Gilman Falls Island bedrock. Category3E (metamorphosed felsite) is a rock type not known from the Kenduskeag Unit(Ludman and Griffin, 1974) and probably represents a higher metamorphic grade.Sedimentary or weakly metamorphosed rock types (Category 4) also are not

from local bedrock sources. They have not experienced the degree of metamor-phism that affected the Gilman Falls bedrock.The nature of the specimens assigned to Category 5 is uncertain, but no rocks

of this type are known from the Gilman Falls site. They are considered to be froma nonlocal bedrock source.Detailed lithologic comparison clearly indicates that the majority of artifacts

examined from the collection (412 of 612, or 67%) are likely to have come fromlocal bedrock sources. Furthermore, five of the seven subcategories in Category 1,accounting for 363 (59%) of examined specimens, can be matched lithologically tospecific outcrops within 100 m of the archaeological site. Equally compelling is thefact that a variety of bedrock types are present in outcrops at the island, and all ofthose types are represented in specimens recovered from the excavation. This ev-idence supports the quarry/workshop interpretation of the Middle Archaic com-ponent at the Gilman Falls site.The lithologic study clearly shows a preponderance of local rock types in the

collection. The nonlocal rock types do not give a clear picture. They are hetero-geneous, not only among categories, but also within categories (Table II). Whilesome artifacts made of nonlocal bedrock types may have been brought to the siteas finished or partially finished objects, they are not from a single bedrock source.It is tempting to speculate that people using bedrock materials close at hand mightalso have used materials from the glacial and fluvial deposits within 0.5 km of thesite, which would have provided a heterogeneous mixture of non-local rock types.

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Table III. Description of stratigraphy.

Stratum Color Thickness (cm) Texture Comments

10YR 5/3I (Brown)

5YR 5/65–25 31% sand, 33% silt,

36% clayModern A Horizon

IIa (Yellowish-red)10YR 6/4

0–20 28% sand, 38% silt,35% clay

Modern B Horizon

IIb (Yellowish-brown)

5–40 30% sand, 39% silt,31% clay

5YR 5/8IIc (Yellowish red)

2.5 Y N85–40 Fine sand, silt, and

clayAssociated with tree roots

IId (White)10YR 5/4

0–10 Fine sand, silt, andclay

E Horizon

IIIa (Yellowish-brown)

7.5 YR 6/4

0–40 Fine sand, silt, andclay with minorgravel

IIIb (Light brown)2.5 Y 4/4

0–20 Fine sand, silt, andclay with minorgravel

III (Olive Brown)5 YR 4/6

0–30 2% gravel, 43% sand,29% silt, 27% clay

B Horizon (Yellowish-red)10 YR 5/4


Zone 3 Spodosol

IV (Light Brown) 0–20 Fine sand, silt, andclay

Broad flood channel

VI 2.5 YR 4/4(Olive Brown)10 YR 5/2


Broad flood channel

VII (Grayish Brown)2.5 YR 4/4

0–25 56% sand, 24% silt,21% clay

Bedded sand, silt, andclay

VIII (Reddishbrown)

0–35 Gravel, coarse andmedium sand

Bedded sand and gravel

GILMAN FALLS SITE STRATIGRAPHY

Archaeological excavations exposed a 80–200-cm-thick stratigraphic sequenceof predominately fine-grained, alluvial sediments overlying stratified gravel andsand or polished, striated bedrock. The section was subdivided into strata on thebasis of grain-size and color. Figure 6 shows an interpreted geologic section fromthe block excavation; Table III contains a description of each stratum described inthe figure. While individual sedimentary units varied in thickness throughout theexcavated area, the major units were continuous across the site. Representativesamples obtained from each of the major sedimentary units were analyzed to fa-cilitate textural descriptions.Strata I, IIa, and IIb are slightly more clay-rich than the more sand-rich lower

Strata III, VI, and VII. This fining-upward sequence is common in alluvial sections(Reinck and Singh, 1980). Small amounts of gravel occur in Strata III, IIIa, IIIb, and



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VI, as small (5 � 5 � 2 cm) lenses or layers of “pea” gravel (0.5 cm in diameter).No artifacts, charcoal, or debitage were closely associated with these gravel de-posits. They may represent coarse sediment deposited by the melting of ice chunksafter the spring freshet, a phenomenon that has been observed along the modernbanks of the Stillwater River. The transition from massive, fine-grained deposits tostratified, coarse-grained material or bedrock is abrupt across the base of the entireexcavation.Bright to faint red, laterally extensive horizons were encountered at several el-

evations throughout the Gilman Falls excavation (Figures 6 and 7). These horizonsoccurred immediately below Stratum I, 60–70 cm below the surface (betweenStrata IIb and IIIa), and 90–100 cm below the surface (below Stratum III). Theyranged from distinct, sharply bounded layers 5–10 cm thick, to broad, diffuse bands15–30 cm thick. Texturally, they are identical to the surrounding sediments. Sed-iment samples from Zone 3 showed greatly increased levels of total available phos-phate, indicating the incorporation of significant amounts of organic material inthe sediments. Seven assays from Zone 3 had values ranging from 280 to 777 ppm(averaged to 515 ppm) , while other strata had average values of 116 to 376 ppm(Sanger, 1996).On the basis of color, lateral extent, and fine-grained texture, these horizonswere

identified as Spodosols (Ivan Fernandez and Laurie Osher, personal communica-tion to Kelley, 2000; Brady and Weil, 1996:87–88; Callum, 1995). While not contin-uous across the site, they could be differentiated by stratigraphic position andassociated artifacts. These Spodosols, combined with archaeological evidence foroccupation, formed the basis for establishing the cultural zones described above.By using the radiocarbon ages from the Gilman Falls site (Table I) and other

archaeological sites in the region, the timing and deposition of the sedimentarysequence at the Gilman Falls site can be determined. The oldest sedimentary unit(Stratum VIII) represents deposition of an active channel spilling over the lip ofthe Gilman Falls rapids just prior to, or immediately after, the establishment of alocal base level.Dating of Zone 3 at the Gilman Falls site provides a minimum age for the ces-

sation of downcutting and the initiation of fine-grained sedimentation. However,information from other sites within the region suggests that this event occurred byapproximately 9000–8000 yr B.P. At the Blackman Stream site, 15 km to the southon the Penobscot River, a Plano-like projectile point was recovered from fine-grained sediments above stratified gravel and sand. The point was located 1 mbelow a soil horizon that contained Early Archaic artifacts associatedwith charcoaldated to 8500–7400 yr B.P. (Sanger et al., 1992). Dating of charcoal associated withartifacts at the Beaver site, 50 m north of the Gilman Fall site provided a minimumage of � 8000 yr B.P. (unpublished) for the rapid sedimentation change in theimmediate area.The overlying stratified, coarse and fine-grained sediments (Strata VII and VIII)

indicate changes in water velocity, either due to channel migration or seasonalchanges in discharge. The general fining upward of the stratified sequence may also

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Figure 6. Photograph of profile from the Gilman Falls site. Note darkened remnant “B” Horizon at 85cm below surface, and associated large bedrock clasts.

mark the overall decrease in discharge of the Penobscot/Stillwater Rivers due toisostatically influenced drainage shifts in the Moosehead Lake/Upper Penobscotdrainage approximately 9000 yr B.P. (Balco et al., 1998).The abrupt change from stratified coarse sediments to massive, poorly sorted,

fine-grained sand, silt, and clay suggests a distinct change in geologic processes.



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Figure7.Stratigraphicsection(6mlong)attheGilmanFallssite.SeeTableIIIfordetailedunitdescriptions.

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Instead of deposition in active, fast water channels, sedimentation from floodsbecomes the primary mechanism. Strata IV and VI form broad, lenticular depositsof finer sediments, composed primarily of sand with associated silt and clay, andrepresenting flood channels. These sediments are topped by the soil horizon andassociated Middle Archaic occupations ranging from 7300 to 6300 yr B.P. The pres-ence of this soil, and the others higher in the sequence, represent a time of land-scape stability and reduced sedimentation that allowed pedogenic processes toform the Spodosols.Following an approximately 1000 year interval of soil formation, sedimentation

resumed, burying the soil horizon and cultural Zone 3 with sediments settled fromponded floodwaters, forming Strata III, IIIa, and IIIb. This style of deposition con-tinued until approximately 5000–4000 yr B.P. (Zone 2), when sedimentation againslowed or ceased, allowing a Spodosol to form. Following a period of undeterminedlength, sediments again began to accumulate to form the parent material for Zone1, which dates from 3000 yr B.P. to the Historic Period (ca. 350 yr B.P.).Once the drainage pattern in the region had developed, and local base levels

were established, climatic variation was the major factor influencing depositionand erosion of sediment by affecting the volume and timing of major flood events(Webb et al., 1993). Paleohydrologic investigations at Mansell Pond, a small pondlocated less than 10 km north of Gilman Falls, documented lake levels through theHolocene (Almquist et al., 2001). The pond is ideally suited to serve as a proxy forprecipitation variation in that it is isolated from groundwater influences becauseof a clay lining formed by the late Pleistocene marine invasion (Thompson andBorns, 1985). It also lacks inlet and outlet streams. A transect of eight cores wastaken across the pond and examined for vegetation and sediment changes associ-ated with lake level variation. Twenty-nine radiocarbon ages provided the chro-nology for the study.The results of our study suggest two periods of decreased effective precipitation.

Lake levels dropped from 8000 to 6000 yr B.P. and remained at low levels untilapproximately 5000 yr B.P. A shorter period of decreased effective precipitationoccurred from ca. 4500 to 3500 yr B.P. The oldest buried Spodosol and associatedcultural Zone 3 at Gilman Falls are correlative with the earlier dry period. TheSpodosol and associated hearth features dated to 4160 � 70 B.P. (cultural Zone 2)may be related to the latter period of reduced effective precipitation.Reduced effective precipitation rates may be responsible for the formation of

the Spodosols that contain cultural Zones 2 and 3. If effective precipitation de-clined, it is likely that the flood frequency diminished and the amount of sedimentcontributed to the floodplain decreased. Reduced sedimentation would allow pe-dogenic processes to form a soil on the floodplain. Human occupation contributedartifacts and organic material to the cultural zones; the latter is indicated by in-creased phosphorus levels in Zone 3.The stratigraphic sequence at the Gilman Falls site reflects approximately 9000

years of geologic processes that included changes in base levels and sedimentationrates that preserved a unique portion of the archaeological record.



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ARCHAEOLOGY

The earliest recorded human occupation in Maine, the Paleoindian, occurred byaround 11,000 radiocarbon years ago (uncalibrated), following the retreat of theLaurentide ice sheet. The Paleoindian period, which ended approximately 9500 yrB.P., is recognized by the distinctive fluted bifaces, made of chert from a varietyof sources, and sites usually located on well-drained sediments above modernfloodplains (Spiess et al., 1998). Unfluted, parallel-flaked points (Plano-like) thattend to occur in modern floodplain environments characterize a Late Paleoindianmanifestation with a chronological span that is not yet agreed upon (Dumais, 2000;Petersen et al., 2000; Petersen, 1995; Sanger et al., 1992).Following the Paleoindian period, Early Archaic (9500–7500 yr B.P.) and Middle

Archaic (7500–6000 yr B.P.) period components occur in a number of riverbanksites in central Maine (e.g., Petersen et al., 1986; Petersen, 1991; Robinson et al.,1992; Sanger et al., 1992). Discovery of these sites depends on the recognition ofearly and middle Holocene alluvium that survived subsequent erosion.Many sites dating to the Late Archaic (6000–3000 yr B.P.) have been recorded

in Maine. Their abundance may reflect favorable site preservation, an increase inhuman population, or both. New artifact forms entered the record at this time,including large, side-notched bifaces (Otter Creek points), plummets, and ulus. Thenear-exclusive use of low-grade metamorphic rocks that dominated the MiddleArchaic assemblages of central Maine during the Late Archaic changed to greaterutilization of porphyritic rhyolite for biface manufacture. The transition is observedin Pushaw Stream sites and in the nearby Piscataquis River Valley (Petersen et al.,1986; Petersen, 1991; Sanger and Newsom, 2000).Throughout the Ceramic period, native peoples used the waterways of central

Maine extensively. Indeed, most known sites date to this period. Seventeenth-cen-tury European visitors to the area found Native Americans who spoke an EasternAlgonquian language (Goddard, 1978). Their descendants form the modern Penob-scot Indian Nation, whose tribal land is less than 1 km from Gilman Falls.

The Archaeology of Zone 3

As noted, cultural Zone 3 represents a period of limited alluviation. Infrequentflooding, probably because of reduced effective precipitation and concomitantlower river levels, resulted in an accumulated record of cultural activity thatspanned just over 1000 years. Zone 3 chronology is constrained by seven radiocar-bon ages that range from 7670 � 240 to 5950 � 165 yr B.P. (Table I). Charcoalfrom Zone 3 was submitted to the University of Arizona in two batches on succes-sive years. Because of the large statistical errors (at 1 sigma) associated with thesecond batch of samples, we follow the advice of Minze Stuiver (personal com-munication to Sanger, 1994) and base our preferred estimate of age on the firstgroup of samples. Following this methodology, we assign an age of approximately7300–6300 yr B.P. for Zone 3.Zone 3 was buried by alluvium about 6000 yr B.P. Although the decrease in

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alluviation between 7300 and 6300 yr B.P. resulted in a succession of campingepisodes and a rich archaeological record, the acidic nature of the forest soil pre-served bone and vegetable remains poorly unless the remains were heavily burnedto the point of being calcined. As noted, we employed water screening through 3mm and finer mesh, flotation, and fine mesh washing techniques in an attempt torecover identifiable organic remains. The Zone 3 faunal assemblage consists of 1682small fragments, weighing 40.0 g. The assemblage represents aquatic mammals,such as beaver and muskrat, together with some fish and bird, plus a few fragmentsof larger mammals, probably deer. In spite of extensive efforts, little new infor-mation relative to subsistence patterns resulted. Summer occupation is suspectedon the basis of location and the presence of some charred floral remains.The lithic artifacts indicate what was probably the main rationale for selection

of the site. As detailed earlier, a very substantial number (over 66%) of the artifactswere manufactured from low-grade metamorphic rocks (our Category 1 and sub-divisions) that could be obtained from bedrock sources within less than 200 mfrom the site. A number (ca. 60) are made from Category 2 rocks (volcanic), manyof which are of the type known locally as “Kineo felsite”(Category 2D), readilyavailable in local ice-contact features and in river beds (Doyle, 1995). Remnants ofdeep weathering rinds and rounded forms of the specimens recovered from thesite suggest cobbles gleaned from local secondary (nonoutcrop) sources.Procurement of local bedrock did not need to involve active mining. Examples

of local bedrock used for experimental flaking were easily picked up on GilmanFalls Island, where blocks had broken along planar surfaces. Similar pieces werefound in the excavation. One piece of rock, weighing more than 25 kilos, wasrecovered from Zone 3. Examination of the block reveals no signs of prying orhitting with a stone hammer. The geometry is that of a three-dimensional parallel-ogram, which is similar to many of the pieces in the site that were being workedinto tools. It seems likely that it was picked up and brought back to the site as rawmaterial. Of Category 1 low-grade metamorphic rock, it matches the lithology ofthe island and most artifacts analyzed for lithologic type.Local bedrock outcrops (especially Category 1) provided raw material for man-

ufacture of utilitarian artifacts, such as choppers, cutting tools, and ground projec-tile points (often called “slate points” in the area) (Figures 8[a] and 8[b]). Some ofthese artifacts exhibit only minimal shaping and, taken out of context, could easilypass as noncultural. Others, more obviously modified, indicate that a specializedtechnique was needed to reduce the rock without crushing the margins. Replicativeexperiments, using rocks extracted from local outcrops, parallel observationsmadeon archaeological specimens. Bedding planes in the bedrock result in relativelythin tabular blanks. These can be shaped by flaking along one margin unifaciallyand then, after reversing the preform, working the alternate edge unifacially. Theresult is alternate, unifacial width reduction, but not necessarily of the overall thick-ness.In order to flake the low-grade metamorphic rocks, a specialized form of hammer



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Figure 8. Pecked and ground stone artifacts from Zone 3, Gilman Falls site: (a, b) ground “slate” points;(c) celt; (d, e) gouge fragments.

stone (ridged hammer stone) (Figure 9) was created from locally derived volcaniccobbles (Category 2). Many still exhibit some cortical surface, usually a smoothand flat portion opposite the working edge. The latter was created bifacially toachieve an arris, or ridge, of about 90–120� (avg. 101�). Seventy-two ridged hammer

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GE

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BA

TC

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Figure 9. A ridged hammer stone from Zone 3, Gilman Falls site, used to reduce low-grade metamorphic rocks; (b) is view of the bifacially formedridge.



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stones average 160 g in weight. Manufacture of these tools apparently created theCategory 2 lithic debitage in Zone 3. Detailed analysis of flake size, morphology,and striking platform characteristics do not match the statistical profiles of otherlocal biface reduction techniques, which lead to thin bifaces, usually assigned pro-jectile point or knife functions (Mack et al., 2001). This observation parallels thelack of such bifaces in Zone 3. Experiments have shown that the specialized formof the ridged hammer stone affords considerably more control over the thinly bed-ded, low-grade metamorphic rocks than can be achieved through the use of a nor-mal spherical or oval hammer stone. The ridged hammer stones may have func-tioned as pecking stones as well, to produce the numerous pecked and groundstone implements that typify Late Archaic sites in central Maine.Rods constitute the most interesting tool class manufactured at Gilman Falls.

Rods are long, cylindrical artifacts usually assigned an abrasive stone function(Figure 10). Several rods exhibit signs of use wear in the form of longitudinal facetsground into the rods as a result of some sharpening activity. At Gilman Falls, how-ever, the faceted rods are not made of local rocks. None of them has ground facets.Rods may have functioned to sharpen the concave bits of gouges (Figure 8[e]).However, another function, one more symbolic in nature, may explain the lack ofuse wear and the number of rods at Gilman Falls.Robinson (1992, 1996) and Cole-Will and Will (1996) have called attention to the

presence of rods of extraordinary length (up to 46 cm) and elaboration in MiddleArchaic cemeteries of the Moorehead burial tradition (Sanger, 1973). One of thesesites, the Sunkhaze Ridge cemetery (Robinson, 1992), is about 6 km north of GilmanFalls on the Penobscot River (Figure 1). The desirability of rods as grave inclu-sions may provide a clue as to why so many fragments came from the Gilman Fallssite.One hundred forty-seven fragments of rods, roughly 24% of the entire Zone 3

lithic assemblage, occur in various stages of manufacture. Some can be refitted(Figure 10[e–g]), which reinforces the workshop interpretation of the site. From aslab of local Category 1 (low-grade metamorphic) bedrock, the maker reduced thewidth of the blank utilizing the alternate, unifacial procedure noted above. Oncethe desired width had been achieved, pecking further reduced the bulk and pro-duced a rounded cross section. Replicative attempts by Richard Will (personalcommunication to Sanger, 1998) found that a firm support running the full lengthof the implement helped to eliminate breakage. However, many rods did fractureat this point in the production process. Limited abrasion completed the specimen,although, even at this stage, breaks occurred, as seen in discarded, nearly com-pleted specimens.It is undoubtedly significant that after about 6000 yr B.P., when rods disappeared

as inclusions in northeastern Moorehead burial tradition cemeteries, people rarelyinhabited the Gilman Falls site. It would appear that while rods were an integralpart of the mortuary ceremonialism, Gilman Falls, situated amidst highly suitablebedrock, served as a rock source and manufacturing site. When tastes changed inmortuary furnishings, the site no longer held much attraction.

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Figure 10. Chipped and pecked rod fragments from Zone 3, Gilman Falls site: (a, b) complete or near-complete specimens (broken and rejoined); (c, d) early reduction stage featuring unfacially chippedmargins; (e) preform broken while pecking to rounded form; (f, g) rejoined fragments broken in man-ufacture.



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DISCUSSION

Our basic geoarchaeological model suggests that people selected certain land-forms and locales (sites) in order to satisfy culturally derived priorities. Once cho-sen, geological and cultural processes affect those sites: These constitute the cur-rent archaeological record. This model provides more than physical context,however, because it also involves human behavior.Pre-Quaternary and Quaternary geologic events shaped the area around Gilman

Falls. The bedrock created erosion-resistant sills that acted as drainage systemcontrols. The sills also resulted in sediment-settling ponds that led to vertically andlaterally aggrading riverbanks. During periods of high discharge, over-bank floodsburied previous surfaces and created stratified deposits. Prolonged periods of littleto no sediment accumulation permitted multiple occupations and a recognizablearchaeological site. In addition, the stability fostered soil development. Subsequentdeposition buried the cultural deposits and associated soils, leaving distinct soilhorizons, recognized visually and geochemically.We now recognize that these processes have occurred at a number of localities

in central Maine (e.g., Sharrow and Brigham sites [Putnam, 1994]; Blackman Stream[Sanger et al., 1992]). Indeed, almost all known habitation sites dated to between9500 and 6000 yr B.P. share aspects of this history. Vast stretches of riverbank thatapparently lack these early to mid-Holocene sites also lack the requisite geologicalcontrols that lead to vertically accreting alluvial sedimentation. In addition, loss ofmiddle Holocene sediments through bank erosion probably occurred more oftenwhere bedrock outcrops did not prevent shifts in river channels. Therefore, anyconstruction of settlement pattern must take these factors in consideration.Gilman Falls provides insights into the non-geological aspects of the model—

the rationale for site selection and subsequent abandonment by people. Archaeol-ogists working in Maine have long recognized the correlation between habitationsites and rapids on rivers and streams (Sanger, 1979). These localities provideopportunities for stationary fish traps or weirs (Petersen et al., 1994). Gilman Fallscertainly provided this; but, in addition, the nature of the bedrock acted as amagnetto people.Here the symbolic nature of culture enters the story. Early and Middle Archaic

cultures of New England practiced a mortuary custom in which the lavish use ofred ocher (hematite) played a key role. Antecedents of the Moorehead burial tra-dition (Sanger, 1973) began by at least 8500 yr B.P. (Robinson, 1996), and continueduntil about 3800 yr B.P. A second distinguishing aspect of the tradition was theinclusion of specially manufactured, ground stone tools that mimicked utilitarianobjects in form. As Robinson (1996) has pointed out, during the earlier millenniaof the tradition, long, cylindrical, rods were common grave offerings. Gilman Fallscombines a quarry and a workshop with a habitation site where people carried outmore mundane activities, as indicated by the presence of utilitarian implements,discarded animal bones, and occasional fire hearths. Occupation of the site andmanufacture of rods continued until around 6000 yr B.P., after which time the site

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was all but ignored by native peoples. At 6000 yr B.P., a new series of high floodevents buried Zone 3 and its associated forest floor. Although people continued tovisit the site occasionally, it never regained the popularity of the period 6000–7500yr B.P.Geological events cannot explain the abandonment of the Gilman Falls site, be-

cause the rapids and their fishing potential would have remained relatively un-changed. Our research indicates that nearby Beaver site, 50 m across PushawStream, became a preferred locality.It is in the symbolic system that changes occurred. The distinctive rods were no

longer one of the key items in Moorehead tradition burial cemeteries. Our hypoth-esis is that, when rods fell from favor as highly stylized and symbolic grave objects,the Gilman Falls site and its associated special lithology lost relevance to people.It became just another place, not shunned, as the record clearly indicates, butlacking the drawing power of rocks so well suited to the erstwhile ceremonial rods.

CONCLUSION

The Gilman Falls project illustrates use and explanatory power of a geoarchaeo-logical model that includes human behavior, both pragmatic and symbolic, as anintegral component. Bedrock geology and Quaternary geologic events provided thesetting for archaeological activities. People selected the island for its bedrock rap-ids and the nature of the low-grademetamorphic rocks, which they found eminentlysuitable for manufacture of specialized mortuary items. They camped repeatedlyon a forest floor made possible by a period of decreased sedimentation and Spo-dosol development. They gathered the local bedrock and made over 60% of allrecovered artifacts from it. Much of the manufacturing activity was directed to-wards the production of ground stone rods, a form frequently included in burialsof the time. When ideas of appropriate artifacts in graves changed, Gilman Fallswas abandoned as a major campsite and used only sporadically thereafter. Sub-sequent flood events, temporally coincident with evidence for increased lake levelsafter 6000 yr B.P., resulted in an increase in over-bank deposition and preservationof earlier sediments and associated artifacts.

It is our pleasure to thank the many archaeological crewmembers who worked at the Gilman Falls site,especially crew leaders William Belcher, James Fenton, and Maureen Sweeney Smith. Stephen Bicknellproduced the figures, except for Figure 9, which was drawn by David Putnam. We are also grateful toour colleagues who shared their information on past regional environments. We extend our thanks forthe perceptive and helpful comments of two reviewers and the editor. We alone take the responsibilityfor any misinterpretations of the data.

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Received April 26, 2000

Accepted for publication December 7, 2000

geoarchaeology at gilman falls: an archaic quarry and manufacturing site in central maine, u.s.a

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