Colonial Williamsburg Digital Library

Test Unit 1

Test Unit 1 measured 2 × 2 m in plan and was located in the approximate center of the site area; the northwest corner was placed at grid coordinate 384N 500E. The unit centered over a concentration of lithic debitage, and yielded Middle and Late Woodland (500 B.C.-1560 A.D.) pottery as well. Two features were encountered during the course of excavation; both were in Layer 2. The first was an irregular, bowl-shaped pit located in the northwest quadrant of the test unit against the west wall. After examination, it was determined a tree hole. No artifacts were found in the fill. The second feature, Context 606, was located in the southwest quadrant (Figure 8). Circular (roughly 1 m diameter) in plan and having a shallow (18 cm deep), basin-like profile, Feature 2 contained one fragment of quartzite shatter, two sherds of aboriginal pottery, and numerous bits of burned clay. Layer 2 was subdivided into arbitrary levels for additional vertical control in the northeast and southeast unit quadrants; no further features were encountered, however, and no distinctions were noted between the subdivided strata.

The lithic concentration was light. A few artifacts were recovered from the topsoil layer (Layer 1), but most came from Layer 2. The topsoil yielded two fragments of fire-cracked Figure 8. Feature 2 (Context 606), Test Unit 1. 17 rock, two secondary flakes, and one unmodified stone. Layer 2 yielded one fire-cracked rock, four unmodified stones, one primary flake, two secondary flakes, and three flake fragments, or shatter. Cortex was present on the primary flake, and on one secondary flake and one flake fragment (none exhibited more than 74% cortex). All of the flakes and shatter recovered from the unit were quartzite.

No ceramic sherds were recovered from the topsoil in Test Unit 1. The sherds found in Feature 2 included one sand-tempered, cordmarked fragment and one unidentified fragment. Layer 2 yielded ten pottery fragments. One was a sherd of shell-tempered, fabric impressed Townsend ware that dated from the Late Woodland period. The remaining sherds dated from the Middle Woodland period; they included one shell-tempered sherd with cord-marked exterior surface treatment, identified as Mockley ware; four other shell-tempered sherds, three sand/grit tempered sherds, and one unidentified sherd. The surface treatment of the latter sherds could not be determined.

Test Unit 2

Test Unit 2 also measured 2 × 2 m, with grid coordinate 414N/500E marking the northwest corner. The unit was centered over the oyster shell midden located in this northern section of the site area. The midden did not coincide with one of the five artifact concentrations defined by the Surfer data, but its location was known due to having been impacted and exposed by a logging road that had previously been cut across the site area. A 50 × 50 cm shovel test excavated in 1991 fell within the northwest quadrant of Test Unit 2, while the logging road obliterated most of the southeast quadrant and a portion of the northeast quadrant. Little remained of Layer 2, as three features cut this layer (Figure 9). Feature 5 (Context 634/635) was shallow (10-20 cm) and amorphous in plan, and consisted of a dark olive brown (2.5Y 3/3) sandy clay loam that contained lithic debitage, Middle Woodland ceramic sherds, and oyster shells. This feature encompassed most of the intact unit area. Features 3 and 4 were two small deposits of oyster shell that lay within Feature 5. Feature 3 (Context 630/631) was encountered in the northwest and southwest quadrants. The oyster shells lay within a matrix of dark brown (10YR 3/3) sandy clay loam that contained several sherds of Middle Woodland pottery and one piece of debitage. The feature was sub-rectangular in plan and 7 cm deep. Feature 4 (Context 632) lay almost entirely within the southeast quadrant. This was the deposit of oyster shell that had been exposed by the road cut. It was comparable to Feature 3 in shape and composition; there were no artifacts. Several smaller pockets of shell also were included within the larger, amorphous feature. This complex of features was interpreted as a refuse midden containing discrete but incidental deposits of discarded oyster shells.

Oyster shells were mixed throughout the soils of the entire test unit. Tools, flakes, and flake fragments all were quartzite. Most of the lithic artifacts were found in the topsoil; they included the tip of a hafted biface, a Stage 1 biface (the least specialized tool type), 38 pieces of shatter, fourteen secondary flakes, and one primary flake. One third of the debitage was cortical (1-74%). A few unmodified stones and fire-cracked rock also were recovered, and one sherd of net-impressed, Mockley ware and one unidentified shell-tempered sherd were found in Layer 1. Feature 5, the large feature that underlay most of the topsoil 18 Figure 9. Test Unit 2, shell deposits and midden. in the unit, contained one sherd of Mockley ware, also net-impressed, two sherds of unidentified shell-tempered pottery, three sand/grit tempered sherds, and six pieces of burned clay. Nine fragments of shatter, three secondary flakes, two primary flakes, and a fragment of a Stage 2 biface were recovered from Feature 5, along with two pieces of fire-cracked rock and one unmodified stone. Both primary flakes and one piece of shatter were cortical (1-74%). Feature 3 included one piece of shatter, two fragments of burned clay, three pieces of net-impressed Mockley ware, and one unidentified shell-tempered sherd. Feature 4 contained only shell.

Figure 10. Potts point Test Unit 3.

Test Unit 3

Test Unit 3 was placed a few meters west of Test Unit 2, at grid coordinate 417N 493E (NW corner). The data showed this area to be the locus of a concentration of prehistoric pottery (see Figure 6), and excavation of Test Unit 3 verified that fact. Moderate amounts of quartzite debitage, fire-cracked rock, and shell-tempered pottery were recovered from Layer 1, or topsoil. Layer 2, however, included a total of 113 sherds from the four quadrants of the 2 × 2 m unit. A hammerstone fragment and a Middle Woodland (500 B.C.-900 A.D.), Potts projectile point were also recovered from Layer 2, along with lithic debitage and fire-cracked rock (Figure 10). Stratigraphy in Test Unit 3 included a third soil layer beneath Layer 2, sealing subsoil. Layer 3 was a brown (10YR 5/3) sandy clay loam that was 8-10 cm thick. Moderate quantities of lithic debitage and shell-tempered pottery were included in this layer. No features were encountered in Test Unit 3.

Test Unit 4

Test Unit 4 was located at grid coordinate 384N 464.5E (NW corner), near the western edge of the terrace and over the second shell midden. The unit initially measured 2 × 2 m, but it was expanded to ten square meters during the course of excavation to encompass more of the shell midden; ultimately, some three square meters of midden fill were exposed (Figure 11). The shovel test excavated during the 1991 evaluation was incorporated in Test Unit 4. The topsoil, Layer 1, was a very dark grayish brown (10YR 3/2) in this area. This was not surprising given the organic nature of the feature directly beneath. The midden both cut and sealed Layer 2. Only the midden was removed; the soil surrounding and underlying it (Layer 2) was not excavated. Two layers made up the midden fill (Figure 12). The upper layer ranged from a very dark grayish brown (10YR 3/2) sandy clay loam to a dark brown (10YR 3/3) clay loam. It was distinguished from the overlying topsoil by texture, sometimes by color, and by a noticeable increase in artifact and oyster shell content. The lower midden layer was a dark grayish brown (10YR 4/2) sandy clay loam.

In addition to oyster shells, both midden layers contained Mockley and other shell tempered wares, sand/grit tempered pottery, bits of burned clay, quartzite debitage, fire-cracked rock, faunal bones, including a large antler fragment, and charred and uncharred seeds. While shells were present throughout the midden, several dense pockets of oyster shell were discernable in the fill. These discrete deposits were given Feature Numbers 6-10 (see Figure 11). Each feature was visible in the upper midden layer, and all but one extended into the lower midden layer. They were amorphous in plan, and nearly all were shallow (6-10 cm), containing mostly shell. A flotation sample from Feature 6 (Context 669/670) included charred nut fragments.

Figure 11. Plan view, Test Unit 4.

Test Unit 5

Test Unit 5 centered over a concentration of lithic material, with its northwest corner at grid coordinate 362N 485E. Excavation of this 2 × 2 m test unit revealed a dense concentration of debitage that included over 1400 quartzite flakes and flake fragments. Twelve tools, including several hafted bifaces, were also recovered from this test unit, along with 32 fragments of unworked stone and one large cobble. Middle Woodland pottery sherds 21 Figure 12. Midden profile, Test Unit 4. and one Late Woodland, Townsend sherd were recovered as well. No features were encountered in the test unit.

Test Unit 5 was located on the southern half of the terrace, approaching the sloped ridge; consequently, the topsoil layer was relatively thin: about 5 cm in depth. Both debitage and pottery were found in this layer, along with a hafted biface of quartzite and a bifacial tool of sandstone. The hafted biface was a Middle Woodland, triangular type called Yadkin. Layer 2 was divided into arbitrary levels for maximum vertical control: 5 cm were removed from the upper portion of the stratum and labeled Layer 2a; the rest of the layer extended to sterile subsoil and averaged from 5-8 cm in depth. There were no artifactual distinctions between the levels; artifact counts were slightly greater in the upper level. Debitage from Layer 2a numbered 746, and from Layer 2b, 649. Middle Woodland pottery was recovered from both levels (32 sherds from 2a, and 16 sherds from 2b). Tools included four unidentified hafted biface fragments from level 2b. Level 2a yielded a Potts hafted biface, a Yadkin hafted biface, and four bifacially-worked tools (Figure 13).

Test Unit 6

Test Unit 6 was located at the extreme southern tip of the site, on the gently sloped finger ridge that overlooks the Grice's Run marshland. The lithics here were not as numerous as at other concentrations on the site (at Test Unit 5, for example), but it was a moderately dense assemblage. Following the procedure used in excavating Test Unit 5, Layer 2 was divided into arbitrary, 5 cm levels. In addition, all soils from Layer 2 were screened through 1/8" mesh. Soils from the northwest quadrant of Level 1 also were passed through 1/8" mesh; the remainder of the topsoil was screened through ¼" mesh. Aboriginal pottery and lithic debitage were recovered from all levels. No features were encountered.

Figure 13. Lithic tools, Test Unit 5.

Twenty-four fragments of fire-cracked rock were recovered from Layer 2, most of it being found in the northwest quadrant of the unit. The fire-cracked rock was deposited in the upper level of the layer (2a); there was no discernable hearth feature resting on top of subsoil. Two quartzite cores, bifacially reduced, were also recovered from Layer 2a along with a quartz, bipolar flake and one quartzite, primary flake. There was one unmodified cobble beneath the plowzone. Of a total of 35 secondary flakes recovered from Layer 2, all but two were quartzite; 11% retained 1-74% cortex. Over 75% of the aboriginal pottery found in the unit was recovered from beneath the plowzone: 22 of 29 sherds; all but three of those sherds were found in Layer 2a. None of the pottery was unidentifiable, with the exception of two shell-tempered sherds in the plowzone and one fragment of Middle Woodland, Mockley ware in Layer 2a.

Taphonomic Processes

To assess site changes through time and to insure the reliability of data derived from the oyster valve (Kent, n.d.:9), shell conditions were individually noted and then compared with one another. Feature-shell relationships, if any, were examined and the application of historic and oceanographic probability incorporated. Criteria for evaluating the taphonomic processes were limited to two primary destructive mechanisms: physical or mechanical degradation and chemical alteration.

Morphometric Analysis of Shell Shape

Measurement of dorsal-ventral/anterior-posterior dimensions to determine height-length ratios (Gunter, 1938:546-547; Kent, n.d.:28; and Galtsoff, 1964:18-22) provided a means to quantify and statistically analyze shell shape differences per context. Frequency and distribution of lower valves, as well as growth types were examined.

Epibiont Analysis

Many marine organisms attach to and/or bore into oyster shells while the oysters are alive in their natural habitat or the shells are remnants of dead oysters, where the shells serve as a permanent part of the reef or bed substrate. The variety, presence or absence and distribution of these organisms can aid in the interpretation of environmental conditions such as bottom character, water movement, salinity and temperature ranges, food supplies, sedimentation, pollution and disease. In this study the main objective of epibiont identification and analysis is to determine salinity regimes (Galtsoff, 1964:420-430; Kent, n.d.:39).

Harvesting Intensity

An attempt to provide a qualitative estimate of harvesting intensity was made based on shell height and shape similarities. The human factor as well as fluctuations in oyster abundance, distribution and growth rates were considered. Other factors evaluated included differences in harvesting methods (spatial or temporal), proximity and accessibility of oyster flats, and when possible, dietary preference (Kent, n.d.:48-51).

Harvesting Techniques

To understand the technological and cultural patterns used in oyster procurement and preparation for consumption during prehistoric time is difficult since no documentation for harvesting methods and oyster processing exist. However, inferred methods used to collect oysters allows some determination of what habitats could readily be exploited. Coupled with other physical evidence on the shell, seasons of harvest can be suggested. Oyster preparation (shucking and cooking) also lends to the interpretation of seasonality as well as diet, spoilage, etc. (Kent, n.d.:52-59).

Analysis of Shell Microgrowth Patterns

Shell deposition and dissolution is responsible for fine banding or layering generally found in the ligostracum (Carriker, et al, 1980); a thin shell layer covering the valve hinge (Kent, n.d.:52-59). The microgrowth increments are believed to contain an accurate record of freeze-shock, heat-shock, spawning, neap tides, storms and other details of environmental change in the course of a bivalve's existence. Acetate peels of the microgrowth patterns were prepared from a selection of valves that represented a complete HLR range from the sampling of each context.

Distribution Patterns

Comparison of salinity regimes for each context, as well as an overall distribution of saline concentrations was examined. Shells from each context were compared by salinity regime, clustering, physical burning, coloring, and ribbing.

Historical Analysis

Review of records of oystering and oyster use during historic periods was conducted to aid in formulating models and trends of human possiblity for a period of time when written records did not exist. In addition, consultation with marine scientists, biologists, geologists, and archaeologists was used as a means of reconstructing possible environmental conditions back in time.

Total Number and Overall Breakdown of Oyster Valves

The overall condition of the shells precludes an exact determination of lower and upper valves. Erosion and solution by ground water has obliterated certain characteristics of many shells in the collection that are used to make these determinations. An estimate, however, has been made. It appears that less than 12% of the assemblage are uppper valves. Both upper and lower valves were subject to analysis even though the lower valve generally yields the most significant ecological information.

In sampling oyster shells from an excavation, valves are catergorized into three groups (Kent, n.d.:19):

• INTACT: This is a valve where both height and length can be measured.
• BROKEN: For this classification, only the height or the length can be measured or neither measurement can be made, yet the valve has a complete hinge.
• FRAGMENT: This is a broken shell that lacks a complete hinge.

Using these catergories, the total quantity obtained from the contexts studied can be grouped as follows:

Percentages per context are as follows:

Oyster Valve Condition

The overall condition of the collected oyster valves is poor, in that 3-27% of the valves in the representative sampling of each context are intact (Figure 1). Broken specimens, which range in quantity between 22-47%, remain analytically useful. Fragments range between 38-66% of the contexts. These fragments were excluded from analysis.

Many factors can account for the degradation of oyster shells on an archaeological site and are generally categorized into two groups: physical and chemical. Most of the damage to the representative sample's microstructures and superstructures appears to be limited to the alteration of mineralization and erosion.

Figure 1.

This limited degradation applies to all specimens in the sampling, whether intact, broken or fragmented. The quantity of broken shells exhibit damage characteristic of:

• 1.Excessive shucking: use of the "cracking" method (Kent, n.d.:55).
• 2.Frost heaving: repeated freezing and thawing while buried in the ground.
• 3.Careless handling at the time of harvest and later when shells were disposed of.

Oysters are commonly categorized by geographic location, particularly in the commercial industries of today. Terms such as "Blue Point," "Cotuit," "Chincoteague," "East Rivers," etc., are examples of marketing classifications. Geographically, the region from which an oyster originates has no bearing on shell shape, although regional variance does appear to affect the interior pigmentation of the valve (Galtsoff, 1964:20). Erosion has destroyed any pigmentation that may have been present in the specimens analyzed. The shell shape variance of the oyster species Crassostrea virginica can be correlated to the environment in which the bivalve lives (Galtsoff, 1964:18).

Kent (n.d.:30) categorizes growth form into four varieties but cautions that habitat can result in some crossover between the groups. The height/length ratio (HLR) of the oyster valves is the primary determining factor for placement within these groups; however, other variables such as ribbing, coloring and extent of clustering are necessary considerations when making these distinctions (Kent, n.d.:28-32).

Of the oyster valves excavated from the contexts represented in the lab sampling, the breakdown of groups in percentages is as follows:

Figure 2 illustrates the extent of valve growth type (in percentages) per context. Bed oysters are the most frequently occurring type followed by sand oysters and channel oysters - in that order. No reef type oysters were present in the assemblages.

Bed oysters generally occur on a mixed muddy sand and can be clustered or individually separated (Kent, n.d.:30). The HLR for bed oysters has been determined to fall between 1.3 and 2.0 cm. Consequently, the mean HLR of oyster valves collected from every context subject to this analysis falls within these parameters (Figure 3). In comparison, the Bassett Hall Woods site, 40BA (BW 40), located near the James River upstream from CG-19, yielded a significant amount of oyster shell, of which the bed oyster was the type most commonly found (Bradshaw, 1990:11).

One determinant of oyster valve growth type is the height/length ratio (HLR) of the shell (Kent, n.d.:30). The mean HLR of the shell ecofacts from the lab samples (See 41 Figure 2. Figure 3. 42 Figure 3), was determined from measurements recorded in Tables I-VII. Each shell, context-by-context, was measured from the dorsal end to the ventral edge to determine height. Length was established from measurements of the anterior-posterior dimension. The individual HLR is derived by using the following equation:

HLR = H/L
(with H being height and L being length)

Ribbing and Coloring

Oyster valves exposed to sunlight characteristically develop "ribs" and undergo color changes depending on the amount of sunlight and duration of exposure. It is generally assumed that intertidal areas yield a greater quantity of sand oysters (and possibly bed oysters), thus, being of a shallow water environment they are much more likely to develop strong radial ribs and exhibit a variety of colorings.

Nevertheless, even oysters which are usually found in deeper water can also display various degrees of ribbing and coloring. Grier (1920:247-285), suggests that color variation can be related to "aging, water acidity and water silt content" (Rhoads and Lutz, 1980:317) , which, coupled with changes in water level, salinity concentrations, bed or reef expansion, etc., could account for this.

The presence or absence of radial, concentric or intersecting ridges on the periostracum of each valve in the sampling was examined and assigned degrees of intensity ranging from slight to moderate, to heavy. Relationships with environmental growth types were calculated context-by-context. The distribution of ribbing for each growth type (by context) is illustrated in Figure 4.

Figure 4.

Bed oysters, the dominant growth type collected (89%), show only a very low percentage of slight ribbing (8.1%). This is unusual in comparison to oyster valves generally associated with historic and prehistoric archaeological sites in the Mid-Atlantic region (Bradshaw, 1989:21; 1990:13; 1990b:12; Egloff, et al, 1988:37; Doms and Custer, 1983:5). The prominent oyster beds located and recorded in historic time (i.e., Hampton Flats, Horsehead Rock, Point of Shoals, Nansemond Ridge, etc.), were subjected to low water levels and tidal shifts. Such action would allow for periodic exposure of the valves to the sun (Bradshaw, 1989:11). Primary oyster beds have been traced into the James River but tend to diminish at Deep Water Shoals near Fort Eustis (Haven and Fritz, 1985:272; Barber, 1992 Personal Communication). Assuming that most, if not all of the oysters harvested by the inhabitants of CG-19 derived from clustered beds in or near Grice's Run; an area that would have had limited tidal shifts, then the existing stressful environment could have prevented the development of periostracal ribbing.¹

Galtsoff (1964), notes that rapid sedimentation is quite destructive to an oyster community. Organic or inorganic solids suspended in coastal waters tend to settle to the bottom, depending on environmental conditions and water activity at the time. Water flows 44 can cause both erosion and accretion of sediments. When the direction and speed of tidal currents in an estuary change, the alternating processes of erosion and deposition occur:

"Depending on the configuration of the bottom, certain areas of an estuary are scoured, while vast quantities of sediments are deposited on others. This is typical on oyster grounds in many tidal streams (Galtsoff, 1964:410)."

The Grice's Run area is conducive to such sedimentation, particularly since that area has been significantly affected by tidal currents and changes in sea level through time (Berquist, Personal Communication, 1991). Moving sand or the deposition of mud (Möbius, 1881) or the accumulation of mud, leaves and twigs (Orton, 1937), would prevent exposures to sunlight.

It must be noted that working a shallow bed consistently over time will reduce the bed slope, allowing for a deeper water environment (Mann, personal communication, 1989). Such an environment could possibly yield a lower percentage of ribbed oyster valves.² In the case of oyster valves collected from CG-19, however, a deeper water environment is unlikely because of the size, condition, and salinity regime depicted by overall shell characteristics.

The affects of coloring in the sampling supports the argument of minimal or no exposure of the valves to the sun or variations in water depth, with little or no tidal fluctuations. The percentage of slight coloring and ribbing is identical in four of the contexts (630, 632, 671, 673). Shells from Context 696 have neither ribbing or coloring. Figure 5 defines the distribution of coloring by growth type. Periostracal color and surface textures are aspects of oyster shell analysis open for continued research into the ecological and evolutionary significance of each (Rhoads and Lutz, 1980:318).

Salinity and Environment

Salinity variability and circulation patterns in typical estuarine environments and between river and sea water is quite complex (Galtsoff, 1964:401). There can be many factors such as size, depth, bottom configuration, flow, etc., affecting salinity patterns and the convergence of water types in any specific estuary (Capper, et al, 1983:137; Galtsoff, 1964:401). Important to oyster survival and subsequently oyster shell analysis is the particular salinity regime in which the bivalve flourished. Reproductive success and continued survival of the oyster appears to be in areas of higher saline concentrations (Capper, et al, 1983:137; Haven and Fritz, 1985:271); however, the bivalve can tolerate a wide range of salinity (Alexandrowicz, 1989:4).

Since pests and parasites of oyster communities also depend on salinity variation Capper, et al (1983:137), Kent (n.d.:39), and Hopkins (1962:121-124) stress the importance of the analysis of such organisms as a salinity determinant. In theory, Kent demonstrates the possibility of salinity estimates by the identification of epibionts attached to the shell and suggests comparisons be made with living bivalves from different regimes as a part of 45 Figure 5. the analysis. Such comparisons would probably produce results on a more precise scale; however, access to and the study of living oysters for purposes of this study were not possible. Therefore, the salinity interpretations discussed here are general, yet provide adequate descriptions supported by existing epibionts present or absent on the valve samples.

The epibiont groups currently used as salinity indicators consist of the boring sponges in the genus Cliona, polychaete worms in the genus Polydora, and encrusting ectoprocts such as the bryozoan, boring clam and barnacle (Kent, n.d.:39). Cliona sponges, Polydora worms and boring clams appear to give the best interpretive evidence of salinity regime and oyster relationships. Consequently, only these three groups have been closely examined for this analysis. The presence or absence of bryozoan and barnacles was noted in the analysis.

Salinity levels have been categorized into four regimes appropriately identified as I, II, III, and IV. Regime I is the least saline with the salinity level in the water below ten parts per thousand (ppt) for at least half the year and seldom, if ever, exceeds twenty ppt. This is a stressful environment for most of the parasitic organisms (and oysters as well); therefore, oyster valves of this regime generally exhibit no boreholes (Doms and Custer, 1983:8; Kent, n.d.:41). Boring clams, Diplothyra smithii (Tryon), produce a large cavity within the oyster shell. Their presence would also indicate a fairly low salinity level.

Regime II represents salinity levels below 10 ppt for at least one-fourth of the year and below 15 ppt for half the year - periodically rising above 20 ppt. Characteristic of shells from this environment would be boreholes with diameters of 0.2-0.5 mm (incurrent) and 0.6-1.6 mm (excurrent). Small borings of this type are usually from the Cliona trutti sponges.

Regime III increases significantly in salinity with the levels sometimes dropping below 15 ppt. However, for at least one-quarter to one-half of the year the salinity rises to over 20 ppt. Both Cliona celata and Cliona trutti sponges are found associated with oysters in this regime, although the boreholes from C. trutti will usually be dominant.

In Regime IV the salinity level rarely drops below 15 ppt and most of the time is well over 20 ppt. The sponge boreholes in this case measure 0.8-2.5 mm (incurrent) and 2.0-4.5 mm (excurrent). Polydora worms generally live in subtidal mud. They are detected by "mud blisters" on the inside of a valve and/or double boreholes around the edge. Boring clams produce a large cavity within the oyster shell. Their presence would indicate a fairly low salinity level.

Overall, salinity regime I is the type of environment from which these oysters were harvested (Figure 6). There were no indications of epibiont destruction characteristic of shells from regimes II, III, or IV. This may be reasoned in several ways. The fact that the Figure 6. 47 major tributaries of Chesapeake Bay and the bay itself have a two-layered circulation pattern would be one possibility. In the lower part of the water column can be found a dense, highly saline water type that travels in a net upstream flow. A net seaward flow of fresher, less dense water is found in the upper section (Capper, 1983:137-138). It is possible that the Grice's Run area suffered the influx of seasonal freshets. Freshets, streams of fresh water invading salt water, can occur during or after long periods of rain or as a result of melting snow (Orton, 1937). Möbius (1881) noted that a shallow water environment during a severe winter is quite destructive to oyster beds. Galtsoff (1964) found that "freshets sometimes kill oysters in the James River, Virginia." An influx of fresh water also kills predators.

It is highly probable that salinity levels were reduced dramatically in and around Grice's Run as a result of severe environmental conditions. "Shells of oysters grown under unfavorable conditions are often thin and fragile (Galtsoff, 1964) ." The condition of valves collected from the features of CG-19 may be attributed to this. One hundred percent of the shells analyzed from each context exhibits those characteristics described in Regime I, with either evidence of D. smithii or no trace of epibiont activity whatsoever.

Boring clams are generally found in water with low salinity levels. The relationships in this study between Boring clams, salinity regimes, and environment show the percentage of Boring clams found within a particular valve type from a given salinity level. The following is the distribution by context for these relationships:

Based on the above data, it is assumed that most of the oystering within the periods covered by these contexts was conducted in a subtidal environment somewhere between the shore and river channel or within the cut of Grice's Run.

Season of Death and Growth Checks

An attempt was made to determine the season of death and growth checks through analysis of the shells' hinge area. The growth history of Crassostrea virginica (Gmelin) is preserved in visible morphological characteristics that developed in its shell. Seen as increments and discontinuities of growth, alternating layers of calcium carbonate and organic material produce a physiological pattern of growth history. These micro-bands are produced by the processes of shell deposition and dissolution on the ligostracum (Rhoads and Lutz, 1980).

Acetate peels were made from a total of 36 shells. The shells were selected from each context on the basis of complete HLR range. Each shell's hinge was washed in water and then allowed to soak for 24 hours in sodium hypochlorite (to dissolve organic matter). Next, shell hinges were again washed in water and then saturated with acetone. Duco cement was applied to the entire hinge area of each shell. Upon drying, shell hinges were heated to release the cement peel. Peels were secured in 2" × 2" coin holders. By magnifying the peels, "relative measurements were made of the amount of hinge growth over the three previous years prior to growth" (Doms and Custer, 1983:6). Using the following formula, these relative measurements were converted to an index of percentage of yearly growth prior to death:

• IG = a/b × 3
• IG = Index of yearly growth
• a = Growth since last winter growth check prior to death
• b = Amount of growth over three years prior to death

The index of growth for each context is as follows:

The mean index of growth for the sample of shells from each context follows:

These figures can be interpreted as the amount of time (or percentage of elapsed year) between the end of the latest winter growth check and the season of death. The IG was then multiplied by 10 (representing the months of the year, excluding January and February when there is no growth):

If a late December, early January winter growth check is assumed, the season of death depicted by the sample of shells from each context would be as follows: 49

The mean IG for the total of all contexts is .105. This would translate into a February-Early March season of death. The age at death for the oysters was determined from a growth ring count. The following is the mean age listing (in years) by context:

The shells from CG-19 are very small. Their size is inconsistent with the age at death average (4.3 years). It also indicates that the oysters were living in a very stressful environment.

Preparation of the peels was difficult for various reasons. In most cases, the quality of the shell prevented a readable peel from being produced (115 attempts with no results). Coupled with limited experience in this aspect of oyster shell analysis, the inferences made relative to season of death and age at death should be used only as a guide, since a margin of error in their interpretation may exist.

Valve Clustering

Valve clustering is important in determining habitat of some oysters, particularly those elongated forms with a height-length ratio of more than 2.0 cm. Shells of this type can be found in areas of soft mud or in large dense clusters characteristic of channels and also loosely clustered in shallow water.

Approximately 99.8% of the entire lab sampling show evidence of clustering. Context-by-context, this breaks down as follows:

When clustered oysters were collected, the clusters had to be transported back to land. Since the makeup of clusters includes both live and "dead" shells, these required separation once on shore. It is very likely that the inconvenience of harvesting, transporting and separating clustered oyster types marked these types as the least desireable, yet because of desperation for survival, any inconvenience was tolerated. This also supports the theory that environmental conditions at the time or during a portion of the time CG-19 was inhabited reduced the reliance on hunting and gathering.

Preparation Techniques

The two general methods used for opening oysters depend largely on whether or not there is a preference to having the oyster meats cooked or raw (Kent, n.d.:55). A further breakdown of these two general methods involve the actual techniques used in either category. For instance, to open oysters without cooking them, various shucking techniques are employed individually or in combination with one another:

• 1.Stabbing
• 2.Hammering
• 3.Cracking

To open oysters while preparing a cooked meal at the same time, they can be roasted, steamed or boiled. Although a number of the shells examined were scorched (n=296), and roasting will leave scorch marks (Kent, n.d.:55), it was determined that none of the total valves had actually been prepared in this manner. All of the shells that were partiallly or totally burned were also shucked by either of the previously described mechanical methods. There would be no reason to employ these opening methods on roasted oysters since they would automatically open while cooking.

The cracking method appears to have been the most popular since 81.9% (n=769) of the total analyzed oyster shells were opened this way. Using the cracking method in prehistoric periods probably required a flat, reworked biface since round stones cannot produce the type of breaks noted in this sampling. Stabbing methods (knife, hatchet, etc.) were used on 7.7% (n=72) of the valves. The remaining 10.4% yielded no evidence of shucking. None of the shells showed signs of both stabbing and cracking. The following is a breakdown by context (in percentages) of shucking techniques:

Results of Analysis

Several trends emerge from the analysis of oyster shell sampled from 44JC659, including methods of preparation for consumption, use of discarded shell, condition of shell, habitat, and method of harvesting.

Careful analysis indicates that the majority of shells were shucked to retrieve the meat of the oyster. The serving of raw oysters is assumed since roasting or steaming does not require the process of shucking.³ Oysters used by the inhabitants of CG-19 were probably 51 collected between late Fall and early Spring. Summertime is the spawning period for oysters and meats are gritty and lack flavor (Jackson, 1988:62). Between August and November, oysters have a higher glycogen level that is stored during the previous summer months. This results in a higher energy-producing food than at any other time (Russell, 1923:9). Another factor that can be attributed to the seasonality of eating oysters is the bivalve's response to salinity levels. The lower the salinity, the more water is absorbed, causing the oyster to swell. In June through October, osmotic pressure causes an increase in salinity and the opposite effect occurs.

In the historic period, oyster shell has proven its worth agriculturally and industrially as a source of lime. Its use in fertilizer and as an agent for acidity reduction of the soil has been widespread (Ingersoll, 1881:563-64). Glassmaking efforts in the 17th and 18th centuries used oyster shell by-products as a flux, where the lime would be mixed with sand, soda ash, and potash (Hudson, 1967:89). Crushed and whole oyster shell has been popular in building construction, roadways, walkways, and drainage systems. Use of oyster shells in prehistoric periods can only be inferred based on some shell-type artifacts and the notion of human posibility. Since empirical evidence for shell use in any manner from the shells of these contexts is nonexistent, the research for this study falls short of delving into this interesting aspect of analysis.

The condition of shells from 44JC659 can be attributed to many factors, mechanical and chemical, through time. Most of the surface and structural degradation appears to be the results of mineralization and erosion. Causal factors for actual breakage can be derived from the excavation itself, reckless shucking techniques, freezing and thawing, careless handling at the time of harvest and handling during subsequent processes. Specifically, though not comprehensive, the following chart illustrates some possibilities for physical and chemical change through time (Bradshaw, 1989:12-15):

In many instances the information stored in the shell during the oyster's life is lost through physical degradation and/or chemical alteration (Kent, n.d.:9-16). Specifically, the physical breakdown of a shell begins the moment it is discarded and continues, depending on the subsequent mechanical activity it is exposed to. Kent (n.d.) cites continued human habitation and related processes such as "tramping, plowing, compaction [as in a midden or trash pit] and excavation" as examples of activities that tend to alter discarded valves without producing any chemical change.

Further physical destruction occurs with the activities of plants, animals, burrowing organisms and insects. Natural processes such as freezing, thawing, drying, wind and water erosion, are all factors that play an important role in the mechanical destruction of discarded oyster valves through time.

Chemical alteration of discarded oyster shells incorporates a complex combination of substance conversions, both organic and inorganic:

• 1.Organic
  Mucopolysaccharides, polypeptides and scleroproteins which constitute conchiolin (Kent, n.d.:11).
• 2.Inorganic
  Mineralogical variation and alteration of calcareous prismatic microstructures. Rhoads and Lutz (1980:100) state that "virtually all mineralogical variations in bivalve shells are associated with at least minor changes in shell architecture or micro-structure."

These conversions occur through dissolution, bacterial decomposition, oxidation, combustion, permineralization, paramorphic substitution, paramorphic transformation and recrystallization (Kent, n.d.:11-16; Rhoads and Lutz, 1980:69-162). An understanding of the chemical modifications of oyster valves is integral to the complete and in-depth shell analysis, as is a complete mineralogical evaluation; however, a full discussion of these processes is beyond the scope of this study.

The reasons why shells may or may not remain intact through generations of time go well beyond those previously cited and are tricky, if not virtually impossible to determine. Since the accumulation of shell in all features of CG-19 were susceptible to the action of ground water and the ground water in and around that particular site is considerably acidic; coupled with the fragility of shells from a stressful environment, it is not unreasonable to 53 infer that the resultant leaching process was the primary cause of chemical alteration and subsequent shell degradation. Additionally, shell middens sometimes have a significant accumulation of human-made debris (broken pottery, lithic debitage and tools, etc., depending on the time period), which could account for some shell breakage during the time of disposal. Also, the overlying weight of additional accumulations could compact the shell midden or shell scatter, creating a degree of stress, thus promoting breakage. The condition of shells from CG-19 suggest that they were not structurally sound enough to withstand a substantial rate of compaction.

An average total of 89% of the valve sampling have been classified as the Bed oyster growth type, commonly found in an environment of mixed sand and mud. A muddy subtidal environment cannot be confirmed, however, since evidence of Polydora worm boreholes and "mud blisters" was nonexistent on the excavated shells. Slightly over 8% of the shells exhibited slight ribbing and coloring with 99.8% scarred from clustering. These factors tend to corroborate the suggestion of a change from the normal subtidal environment.

Only 9.5% (mean) of the total sampling was classified as Sand oysters, 1.4% as the Channel type and 0% as Reef oysters. This indicates that the majority of oysters were neither from the intertidal waters of the shoreline or from very deep waters.

Considering the termination of extensive oyster beds in the James River at or near Deep Water Shoals (a considerable distance from CG-19 on foot), unfavorable environmental conditions as depicted by shell characteristics, the dominance of Bed oyster valves in all archaeological contexts evaluated, and the HLR distribution, it can be argued that the source for most, if not all of the oysters collected by the inhabitants of site 44JC659 during the Middle Woodland Period, was a densely clustered flat - probably existing in the waters of Grice's Run.

Ingersoll (1881:512), noted that Sand oysters were probably the type most frequently acquired and used by Native Americans and colonists of the 17th century. This was because the oysters were plentiful and could be easily collected by hand along the shorelines. It is apparant, then, that at some point between 200-900 A.D., some type of environmental devastation occurred; otherwise, Sand oysters would have probably been preferred and their valves would dominate the midden and associated features.

Hand gathering was probably the only method used to harvest oysters from the Grice's Run flat(s). This method poses little difficulty since estimates show a group of 40-50 individuals can gather by hand approximately 60,000 oysters in 2 hours (Möbius, 1881:739).