Identifying Grog In Archaeological Pottery

1

IDENTIFYING GROG IN ARCHAEOLOGICAL POTTERY

By Joseph M. Herbert and Michael S. Smith

Paper submitted at the First Annual Conference, Reconstructive/Experimental Archaeology,

Gastonia, NC

October, 2010

Joseph M. Herbert, Cultural Resources Management Program, IMSE-BRG-DPW (HERBERT), 2175 Reilly Road, Stop A, Fort Bragg, NC 28310-5000, [email protected].

Michael S. Smith, Department of Geography and Geology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403-5944, [email protected].

2

ABSTRACT

Constructing ceramic sequences by assigning pottery samples to types that relate to specific

geographic regions and time periods is an important archaeological tool for understanding

prehistoric culture. Many regional sequences of Woodland period pottery in the Southeastern

U.S. include grog-tempered types, and often the identification of grog is a sufficient condition

for classifying a potsherd to a particular type. The identification of grog in archaeological

pottery, however, is not a straightforward process. To the archaeologist, grog is pulverized or

crushed ceramic material that is added to clay by the potter to change the clay’s workability or

firing properties; however, natural clay often includes lumps, such as clay clasts, argillaceous

fragments, or hematitic clots that can closely resemble grog. Distinguishing among naturally

occurring clay lumps and grog can be difficult even microscopically in thin section. This paper

describes a petrographic analysis of grog-tempered pottery replicated under anthropologically

appropriate experimental conditions that was designed to establish a baseline inventory of the

visual characteristics.

3

INTRODUCTION

Precontact period archaeological pottery sequences from the North American Atlantic

Coastal Plain include several grog-tempered types such as San Pedro (a Contact period type

associated with 17th

century Spanish missions in Florida and southern Georgia), Wilmington and

St. Catherines (Middle and Late Woodland types from South Carolina), Hanover (a Middle and

Late Woodland type from North Carolina), Croaker Landing (an Early Woodland type from

northern North Carolina and southern Virginia) and Coulbourn (a Middle Woodland type from

Maryland and Delaware). The key characteristic used to classify pottery to these types is the

presence of grog particles included in the ceramic paste, usually observed in the broken cross

sections of potsherds, sometimes aided with a 10-x hand lens. The problem arises when

ceramicists have difficulty distinguishing among naturally occurring clay clasts, mineralized

lumps, hematitic concretions, and crushed ceramic used as grog temper. When these aplastic

materials appear similar in hand samples ambiguity is encountered in the sorting process and the

misidentification of anthropological grog is possible.

This paper describes the experimental replication of ceramic briquettes tempered with grog

made with clay from several different sources, and the comparison of these briquettes to

archaeological samples of Hanover series pottery from the Coastal Plain of North Carolina. This

experiment was designed to provide baseline information characterizing the visual properties of

grog, and to allow comparison of experimentally produced and archaeological grog-tempered

pottery.

4

RESEARCH PROBLEM

In Americanist archaeology the word temper is used to designate nonplastic materials added

to clay by the potter to counteract shrinkage and cracking during drying and firing (Shepard

1985:24–25). It is often thought that temper acts a binder, strengthening the plastic clay body,

but generally speaking the addition of nonplastic particles to clay actually weakens the body, as

the bond between clay particles and nonplastic particles is weaker than that among clay particles

themselves. The value of adding grog or any nonplastic temper is that it enhances uniform

evaporation of moisture from the core to the surfaces and moderates excessive shrinkage, thus

reducing the likelihood of cracking during drying and firing. Grog is one type of temper made of

crushed or ground ceramic material added to clay to modify its properties (Rice 1987:476). As

the presence of grog in prehistoric Native American pottery is a key feature for the classification

of several archaeological types, it is critical that it be accurately identified.

The potential exists for naturally formed clay clasts, or argillaceous mineralized concretions,

to be misidentified as grog. In experiments involving clay slaking, Owen Rye (1981:36) noted

that montmorillonite clay (in the smectite group) did not slake well, but tended to form lumps

when minerals at the surface of clots swelled rapidly as water was added, preventing moisture

from penetrating the clots. Atlantic Coastal Plain clay deposits in sedimentary contexts whose

source rivers are contained within the Coastal Plain are rich in montmorillonite (Neiheisel and

Weaver 1967:1085; Steponaitis et al. 1996:564; Windom et al. 1971: 500). This suggests that

clay with rapid or extreme swelling properties that exist in deposits across the coastal region may

naturally create clots when wetted, producing pastes with clay-clast inclusions.

5

Another challenge in identifying grog is the presence of argillaceous or mineralized

concretions. Such mineral concretions are commonly observed in Coastal Plain clays and are

routinely found in locally made pottery. Daniel (1999:113, Figures 4.1 and 4.2) describes the

presence of “the ferric concretion limonite” in clay deposits and sherds found on the coast of

Onslow County and it is assumed, quite rightly, that such lumps are incidental to the tempering

process. Europeanist archaeologists have taken pains to distinguish naturally occurring

“argillaceous inclusions” from grog in pottery from prehistoric Aegean and Roman sites in Italy

and elsewhere (Cuomo di Caprio and Vaughan 1993; Whitbread 1986, 1989) and have described

the differences in quite explicit terms. Despite this effort, there continues to be some confusion

in distinguishing grog from argillaceous inclusions in hand samples, echoing Shepard’s warnings

of the challenges of positively identifying grog without thin sections (Shepard 1985: 406–407,

438–439).

The description of grog-tempered pottery by archaeologists working in coastal North

Carolina in the mid 1970s reflects some uncertainty about the nature of grog, when the

descriptive term “clay-tempered” crept into use as a means of characterizing sherds tempered

with something that looked like grog, but was not conclusively identifiable as crushed pottery.

Loftfield (1976:154) described the temper found in the Carteret series in the following way:

The temper consists of intentional inclusions of aplastic clay. These were either old

sherds or fire-hardened pieces of clay added to the wet, plastic clay of which the vessel

was formed. The pieces of aplastic tended in the construction process to begin to soften

and lose definition in relation to the plastic portion of the paste. Consequently it is

difficult to measure the size of the inclusions or to determine much about their original

condition.

6

This is an interesting characterization as it suggests that grog may be made from either

crushed pottery or any “aplastic clay” mass. The description implies some difficulty in

distinguishing between sherd and fired-clay grog particles, suggesting that fired-clay grog

“softens and looses definition” when it is added to wet clay paste. This proposal had the effect

of expanding the definition of the Hanover series (or in Loftfield’s sequence, the Carteret series)

to include “clay-tempered” pottery, thereby raising another set of questions concerning the

properties of dried clay added as temper.

Subsequently archaeologists working in other areas of the Atlantic coastal region began to

conclude that the identification of grog was perhaps more complicated than initially conceived.

Espenshade (1996:44) for example argued for a tripartite classification system including (1)

sherd-tempered bodies with discernible crushed sherds, (2) grog-tempered bodies with distinct

clay lump inclusions, and (3) clay-tempered bodies with indeterminate grog temper where sherd

or clay lumps are present. Although this solution is more nuanced, the classificatory distinctions

are not clear, and the terms are problematic. Grog has long been understood as crushed sherds,

ground brick, tile, or other fired product (Rice 1987:74,409; Rye 1981:33; Shepard 1956:25), and

we really have no idea what might be meant by clay tempered bodies. Were prehistoric potters

crushing masses of dried clay into fragments that were added to potting clay? Is “fire-hardened

clay” to be understood as ceramic material or perhaps simply clay baked at temperatures not

sufficient to create ceramics?

Other researchers (Herbert 2003, 2009) have chose to split the class “grog” into two

categories, (1) clay lumps distinguished from the surrounding matrix primarily by contrasting

color and texture, and (2) grog inclusions with observable remnant sherd surfaces. Although this

distinction was attempted in the analysis of a large sample of sherds from the Carolina coast, it

7

was determined that ceramic and nonceramic grog inclusions could not distinguished with any

confidence, as only the most obvious examples of crushed sherd inclusions (those with remnant

surfaces) were positively identifiable.

Similar problems have been encountered with grog-tempered pottery from sites on the

Atlantic coast of Florida. In describing the San Pedro pottery type Ashley and Rolland (1997:56)

draw the distinction between clay and ceramic-grog temper, noting that “San Pedro series pottery

used crushed fired clay as temper.” In addition to San Pedro, Ashley and Rolland (1997:61)

analyzed other sherd-, grog-, and clay-tempered pottery found on Florida coastal sites, noting

that it was “difficult to determine whether these sherds were indeed tempered with prefired clay

(e.g., crushed potsherds) or instead contained lumps of dried clay. Thus, and explicit distinction

needs to be made between these two types of clay inclusions when classifying grog-tempered

sherds.” Also working in this geographic area, Saffer (1979:24–25) came to a similar

conclusion remarking that, “Lumps of clay in paste, as opposed to ground sherd, may be the

result of insufficient grinding of the clay prior to its use in the vessel.” Saffer (1979:24–25) also

observed that, “In some coastal clays…the lumps are commonplace. These clays are very hard

when dried and very difficult to grind. Thus, it bears noting that what has been called “sherd

tempereing” may not be deliberately added pieces of sherds, but lumps of clay.”

Following Cuomo di Caprio and Vaughan (1993: 25, Table 1) and Whibread (1986), grog

should be distinguishable by such characteristics as particle angularity, presence of a shrink rim,

internal micro-structure, composition distinct from the host matrix, difference in proportion and

sorting of grain sizes, the distribution and proportion of inclusions within host matrix, color, and

presence of remnant vessel surfaces. In addition to the fact that most of these distinguishing

characteristics can only be recognized through petrographic analysis, small size and low

8

proportion of grog particles may prevent recognition in weathered cross sections, even with the

aid of a microscopic. In one petrographic study of Lowland Maya pottery, grog particles were

typically less than one millimeter in size and relatively infrequent (Jones 1986:20). A

petrographic analysis of pottery samples from sites in the North Carolina Sandhills and

surrounding area (Herbert et al. 2003) discovered that many sherds contained fine- to granule-

size grog particles in proportions from 3–15 percent, occasionally found alongside what

appeared to be clay lumps also ranging in size from fine to granule size. These results suggest

that the distinction between crushed sherds and clay lumps is difficult with petrographic

techniques, and probably very unreliable in a hand sample. Nevertheless, the accurate

identification of grog and clay clasts is a critical if a distinction is to be made between natural

and cultural artifacts.

At this juncture readers may be asking, why should we be concerned with distinguishing clay

lumps from crushed sherds anyway? Perhaps the most important reason is that the chain of

technical operations used to prepare the two tempering agents stands to be quite different and

may therefore be linked to different prehistoric communities of cultural practice. One might

expect the process for preparing grog to be well understood in archaeological context and fully

documented ethnograpically, but in fact specific information is scarce. Although materials-

science based studies have discussed the theoretical advantages of grog-tempered pottery in

terms of pottery performance characteristics (Rice 1987:229–230; Rye 1976:117; Steponaitis

1984:111), there are few studies from the Eastern Woodlands that present explicit descriptions of

grog, or consider the ways in which naturally occurring argillaceous clots may be mistaken for

grog.

9

Problem Summary

Grog-tempered pottery is used the archaeological index fossil for culture periods and

assemblages from coastal North Carolina to Florida. Pottery such as Hanover, Wilmigton, St.

Catherines, Colorinda, and San Pedro are classified to their type series based on the presence of

grog. Grog is defined as crushed ceramic material added as temper to raw clay. The

identification of grog in pottery samples is most often made in broken cross section, either

macroscopically or with a hand lens. Over the years archaeologists have registered uncertainty

in positively identifying grog as cross sections often appear to be lumpy, but with no clear

evidence that the observed lumps are particles of crushed ceramics.

Research Design

The current research is designed to resolve ambiguity concerning the identification of grog.

This project is envisioned as proceeding in three stages. The first stage, which we are reporting

on today, provides baseline comparative data consisting of the visual properties of grog- and

clay-tempered pottery. This is accomplished in two ways: first, through the implementation of

microscopic analysis of flat and thin sections, and second, by the comparison of archaeological

grog-tempered pottery and ceramic test tiles, or briquettes, tempered with crushed ceramics and

dried clay. The second and third stages, which have not yet been undertaken, will consist of

collecting a representative group of clay samples from the Atlantic Coastal Plain to determine the

commonness of naturally lumpy or heterogeneous clays, and when made into pottery, the

likelihood of mistaking such clay for its grog-tempered counterpart. The third stage will consist

10

of compiling a collection of relevant archaeological grog-tempered pottery from the study area

for comparison.

Sample Parameters

The flat- and thin-sections of archaeological pottery analyzed for this study were drawn from

a collection that was compiled as part of a recent research project designed to identify the

geographic sources of pottery and clay in and around the North Carolina Sandhills (Herbert and

McReynolds 2008). The Hanover pottery examined was from four sites: the Breece site in the

upper Coastal Plain, the Waccamaw on Lake Waccamaw in the lower Coastal Plain, the Kolb

site on the Pee Dee River in the upper Coastal Plain of South Carolina, the Haw River site on the

Haw River in the North Carolina Piedmont, and from several Fort Bragg sites in the Sandhills.

Test briquettes were made from three clay sources located near the archaeological sites from

which the pottery was drawn. These include clay from a source near the Haw River site, clay

from a source near the Waccamaw site, and clay from the area near the Kolb site on the Pee Dee

River. Clay from each of these sources was fired to make ceramic objects, and air dried to

make hardened clay objects, then crushed into grog and added as temper to each of the three clay

types.

The resulting sample of 21 briquettes consisted of nine grog-tempered, nine clay-tempered,

and three nontempered controls. Ceramic grog or clay fragments were added to the paste of each

of the three clay types in 20 percent proportion, measured by weight. This proportion

approximates that observed in Hanover pottery analyzed in the sourcing study (Herbert and

McReynolds 2008). Briquettes were made in a mold, 10-x-5-x-1-cm in size, then removed and

11

dried for a week, after which time they were fired in an open fire with no attempt to control the

firing atmosphere.

Methods of Analysis

The pottery and test tiles for this study were analyzed with two techniques: using a binocular

microscope with incident light to observe flat sections, and using a petrographic microscope with

transmitted light to observe thin sections. Pottery and replica briquettes were submitted to a

commercial firm for thin sectioning. As part of the thin-sectioning process the ceramic samples

were encased in epoxy under vacuum. The resulting pucks were cut to produce thin sections and

the faces of the pucks from which the sections were cut provided the flat sections.

The method used to identify grog as opposed to naturally occurring argillaceous clay

fragments (ACF) followed the experimental work of Cuomo Di Caprio and Vaughan (1993) and

Whitbread (1986) with European pottery (we call this the European experiment). The relevant

criteria identified by these researchers were: (1) particle angularity, (2) presence of shrink rim,

(3) internal microstructure and mineral composition distinct from the host matrix, (4) consistency

of particle size, (5) consistency of spatial distribution of particles, and (6) particle color. In the

European experiment, as in ours, clay was air dried, crushed, and added to clay briquettes,

however, the European experimenters added clay fragments in order to model raw clay that

naturally included argillaceous fragments. In our case, we added clay fragments in order to

model clay grog, assuming that natural argillaceous fragments would take yet another form.

12

SUMMARY OF RESULTS

Analysis of the pottery indicates that there is indeed variability among the samples in the

degree of contrast between grog particles and the ceramic host matrix. Poor contrast results in

difficulty distinguishing between grog particles and matrix in both flat and thin section, and the

difficulty seems most pronounced under three circumstances: (1) when the grog and the host

matrix clay types are the same (isomorphic), (2) when the grog particles occur in low frequency

and small size, and (3) when grog is introduced to clay that is only minimally mixed and is

consequently folded or contorted in cross section.

With reference to the European experiment, our observations are as follows:

1. particle angularity: grog is more angular than clay

2. shrink rim: rim is more pronounced with clay than with grog

3. internal microstructure: no difference was observed in internal microstructure of grog vs.

clay

4. consistency of particle size: no difference was observed in size sorting between grog vs. clay

5. spatial distribution: no difference was observed in spatial distribution of grog vs. clay

6. color: grog was found to have a wide range of colors relating to firing atmosphere, while clay

exhibited less variation.

Regarding the European experiment, we should note that there is a little added complexity in

the present study. In the replication experiments of Cuomo Di Caprio and Vaughan (1993),

crushed dried clay was added in order to mimic or model natural argillaceous clay fragments

(ACF). In the present experiment, crushed dried clay was added to model the possibility that the

prehistoric potters were actually adding dried clay as temper. We therefore expect to find that

13

argillaceous clay fragments look different from the clay used in this experiment. This means that

there are actually four categories of particles that we are attempting to sort out: (1) ceramic grog,

(2) clay added as grog, (3) argillaceous clay fragments, and (4) hematite-stained clots. The

comparative sample compiled for this phase of the study gives us a good idea of the range of

visual characteristics of categories grog, clay and hematite clots, but not category argillaceous

clay fragments. We hope that it will be possible to document the distinguishing characteristics

of ACF in the next phase of research when it will be our task to find as many sources as possible

of lumpy (ACF-laden) clay from Atlantic Coastal Plain deposits.

14

REFERENCES CITED

Ashley, Keith H., and Vicki L. Rolland

1997 Grog-tempered Pottery in the Mocama Province. The Florida Anthropologist

50(2):51–65.

Cuomo di Caprio, Nina, and Sarah Vaughan

1993 An Experimental Study in Distinguishing Grog (Chamotte) from Argillaceous

Inclusions in Ceramic Thin Sections. Archaeomaterials 7:21–40.

Daniel, I. Randolf, Jr.

1999 Archaeological Excavations at Hammocks Beach West (31On665): A Woodland

Shell Midden on the North Carolina Coast. Occasional Papers of the Phelps Archaeology

Laboratory, No. 1. East Carolina University, Greenville.

Espenshade, Christopher T.

1996 South Carolina Prehistoric Pottery: Reflections on the 1995 Conference at

Georgetown, S.C. In Indian Pottery of the Carolinas: Observation from the March 1995

Ceramic Workshop at Hobcaw Barony. Edited by D. G. Anderson, J. S. Cable, N. Taylor, and

C. Judge, pp. 42–52. Council of South Carolina Professional Archaeologists.

Herbert, Joseph M.

2009 Woodland Potters and Archaeological Ceramics of the North Carolina Coast.

University of Alabama Press.

15

2003 Woodland Ceramics and Social Boundaries of Coastal North Carolina.

Unpublished Ph.D. dissertation, Department of Anthropology, University of North Carolina,

Chapel Hill.

Herbert, Joseph M., James K. Feathers, and Ann S. Cordell

2002 Building Ceramic Chronologies with Thermoluminescence Dating: A Case Study

from the Carolina Sandhills. Southeastern Archaeology 21(1):92–108.

Herbert, Joseph M., and Theresa R. McReynolds

2008 Woodland Pottery and Clay Sourcing in the Carolina Sandhills. Research Report

No. 27, Research Laboratories of Archaeology, University of North Carolina, Chapel Hill.

Jones, Lea D.

1986 Lowland Maya Pottery: The Place of Petrological Analysis. BAR International

Series 288, Oxford.

Loftfield, Thomas C.

1976 A Brief and True Report . . . : An Archaeological Interpretation of the Southern

North Carolina Coast. Unpublished Ph.D. dissertation, Department of Anthropology, University

of North Carolina, Chapel Hill.

Neiheisel, J., and C. E. Weaver

1967 Transport and Deposition of Clay Minerals, Southeastern United States. Journal

of Sedimentary Petrology 37:1084–1116.

16

Rice, Prudence M.

1987 Pottery Analysis: A Sourcebook. University of Chicago Press, Chicago.

Rye, Owen S.

1976 Keeping Your Temper under Control: Materials and the Manufacture of Papuan

Potter. Archaeology and Physical Anthropology in Oceania 11(2):106–137.

1981 Pottery Technology: Principles and Reconstruction. Taraxacum, WA.

Safer, Marion

1979 Aboriginal Clay Resource Utilization of the Georgia Coast. M.A. thesis,

Department of Anthropology, University of Florida, Gainesville.

Shepard, Anna O.

1985 Ceramics for the Archaeologist. Braun-Brumfield, Inc., Ann Arbor. Originally

published 1956, Publication No. 609, Carnegie Institution of Washington, Washington, D.C.

Steponaitis, V., M. J. Blackman, and H. Neff

1996 Large-Scale Compositional Patterns in the Chemical Composition of

Mississippian Pottery. American Antiquity 61:555–572.

Whitbred, I. K.

1986 The Characterization of Argillaceous Inclusions in Ceramic Thin Sections.

Archaeometry 28:79–88.

1989 A Proposal for the Systematic Descriptions of Thin Sections Towards the Study

of Ancient Ceramic Technology. In Proceedings of the 25th International Symposium

(Archaeometry), edited by Y. Maniatis, pp. 127–138. Elsevier, Amsterdam.

17

Windom, H. L., W. J. Neal, and K. C. Beck

1971 Mineralogy of Sediments in Three Georgia Estuaries. Journal of Sedimentary

Petrology 41:497–504.

IDENTIFYING GROG IN ARCHAEOLOGICAL POTTERYJoseph M. Herbert and Michael S. Smith

You call that grog?

Cultural Resources Management Program, Fort Bragg, NCDepartment of Geography and Geology, University of North Carolina-Wilmington, NC

From Herbert and McReynolds 2009

Waccamaw (upper) and Haw River (lower) ceramic objects used for making grog.

Pee Dee (upper and Waccamaw(lower) nonfired clay objects used formaking crushed clay-grog.

Crushed nonfired clay-grog; note uniformity of color.

Replica briquette samples

(1) particle angularity(2) presence of shrink rim(3) microstructure and mineral composition

distinct from the host matrix(4) of particle size(5) of spatial distribution of particles, and (6) color

Adapted from: Cuomo Di Caprio and Vaughan (1993) and Whitbread (1986)

Criteria for Identifying Grog

Grog-tempered pottery on the sorting tray

Hanover Fabric Impressed, var. 2 (31HK103)

Interior surface of sherd Cross section of sherd

Quick, flat section of sherd

Hanover Fabric Impressed, var. 4 (31HK123)



Hanover Cord Marked (31HK59)



Grog-tempered pottery in flat section

<25% grog

JMH005

25-50% grog

JMH002

JMH004

<25% grog

>50% grog

JMH001

Flat sections: Lower Little River (Ft Bragg) grog-tempered pottery

25-50% grog

JMH012

25-50% grog

JMH011

Flat sections: Lumber River (Camp Mackall) grog-tempered pottery

<25% grog/sand

JMH024

<25% sand/grog

JMH028

<25% sand/grog

JMH027

JMH030

25-50% grog/sand

Flat sections: Cape Fear River (Breece site) grog-tempered pottery

25-50% grog

JMH063

<25% clay/sand

JMH068

25-50% grog/sand

JMH065

JMH064

25-50% grog

Flat sections: Lumber River (Waccamaw site) grog-tempered pottery

25-50% grog/quartz

JMH052

<25% clay/sand

JMH068JMH060

JMH053

25-50% quartz/grog

JMH052 and JMH053 are classified as Yadkin/Hanover, a provisional type.

Flat sections: Pee Dee River (Kolb site) grog-tempered pottery

Grog-tempered pottery; problems in identification

25-50% grog/quartz

JMH047

JMH05325-50% quartz/grog

<25% grog/sand

JMH024

JMH068

25-50% grog/sand

You call that grog?

Flat sections: grog-tempered pottery

JMH060JMH060

JMH060

Thin sections: Waccamaw and Pee Dee River grog-tempered pottery

JMH068

Hematitic clotsArgillaceous fragments

Raw clay, no temper 10% non-local grog

10% non-local grog 10% non-local grog

Thin Sections: Cape Fear River (Breece site) clay briquettes

FBR 11.1

FBR 11.2 FBR 11.2

FBR 11.2

Hematitic clots

FBR 27.1FBR 23.1

Thin Sections: Pee Dee River (Kolb site) clay briquettes

Raw clay, no temper

FBR 23.3

10% local grog (ppl)

Raw clay, no temper

FBR029

Sand tempered, no grog

Hematitic clots

Grog-, and clay-tempered briquettes in flat and thin section

Flat sections: Haw River clay plus grog

nontempered 20% grog, Haw River source

20% grog, Waccamaw River source 20% grog, Pee Dee River source

I-01

I-04 I-06

I-02

Thin sections: Haw River clay plus grog

nontempered 20% grog, Haw River source


I-01

I-04 I-06

I-02

nontempered 20% clay, Haw River source

20% clay, Waccamaw River source 20% clay, Pee Dee River source

Flat sections: Haw River clay plus dried clay

I-01

I-05

I-03

I-07

nontempered 20% clay, Haw River source


Thin sections: Haw River clay plus dried clay

I-01

I-05

I-03

I-07

Flat sections: Waccamaw clay plus grog

20% grog, Haw River source


nontempered

EXPLODED

I-08

I-11

I-09

I-13

Thin sections: Waccamaw clay plus grog



nontempered

EXPLODED

I-08

I-11

I-09

I-13

Flat sections: Waccamaw clay plus dried clay

20% clay, Haw River source


nontempered

EXPLODED

I-08

I-12

I-10

I-14

Thin sections: Waccamaw clay plus dried clay



nontempered

EXPLODED

I-08

I-12

I-10

I-14

Flat sections: Pee Dee clay plus grog



nontempered

EXPLODED

I-15

I-18

I-16

I-20

Thin sections: Pee Dee clay plus grog



nontempered

EXPLODED

I-15

I-18

I-16

I-20

Flat sections: Pee Dee clay plus dried clay



nontempered

EXPLODED

EXPLODED

I-15

I-19

I-17

I-21

Thin sections: Pee Dee clay plus dried clay



nontempered

EXPLODED

EXPLODED

I-15

I-19

I-17

I-21

Summary of results

1. particle angularity: grog is more angular than clay 2. shrink rim: rim is more pronounced with clay than with

grog3. internal microstructure: no difference was observed in

internal microstructure of grog vs. clay4. consistency of particle size: no difference was observed in

size sorting between grog vs. clay5. spatial distribution: no difference was observed in spatial

distribution of grog vs. clay6. color: grog was found to have a wide range of colors

relating to firing atmosphere, while clay exhibited less variation.

Summary of Results

Documents

Identifying Grog In Archaeological Pottery