Marine Shell Tools

Along the Texas coast where access to raw materials for stone working was relatively scare, enterprising aboriginals made tools out of the toughest material at hand—marine shell.  Implements manufactured from shell were used for a wide variety of kitchen tasks, animal and plant processing, and woodworking.  The more durable species of whelk and sturdy clam shells were adaptable to precise modification while others, may have been picked up, sharpened, and used on the spot for expedient cutting and scraping tasks and then discarded.

Lightning whelk (Busycon perversum), common rangia (Rangia cuneata), sunray venus (Macrocallista nimbosa), and oyster (Crassostrea virginica) were the species most commonly worked.  These, and occasionally a few other species of bivalves and gastropods, were fashioned into many essential tools:  scrapers, knives, projectile points, net weights, gouges, adzes, hoes, vessels, scoops, containers, fish hooks, barbs, and weaving tools. The use of marine shells along the Texas coast is part of a much broader widespread pattern along the shores of the Gulf of Mexico and the Caribbean.

In Texas the geographic range of different species plays a role in the types of tools found in archaeological contexts.  For example, in the warmer waters of south Texas, sunray venus bivalves and the robust whelk columella tools (made from the sturdy, central column after the outer whorl has been removed) are more prevalent than on the Upper Texas coast.  In general, there is a north-south gradient of increasing salinity along the Texas coast, due to dryer climate to the south which results in less freshwater inflows into coastal bay/estuarine systems.  Because of this, low to moderate salinity oysters predominate to the north, while higher salinity bivalves and gastropods are more abundant toward Corpus Christi Bay. In the central and upper coast, rangia are found clustered in dense beds in the brackish water of the marshland estuarine zones along the lower stretches of rivers and streams entering bays.

Common Rangia:  Alteration patterns seen on Rangia cuneata bivalves may be attributable to direct or indirect human activity. Some valves may have been used as is as expedient fish scalers, while others that show patterns of nicks, notches and cut marks on their margins probably resulted from human shucking activity, or simply from natural breakage in the shell midden.  Because these brackish-water clams were major food resources and most easily opened by briefly heating them in small fires (hearths), many rangia shells have been burned, which weakens the shell. Another reason rangia are often found in relatively poor condition is because discarded rangia shells are found in dense accumulations (shell middens) that were no doubt tromped on and deteriorated as the exposed shell deposits weathered.

Thus it is not surprising that patterns of natural and intentional modification are sometimes hard to distinguish. This is especially true for perforated valves because the holes can result from either natural predation, or from human alteration. Of the perforated rangia found at the Guadalupe Bay site on the central coast, only the larger sized valves had holes consistently located on the upper posterior portion of the shell body. Whether or not the holes were intentionally or naturally drilled may not really matter because these perforations provided fisherman or hunters an easy way to use the shells for net weights or bolo weight.  Also, the holes allowed the bivalves to be tied together with cordage for a variety of functional and ritual uses.

Oyster:  The Crassostrea virginica species of oyster inhabits bays and estuaries along North America’s eastern seaboard, the Gulf states, Mexico, and the West Indies. Oyster tools have been found primarily in middens along the shores and barrier islands in the upper and central Texas coast, but are less frequently reported for the lower coast. Harvested primarily as a food source, the shell was only secondarily put to functional tasks. Naturally robust, oyster shell would have held up well to casual modification.  Cabeza de Vaca may have offered oyster tools as trade items on his inland journeys as a trader.

Oyster shells were used as knives, scrapers, net weighs, awls, or possibly as hafted digging tools.  Used in such ways, they exhibit a combination of notches, nicks and cut edges along one or more margins. Man-made alterations differ from naturally abraded oyster shells, which tend to exhibit smoothing over the entire valve surface. 

Rangia cuneata shells from the Guadalupe Bay site exhibiting edge damage patterns interpreted as resulting from shucking. (Most clam shells do not have edge damage, suggesting that most clams were opened by heating. Adapted from Weinstein 2002, Figure 9-8.



Rangia shell with intentional perforation, suggesting it was used as a net weight. Adapted from Weinstein 2002, Figure 9-9.

Lightening whelk hammer from the Johnson site on Copano Bay. TARL Archives.

Oyster shell tools from the Guadalupe Bay site and a site on Matagorda Bay (upper right).

Perforated oyster shells from the Guadalupe Bay site. Such artifacts are found at many coastal sites and are thought to have been used as fishing net weights. Adapted from Weinstein 2002, Figure 9-10.

Sunray venus scraping tools from the Guadalupe Bay site. Adapted from Weinstein 2002, Figure 9-1.

Oyster valves with perforations may have been employed as net weights, fishing sinkers, or as hafted implements for tending and harvesting edible plants. Larger holes in the shell body that were drilled (or pecked) from both directions were most likely modified by humans.  Smaller holes drilled from one direction with remarkably symmetrical diameters may have been bored by encrusting ectoprocts, marine sponges (C. celata), algaes, and/or other predators.  It is interesting to note that most of these holes are positioned in the left oyster valves, which were presumably invaded while the living oyster was attached to substrate (left valve is attached to substrate; right valve is smaller and lid-like).  Perhaps naturally perforated oyster valves were collected specifically for tool use; the holes were then subsequently enlarged to accommodate hafting or cordage, or became broken out and irregular as a result of usage. 

Sunray Venus:  Macrocallista nimbosa shell is tough enough to be flaked using flintknapping techniques, making it an especially desirable stone substitute in a lithic-poor area. Bivalve tools with heavy nicks, crushing, and retouch to the shell edge were used as knives or to scale fish, while the more robust valves served as anvils, choppers, scrapers for skin processing, and weights for weirs or other fishing gear.  In extreme south Texas in the Rio Grande Delta region, sunray venus scraping tools are very common, and in some cases comprise the largest single artifact class found in surveys of the area.

Sunray Venus clam shells, formed into blades or triangular shaped projectile points, have been found at sites in the vicinity of Corpus Christi Bay and Baffin Bay.  At site 41SP78 in San Patricio County on Redfish Bay, whole valves with abraded ventral margins were recovered stacked together within burials, presumably after being used to dig the grave.  Such a custom is reminiscent of the placement of stacked, unmodified bivalves, interpreted to be food offerings, in early graves at Mitchell Ridge on the upper Texas coast. 

Lightning Whelk:  The most useful marine shell of all was the gastropod Busycon perversum, the largest, most complexly structured, and densest shell.  Tools were fashioned from either the detached outer whorl or the columella (central column) section of the shell.  In some cases, portions of the entire shell are used, such as for containers, bowls, or drinking vessel.

Columella tools include hammers, picks, gouges, chisels, perforators, awls and projectile points.  In most cases the columella and spire are completely removed from the whorl body.  Hammers appear worn on both ends, and are grasped in the middle, while gouges, or chisels, have one steeply beveled edge at the anterior or canal end.  Whelk columella adzes occur at some inland sites, such as Morhiss Mound where they are found along with the stone adze form known as the Guadalupe tool.

Dipper (drinking cup) made from lightning whelk. Gulf coast ethnographic accounts describe shell cups being used to consume the Black Drink, a strong tea made from the yaupon bush. Adapted from Weinstein 2002, Figure 9-14.

Bipointed columella tool similar in shape to bone awls from the Mitchell Ridge site on Galveston Island. Adapted from Ricklis 1994, Figure 5.19.

This style of shell adze is the most common of the three types of shell adzes recovered from midden deposits at Morhiss Mound. It is manufactured from a rectangular section of exterior whorl from a conch shell. The proximal or bottom edge of this adze exhibits a portion of the ornamental ridge where the exterior whorl and the shoulder of the spire meet. Note that the ridge has been partially ground, probably to facilitate hafting. The scooped or spoon-shaped cross-section reflects the natural character of the shell. Lateral edges exhibit some chipping and smoothing, probably also to facilitate hafting of the adze. Also note the very well-shaped cutting edge characteristic of this adze type. The general morphological similarity of this shell adze type to Clear Fork tools may suggest a similar range of functions, primarily as woodworking tools.

The second most numerous shell adze type from the Morhiss site were manufactured from the interior columella obtained from large horse conch shells procured from the Texas Gulf coast. A columella section of suitable length was removed from the shell by either the groove and snap technique or direct percussion. The cutting edge or bit was shaped by grinding and the proximal end was roughly prepared by light smoothing or grinding. Note the general morphological similarity of this shell adze type to the Guadalupe biface or adze, again suggesting this form was primarily used as a woodworking tool.

The third type of shell adze recovered from Morhiss. This type of adze is not currently known from sites along the Texas coast. Interestingly this adze type is manufactured from the end of the conch shell that terminates in the siphonal canal. It is not known how these small adzes were hafted but the cutting edge or bit was created in a similar manner to the second shell adze type manufactured from the internal columella. Only three specimens of this type of adze were recovered from 41VT1. That these are not bit fragments of broken adzes is suggested by the presence of light grinding and smoothing along all broken edges.

In general, small whelk columellas were used as perforators, awls or maybe as hairpins.  One end was ground to a sharp point (in some cases, bi-pointed implements were fashioned) while the remainder of the columella was left unaltered.  Because they exhibit no grinding marks, several researchers have suggested that these items may have been natural fragments smoothed by weathering or wave action on a sloping beach.  Naturally formed or not, these pointed cylindrical artifacts have been found in many sites in the coastal plains, showing that they were transported from the beaches to their living areas by local inhabitants.

Exquisite projectile points were fashioned from large whelk columella, either of Busycon or the giant horse conch Pleuroploca gigantia.  Although these are found in small numbers in the central coast, they are very common in the lower coast in the Rio Grande delta area. They were abraded and polished forming a lanceolate, bullet-shaped point with tapered and slightly convex or squared-off base.  There is very little data on the hafting of these points but they are usually found in Late Prehistoric contexts and appear to represent arrow tips or perhaps the prongs of small fishing spears.

Shell tools, fashioned from the outer whorl segments of gastropods, have a large distribution range in Texas.  Described as adzes or gouges in the literature they have two basic shapes, rectangular or triangular.  These forms have smooth lateral edges with ground bits at the anterior or posterior end of the shell.  The cutting edge or bit is usually ground on the concave face of the shell with an average angle of about 50 degrees.  These kinds of whorl tools are thought to have been used in woodworking and/or animal skin processing (i.e., hide scraping).

Contributed by Meredith L. Driess.

Sources

Aten, Lawrence E.
1983    Indians of the Upper Texas Coast. Academic Press, New York.

Classen, Cheryl
1998   Techniques and Controls for the Determination of Seasonality Shellfishing Activities.  In Recent Developments in Environmental Analysis in Old and New World Archaeology, edited by R.E. Webb, pp. 51-66.  BAR International Series, No. 416, London.


Dockall, Helen D., and John E. Dockall
1996   The Shell Assemblage from Morhiss (41VT1), an Archaic Site on the West Gulf Coastal Plain.  Southeastern Archaeology 15(2):211-229.

Dreiss, Meredith L.
1994    Marine and Freshwater Shell Artifacts.  In Aboriginal Life and Culture on the Upper Texas Coast:  Archaeology at the Mitchell Ridge Site, 41GV66, Galveston Island, edited by R.A. Ricklis, pp. 417-445.

2002   Shell Artifacts.  In Archaeological Investigations at the Guadalupe Bay Site (41CL2):  Late Archaic Through Historic Occupation Along the Channel to Victoria, Calhoun, Texas, edited by R. A. Weinstein, pp. 443-512, Volume 2.  Coastal Environments, Inc., Baton Rouge Louisiana.

Steele, D. Gentry.
1988    Utilization of Marine Mollusks by Inhabitants of the Texas Coast.  Bulletin of the Texas Archeological Society 54:287-308.

Large numbers of columela points have been found in the Rio Grande delta in northeastern Tamaulipas. These very carefully shaped and polished artifacts typically have a sharp distal tip and a squared-off and thinned proximal end to facilitate hafting. Although they are assumed to represent arrow points, the larger ones weigh 6-12 grams, heavier than the 5 gram threshold said to be the dividing line between dart and arrow points. In fact, we do not know how they were hafted and these may represent prongs from fishing spears or other weapons. A.E. Anderson Collection, TARL.

Flaked shell scrapers from the Rio Grande delta. The thick heavy ones on top are made from Texas Quahog shell, while the thin delicate ones on the bottom row are made from Dosk Dosinia. A.E. Anderson Collection, TARL.