Archaeological studies are limited by the fact that they must rely on the materials that are preserved in the ground. Only in extraordinary circumstances are materials such as textiles, leather, wood, or basketry preserved in archaeological sites: in most circumstances, we can only infer their presence. Further, archaeology relies upon the study of material remains: we can only speculate and make inferences about how tools were used, why they were made, or what their users thought, intended, or believed.

Nonetheless, artifacts and archaeological features provide a picture of the material culture and the technology of a group and people. In a site like the Emeryville Shellmound, which represents a long period of occupation, we also can investigate changes in artifact types and styles over time, which may be indicative of new contacts, between cultures, or technological advances.

Artifacts or Groups of Artifacts
The 1999 excavation at Emeryville Shellmound recovered over 1,800 artifacts or groups of artifacts. These fall into 4 general technological and material classes: bone tools, chipped stone tools ("arrowheads" and cutting tools), ground stone (mortars, pestles and charm stones), and shell (ornaments and beads).

Bone Tools
The bone tool complex could be considered as 2 subclasses; bone awls and other tools presumed to relate primarily to the production of basketry and leather items; and bone whistles, spatulas, pendants and pins, which may have had more ceremonial or ideological uses. A wide variety of well-made bone tools in large numbers were recovered from the excavation.

Most common of these are implements of the awl type; elongate pointed tools presumed to have been used for perforating activities such as sewing and basketry or possibly as implement points in hunting and fishing. Studies by a zooarchaeologist indicate that a standard manufacturing technique was used to produce many of these specimens.

Awl Tools
To make an awl, an animal leg bone was selected, most often the front leg of a deer or elk. A sharp-edged stone tool was used to cut a groove around 1 end of the bone and the head of the bone was snapped off. Next, the bone was grooved lengthwise so it could be snapped in half to produce 2 elongate "blanks," each with a portion of the remaining head of the bone at 1 end. Narrower forms could be produced by repeating this process. Finally, an abrasive stone sometimes was used to smooth the split edges at the "handle" end, and shape the opposite end to a point.

Although modern basket makers suggest that the Emeryville tools may not have been sufficiently fine-pointed to be useful for coiled basketry, they could have been used to make the coarser twined baskets. Sewing and working of hides at the site is inferred from the abundance of perforating tools, which included a number of thin, eyed tools presumed to have been used as needles.

Ornaments
Some graves include sets of elongate, spatulate bone objects that may have been ornaments. The arrangement of perforated bone ornaments in graves also suggests that such ornaments may have been attached originally to clothing or headgear of hides or textile. Groups of bone tubes or whistles also were found in some graves. Likely these were musical instruments. They may have had a role in ritual practices as well.

Chipped Stone Tools
The major components of the chipped stone category are projectile points and cutting tools of obsidian and chert. These are believed to have been used for hunting, meat processing and other tasks where a sharp edge was useful. Siliceous rocks (high in silica) were used for these tools because it is possible to control the way they fracture, to create shaped sharp edges. Chert was available locally. The nearest obsidian sources were in Napa and Sonoma counties, but some obsidian in the site came from the eastern Sierra as well. Obsidian almost certainly was obtained in trade.

Among the collection of chipped stone tool manufacturing debris (debitage) from the big mound, there was only about 1/3 as much obsidian as chert, although obsidian and chert are equally represented among finished tools. Obsidian tools and projectile points often show evidence of reworking of broken and worn tools. This suggests that obsidian was relatively scarce and valuable. It is possible that much of the obsidian at the site was obtained in relatively small pieces, or even in the form of ready-made tools which, if broken, were reworked and reused.

Chert waste material was much more common in the deposit. Chert was used at the site for large flake and core tools, as well as in the production of large projectile points. Chert probably was relatively easy to obtain and therefore less valuable. A number of small serrate obsidian projectile points were found in the most recently occupied part of the shellmound site. Points of this style are common in central California during the late period. Antler tools found at Emeryville probably were used in the manufacture of chipped tone tools.

Ground Stone Tools
Ground stone tools are shaped by abrasion. For production of mortars and pestles, (grinding bowls and pounding implements), the most common rocks at Emeryville were vesicular basalt, obtained from the East Bay hills, and sandstone, probably available as stream cobbles in the bed of Temescal Creek.

Mortars of several forms were shaped from large cobbles. In some cases a basin was ground into the interior of a rounded boulder, with only minimal shaping of the exterior. Other mortars, particularly in the later period, were fully shaped both inside and out, and have a squared-off rim and sloping walls of even thickness. The pestles recovered generally are based on elongated stream cobbles, with minimal elaboration. Ethnographically, mortars and pestles were used to grind berries and meats, as well as seeds and acorns.

Charm Stones
Also of interest at Emeryville is the wide variety of "charm stones." These are small globular or elongate cobbles of sandstone or other finer-grained rocks, shaped in a variety of plummet-type forms, and often smoothly polished. Early types are perforated at 1 narrow end, while others often have markings of asphaltum and twine, indicating that a cord was attached at 1 end, probably for suspension.

Many specimens have battered faces or tips. There is little ethnographic evidence of how "charm stones" were used. It has been suggested that they were attached to fishing or hunting nets as hunting magic, or used for unspecified ceremonial purposes. Several charm stones of a variety of forms were found in a 2,000-year-old grave at Emeryville. In addition to charm stones, several beautifully shaped and polished stone pendants were recovered.

Abalone Shells & Olivella Beads
Shell pendants cut from abalone shells and olivella beads (made from the shell of a small sea snail) were found at Emeryville almost exclusively in graves. Shell pendants were made in a variety of forms. Most spectacular are several large disks, incised on the shiny nacreous face with a series of concentric rings. A number of teardrop or rectangular forms also were decorated with lines of incised dots. Since no unworked abalone shell was found at Emeryville, it is clear that abalone ornaments were arriving at the site ready-made. They likely were acquired in trade with coastal people of the San Francisco Peninsula or Marin.

The source of olivella beads is less clear. Some, at least, may have been made at Emeryville. Both whole shell beads created by grinding or cutting off the tip of the shell spire, and fraction beads are present. Fraction beads are produced by cutting an oval or round out of the side of the snail shell. The round is then smoothed by chipping or abrasion and centrally perforated. Both beads and pendants probably were strung on cord as necklaces, and also sometimes attached to clothing or headdresses.

Shell ornaments and beads were the items most commonly found in graves. The preferred styles of beads - very subtle shifts in form - changed over time, and have been found to be sensitive time markers. Groups of beads found in graves can be assumed to date to a single time period, and thus are useful in characterizing the stylistic preferences of a single time period. Other artifacts in the grave or the stratum then can be linked with these characteristic beads. This is useful in identifying strata of similar periods elsewhere in the site or at other sites.

Hunting Techniques
The wide variety and huge quantities of animal bone at Emeryville indicates that its people were very successful hunters. There is relatively little evidence of specific hunting and fishing techniques in the tool kit, but the bone assemblage testifies to a wide variety of hunting and fishing strategies. Early in the site's occupation, darts or spears with chipped stone tips probably were used. By the time of the last occupation of the site, a transition had been made to the bow and arrow, as indicated by the advent of small projectile points. One item in the bone tool assemblage was identified as a harpoon toggle on the basis of ethnographic analogy.

Certainly the people of Emeryville possessed the technology to capture large sea mammals and fish, but we have little direct evidence of what that technology was. Whalebone is present in the site, but there is no evidence that Emeryville people had the technology to capture whales; it is assumed that they simply took advantage of occasional beachings. The large number of bat ray specimens in the assemblage suggests that the Emeryville people used nets or weirs for fishing, although there is no direct archaeological evidence of this technology. Some of the many bone tools at the site may have been used in the production of nets or woven traps.

Housing
No archaeological evidence of structures was found in the midden at Emeryville. Some archaeologists maintain that this indicates that people did not live at the site and that it was used only for ceremonial purposes. Based on the volume of food debris and numbers of discarded tools in the massive midden, this seems improbable. The ethnographic record suggests that Emeryville houses would have been simple poles covered and tule mat structures.

It is likely that evidence of such structures, such as post holes and hard-packed earth house floors, simply did not preserve in the soft, damp midden of the site. Excavation did reveal hearth features, rings and clusters of rock, and numerous lenses of ash and charcoal, indicative of cooking.