Bedrock outcrops are relatively more common in the southeastern and southwestern corners of the state. There are significant differences between the rocks exposed in these western and eastern parts of the Southern Resource Region. In the southeastern part of the state, more recent sedimentary rocks are exposed. They consist principally of limestone and other carbonates. Raw materials associated with bedrock in this area include Grand Meadow Chert, Cedar Valley Chert, Galena Chert and Maquoketa Chert. All of these materials except Maquoketa Chert are relatively important and widely utilized. In the southwest, very old volcanic, metamorphic and sedimentary rocks are exposed. Bedrock materials in this area include the Sioux Quartzite and the quartz, jasper and chert which are incorporated in the basal conglomerate of this formation. These raw materials were not widely used for flaking.

In the central part of the Southern Resource Region, outcrops are less common, being confined principally to stream valleys. Glacial drift is again the most important raw material source. Many or most of the raw materials available in the state probably occur naturally in this area. This leads to a great diversity of raw materials at many archaeological sites in the area, and complicates raw material identification somewhat.

Among the Southern Resource Region raw materials, Prairie du Chien Chert (PDC)(Gonsior 1992; Withrow 1983:40, 45-50) is one of the most widely utilized. Its distribution includes large parts of south central and southeastern Minnesota and extends into Wisconsin and Iowa. The widespread utilization of PDC may be due more to availability than quality. The quality of PDC appears to vary considerably, as do its characteristics. In appearance, it sometimes overlaps with such diverse materials as Swan River Chert, Red River Chert or Burlington Chert -- all materials which would not usually be mistaken for each other. PDC is most easily identified in its oolitic form. Nonoolitic forms are less common but more difficult to identify. One form has a grainy appearance; the other may be characterized as "sandy." It appears that PDC was commonly heat treated, although identification of heat treatment is complicated by the fact that some PDC has a natural reddish tint. Texture may be a better indication of heat treatment in this material.

In some areas, PDC is identified as two separate raw materials -- Shakopee Chert and Oneota Chert (e.g., Morrow 1994). These raw materials originate in the Shakopee and Oneota formations of the Prairie du Chien Group. In Minnesota, however, the Shakopee and Oneota formations are not always distinguishable (Austin 1972b:466) and the cherts they contain do not seem to be visually distinguishable. When these raw materials are redistributed in glacial drift, it is not practical to separate them. The inclusive term "Prairie du Chien Chert" provides a category under which they may be grouped.

Grand Meadow Chert (GMC) is a good quality raw material with a more restricted natural distribution (Gonsior 1992; Trow 1981:102). GMC has a narrow range of variation and therefore is fairly easy to identify. Color ranges from light to medium grey, and may be homogenous or broadly mottled. Transmitted light almost always has a golden tint. Patination, when present, is a distinctive olive color. Cortex, when present, is thin and buff to light brown. Texture is fine. The cobble form is also distinctive, although this is seldom seen on reduced archaeological specimens (occasionally taking the form of fossil casts or exhibiting fossil casts on the exterior). It is helpful to be able to specifically identify this material because it had a fairly wide circulation (although not as widespread as KRF or Burlington Chert). At least one quarry location is known (discussed below). This quarry complex is located near the town of Grand Meadow, from which the raw material takes its name. Outside of this quarry, the natural distribution of GMC is not well known.

Galena Chert occurs in southeastern Minnesota, northeastern Iowa, southwestern Wisconsin and far northern Illinois (Gonsior 1992; Stoltman et al. 1984; Withrow 1983:40, 50-54). This raw material has a restricted range of variation, and is not hard to identify. The inclusion of scattered, small white flecks (probably crushed fossils) is one of its most distinctive characteristics. It is usually opaque. Texture is normally chalky, although more vitreous textures do occur naturally or as a result of heat treatment. Small, flattened vugs are usually present. Color is normally pale brown, less often pale grey; heat treatment produces reddish tints. This moderate to good quality raw material was fairly widely utilized, and is common in small amounts at archaeological sites some distance from the source area. Several Galena Chert procurement sites (discussed below) have been documented in southeastern Minnesota.

Cedar Valley Chert (CVC) has a limited distribution in parts of southeastern Minnesota, focussed on Fillmore County (Gonsior 1992; Ready 1981). Known quarry sites are discussed below. The material has two distinct forms: opaque and translucent. There seems to be little or no overlap between the two. The opaque form is also called Cedar Valley Jasperoid (Ready 1981). This form has a narrow range of variation. It is very opaque, and varies in color from yellowish brown to ocher and, less commonly, dark brown. Mottling occurs in some pieces. The texture is chalky. Heat treatment turns lighter pieces a distinctive cranberry red, and may deepen or redden the color of dark brown pieces. Heat treatment may also produce a waxy to highly vitreous texture, probably depending on maximum temperature reached. Quality is generally good, with or without heat treatment. This material has also been called "Root River Chert" in some reports.

A very similar raw material called Cochrane Chert occurs in nearby parts of Wisconsin (Robert Bozhardt, personal communication 1994). Some cobbles of Cochrane Chert appear to have more distinct grainy patterning, consisting of dark, subparallel lines. The texture may also be naturally more waxy or vitreous in some specimens. Otherwise, the materials are macroscopically nearly identical. Whether they share a common geological origin in unclear.

Translucent Cedar Valley Chert is as variable as the opaque variety is homogenous. In macroscopic appearance, it can resemble colorless and transparent chalcedony, white chert or even Hixton Quartzite. Any or all of these phases can be found in a single cobble. Identification of this raw material can be challenging. Most pieces of translucent CVC show a distinctive, strong golden color of transmitted light. The pieces which macroscopically resemble quartzite are also easily identified. If these pieces are examined under a microscope, the apparent granular quartzitic texture disappears and the material looks distinctively cherty. Cortex can also help in identification. Heat treatment affects both the color and texture of this variety of CVC. Because of its variability, identification of translucent CVC is best conducted with the use of a reference collection, including whole cobbles and heat treated samples (available at the Minnesota Historical Society, Fort Snelling). Quality is generally good, sometimes very good. The translucent variety of CVC does not seem to be as widely distributed as the opaque variety at archaeological sites, despite overall better quality. The reasons for the differences in archaeological distribution are not clear.

Swan River Chert (SRC) (Bakken 1985, 1993; Campling 1980) is present in glacial drift in the Southern Resource Region. Although it is found at many archaeological sites in the region, it is probably not as important here as in the Western Resource Region. As discussed above, SRC has a vast distribution to the north, and probably also occurs into parts of northern Iowa. Also as discussed above, this material is extremely variable, especially in color. The "orange peel" texture of fracture surfaces, cloudy yellow color of transmitted light, and microscopic, agate like banding are normally the most useful diagnostic characteristics. The spongy or ropy texture of the cortex is also distinctive, when cortex is present. SRC might be mistaken for Maynes Creek Chalcedonic Chert (from Iowa) (Morrow 1984, 1994) or certain varieties of Prairie du Chien Chert, although careful examination should serve to distinguish SRC. Neither of these materials seem to exhibit the microscopic agate-like banding seen in SRC or its distinctive cortex.

SRC is a difficult material to work. Cobbles are extremely tough, and even breaking open a raw cobble can be difficult. At some sites, analysis of lithic debitage suggests that whole SRC cobbles -- rather than partly reduced blanks -- were heat treated (Bakken 1995a). Presumably this was a response to the tenacity of the material, which impedes even the earliest stages of reduction. Once SRC was reduced to the form of a tool, however, it might be expected that the tool would also be tough and durable.

Tongue River Silica (TRS) occurs in much of the Southern Resource Region, and into north central and northwestern Iowa (see Anderson 1978) (in addition to its northern distribution). TRS commonly occurs in small amounts at archaeological sites in the region. Because of its generally poor flaking quality, other materials seem to have been preferred whenever available; locally TRS constitutes a minor part of the raw material resource base. As discussed above, this material has a relatively narrow range of variation and is easily identified. Its natural color is restricted to a fairly narrow range of ocher or yellowish brown. Weathering may produce an orange or reddish discoloration on the surface and along cracks or root molds. Heat treatment is easy to identify because the color changes to orange-red or red (Anderson 1978). Other diagnostic characteristics include a fine grained "sparkle" on fracture surfaces, and the presence of hollow root molds. Most TRS is highly opaque; rare pieces are slightly translucent on thin edges. Related but distinctive forms of grey TRS have been identified in North Dakota (Ahler 1977). These do not appear occur naturally in Minnesota but may occasionally be found at archaeological sites in the state.

Red River Chert (RRC) also occurs in glacial drift in the Southern Resource Region and at regional archaeological sites. It does not seem to be as commonly utilized here, however, as in the Western Resource Region. This may be because of the tendency of RRC to fracture uncontrollably into small, blocky chunks which are useless for further reduction. The relative abundance of other, more reliable raw materials in the Southern Resource Region would minimize the need to rely on utilization of RRC. Specifically identification of RRC at archaeological sites in this region may not be feasible in many cases, unless distinctive mottling patterns or fossils are present. RRC resembles may other light colored, fine grain cherts which may occur at sites in the region. Visually separating cherts with these general characteristics is, in my experience, among the most difficult undertakings in raw material identification.

Shell Rock Chert is believed to occur naturally only in a small part of south central Minnesota and possibly in adjacent parts of north central Iowa. It is probably available in drift rather than from bedrock, even though the distribution would to be quite restricted for a drift source. The archaeological distribution also appears to be limited. So far, this raw material has been identified in small amounts at archaeological sites only in Freeborn, Mower and nearby counties. Shell Rock Chert is highly distinctive. It is near white to light grey in color, and is mottled. In many respects, it resembles Swan River Chert. However, the chert's most distinctive feature is the presence of easily visible colonial coral fossils, probably a species of Hexagonaria (cf. McLean and Sorauf 1988); the entire rock matrix consists of coral fossils. The cortex on unmodified cobbles is chalky and white, although it may be stained yellow or brown. On some pieces the cortex also clearly displays the form of the coral colony (Bakken 1995b; Olmanson et al. 1994).

Maquoketa Chert has been found in the vicinity of Cedar Valley Chert outcrops, and is believed to come from the underlying geological stratum (Gonsior 1992). Maquoketa Chert resembles Swan River Chert in its coarse texture and fracture. Maquoketa Chert, however, appears to be limited to a pale grey color. This material seems strongly inclined to fracture along circular layers concentric to the cortex. This characteristic, combined with generally poor flaking characteristics, seems to have ensured that the material was not often utilized.

Sioux Quartzite occurs in the western part of the Southern Resource Region. Although outcrops of the quartzite were used as a substrate for petroglyphs (Lothson 1976), it is unclear whether this material was used to any extent to make flaked stone tools. Sites in this part of the state sometimes contain fractured bits of Sioux Quartzite, but almost all of these pieces lack clear flake morphology. At some locations, the base of the Sioux Quartzite consists of a conglomerate containing pebbles and cobbles of quartz, jasper, and other potentially flakable materials (Austin 1972a:450Ð453; Sims and Morey 1972:3) which may have occasionally been utilized (Peterson et al. 1989). However, conglomerate outcrops are very limited in extent, and the flakable stone it contains represents a minor raw material source.

Although Knife River Flint is listed as a local raw material (Table 3), locally available quantities are negligible. It is likely that most of the KRF found at sites here come from outside the region, specifically from the primary source area in west central North Dakota (Gregg 1987). As noted above for the Western Resource Region, an exception may be the reduction of locally occurring KRF pebbles by bifacial techniques in order to produce expedient flake tools. KRF is much less common at sites in this region than in the Western Resource Region. KRF is easily identified by its translucency, coffee brown color and pattern of diffuse inclusions (see Clayton et al. 1970). Occasionally it develops a white patination. Burning makes KRF nearly opaque and pale bluish grey in color. Even when patinated or burned, however, KRF displays the same distinctive brown color to transmitted light and may usually be identified.

Quartz is available in glacial drift throughout the state, including the Southern Resource Region. It is normally easily identified by the presence of flat fracture plains which follow its crystalline structure. Better quality raw materials are more abundant in most of the Southern Resource Region than in most other parts of the state; because quartz is relatively difficult to work, these better quality materials were preferred whenever available. Quartz is therefore less common at archaeological sites here than in areas where good quality materials were rare. Bipolar techniques were still locally utilized with this raw material, again suggesting the presence of an expedient flake tool technology.

Rhyolite and siltstone probably both occur in small amounts in glacial drift in the Southern Resource Region. They are found at archaeological sites in the region, but generally only in small amounts. These raw materials may be similar in appearance, especially in color. The two may be distinguished by relative opacity; siltstone is opaque, while rhyolite displays moderate to strong translucency. Rhyolite sometimes also has patches and streaks of brown to orange brown, and usually has clear, colorless phenocrysts in a finer grained matrix; these characteristics are lacking in siltstone. The slightly porous or chalky patina which develops readily on siltstone is not seen on rhyolite.

Pebbles of chalcedony, jasper and silicified wood are occasionally found in drift in this region, and silicified wood is relatively more common here than in other parts of the state. These materials rarely occur in cobbles large enough to facilitate standard patterned reduction techniques. It should be noted that these raw material terms are used here in a descriptive, generic sense. Chalcedony includes fine grained, translucent to transparent, waxy textured materials which are usually pale brown, gold or colorless. Jasper includes fine grained, waxy textured materials which are yellow, yellowish brown, olive, brown or red to reddish brown in color. The color may be solid or mottled. Silicified wood may be distinguished by its visible wood grain. Pieces of this material often fracture along lines between growth rings. The origin and distribution of these materials are not well understood. When materials matching these descriptions are found at regional sites, some care should be taken in their identification. This is particularly true with chalcedonies and jaspers, especially if patterned tools made of these materials are found. Such pieces may indicate import of raw material from sources outside the region, especially to the west where larger, better quality pieces are available. In some cases it may be possible to specifically identify such nonlocal raw materials.

Quartzites (besides Sioux Quartzite) are found in drift in the Southern Resource Region. In general they resemble the forms found in the Western Resource Region: a white to golden yellow form which tends to have larger crystals, and a dull red to dull purple form which tends to be finer grained. This quartzite is very brittle and largely useless for standard lithic reduction. The flakes occasionally found at sites are probably detached from quartzite cobbles used as hammerstones. It is possible that there are also quartzites of northeastern derivation present in the region, although this has not been specifically documented.

In addition to the drift quartzites, there may be orthoquartzites available from primary geological contexts on the extreme southeastern edge of Minnesota. These would be related to such materials as Alma Quartzite (Penman 1981) and Arcadia Quartzite (Robert Bozhardt, personal communication 1994). To date, however, there is no clear evidence for such sources.

Small amounts of raw materials from Iowa and other southern areas are common at archaeological sites in southern Minnesota. The creates identification problems. The problem is particularly noticeable if you try to separate certain local and southern materials which share elements of geological origin and, therefore, have similar characteristics. In some circumstances, it is sometimes best to avoid specific raw material identification unless clear diagnostic characteristics are present, and group similar raw materials in a generic "chert" category.

Some of the Iowa and other southern materials found at archaeological sites in Minnesota, however, are very distinctive and can be specifically identified. Some of the more often encountered and easily identified include the various kinds of Fusulinid Chert (Argentine, Winterset, etc.), Moline Chert, Maynes Creek Speckled Chert and Burlington Chert. It appears that many of these raw materials, as well as other materials of southern origin, were moving into southern Minnesota along some of the major river systems that traverse Iowa. This hypothesis, however, must be studied more carefully.

A very useful key to the identification of these and other Iowa raw materials is provided by Morrow (1994). Remember that this key and any other written descriptions produce better results when used in connection with reference collections. Representative samples of Iowa cherts are available at both the Minnesota Historical Society (Fort Snelling) and the University of Minnesota (Interdisciplinary Archaeological Studies, Minneapolis).

Burlington Chert is one of the most common exotic raw materials at archaeological sites in the southern part of Minnesota. Hixton Quartzite (and related orthoquartzites) and Knife River Flint are also found, but are less common. Nonlocal materials which may be encountered (in addition to the materials of southern origin discussed above) include Bijou Hills Silicified Sediment (Church 1994), and possibly raw materials originating in the vicinity of the Black Hills of South Dakota.

In the Southern Resource Region, as in the Eastern Resource Region, it is useful to have detailed information on raw material sources in the vicinity of a site which you are studying. Some information of this sort is available in the geological literature (e.g., "Chapter IV: Paleozoic and Mesozoic," pages 457-512 in Sims and Morey 1972, specifically Austin 1972b:459-473). A first hand, on the ground inspection of raw material sources would also be valuable. However, an adequate raw material analysis may be conducted without such detailed information by placing the analysis within the context of regional raw material resources.

A few quarry and procurement sites are known in the Southern Resource Region. At the Grand Meadow site (21MW8), "scores of large pits, up to 3 m deep and 5 m in diameter, were dug through prairie soils and the weathered limestone of the... of the Cedar Valley Formation" (Trow 1981:102)in order to extract Grand Meadow Chert. The pits still cover several acres, and were previously more extensive. The Archaeological Conservancy has purchased part of the quarry acreage in order to preserve it (see Archaeological Conservancy 1992).

The Hadland site (21FL60) (Ready 1981) and the nearby Chally/Turbenson site (21FL71) (Gonsior and Myster 1994) are two known locations where Cedar Valley Chert (CVC) was procured. In both cases, the source appears to be lag deposits. The Chally/Turbenson site, located in Mower County, southeastern Minnesota, covers an extensive area. Surface collection and excavation at the site to date has not provided clear evidence of site chronology. However, incorporation of artifacts into loess deposits suggests that at least parts of the site may be relatively early. The nearby Hadland site represents similar procurement patterns.

The St. Croix River Access site (21 WA 49) is a lithic procurement site where Prairie du Chien Chert (PDC) was gathered either from outcrops or alluvial gravels (Hoffman and Myster 1992). At the LeSueur site, in the city of LeSueur, PDC was taken from nearby outcrops. Roetzel and Strachan (1992) suggested that is was then heat treated in a kiln built from cobbles.

Gonsior et al. (1994) documented the procurement of Galena Chert from lag deposits at six sites in Fillmore County of southeastern Minnesota. The sites include Kindem (21 FL 65), Tieskotter/Stevens (21 FL 66), Tessum/Lunde (21 FL 67), Evenrud (21 FL 68), Hahn (21 FL 69), and Simonson (21 FL 70). The investigators suggest that raw material was acquired on an opportunistic basis from eroding ravines or other exposures. In addition to procurement, all stages of reduction are represented. Heat treatment was apparently applied to both whole cobbles and partly reduced bifaces.

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