The Calico Lithic Industry

The Calico Lithic Industry is found within nested, deeply-eroded and thoroughly-indurated alluvial deposits in the northwest part of the Manix Basin, northeast of Yermo (3 km north of the Minneola Road exit from Interstate Highway 15)(Simpson 1978, 1980, 1982, 1986; Budinger 1983; Budinger and Simpson 1985; Shlemon and Budinger1990).



The artifact-bearing sediments, variably cemented by calcium carbonate, have been dated by thermoluminescence (TL) at 135,000 years, (Debenham 1998), and at approximately 200,000 years by uranium-thorium analysis (Bischoff et al. 1981). The uranium-series date was confirmed at ~ 204,000 years by Bischoff, using more refined technology, in 2007. Andesite boulders in the deposit, closely associated with in situ artifacts, are thoroughly decomposed, resembling those in California glacial deposits older than 125,000 years. The surface soil has an estimated age of approximately 100,000 years (Bischoff et al. 1981). The artifact-bearing deposits are inset into much older alluvial fans that formerly issued from East Mule Canyon in the eastern Calico Mountains.

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Objects interpreted as artifacts are found 3 to 8 m (10 to 26 ft) below the eroded fan surface, with peak concentrations of greater than 1.5 tools per cu ft at depths of approximately 3.6, 4.2, 6.9, and 7.54 m (11, 13, 21, and 23 ft). The artifacts are presumed to have been buried either by natural fan aggradation by flows of debris from Mule Canyon in the Calico Mountains or by local aggradation accompanying erosion of higher portions of the fan after its separation from the Calico Mountains. The latter hypothesis is preferred as the former would imply that the artifacts were left on an aggrading fan surface in excess of 500,000 years ago.

Tools in the Calico lithic assemblage were fashioned on cores, flakes, and blades (Simpson 1978, 1980, 1982, 1986; Singer 1979; Budinger 1983; Budinger and Simpson 1985). Most were fashioned by simple hard hammer percussion flaking, some were made using ground or lap anvils (including by bipolar techniques), and a few by pressure retouch (distinguished here from pressure flaking which would involve an antler or bone flaker).

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Specimens characterized by unifacial face and edge retouch are interpreted as scrapers that may have been used for working wood, hide, bone, or antler. They were fashioned on flakes and blades. Nine sub-types have been identified and are listed here with their incidence from the site’s Master Pits I and II (a combined excavated volume of 354.6 m3): concave (630), notched (557), convex side (347), straight-edged side (182), end (135), convex side and end (33), strangulated (15), concave side and end (7), and thumb-nail (7).

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Cutting tools are the most sophisticated artifacts in the assemblage. They have bifacially modified edges that are typically acute and equal. Three types of cutting tools have been identified: gravers, denticulates, and burin-like tools. Gravers (620/354.6 m3) exhibit small, delicately retouched spurs used for incising. Denticulates (116/ 354.6 m3) are tooth-edged tools thought to have been used as saws. Burin-like tools (591/354.6 m3) with transverse chisel-like edges include burins on truncations, burins on breaks, dihedral burins, and becs (small tools with curved or beak-like spurs).

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Most rotational tools in the assemblage are reamers. Reamer points range from stout spurs to sharp points with deliberate retouch. Use-wear includes minute scaling indicative of clockwise or counterclockwise usage. Feather-like scaling is often observed on lateral aretes, just behind the point. Points often also exhibit crushing or rounding and polishing.

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Piercing tools (percoirs) have slender splinter-like spurs without retouch. Use-wear includes crushed tips and minute step-fractures. Modified edges that support piercing spurs often evince retouch and use-wear indicative of use as scrapers, cutting tools, or burins. Such specimens are classified as multifunctional tools.

Both blades and bladelets are present. Blades are flakes that are more than twice as long as they are wide, have approximately parallel lateral margins, and are longer than 4.5 cm. They have triangular or trapezoidal cross sections. Bladelets exhibit similar attributes but are shorter than 4.5 cm. Some 710 blades, 683 bladelets, and 182 blade or bladelet cores have been recovered from Master Pits I and II.

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Heavy-duty tools were fashioned from cores and core-like large flakes. Most cores were simple unprepared blocks from which flakes had been struck. A few exhibit striking platform preparation. Bipolar cores are present; spectacular polyhedral cores are not.

Both large (more than 50 cm) and small formed and unformed anvils were used. With large anvils, a piece to be flaked was brought down forcefully on an anvil crest; with lap anvils the object to be modified was held on the anvil surface and then struck. Ground anvils of chalcedony or jasper are bifacially modified or unmodified high-crested blocks. The crests exhibit localized crushing, battering, and incipient cones of percussion.


Most choppers exhibit bifacial flaking, however, a few are only unifacially worked. Side choppers outnumber end choppers. Lunate-shaped examples with thick, blunt backs and bifacial face and edge flaking are morphologically similar to Asian tools called skreblos.

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The Calico Cutter is a multifunctional tool type that has one lateral margin with a well-fashioned sinuous chopper edge and the opposite lateral margin has diagonal crests retouched for use as cutters.

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Handaxe-like tools, typically with massive butt areas, were bifacially flaked from cores or large flakes. One example with a long, broad, thin tongue-like blade exhibits an S-shape outline similar to Old World forms. Pointed tools are usually bifacially modified and most are picks of various sizes (8 cm – 28 cm). Most picks exhibit retouch and/or use-wear indicating use as multifunctional tools, e.g., as both a pick and a chopper.

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Hammerstones (>250), sub-rounded to oval unmodified or naturally faceted clasts of chalcedony, chert, andesite, or dacite, are typically about 10 cm in diameter and exhibit crushing/battering use-wear. Pecking stones are similar, but taper to one end.


In addition to formed tools; other lines of evidence indicating a human presence at the Calico Site include, in an excavation volume of 354.6 cubic meters:

Selective use of high-quality chalcedony, including that available within 100 m of the site’s major excavations;

Technical flakes with prominent force bulbs (439), diffuse force bulbs (2,793), concentric ripples (2,048), bulb scars (577), and striking platforms (855). Many have evidence of platform preparation such as edge grinding or multiple facets (Singer 1979; Simpson et al. 1986; Simpson et al. 1999);

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Interior flakes with multiple dorsal scars;

Concavo-convex flakes (second flakes) with force bulbs aligned with negative bulbs of preceding flake removals (296);

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Soft hammer flakes with diffuse force bulbs and platform lipping (95);

Clusters of sharp-edged flakes exhibiting size distributions similar to clusters generated by experimental flintknapping;

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Evidence of hinge flaking (676);


Evidence of use-wear, especially crushing, spalling, and rotational wear;

A concentration of non-local red ochre;

Rounded stone balls (possible bola balls);


Non-local quartz crystals, some of which have been modified by percussion flaking;

Non-local Eocene moss agate flakes.

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