«CALICO REDUX: ARTIFACTS OR GEOFACTS? CHRISTOPHER HARDAKER EARTHMEASURE RESEARCH On closer inspection, Calico does not appear to be a natural rock ...»
CALICO REDUX: ARTIFACTS OR GEOFACTS?
On closer inspection, Calico does not appear to be a natural rock crushing geofactory. Nor is it the case
that Calico is bereft of definite and repetitive artifact types. Most tool types are either unifacial (including notched specimens) or bifacial in nature, hundreds of them, and delicately notched perforators (reamers, gravers). There are dozens of artifact types and subtypes represented, and there are thousands of flakes and tool types without cortex and with multiple flake scars. After a review of the controversy, tabulated data are presented.
This paper reports on the findings from an examination of over 70,000 fractured subsurface lithic specimens from SBCM 1500A, the Calico Early Man Site, located just east of Barstow, California. The fractured materials are chert, chalcedony, agate, jasper, and other siliceous varieties from medium to high quality. The specimens were collected during excavations from Master Pit 1 (MP1), Master Pit 2 (MP2), with a small fraction from other associated excavations, including Master Pit 3, Trench 1, and several pieces collected from Control Pit 1. Ninety-five percent of the pieces were collected during the 1960s and 1970s in 3-in. levels inside 5-ft.-by-5-ft. units.
The classification system was established in the 1960s and 1970s with very few subsequent changes. Occasionally assisted by avocationalist and longtime member of the Friends of Calico, Chris Vedborg, the examinations took place in the Anthropology Laboratory at the San Bernardino County Museum (SBCM) where all specimens are stored. The classified contents of MP1 and MP2 are contained in roughly 60 standard museum boxes. About 30 other boxes of specimens from other associated excavations remain to be examined and classified.
Over the past three decades, examinations often consisted of sampling single boxes of specimens or one or more total excavation unit collections, with results often unpublished in the form of notes and comments logged into catalogue binders. In addition, a number of filled binders of comments by professionals date directly to the 1970 Calico international conference. Several significant publications, pro and con, will be discussed below.
These results are preliminary. Each specimen received only a quick and cursory inspection. The primary mission of this first stage of analysis is to record specimen attributes on a spreadsheet for the purpose of developing an inventory of the collection that is easily accessible. A more thorough examination of the lithic specimens will proceed once the inventory is complete.
Each specimen is given a serial number, except for collections of multiple flake fragments and clusters (e.g. concentrations of multiple flake fragments, or debitage) that routinely turned up in the 3-in.
levels. In many instances, the materials had been presorted by unit into specific artifact types. Many of these earlier designations held up, but others were interpreted differently when the need arose.
One of the advantages of running all specimens by a single set of eyes is that it promotes consistency and continuity throughout the collection’s classification, and this applies to correct as well as incorrect attribute assignments. It will hopefully provide a consistent, or at least orderly, foundation for other analysts studying the collection in the future.
My approach to examining the collection initially focused on the concept of fracture densities and that all specimens with hard (conchoidal) fracture signatures were “suspects,” be they artifacts or geofacts. Laws of fracture mechanics dictate that something had to conchoidally fracture the rocks.
Discerning chemical splitting or thermal fractures from conchoidal (hard) fractures is fairly easy given my background rooted in flintknapping, including thermal experimentation with various siliceous materials.
SCA Proceedings, Volume 22 (2009) Hardaker, p. 1 The collection is largely composed of pieces with conchoidal features, exceptions being the crushed surfaces of anvil- and hammerstone-types. The vast bulk of the collection (70 percent or more) consists of debitage, flakes, and tools with little or no cortex.
A rock does not conchoidally fracture all by itself. It needs help. Further, many of the specimens exhibit multiple flake scars indicating that multiple fracture events occurred around the same time on a given piece.
Very few subsurface specimens exhibit multiple generations of flake scars; also, very few were weathered or patinated, suggesting minimal surface residency times. In general, edges were in fairly good shape, and some were still sharp.
An abiding issue is whether the fracture densities are homogenous throughout the entire subsurface of the fanglomerate complex. As geofacts, it is reasonable to expect that if natural agencies capable of fracturing siliceous rocks are represented in the Master Pit (MP) zone, then the same agencies should have been operative in the fanglomerate deposits beyond these excavations. In other words, the same fracture densities at the MPs should exist throughout the fanglomerate in general. Whatever natural agencies were involved in breaking the rocks at the MPs, it is reasonable to expect that they would also be in play in other areas of the deposit.
Preliminary assessments suggest, however, that the fracture densities in the Master Pit zone are perhaps hundreds of times greater than in the sediments excavated in the test and control units located within the fanglomerate beyond this zone. No natural agency -- other than perhaps some kind of smalldiameter explosion -- can account for or explain this super-local increase in fracture densities. Another feature related to site deposition is that the fanglomerates of the Yermo Formation in the MPs are virtually parallel with a slope of about one degree.
It is fortunate that any and all issues and data entertained in this article can be physically tested, checked, and rechecked. There is still plenty of site area left for excavation and testing of a multitude of issues. Archaeology as forensics is coming of age, and Calico represents an ultimate challenge.
THE GEOLOGICAL CONTEXT OF THE CALICO SUBSURFACEThe alluvial fan complex of the Calico Hills is made up of sediments laid down in possibly a dozen depositional events (Baty and Seff 1994; Shlemon and Budinger 1990). The alluvial fan was cut off from its source possibly tens of thousands of years ago and began to erode over the millennia. In turn, it has become the source of smaller alluvial fans jutting out from its perimeter. The specimens were captured within the alluvial matrix during the period that the Yermo Formation was building. To date there is no evidence that the specimens were redeposited within secondary depositional insets. Uranium Series dates of 200,000 years were obtained from the base of the formation in the early 1980s (Bischoff et al. 1981). Thermoluminescence dates suggest a minimum antiquity of 135,000 years (Debenham 1999).
From the Calico Early Man Site (EMS) website, Fred Budinger (2005) provides a summary of
what is currently known of the Yermo Formation:
Calico Site Stratigraphy The artifact-yielding Yermo Formation overlies the Barstow Formation, and consists of two depositional units: a basal mudflow and overlying, crudely intercalated debris flows and fanglomerates;
and overlying, reworked fan deposits, primarily arkosic sand, with a strongly developed relict paleosol at the surface (Shlemon and Budinger 1990).
The mudflow and fanglomerate consist of lenticular, poorly stratified layers of sands and angular gravel. There are no buried paleosols or significant unconformities. Deposition probably occurred within one climatic cycle of perhaps a few tens of thousands of years.
The upper, reworked arkosic sand unit (about 1.5-m thick at Master Pit I) contains highly weathered tuff fragments. Based on its lithology, distinctive red color, and other weathering SCA Proceedings, Volume 22 (2009) Hardaker, p. 2 characteristics, the sand was probably derived from nearby, previously weathered fan-deposits. The overall stratigraphic section provides evidence that deposition occurred in response to gradual changes from semiarid to arid climatic conditions.
There is no evidence for depositional insets or cut-and-fill episodes observed in the Master Pits that could theoretically account for the redeposition of the specimens. The sedimentary matrix is well lithified and unattractive to reworking by local rodentia as well as to human trowelbearers who must learn the way of the hammer and chisel.
A main question is, where did the fractured specimens come from? Were they redeposited from elevationally and/or stratigraphically higher exposures of the fan complex, which presumably were nearer the source outcrops? Or were the specimens fractured in situ prior to final deposition and burial? Are both true to a degree? If so, how can we tell the difference? These issues will be dealt with below in response to a series of papers supporting the geofact hypotheses, followed by a couple papers supporting the artifact hypothesis.
THE GEOFACT-ARTIFACT CONTROVERSIES
Background Histories of the Calico Early Man Site excavations and research and photographs of the artifacts can be reviewed in several works (Budinger 1983, 2000, 2004; Budinger and Simpson 1985; Calico Early Man Site 2005; Leakey 1972; Leakey et al. 1968, 1970; Minshall 1976:30-40; Schuiling 1979; Simpson 1980). Briefly, dense lithic workshops captured in wide swaths of desert pavement in the Calico Hills were brought to Dee Simpson’s attention during the 1950s. With degrees in both archaeology and geology from University of Southern California, she was uniquely qualified to reach the conclusion that Calico's surface lithic workshops were different than the assemblages of other early surface sites in the region, most notably the artifact types from Pleistocene Lake Mojave (Simpson 1960). Walking over the square miles of workshops on the western alluvial fans near Calico, above Pleistocene Lake Manix, the assemblages had a more ancient quality about them than other paleo-artifact assemblages. There was also a nearly total absence of projectile points and other artifacts typical of later prehistoric periods. Further, the artifacts observed above the higher lake stands were much more weathered, hence older, than those at lower elevations.
Armed with a small collection, she set off for London to show them to Dr. Louis Leakey. He was immediately interested. He had never seen artifacts like this from the New World before. A few years later he came out to the area to have a look for himself and came across buried artifacts in the profile of a bulldozer trench. In 1964, with support from National Geographic, the Calico Early Man Site was born.
The geofact-artifact controversy started soon after.
The oldest accepted Paleoamerican finds in the Mojave Desert were all surface artifacts. Calico’s 5 ft. by 5 ft. units were going down 20 ft. in a dead fan. Tensions were high. A conference held in 1970 resulted in a hung jury and thoughts that the site’s age might be a half million years old. Such an antiquity (500,000-100,000 years) for a New World site was simply too extreme at the time.
In 1973, Science published C. Vance Haynes’s critical article that effectively, though hypothetically, dismissed Calico’s collection from serious attention. Haynes listed a number of agencies capable of fracturing chert -- at the outcrop source of the fan materials, during transport, and postdepositionally (1973:107). The article is persuasive because it ascribes a highly dynamic geological scenario to the alluvial fan-building process at Calico. With all those forces in play, nature could just about make any kind of simple tool form imaginable, even bifacially flaked edges and delicate becs. The continuing absence of spearheads and human bone apparently clinched for Haynes the non-artifactual nature of the assemblage.
Most, if not all, of the professionals with a curious eye on Calico after the 1970 conference turned away when the article was published. Few felt confident enough about their lithics acumen to stake their
Geofacts Gone Wild The political and scientific status of Calico has remained essentially the same since that time. The vision of the Yermo Formation as a gigantic rock crusher still persists. Most New World debunkers seem to have no problems believing that the simple nature of non-handaxe Middle Paleolithic tool assemblages, like those from East Asia, can be readily mimicked by Calico's fan building processes, and that it would be next to impossible to distinguish natural fracture from artificial under such circumstances. And the critics have won out in popular society, as shown in a recent article in Science Illustrated about the earliest Americans; the unknown author of the piece refers to Calico as “The Oldest Mistake” (Footprints from Our Past 2008:49).
Haynes lists agencies associated with the source of the rock itself, followed by those agencies related to transport, and ending with postdepositional fractures as the most logical geofact contributors -from start to finish (Figure 1).
(1). Fracturing of outcrops by tectonic stress and weather fracturing, root pressure, freeze-thaw cycles, solar heating.
(2). Movement of cherts down steep slopes by free-falling, tumbling, sliding, either individually or en masse.
(3). Tumbling for several miles down low to intermediate slopes by water and mudflows, carrying igneous rocks as well as cherts.
(4). Buried in aggrading alluvial fan, erosion can re-expose cherts to further fracture and flaking by intergranular pressure.
(5). Erosion and redeposition can account for several generations of flaking observed on some pieces of chert (Haynes 1973:307).
Source of Cherts The source of the material carried down by the ancestral fan has not been located, so the fracture agencies listed under (1) above cannot yet be verified. Although such processes may be observed today at siliceous rock outcrops elsewhere in the Calico Mountains, these have not been studied (George Jefferson, personal communication 2008).