INVESTIGATIONS AT THE
MOCKINGBIRD GAP CLOVIS SITE

by Vance T. Holliday, Bruce B. Huckell, and Robert H. Weber

The Mockingbird Gap site, ~40 km southeast of Socorro, New Mexico, is one of the largest and perhaps least known Clovis sites in the southwestern United States. It was discovered in the late 1950s (by RHW) in the desert grassland of the northern Jornada del Muerto, a structural basin just east of the Rio Grande. Surface collecting and detailed mapping of the site produced hundreds of Clovis artifacts—projectile point bases, fluted point preforms, end scrapers, gravers, and other flake tools—from an area 800 m by 80-150 m. The site occupies a northeast-southwest trending ridge composed of sand and gravel, capped by s strongly developed gypsite/calcrete, and bordering the floor of Chupadera Wash, which drains southwestward to the floor of the basin (and likely drained into paleo-lake Trinity). The ridge is divided into northern and southern segments, separted by a broad, shallow swale that drains into the flat, untrenched floodplain of Chupadera Wash. Artifacts come from both segments of the ridge and from some areas of the swale. In the mid-1960s Weber contacted George Agogino of Eastern New Mexico University (ENMU) about the site, resulting in excavations on the south ridge (1966-1968). 2-m wide trenches were used to explore promising areas, and, where results warranted, blocks of contiguous 2 m units were dug. The site was determined to be largely Clovis, although scattered Archaic occupation and a small Ancestral Pueblo pithouse component were encountered. During and after the excavations, Weber conducted geological investigations on the site and along Chupadera Wash. Results were reported briefly (Weber and Agogino 1997; Weber 1997).

A 2004 visit suggested to us that there was potentially much to be learned from the site and surrounding area about the Clovis occupation. In 2005 we began test excavations at the site and stratigraphic coring in Chupadera Wash (Huckell et al. 2006). Our field work continued through the 2006 and 2007 field seasons.

The 2005 archaeological investigations consisted of facing up portions of the eroded walls of the unbackfilled ENMU excavations. Eight 1.0 x 0.5 m units were excavated from the point of break-in-slope between the modern surface and the old excavations to culturally sterile sediments, typically 0.4-0.6 m below ground surface. Six units were excavated in the largest (ca. 18 m by 30 m) excavation area, with one more in an area to the south and the final one to the east of it. Five units produced from 30-55 subsurface artifacts each—almost entirely biface reduction debitage—of probable Clovis origin, given that they are made of the same suite of jasper and chert materials as previously recovered diagnostic Clovis implements. This differentiates them from Archaic and Ancestral Pueblo assemblages. Two of the units yielded fragments of tooth enamel morphologically and metrically consistent with bison. The artifacts and enamel fragments were recovered from a similar suite of soil horizons, consisting of a thin veneer of eolian sand atop a well-developed Bw-Bk-BCk-Km/Ky sequence. Artifacts were vertically dispersed by bioturbation and eolian processes, but tended to be concentrated in the lower Bw and throughout the Bk horizons. The degree of soil development suggested that none of the sand layers was older than perhaps middle Holocene age and, therefore, the primary Clovis occupation surface was not preserved on the south ridge.

In 2006 and 2007 the archaeological excavations concentrated on the northern side of the swale that separates the two ridge. Over the years, Weber found a large quantity of Clovis artifacts in this area where wind deflated the sand sheet down to resistant units. No artifacts were found where the sand sheet was intact. The situation indicated the presence of a buried occupation surface. Approximately 20 1.0 x 1.0 m units were excavated through the sand sheet. The work revealed that the sheet was composed of two layers of sand. On top is a younger deposit with a Bw horizon over a thin Bg horizon; the latter quite unusual in such an arid and well-drained setting. Below the surface sand is an older sand with a Btb-Bkyb soil horizon sequence. The testing produced over 1000 artifacts; mostly flaked stone including a Clovis point base, a few biface fragments, some 20 flake tools, and hundreds of flakes, along with pieces of tooth enamel and occasional splinters of large mammal bone. Most of the flaked stone was debitage, representing a variety of different sources. Many flakes were clay-coated and from within the Btb or Bkyb horizons. While not diagnostic, these artifacts were of materials consistent with those used in the manufacture of Clovis tools at the site. A green toblack chert of variable quality was the dominant material, and at this time its geological source is not known. Socorro jasper, actually a silicified rhyolite available from a number of individual sources south and west of Socorro, was common. Nonlocal materials included china chert from the northeastern Zuni Mountains, two pieces of Mt. Taylor obsidian from the Grants area, and numerous flakes of Chuska chert from the Chuska Mountains on the Arizona-New Mexico border. China chert was transported over some 190 km, and Chuska chert over 315 km.

Along the eroding east margin of the sand sheet Weber recovered Clovis point fragments and other artifacts. Test units near the area of the point finds yielded 48 flaked stone artifacts, including the basal corner of a Clovis point and a fragment of a flake tool, and one piece of large mammal (bison-sized) tooth enamel. Importantly, the same suite of soil horizons was present in this unit, and 65 percent of the artifacts were recovered from the Btb horizon; they also displayed clay films. The second test unit yielded nine flakes, four or five from the Btb. Our interpretation of these results is that these units lie within a discrete Clovis occupational locus within the site.

The results of three seasons of field work show that significant deposits of Clovis age are locally buried beneath eolian sands at the site. On the south ridge in the area of the ENNMU excavations, the stone artifacts and teeth are not in primary context but the area still has the potential for yielding evidence of Clovis tool manufacture and subsistence activity. To the north, the swale below the northern ridge was the scene of considerable Clovis activity. Shallowly buried but minimally disturbed archaeological deposits exist here. We found no evidence of younger occupations. The areal extent of Clovis occupation within this large area is uncertain, but potentially is extensive. The sand plain in the swale appears to have been geomorphically relatively stable since the late Pleistocene, in contrast to areas of Clovis occupation on the ridge.

Stratigraphic studies in Chupadera Wash adjacent to the site consisted of recovery of 15 cores using a Giddings soil-coring rig plus excavation of one bucket-auger hole. Three of the cores penetrated >6.0 m. Above that depth the sediments include middle to late Holocene sand, gravel, and very dense clay. Below 6 m are 2-3 m of black, massive to stratified muds—indicating palustrine conditions—that yielded radiocarbon ages (on decalcified humates) of 9925+155/-150 RCYBP (A-13929) at 635-645 cm depth and 10,590+95/-90 RCYBP (A-13930) at 898-920 cm depth. More muds are present below 920 cm, but we do not know their maximum depth. These data indicate that a marsh was adjacent to the site, likely providing resources that attracted Clovis occupants.

Our thanks to the New Mexico State Land Office and the New Mexico Historic Preservation Division, Office of Cultural Affairs for their support of our research, conducted under permit AE-112 (2005) and SE-239 (2006). In addition to AARF, the 2006 and 2007 investigations were supported by funds from the Maxwell Museum of Anthropology, University of New Mexico.

References Cited

Huckell, B. H., V. T. Holliday, R. H. Weber, and J. H. Mayer 2006 Archaeological and Geological Test Investigations at the Mockingbird Gap Clovis Site, Central New Mexico. Current Research in the Pleistocene 23:115-116.

Weber, R. H. 1997 Geology of Mockingbird Gap Site in Central New Mexico. In Layers of Time, Papers in Honor of Robert H. Weber , edited by Meliha S. Duran and David T. Kirkpatrick, pp. 115-122. The Archaeological Society of New Mexico 23, Albuquerque.

Weber, R. H. , and G. A. Agogino 1997 Mockingbird Gap Paleoindian Site: Excavations in 1967. In Layers of Time, Papers in Honor of Robert H. Weber , edited by Meliha S. Duran and David T. Kirkpatrick, pp. 123-127. The Archaeological Society of New Mexico 23, Albuquerque.