mesa2ctype1

Mesa Field Services

Fire Hearth Analysis

Type 1 (7430 to 2870 B.P.) Early to e. Late Archaic

A total of 16 thermal features of this type were encountered and excavated during the scope of the project (Table 1). These thermal features have not been previously identified in the archaeological record of southeastern New Mexico. This thermal feature type is one of the more easily distinguished types and can be described as a small 50 cm diameter hearth with a single layer of adjoining thermally altered quartzite cobbles lining the base of an excavated depression. The layer of rock typically includes between 10 and 20 thermally altered quartzite cobbles adjoining one another in a circular arrangement covering the entire circumference of the thermal feature basin. The layer of rock typically varied between 40 and 60 kg in weight. All dates are in reference to before the present.

Little is know about the transition between the PaleoIndian and Archaic time periods. Two of the features presented below (Feature 2 and 16 with LA 138517) are rare examples from an excavated context of an occupation dating to between 8,000 and 7,000 B.P.

Site and Feature Designations	Age (2 sigma) calibration B.P.	Site and Feature Designations	Age (2 sigma) calibration B.P.
LA 101481 Feature 1	6800 to 6660	LA 138517 Feature 5a	6610 to 6590 6570 to 6400
Feature 8	6770 to 6640	9a	3320 to 3050
LA 138517 Feature 2a	7270 to 7160 7110 to 7100	9b	3140 to 2880
2b	6420 to 6170	11	3230 to 2870
2c	6610 to 6590 6570 to 6270 6240 to 6210	16	7430 to 7270
4a	3060 to 2760

LA 101481 Feature 1: 6800 to 6660 B.P.

Trench Profile	Excavation just above rock layer	Rock removal with charcoal staining

LA 101481 Feature 8: 6770 to 6640 B.P.

Found while mechnical blading	Close up view	Feature bisected

LA 138517 Feature 2 was identified as an isolated cluster of fire affected rock containing three subterranean pit strucures each approximately 0.5 meters from one another. Each pit feature was subject to a separate carbon dating. Although there is a slight discrepency with the three feature dates, due to the clusters isolation for other materials associated with the site and the similarity in subterranean pit feature form, all are believed to be associated with the same use epsiode.


Feature 3a: 7270-7160, 7110-7100 B.P.	Feature 3b: 6420-6170 B.P.	Feature 3c: 6610-6590, 6570-6270, & 6240-6210 B.P.

Feature 9 is another group or cluster of subterranean pit features found within a concentration of fire affected rock. Feature 9b (3320 to 3050 B.P.) was the most intact the remaining feature were highly disturbed by rodents and erosion of the soil surface.

Mapped view of cluster looking north	View looking west

After removal of overlying fire affected rock layer	View after bisecting feature

LA 138517 Feature 11 (3230 to 2870 B.P.) one of the best preserved and examples of this feature types form.

Pre-excavation planview	Feature bisected	Detailed mapping

LA 138517 Feature 16 (7430 to 7270 B.P.) was not one of the best preserved but is the oldest feature recorded in southeastern New Mexico and what was observed fits within the overall pattern for Feature Type 1. The 7430 B.P. dates this feature within the transition period between the PaleoIndian and Archaic time periods.

Pre-excavation planview	Feature bisected	Detailed mapping

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