Shell Middens in Punta Mazo: Windows to the Past

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By Luis Fernando López, Cecilia Alducin, Andrea González, Verónica Vargas, Juan López and Enah Fonseca

What we know about the ancient human groups in the peninsula of Baja California has been thanks to the remains of materials located in archaeological sites called shell middens. Although their main component defines them, shells are not the only elements present, and we can find remains of the consumption of mollusks but also of animals and plant species. We can infer activities of preparation, consumption and disposal of food, as well as the development of productive and overnight activities. That is why, from the study of shell middens we can investigate the daily life of the hunter-gatherers-fishers who lived hundreds of years ago.

Extensive excavations were carried out in order to obtain as much information as possible about the groups that settled in the Punta Mazo Nature Reserve in San Quintín, as part of the 2018 season of the project “Study of camps on the coastline and intermontane valleys of Baja California”. This field season was the result of a collaboration between the National Institute of Anthropology and History in Mexico and the non profit organization Terra Peninsular.

Figure 1. Rocky shelter number 3. It is an archeological shell midden. Photo: Enah Fonseca.

Fieldwork was conducted in the southern part of the Punta Mazo Nature Reserve, in an area of ​​volcanic rock formations. The excavation point where we worked had been previously selected from a surface survey project carried out in 2017 (Fonseca, 2017, Fonseca and Mejía 2017).

During that field season, a series of rock shelters – shallow natural caves – were identified and numbered from 1 to 6, from north to south. For this year’s excavation season,  rock shelters number 3 and 4 were selected due to their good conservation status, as well as the diversity of lithic and malacological materials observed on the surface of shelter 3, and a mortar carved in fixed rock identified on the shelter 4 (Fig. 1).

Reticles were mounted within the rock shelters to divide the excavation grid in order to systematize the information of each square unit. Fieldwork dynamics consisted of excavating layers of soil inside the shelters (Fig. 2); subsequently, the sediment was sifted using a 1/8 inch screen mesh to identify and classify shells, lithic – stone artifacts – and bones (Fig. 3).

Figure 2. Rocky shelter number 4 during the excavation process. Photo: Enah Fonseca.

Excavation tools such as trowels, pickaxes and different brushes were used. In addition to the mechanical process of soil removal, the process of registering the layers at different depths was fundamental. Photographs and drawings of the archaeological elements on the surface were taken and sketched. At the end, a description of all the layers in the excavation profiles (vertical differences in the layers) was made (Fig. 4).

Figure 4. Record of the excavated profiles of shelter 3. Photo: Enah Fonseca.

Later, at El Refugio – our home and center of operations during the field season -, the shell materials were separated by species and size (length of the shell). The specimens or fragments that were burned were registered to identify if they showed signs of having been modified to make tools or ornaments (Fig. 5).

One of the significant findings worth highlighting was the difference in shell content between both shelters. In shelter 3 large, amounts of shell fragments were found, mainly black abalone (Haliotis cracherodii), California mussel (Mytilus californianus) and owl limpet (Lottia gigantea). Because of the perforations and angular cuts that some of these fragments presented, it was inferred they had been used to make jewelry; hence the importance of the malacological material for its ornamental and aesthetic value. (Fig. 6). Unlike shelter 3, there were few shells in shelter 4, however a large amount of lithic material was found, most of it chipped-off stone (flakes). The differences noted between the two shelters are related to the use/function of the area and the objects, which indicates on the one hand that there were areas destined to the preparation/consumption of food where certain specimens of shell were also selected for the elaboration of ornaments, and on the other hand there were areas destined to the manufacture of stone tools.

Figure 5. Shell analysis in process. In addition to the taxonomic identification, burned fragments or with any traces of having been modified to elaborate artifacts or ornaments must be separated. Photo: Enah Fonseca.

Regarding the bone material found that was found, there was a predominance of fish, rodents and birds; however, otter teeth and part of a burned whale vertebra were also identified (Fig. 7).

Figure 6. Abalone shell with perforation and angular cuts. Probably used as an earring. Photo: Enah Fonseca.

Finally, one of the greatest contributions of the field season to our training was to discover the importance of biology in archaeological studies. In addition to the taxonomic recognition of the species that were found, we can analyze abundance and size to understand the behavior of past societies regarding their consumption patterns, resource management and changes over time.

Figure 7. Fragment of a burned whale vertebra. Photo: Enah Fonseca.

This article was published in the November issue of the Mediterranews magazine.

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