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El área septentrional andina

14C and TL chronology for the Ecuadorian formative

Jorge G. Marcos et Bogomil Obelic

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Universitat Autònoma de Barcelona, Departement de Geologia, 08193 Bellaterra, Spain

1The purpose of this presentation is to give an absolute chronological synthesis for the Ecuadorian Formative. All 14C assays related to secure contexts were calibrated and compared. When radiocarbon dates were not available, TL absolute dates were taken into consideration. The country was divided into three natural regions, and when possible, these regions were in turn divided into subregions. The coastal plain, between the Pacific Ocean and the western Andean Cordillera, is referred as the Coast, and is divided into northern, central and southern subregions. The Andean valleys and the paramo, named the Sierra, was divided into northern and southern subregions, while the Amazonian sector of Ecuador, referred as the Oriente, has not been divided because of the small number of data available.

2Samples were divided into different phases, each phase corresponding to a well defined archaeological deposit. Results of radiocarbon measurements made by various laboratories were calibrated by using the program OxCal v.2.18 (Ramsey, 1995) to obtain the "prior" probability distributions. After this calibration, combinations of TL and calibrated 14C dates for each phase were made by multiplying the probability distributions. For each combined distribution an agreement index was calculated and compared with the threshold corresponding to the c2 test at 5%. The application of these agreement indices allowed us to test for unreliable dates.

3Radiocarbon dates that served to date Valdivia broadly defined sub-phases A, B, C and D by Meggers, Evans and Estrada (1965) have not been considered. Only dates that are referred to archaeological secure contexts at Real Alto, and Loma Alta and to the 8 phase sequence by Hill (1975) have been taken into account.

4Radiocarbon assays are not available for all phases. In order to complete the absolute chronology for the 8 phase Valdivia sequence, TL determinations have been considered too.

5Statistical treatment of these dates permitted us in some border-line cases to place some features in their appropriate sequence. An example: two hearths, labeled r-1 and r-2, were found at Real Alto (Unit-1-1991). They were located on the same structure-floor and under a crumbled wattle-and-daub wall. Although, their micro-stratigraphic position was not clear and one's precedence over the other could not be determined, the statistical treatment of TL dates permitted the assignment of each one to their proper place in the chronological sequence.

6Dates presented in DeBoer (1996) were not considered for the Early Formative Northern Coast sequence since these are mostly associated with a surface collection and therefore do not provide secure association with archaeological events.

7The charcoal samples which gave earlier dates for Valdivia phase la at Real Alto came from the bottom of the site under the shell deposit and over the sterile stratum. These might actually date a non-ceramic initial occupation of the site. In this deposit the principal material recovered were stone spindlewhorls and other lithic artifacts (see Damp 1988: 58-59).

8Late Formative data for Southern Coast are presently unavailable. The data for Guarumal correspond to the Regional Developmental Period (Jambelí phase) dating between 2040_120 BP (BM-1682R) and 1475_35 BP (BM-1688) (Currie 1985).

Figura 1. Nortern Coast

Figura 1. Nortern Coast

Figura 2. Central Coast

Figura 2. Central Coast

Figura 3. Southern Coast

Figura 3. Southern Coast

Figura 4. Northern Sierra

Figura 4. Northern Sierra

Figura 5. Southern Sierra

Figura 5. Southern Sierra

Figura 6. Oriente

Figura 6. Oriente


Table 1. Radiocarbon and TL measurements of the Ecuadorian Coastal Formative (14C measurements expressed in BP; TL measurements expressed in BC)


10(Esmeraldas, Northern Manabí)


12(Peninsula Santa Elena, Southern Manabí, Guayas Basin, Gulf of Guayaquil)


14(El Oro)

Table 2. Radiocarbon and TL measurements of the Ecuadorian Sierra Formative (14C measurements expressed in BP; TL measurements expressed in BC)


16(Quito valley, Cotocallao site)


18(Cañar, Azuay, Loja)

Table 3. Radiocarbon and TL measurements of the Ecuadorian Oriente Formative (14C measurements expressed in BP; TL measurements expressed in BP)

Table 3. Radiocarbon and TL measurements of the Ecuadorian Oriente Formative (14C measurements expressed in BP; TL measurements expressed in BP)


DeBoer, W. R.
1996 Traces behind the Esmeraldas Shore - Prehistory of the Santiago-Cayapas Region, Ecuador, The University of Alabama Press, Tuscaloosa and London.

Hill, B.
1972/74 A new chronology of the Valdivia ceramic complex from the coastal zone of Guayas province, Ecuador; Ñawpa Pacha 10-12, p.1-39, Berkeley, CA.

Currie, E.J.
1985 "La cultura Jambelí con referencia particular al conchero Gua-rumal", in S.E.Moreno (ed.) Memorias del Primer Simposio Europeo sobre Antropologia del Ecuador, p.31-45, Universidad de Bonn - Ediciones Ab-ya-Yala, Quito.

Damp, J.
1988 La Primera ocupación Valdivia de Real Alto: patrones económicos, arquitectónicos e ideológicos. Biblioteca Ecuatoriana de Arqueologa Vol.3. ESPOL/Corporacion, Editora Nacional, Quito

Martini, M., E.Sibilia, G.Spinolo, C.Zelaschi, A.Alvarez and J.M.Marcos
1996 The Early Formative Period pottery from the Santa Elena peninsula in South West Ecuador: Absolute TL Chronology; Presented for publication in Latin American Antiquity.

Meggers, B.J., C. Evans and E. Estrada
1965 Early Formative Period of Coastal Ecuador: The Valdivia and Machalilla Phases; Smithsonian Institution Washington D.C.

Ramsey, C.B.
1995 Radiocarbon Calibration and Analysis of Stratigraphy: The OxCal Program; Radiocarbon, 37, p.425-430.

Zió»kowski, M.S., M.F.Pazdur, A. Krzanowski, A.Michczy_ski
1994 ANDES -Radiocarbon Database for Bolivia, Ecuador and Perú, Joint publication - Andean Archaeological Mission of the Institute of Archaeology, Warsaw University & Gliwice Radiocarbon Laboratory of the Institute of Physics, Silesian Technical University, Warszawa -Gliwice.

Table des illustrations

Titre Figura 1. Nortern Coast
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Titre Figura 2. Central Coast
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Titre Figura 3. Southern Coast
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Titre Figura 4. Northern Sierra
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Titre Figura 5. Southern Sierra
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Titre Figura 6. Oriente
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Titre Table 3. Radiocarbon and TL measurements of the Ecuadorian Oriente Formative (14C measurements expressed in BP; TL measurements expressed in BP)
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Centro de Estudios Arqueológicos y Antropológicos Escuela Superior Politécnica del Litoral, Guayaquil

Ruler Bo {kovi} Institute, Zagreb

© Institut français d’études andines, 1998

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