Refuse units considered here were classified according to the existing Initial and Early Formative chronology for the Mazatán zone (Blake et al. 1995; Clark and Cheetham 2005; Clark personal communication). The phases are identified in Figure 1.4 and a seriation of refuse samples is discussed in Chapter 20. There are four principal phases involved: Barra (1900–1700 BC), Locona (1700–1500 BC), Ocós (1500–1400 BC), and Cherla (1400–1300 BC). Paso de la Amada appears to have been abandoned by the Cuadros phase (1300–1200 BC). There was ephemeral occupation in the Jocotal phase (1200–1000 BC), but none of the refuse samples considered in this volume dates later than the Cherla phase. No Barra-phase refuse deposits were discovered in the excavations reported in this volume. In addition to refuse samples identified as Locona, Ocós, and Cherla, certain units were identified as Early Locona (perhaps 1700 to 1650 BC) and others as Late Locona (perhaps 1500 or 1450 to 1400 BC).