An Unexplored Realm in the Heartland of the Southern Gulf ... - Famsi

experienced an upward trend in population levels throughout the Formative period. This
trend has been observed in other areas adjacent to the northwest and west of the severely
depopulated area as well. Surveys conducted by Killion and Urcid (2001), Pool (2000,
2003), and Arnold (2000, 2003b) indicate a rise in populated sites at the same time the
eastern sites are being abandoned. These data may also suggest that some people in the
distressed area were moving to nearby localities.
The decline of San Lorenzo Tenochtitlán has been at the center of hypotheses
constructed to explain this event, which has been attributed to internal revolt, external
invasion, the rise of competing polities, and the collapse of social adhesion (Borstein
2001; Coe and Koontz 2002; Cyphers 1996b; Symonds 2000). An alternative hypothesis
holds that changes in the course of the Coatzacoalcos River moved the river away from
the centrally located plateau. Cyphers (2001:649) ascribes the substantial change in river
channels to more than an above normal flooding sequence. She suggests there was a
geological uplift event in the region, and that this rapid and dramatic rise of the landmass
caused the waters to flow to lower ground, away from the Olmec core site. She implies
the cause of the uplift was tectonic activity that occurred in the Tuxtla Mountains and
may “have had repercussions in the San Lorenzo region” (Cyphers 2001:649). Symonds
(2000:69) also posits that tectonic activity may, in conjunction with sea-level rise, have
caused the rivers’ emigration away from the site. These reasons could explain the
movement of the river channels, but they do not necessarily justify the subsequent
abandonment of sites across the entire region over such an extended period of time and
along a rather clear line of demarcation. Understanding why the bordering regions to the
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