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An extensive peat deposit on the Caribbean coast near Changuinola, Panama, has developed in an area subject to periodic earthquake-driven coseismic subsidence. Thick, low-ash, low-sulfur peat is accumulating immediately behind an aggrading and prograding barrier system and adjacent to a flood-prone, sediment-laden riven Measurements of changes in local sea level as a result of a recent (April 1991) earthquake reveal 30-50 cm of subsidence, greatest at the southeastern extent of the study area, where the peat surface is submerged to a depth of 3 m beneath the shallow waters of Aimirante Bay. Transgression is proceeding from southeast to northwest, parallel to the trend of the coast and the long axes of both the peat deposit and the major sand bodies. In the eastern part of the deposit, the effects of sea-level rise are evident in the degree of humification, mineral matter, and sulfur content of mangrove and back-mangrove peats offshore and immediately adjacent to the marine margin, and in peats associated with brackish tidal channels that drain the deposit. However, most of the deposit shows no indications of marine influence, even though [approximately equal to]40% of the peat is below present sea level. The western section of the deposit has evolved from low-lying palm swamps, which originated in swales on the barrier bar, into an oligotrophic bog plain with a water table elevated 6.75 m above sea level. As the mire evolved, transitions in vegetation resulted in transitions in peat types. Highly humified forest-swamp and palm-swamp peats underlie and surround well-preserved, fibric sedge peats, and create a partial hydrological bounding surface that restricts subsurface drainage from the central bog. The high water table and elevated topography of the mire and the low permeability and erosion resistance of the dense, woody peat effectively insulate most of the deposit from both elastic influx and the extensive intrusion of rising marine waters. It is evident that thick peat, and hence coal, deposits can accumulate due to tectonically driven, punctuated subsidence without leaving a record of high elastic input within the peat, even immediately adjacent to environments of active elastic deposition.

High sulfur content of coal is generally attributed to marine inundation during or shortly following peat formation. When a large peat deposit on the Caribbean coast of Panama subsided during a 1991 earthquake, sulfate-rich seawater inundated the margin of the deposit, providing the opportunity to evaluate the role of short-term marine flooding on sulfur abundance and chemistry. Salinity and pH measurements across the new marine margin indicate that penetration of saline waters into the peat is restricted to

Working memory limits are best defined ill terms of the complexity of the relations that can be processed in parallel. Complexity is defined as the number of related dimensions or sources of variation. A unary relation has one argument and one source of variation; its argument can be instantiated in only one way at a time. A binary relation has two arguments, two sources of variation, and two instantiations, and so on. Dimensionality is related to the number of chunks, because both attributes on dimensions and chunks are independent units of information of arbitrary size. Studies of working memory limits suggest that there is a soft limit corresponding to the parallel processing of one quaternary relation. More complex concepts are processed by 'segmentation' or 'conceptual chunking.' In segmentation, tasks are broken into components that do not exceed processing capacity and can be processed serially. In conceptual chunking, representations are 'collapsed' to reduce their dimensionality and hence their processing load, but at the cost of making some relational information inaccessible. Neural net models of relational representations show that relations with more arguments have a higher computational cost that coincides with experimental findings on higher processing loads in humans. Relational complexity is related to processing load in reasoning and sentence comprehension and can distinguish between the capacities of higher species. The complexity of relations processed by children increases with age. Implications for neural net models and theories of cognition and cognitive development are discussed. Keywords: capacity limits: chunking; cognitive development; comparative psychology; complexity; neural nets; relations; representations; resources; working memory