Description: Slope deposits drilled during Leg 67 were later detailed in redisplayed seismic-reflection records. These deposits are of significantly lower seismic velocity and probably lower density than the underlying basement. This relationship indicates a contact between rocks of differing consolidation rather than a continuous sedimentary sequence. The slope deposits cover basement terranes of three different topographies. The shelf edge is an arch whose seaward flank forms a steep (up to 15°) upper slope. The midslope area has a rugged topography covered by thick slope deposits. The lower slope is relatively smooth except where broken locally by benches. The upper and middle slope areas are associated with strong magnetic anomalies and rare, landward-dipping reflections truncated by the rough surface. The rough midslope topography may reflect erosion succeeding the Paleocene uplift of this area and at least local subsidence in the early Miocene. Slope deposits covered the Trench landward slope, contemporaneous with the increased arc volcanism indicated by ash layers and with the present period of subduction. The subducting ocean crust and sediment of the Cocos Plate has a linear horst and graben topography of hundreds of meters relief that disappears beneath the landward slope of the Trench without disturbing its topography. This passive assimilation of oceanic material without significant accretion in the late Neogene argues for significant decoupling at the front of the subduction zone. A base of gas-hydrate reflection is evident in many of the redisplayed seismic records off Guatemala. These reflections are most common where slope deposits are thick; the reflections have not been identified in the underlying acoustic basement. This observation is consistent with the geochemical evidence that gas hydrate has its source in the organic- rich slope sediment. The hydrate depth and the temperature measurements in drill holes indicate a temperature gradient of 30°C/km.