Two single-channel, seismic-reflection profiles were obtained across the site by the JOIDES Resolution during Leg 149 (Fig. 1 and Fig. 2). Consequently, these profiles are less distinct than multichannel profiles. Nevertheless, they show a number of reflectors that have been recognized on a regional scale in the vicinity of the Iberia Abyssal Plain and that have been dated by tracing them back to Leg 103 sites west of Galicia Bank (Mauffret and Montadert, 1988) and to Site 398 near Vigo Seamount (Groupe Galice, 1979). JOIDES Resolution Line 3 crosses the site in an east-west direction and one of these reflectors, separating acoustic formations 1A and 1B (Groupe Galice, 1979; Fig. 1), appears to cross the site. This reflector marks a regional unconformity produced by the folding that accompanied the Miocene compressional episode in the Rif-Betic Mountains to the south. The reflector has a rough indistinct surface near the site, which makes it difficult to recognize. The acoustic basement, which is composed of many hyperbolae, is not clearly seen at the base of the sedimentary section either.
Only very limited downhole measurements were obtained at Site 899; downhole velocity logs were obtained from 394 to 455 mbsf. However, the results of two sonobuoy lines shot over the Iberia Abyssal Plain (Whitmarsh, Miles, and Mauffret, 1990) were used to convert from two-way traveltime to depth (Fig. 66 in "Site 897" chapter, "Integration of Seismic Profiles with Observations from the Site" section, this volume). Thus, we did estimate the downhole depths of the formation 1A/1B and basement reflectors seen in the JOIDES Resolution Line 3 seismic-reflection profile; these are summarized in Table 22.