Occasional excavation of in situ and ex situ deposits at the formerly mined Gondolin paleocave system has yielded large and diverse samples of Plio-Pleistocene faunas, including isolated hominin and non-hominin primate remains. In 2003, new excavations into naturally decalcified, in situ sediments near the GD 1 datum point near the northwest corner of the cave system were undertaken. This paper describes the recovered faunal remains, taphonomy of the assemblage, and the geological and paleomagnetic context of the GD 1 deposits. The deposits represent a series of inter-stratified speleothem, in-washed sediments and talus deposits we suggest date to a time period prior to, and just after, the Olduvai normal-polarity event at around 1.7-1.8 Ma. Surface sediments and clasts were introduced into the cave by rain water runoff entering a vertically-oriented entrance that had formed along a rift in the area of GD 1. The faunal assemblage consists primarily of fragmentary diaphyseal fragments and isolated teeth. Taxonomically, the small collection of specifically identifiable bovid and equid fossils is generally consistent with remains previously excavated from in situ deposits in the Gondolin paleocave system (GD 2) and dated to around 1.8 Ma; however, the depositional histories of these two assemblages from Gondolin are remarkably different. The preservation and relative proportions of recovered skeletal elements at GD 1 is consistent with these materials having been initially accumulated outside the karstic system near the vertical cave entrance, and then later hydrologically sorted and deposited inside the cave. The sporadic to continuous water flow into the northwest corner of the cave system during the Pleistocene gradually decalcified the excavated fossilbearing breccias and further modified the composition and spatial distribution of the fossil assemblage by introducing potentially younger deposits and skeletal materials. This study highlights the variation in taphonomic processes that can occur within a single cave system, and the complex pre- and postdepositional geological and hydrological processes that can influence the taphonomic history of South African Plio-Pleistocene karstic fossil assemblages.