No records of the date of lime mining activities at Gondolin, maps or photographs of the cave prior to mining are known to exist. Long-term residents near Gondolin report that the system was mined prior to the 1950s. The cave was named after J.R.R. Tolkien's Gondolin by the early 1970s. Exposed fossils in the cave system were noted at least as early as the 1970s and brought to the attention of Elisabeth Vrba and David Panagos at the Transvaal Museum, who initiated excavations in early 1979. The first phase of excavation addressed the extremely fossiliferous in situ remnant deposits adhering to the northern wall of the cave system. The three-week 1979 excavation removed approximately of calcified sediments from the northern cave wall. While two distinct sediment phases were recognized during the original excavation, later work with the fossil fauna and geology of the GD 2 deposits did not find any basis for multiple depositional phases within the sampled sequence. The removed sediment blocks were organised into 43 blocks/trays and processed using acetic acid at the Transvaal Museum. A significant gap in research at Gondolin occurred in the 1980s, during which time all of the excavated blocks were processed. The first description of the result fossil assemblage in 1993 only partially described 4,344 individual specimens that could be assigned to a specific taxonomic levels. In 1997 a survey of the sediments at Gondolin included the first sampling of the extensive ex situ dumpsite deposits at the locality via a test trench. Materials removed from Trench A included fossiliferous breccia blocks from most, if not all, of the stratigraphic units present at the site. From this sampled material, two isolated hominin teeth were recovered. The first, GA 1, is a worn and fractured left molar that has not been confidently attributed to either genus or species. The most recent excavations at Gondolin were undertaken in 2003 and 2004 to explore the largely decalcified GD 1 deposits along the northwestern rim of the Gondolin locality. A four-week excavation season produced a sample of 4,863 fossil specimens from approximately of soil overburden and naturally decalcified sediments that were screened with 1mm mesh. Critically, integration of taphonomic and geologic data from the GD 1 excavations indicated that fundamentally different processes of fossil record formation were occurring at Gondolin during the formation of the GD 1 and GD 2 fossil assemblages. This result highlighted the complex, heterogenous geologic processes that can influence fossil deposition and assemblage composition in South African cave systems during the late Pliocene and early Pleistocene.
Fossil fauna
The original description of fossil specimens from the GD 2 deposits only addressed a small portion of the assemblage. A single hominin tooth that was originally thought to have been derived from the GD 2 sampling was later determined to be an intrusive modernHomo tooth. A comprehensive reanalysis of the Gondolin GD 2 assemblage undertaken from 2002 to 2004 led to the identification of 95,549 total individual specimens, of which 16,477 are identifiable craniodental or postcranial specimens; with the remaining 79,076 specimens being unidentifiable fragments. The assemblage composition described from this reanalysis differs in key respects from that of the initial 1993 description, including significant shifts in the specimen counts attributed to individual taxonomic categories and the removal of several species. The revised description of the GD 2 assemblage also reinforced several unique features of the collection compared to other South African late Pliocene and Pleistocene:
The numerical dominance of two rarely encountered antelope species - klipspringer and a species of reduncin similar to the extant mountain reedbuck.
The first described occurrence of the extinct porcupine from an assemblage other than the Makapansgat Member 3 deposits.
The first comprehensive taphonomic analysis of a South African early Pleistocene assemblage solely derived from in situ ''deposits.
A robust sample of directly associated cranial and postcranial remains for many fossil species, including several groupings of articulated fossils.
The recovery of fragile elements including hyoids and fetal/neonatal remains.
The absence of any identificable primate remains within the assemblage.
Age of the deposits
The Gondolin Palaeo-cave deposits have been dated using a combination of biostratigraphy and palaeomagnetism which indicate an age of around 1.8 million years.
