**3.3 Case 3: Archeological evidence from Bubog 1 rockshelter on Ilin Island, Mindoro**

Ilin Island is a small elongated island just off the coast of Mindoro Occidental at its southern end and situated along the direct route from Sundaland (via Borneo and Palawan) to the Wallacean part of the Philippines. East of Huxley's Line, the island was close to the northern end of Pleistocene Palawan and possibly served as a steppingstone for the migration of early humans into the main Philippine archipelago. Ilin Island is part of the municipality of San Jose and separated from the

### *Island Migration, Resource Use, and Lithic Technology by Anatomically Modern… DOI: http://dx.doi.org/10.5772/intechopen.93819*

mainland by the narrow, c. 900-1300 m wide Ilin Channel (**Figure 6**). It is mostly composed of bedded, coralline and fossiliferous limestone of the Pliocene Famnoan Formation with a small area of volcanic flows in its northeast. Most of the island is highly prone to karstic erosion and possesses numerous caves and rockshelters [33].

Among the over 40 caves and rockshelters discovered during initial surveys in 2010 and 2011, four sites have been excavated, Salamagi, Bubog 1 and 2, and Cansubong 2. Excavations focused mainly on Bubog 1 and 2, two rockshelters close to each other and located at the southeastern end of Ilin Island [9, 33, 41, 42]. Both sites face east and are situated at an altitude of *c.* 30 m amsl (Bubog 1) and 42 m amsl (Bubog 2). Bubog 1 is between 40 and 50 m long with a rock overhang in excess of 4 m wide. Its platform was disturbed by three more or less circular shaped pits that were dug by treasure hunters to a depth of over 1 m in the misconceived belief that they would find gold or other treasure. The pits cut through deposits of marine shells and exposed a well-stratified archeological shell midden. The edges of the treasure hunter pits were straightened in the course of the archeological excavation to provide vertical profiles for drawing and recording, and the pits were conjoined in the following seasons (**Figure 7**).

By 2016, the excavations in Bubog 1 had reached a depth of c. 4 m below the surface and exposed silty terrestrial deposits with a few artifacts, including a fully worked bone fishing gorge [9] (**Figure 8A**). While no more marine shells appear in those layers, the remains of pelagic fishes still provide evidence for open sea fishing [43]. The shell midden stratigraphy is connected to a radiocarbon chronology beginning at c. 4 ka cal. BP near the surface to 28-33 ka cal. BP at the lowest shell midden layer 9/9a (**Figure 7**). The absence of sufficient organic material prevented 14C dating for the layers below the shell midden, however at least an age of older than the 33 ka cal. BP retrieved from a *Geloina coaxans* shell from the lowest shell midden layer above can be assumed [9].

Associated with the shells from the midden deposits were several pebble and pebble fragments as well as fish remains and mammal bones. These animal bones were mainly from the endemic pig *Sus oliveri*, with few remains of deer (*Rusa marianna and Cervus alfredi*) and tamaraw (*Bubalus mindorensis*) as well as rodents, notably the cloud rat *Crateromys paulus*, known only from Ilin Island [44] and lizards [9, 33, 43]. While the use of the pebbles was obviously for breaking open the larger marine shells, flaked lithics were extremely rare in the shell midden [33]. Instead,

**Figure 6.** *Location and aerial view of Bubog 1 and 2 sites on Ilin Island.*

white and yellowish chert, with ventral scars that were either caused by use or retouch. Some of these flakes display potlid fractures which might be heat-related. The flat polishes and diagonal and transversal striations on these tools indicate prolonged contact with phytolith-rich plants through scraping during the terminal LGM (**Figure 5G, H**). Retouched tools were recovered in Topogaro 1 during the

*Topogaro lithic tools (A-D) and use-wear traces of plant-working on their edges. E, F: edge scarring; G, H:*

*Pleistocene Archaeology - Migration,Technology, and Adaptation*

**3.3 Case 3: Archeological evidence from Bubog 1 rockshelter on Ilin Island,**

Ilin Island is a small elongated island just off the coast of Mindoro Occidental at its southern end and situated along the direct route from Sundaland (via Borneo and Palawan) to the Wallacean part of the Philippines. East of Huxley's Line, the island was close to the northern end of Pleistocene Palawan and possibly served as a steppingstone for the migration of early humans into the main Philippine archipelago. Ilin Island is part of the municipality of San Jose and separated from the

Holocene period (**Figure 5C, D**).

**Mindoro**

**94**

**Figure 5.**

*micropolish.*
