Possible obsidian sources for artifacts from Timor: narrowing the options using chemical data

Measurements made at the Australian National University using laser ablation ICPMS show that none of the 88 analyzed obsidian artifacts from East Timor match either the known Papua New Guinea or the five Island SE Asian source samples in our ANU collections. There is a coastal journey of more than 3000 km between the occurrence of obsidians from the Bismarck Archipelago volcanic province of Papua New Guinea and the Sunda-Banda Arc volcanic chain, yet obsidian artifacts from the two important PNG sources of Talasea and Lou Island are found at coastal Bukit Tengkorak in eastern Sabah at a similar distance along with material that has no known source. Timor lies south of the eastern section of the active volcanic Banda Arc island chain but it is within range of possible rhyolite sources from there. Although there is a continuous chain of around 60 active volcanoes stretching from west Sumatra to the Moluccas most are basaltic to andesitic with few areas likely to produce high silica dacite–rhyolite deposits. This does not exclude the possibility that the volcanic landscapes may contain obsidian, but without detailed survey and chemical analysis of sources from the Sunda-Banda Arc the attribution of the Timor obsidian artifacts remains to be demonstrated. Timor may seem to be an unlikely source for the presence of obsidians as it lacks reports of the silica-rich rhyolite volcanic centers necessary to produce this material. Despite the absence of detailed survey and analysis of Indonesian obsidian sources, especially from the volcanically active Banda Arc, this paper presents evidence that one of two obsidian sources is clearly from Timor while the other, with less certainty, is also from an unknown local source.     

Neolithic occupation and mid-Holocene soil formation at Encosta de Sant'Ana (Lisbon,Portugal): a geoarchaeological approach

Excavations at the archaeological site of Encosta de Sant'Ana (Lisbon, Portugal) uncovered a mid-Holocene buried alluvial soil associated with early Neolithic occupation layers. Routine laboratory analyses and micromorphological observations were undertaken on the soil material. Humic acids from its Ab horizon, as well as Neolithic ecofacts, were radiocarbon dated. The dates obtained indicate that soil was formed between c. 8.0 and 6.0 cal ka BP and that the pedological evidence fits the record of the North Atlantic Holocene IRD events (“Bond events”) and the so-called “Holocene climate optimum”. The geoarchaeological record reveals that Neolithic inhabitants settled upon a stable surface, still affected by soil formation that was suddenly interrupted by slope wasting, probably in correspondence to Bond event 4, at c. 6.0 cal ka BP.     

Gaiola vs. Borbone System: A Comparison between 18th Century Anti-Seismic Case Studies

This article briefly discusses the seismic-resistant heritage of the 18th century, circumscribed in Lisbon’s Baixa Pombalina (post 1755) and case baraccate of Southern Italy (post 1783).

A comparison of these anti-seismic systems is discussed through the architectural principles and the mechanical behavior. It is shown that, despite the wide diversity of cases and the different geo-historical conditioning, both systems arise from an intuition of the compound seismic efficiency, the typical pragmatism of the enlightenment period and an interpretation of the classic composition code.

Two specific case studies, a private building in Baixa Pombalina (Lisbon) and the Bishop’s Palace of Mileto (Calabria region) are compared. We briefly analyze: (i) configuration and structural principles; (ii) characteristics of the materials; and (iii) seismic behavior.

A standardized spatial morphology closely linked to traditional construction techniques positively determines the seismic response and it is one of the key common factors in this heritage to be preserved.

In both cases, the architectural and structural choices are crucial to the seismic response of the building and must be respected as an identity of a specific technical knowledge. Moreover, this materiality represents a historical continuity of the community’s memory that requires transdisciplinary, critical understanding, and preservation.