An international team lead by Sue O'Connor of the Australian National University and reported in a recent article in the Journal of Archaeological Science have developed a new rock art dating technique based on calcite laminations, and tested the technique on deposits at Lene Hara Cave.
Lene Hara Cave is a large limestone solution cave located on the island of East Timor in the Indonesian archipelago. Excavated beginning in the 1990s by Sue O'Connor of the Australian National University, Lene Hara has proven to contain several stacked occupations, the oldest between 30,000 and 35,000 years ago. The earliest evidence of pre-Lapita fishing has been found at Lene Hara, in the form of shell fish hooks, made of Trochus niloticus and recently dated between 9741+/- 60 years before the present.
Rock art paintings are visible on the walls of Lene Hara Cave, which have mostly attributed to the post-pottery Neolithic occupation (ca 2000 years ago). Motifs of the rock art include boats, animals and birds; some combined human and animal forms; and, most frequently, geometric shapes such as sun bursts and star shapes. Most of the art is monochrome, but pigments of black, yellow and brown and a few of red and green are also noted.
The new technique involves the dating of small quantities of uranium and thorium identified within the calcite deposits laid down on top of the rock art. The isotopes of U238, U234 and Th230 are identified within the calcium carbonate crystals that are precipitated in the coatings, and since the decay rate is known, this method can be used to determine the age of the sediments covering the paintings.
The uranium/thorium dating method used in Aubert et al. to date the rock art using examination of the calcite laminations suggests that while the visible rock art is less than 6300 years old, there are remnants of art beneath that which may date as old as 24,000 years ago.
Lene Hara Cave is a large limestone solution cave located on the island of East Timor in the Indonesian archipelago. Excavated beginning in the 1990s by Sue O'Connor of the Australian National University, Lene Hara has proven to contain several stacked occupations, the oldest between 30,000 and 35,000 years ago. The earliest evidence of pre-Lapita fishing has been found at Lene Hara, in the form of shell fish hooks, made of Trochus niloticus and recently dated between 9741+/- 60 years before the present. Rock art paintings are visible on the walls of Lene Hara Cave, which have mostly attributed to the post-pottery Neolithic occupation (ca 2000 years ago). Motifs of the rock art include boats, animals and birds; some combined human and animal forms; and, most frequently, geometric shapes such as sun bursts and star shapes. Most of the art is monochrome, but pigments of black, yellow and brown and a few of red and green are also noted.
The new technique involves the dating of small quantities of uranium and thorium identified within the calcite deposits laid down on top of the rock art. The isotopes of U238, U234 and Th230 are identified within the calcium carbonate crystals that are precipitated in the coatings, and since the decay rate is known, this method can be used to determine the age of the sediments covering the paintings.
The uranium/thorium dating method used in Aubert et al. to date the rock art using examination of the calcite laminations suggests that while the visible rock art is less than 6300 years old, there are remnants of art beneath that which may date as old as 24,000 years ago.
More information
Lene Hara Cave, Indonesia
Aubert, M., O'Connor, S., McCulloch, M., Mortimer, G., Watchman, A., Richer-LaFleche, M. (2007). Uranium-series dating rock art in East Timor. Journal of Archaeological Science, 34, 991-996. DOI: 10.1016/j.jas.2006.09.017
O'Connor, Sue and Peter Veth. 2005. Early Holocene shell fish hooks from Lene Hara Cave, East Timor establish complex fishing technology was in use in Island South East Asia five thousand years before Austronesian settlement. Antiquity 79(304):249-256.
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