The Date of the Olive Trees in the Garden of Gethsemane

Bible Places Blog:

The olive trees in the Garden of Gethsemane are about 900 years old and were all shoots of a single tree, according to a three-year study by the National Research Council announced last week in Rome. From TerraSanta.net:

The research results show that three of the eight olive trees (the only ones on which it was technically possible to carry out the study), as dating from the middle of the twelfth century. Hence, the trees are about nine hundred years old. But one point needs to be made clear: the date indicated refers only to the aboveground part of trees – the trunk and foliage. In fact, the same research has shown that the part below ground, i.e. the roots, is certainly more ancient.

The outcome of the investigation must also be put in relation with ancient travel chronicles of pilgrims, according to which the second of Gethsemane basilica was built between 1150 and 1170 (the period during which the Crusaders were engaged in the reconstruction of the great churches of the Holy Land and Jerusalem in particular). It therefore seems likely that, during the construction of the Basilica of Gethsemane, the garden was rearranged, creating a renovation of the olive trees present at that time.

The rest of the story describes the genetic relationship between the trees. Pat McCarthy (seetheholyland.net) informs me that radiocarbon tests carried out by the University of California in 1982 dated some of the tree roots to 2,300 years old. I have not been able to locate a reference for that study yet. Reuters covers the story here.

Ancient olive trees in the Garden of Gethsemane

Equation: Radiocarbon Dating

Wired:

Right now, 40,000 feet overhead, a cosmic ray is sending a neutron smashing into a nitrogen atom, smacking a proton out of its nucleus and forming an isotope called carbon-14. Armed with the equation below, archaeologists use these atoms to pinpoint how old the Dead Sea Scrolls are, or the drawings in Chauvet Cave, or Ötzi the Iceman.

Living things constantly consume carbon—through photosynthesis, for plants, and for animals, ingestion of those plants. The atmospheric ratio of carbon-14 to regular carbon-12 remains consistent at one part per trillion, so if something is alive, one-trillionth of its carbon atoms will be C-14. But once a plant or animal dies, its carbon-14 is no longer replenished. C-14 is radioactive and unstable, with a half-life of 5,730 years, which means that half the atoms will turn back into nitrogen over that period. That rate of decay is key to gauging age.

Amount of carbon-14 detected in the sample

Amount of carbon-14 in the sample at the time of death, which would have been
a trillionth of the total carbon present

Half-life of carbon-14: 5,730 years

What we’re solving for: time elapsed since the thing—or the organic materials
used to make the thing—died