Radiocarbon dating standard error Live sex chat in birmingham
The surface of the mortar sets up quickly - in as little as a few hours.
The interior portions of the mortar will ordinarily set up eventually, but this requires carbon dioxide to diffuse through pores in the mortar, either in gaseous form, or in solution in the water that has been added to the slake lime.
HJ admit that there are two factors that potentially could make the measured age of the mortar appear younger than the true age of the construction.
The first of these is slow absorption of atmospheric carbon dioxide.
I have had a little chemical training (as an undergraduate at Caltech), and some prior familiarity with dendrocalibration, which is an important complication in the HJ paper.
Perhaps they or someone else will be able to correct me, but my reading of their paper is that although the C-14 results are certainly consistent with a 17th century colonial origin for the tower, they by no means conclusively rule out a pre-Columbian origin.
As originally devised circa 1950, radiocarbon dating was based on the assumption that the proportion of C-14 in the atmosphere has been constant over time, so that the amount of C-14 left in a sample would fall exponentially with its age.
However, C-14 dating of tree rings of known age subsequently demonstrated that this is not strictly true.
However, Carlson admits that she, as an architect, does not understand the highly technical carbon-14 dating of the mortar.
In a widely cited 1997 paper, Johannes Hertz raises a number of arguments against a pre-Colonial origin for the famous Newport, Rhode Island Stone Tower.