They would all have fitted nicely into the field relationships that he had observed and his interpretation of them.The field relationships are generally broad, and a wide range of ‘dates’ can be interpreted as the time when the lava solidified.Egyptian records, such as the writings of the 3rd century B. On the other hand, they sometimes refer to astronomical events whose dates can be calculated today. But one recent paper by Spence, based on astronomical calculations, put it as much as 75 years later.Thus, scholars are confident that they are not wildly off the mark. For example, the first known pyramid, the Step Pyramid at Saqqara, was built as a tomb for King Djoser, and historians usually put the beginning of his reign between 26 B. Radiocarbon dating has been too imprecise to resolve these contradictions because in this period it usually has error ranges of between 100 and 200 years. The dating ranges are earlier than some historians had previously proposed.Just when did Egyptian pharaohs such as King Tut and Rameses II rule? Now a radiocarbon study concludes that much of the assumed chronology was right, though it corrects some controversial dates and may overturn a few pet theories."This is an extremely important piece of research that shows clearly that historical dating methods and radiocarbon dates are compatible for ancient Egypt," says Kate Spence, an archaeologist at the University of Cambridge in the United Kingdom. historian Manetho and inscriptions found at key sites such as Saqqara and Karnak, provide what are called "floating chronologies" because they are internally consistent but not anchored to absolute dates.On his return, he sends his sample to the laboratory for dating, and after a few weeks receives the lab report.
First, researchers searched museum collections around the world for plant remains directly associated with the reigns of particular kings or periods, often using offerings from pyramids where the kings were buried. Second, the team used a mathematical modeling approach called Bayesian statistics to compare the patterns in the radiocarbon and historical dates and come up with the most likely correlation between them. "I am more than happy to accept" the new results, Spence says, adding that the Old Kingdom dating is "particularly important" because "this is the first time there has been anything firm to which to pin our historical relative chronologies." Yet the new study does not resolve all of the outstanding issues.
By looking at other outcrops in the area, our geologist is able to draw a geological map which records how the rocks are related to each other in the field.
From the mapped field relationships, it is a simple matter to work out a geological cross-section and the relative timing of the geologic events.
As the researchers will report in tomorrow's issue of , they found that the Old Kingdom, which kicked off with Djoser's reign, began between 26 B.
by Tas Walker A geologist works out the relative age of a rock by carefully studying where the rock is found in the field.