Radiocarbon dating can limit the dates of tree rings to a theoretical range of years. (However, regional offsets sometimes cause that range to be outside the actual age.) Within that radiocarbon-dated age range, is it possible to date tree-ring sequences astronomically to exact years in the Julian calendar (years BCE)? Initially, this might seem utterly incredible, even absurd. Nevertheless, under certain unusual circumstances, it is possible to chronologically link a dendrochronological index to celestial configurations. The prerequisite conditions exist with the Aegean Dendrochronology Master Index (ADMI) and related historical data.
Trees in temperate forests develop tree rings with denser cell growth in colder and porous growth in warmer seasons. Besides these seasonal variations, tree-ring widths vary yearly depending on temperature and precipitation. Dendrochronologists intentionally select trees (or logs) that grow (or grew) where the water table is deep. Consequently, their annual growths are closely related to the relative abundance of water via rain and snow.
Milankovitch cycles caused the correlations between tree-ring widths and Mesopotamian flood levels to be extremely high in the second millennium BCE. Therefore, the extremes of ring width in the Aegean Dendrochronology directly equate with extremes in precipitation, i.e., droughts or excessive flooding. Moreover, ancient historical records often included details of those same events. Therefore, it would be theoretically possible to relate recorded droughts and damaging inundation events with the tree-ring index.
The sets of tree rings that comprise the ADM Index are from Anatolia, and such weather-related ancient historical records from that location are rare. However, those growing sites were near the upper Euphrates River watershed—furthermore, the mountains trend toward increased heights to the east. Consequently, the eastward-moving weather systems that brought rain to the ADMI sites also usually caused rainfall in the upper Euphrates and Tigris Rivers watersheds. The Mediterranean weather systems produced heavy precipitation in winter and, in some areas, in the spring, whereas summers were dry.
Due to the elevation of those eastern Anatolian mountains, winter precipitation was typically in the form of snow or freezing rain. When the spring thaw came, it caused increased river water volumes, bringing annual flooding in the regions of Assyria and Chaldea (Babylonia and Sumer). Although occasional winter rain fell in Mesopotamia, most Mesopotamians depended on river irrigation to raise their crops. When droughts occurred, diminished annual flooding affected their food supply.
Ancient Assyrian records often included details of repairs to their capital city’s wall adjacent to the Tigris River, implying flood damage. A few records specifically stated such repairs were necessary due to excessive inundations. Their dating system used limmu for year names, but extant eponym lists are rare. Thus, not many of those events are datable to specific regnal years, but a few are. The Babylonians had fewer problems with damaging floods but reported repairs to dikes are usually exactly datable, and some stated excessive flooding caused the damage.
Droughts in ancient Mesopotamia were not unusual. The people stored food in case precipitation and flooding failed the following year. When that occurred, it harmed the farmers financially, but people generally survived on stored food and alternate sources such as hunting, gathering, and fishing. Nevertheless, when a severe drought continued into a second year, food prices skyrocketed, and it could result in starvation among some of the poorer class. When a severe drought lasted into a third year, it caused widespread famine.
Historical data records two such severe famines in Mesopotamia and the regnal years they occurred. Within the indicated radiocarbon-dated ages, it is no coincidence that each set aligns with three excessively narrow rings in the ADMI. Moreover, reliable king-list and historical data identify the intervals between those events and recorded astronomical events, anchoring the entire floating tree-ring index to exact Julian calendar years.
This unusual situation means every annual growth in the 1291-year-long ADMI represents an indirect astronomical date. Consequently, it provides a general index of yearly Mesopotamian precipitation for the entire millennium. Moreover, every event related to a specific tree ring is precisely datable.
Despite what dendrochronologists say, this astronomical dating of the Aegean Dendrochronology is superior and more precise than radiocarbon dating. Furthermore, claims that radiocarbon dating disproves statistical crossmatching of tree-ring sets are mistaken because each Anatolian ADMI growing site has a different average offset from IntCal.
The Six Pillars (forthcoming) Chapter 3 and Appendix B provide more details about the astronomical anchoring of the ADMI. Scientific Explanations for Radiocarbon Offsets at Astronomically Dated Sites, Volume I (forthcoming) explains Anatolian radiocarbon offsets at the ADMI sites.
3 comments