A remarkable result of our astronomical study is that the postulated astronomical/historical error (232 years) appears to be offset by 14 years from the dendrochronological error (218 years) found in a previous study. This means that, if we are right, then all current dendrochronological dates within the Roman time complex are given 14 years too young. According to our interpretation, the 14 years offset is caused by an improper synchronization of the Roman dendro complex towards Roman history.

Read here how this fateful synchronization was done more than thirty years ago. Our correction will also reestablish Tacitus' chronological trustworthiness which has been doubted because the generally accepted dendrochronological dates are not always compatible with Tacitus' writings.

Several Greek and Roman writers recorded a lunar eclipse that occured before the battle between Alexander the Great's army and Persian forces at Gaugamela near Arbela (todays Erbil in northern Iraq). The date of the battle is given by Arrian as during the month Pyanopsion when Aristophanes was archon at Athens. This means early in the autumn (October) -330 or -329 in our calendar.

There was a large lunar eclipse on -330 September 20, but also a second one on -98 October 6. Both eclipses would date the battle to October as Arrian says, and both were visible in northern Iraq, but at different hours of the night. A strange coincidence is the fact that the two solutions for Pliny's quadruple (see separate report) and the two candidates for the Arbela eclipse are offset by exactly the same number of days: 232 (Julian) years + 16 days = 84754 days.

Moreover, it seems that a Babylonian clay tablet mentioning the battle at Gaugamela has been preserved by a rare coincidence. This tablet contains sufficient astronomical information to date the described battle to -330 October 1 as conventionally assumed.

Even though there are two solutions with 232 years offset for both Pliny's quadruple and the lunar eclipse before the battle at Gaugamela, the Babylonian clay tablet tilts the scales in favour of the conventional solution. However, if our dendrochronological results are correct, something must be wrong with the astronomical records in some way. Ultimately we have to decide which dating method we trust most, and why. Follow our argumentation here.

Starting with the later Han period (25 to 220), there are references to a large civilisation far to the west from China in the Chinese historical records. This civilisation is called Da Qin and has been identified as being either Rome, the Roman Empire or the Roman eastern provinces.

The annalist makes quite fantastic statements about this civilisation, e.g. "their kings are not permanent", and the name of the king of Da Qin in the year 166 was "Andun".

Now, guess what happens if Roman time is offset (i.e. conventionally dated too old) by 232 years. Do the fantastic statements make any sense? Read more about it here.

The Minoan eruption of the Thera (Santorini) volcano provides an archaeological key marker for the Bronze Age chronology of the Eastern Mediterranean civilizations. The exact date for this large eruption is still unknown. Based on published tree ring and ice core chronologies, we investigate the candidates for major volcano eruptions in the middle of the second millennium BC.

Ice core analysis provides indication for the volcanic nature of prominent events which resulted in climatic downturns and which are therefore visible in the tree ring chronologies. Our conclusion is that there are only two candidates for a "supervolcano" eruption in the time range -1675 to -1450. Only one of them has so far been scientifically considered as a candidate for the Thera eruption. However, recent investigations seem to indicate it to be less likely that this candidate is Thera. But there is one unexplored candidate left!

The evaluation of which of the two eruption candidates is the most probable, is backed up by a re-investigation of the so called "Ugarit Eclipse". We also suggest a new synchronization of tree ring and ice core time lines for the time range mentioned.

Read more here.

For quite some time we have been arguing that wood archaeologically anchored in West-Roman time has never been properly crossdated with dendrochronology towards wood of later times. The absence of proper crossdating is apparent as it was necessary to "calibrate" the Roman dendro complex with wood from the Roman camp at Oberaden. (The time that this camp was used can be constrained to a limited range historically.) We argue that the conventional date of the Roman dendro complex is too old by more than 200 years.

Nevertheless modern natural scientists have not always refrained from connecting e.g. their ice core data to historical events of the Roman period, a practice which possibly has led to incorrect results.

But there is hope. Now a group of scientists report on ice core chronologies which do not rely on calibration with historical events like the Vesuvius eruption of RomAD 79 (which occurred in 311 if we are right).

Read more as an update to "Dendro audit".

After our dendrochronological re-investigation of European major oak- and pine-chronologies, we suspect that the part anchored archaeologically in Roman time is dated 218 years too old conventionally (see under tab "Dendro audit").

To validate this puzzling result, we have been looking at historical astronomical observations and tried to verify them towards the NASA catalog of eclipses. We have described this effort under tab "Ancient history", where we conclude that if we are right, then the error in our time count is exactly 232 years (though the dendrochronological error is "only" 218 years).

Very recently we had a discussion about the Julian star, which is historically described in multiple sources as a comet that occurred after the assassination of Julius Caesar in RomBC 44. As a commemoration of this event, the star can be seen on several Roman contemporary coins. However, it has been hard to find a celestial body which exactly matches the observations, therefore certain scientists regard Caesar's star as fiction.

This is not miraculous, because if we are right about this 232 years calendar error, then everybody has been looking at the wrong place on the astronomical time line. Looking instead 232 years later than assumed conventionally points at a comet exactly matching the sources, which indicates that we actually might be right.
Read the story here: Caesar's comet

Now we launch our new pages about various aspects of dendrochronology.
Try the tabs under "Tools and basics" if you are new to the topic.

We would like to push for some interesting news about our chronology project which has progressed to the next phase. Read more under the tabs "Dendro audit" and "Ancient history".
Also our "Local history" about dendro-dating in the Stockholm archipelago has been updated.
A search-function which covers the whole new site is available on each page.

Click here to see the latest blog post.

Our CDendro & CooRecorder tutorial site is found as before at