Thanks to Michel Molia I discovered something amazing: the borderline between bm356 and 357 and between bm408 and 409 will most probably change.

The INSPIRE-project is a broad international attempt to synchronize geodata in the EU. One part consists of re-measuring and re-establishing the borderlines in bilateral agreement. Narrowing down to the ESFR-border: in 2015 an agreement was reached in the bilateral Commission Mixte d’Abornement in Toulouse.

You can see the result for the Pyrenees on this website showing the map with the borderline agreed-upon and the bordermarkers. The main purpose of the project is explained at this page
and specific to the ESFR-border on this webpage.

We read: “Commission mixte 2015. Une ligne frontière unique, bilatérale et numérique a été validée à la CMA de Toulouse en octobre 2015. Mais elle reste temporaire à proximité des bornes non encore mesurées précisément ainsi que de quelques sites où une mise en évidence contradictoire pourrait être produite.” So the newly measured (digitally) borderline is still provisionary because not all bordermarkers have been precisely measured yet.

There are many details still to study and to discuss here but let’s focus on two very interesting areas

Bm356-357
Last year I launched a new hypothesis how the borderline between bm356 and 357 was wrongly re-established in the 1950-ies (see this page). So I was happily surprised that the new borderline is exact as I thought it was meant in the Treaty of 1862 . Finally justice.

Bm408-409
I was even more surprised – but less happily – by the new borderline on this steep hillside. I have written about its intriguing story on this page. Conclusion then: the treaty leaves no doubt about the right borderline, the placement of four submarkers by Jean Sermet around 1965 served a diplomatic purpose but changed the borderline wrongly. Problem: no one knows nowadays where that new borderline was because 2 of the 4 submarkers are unfindable.
The CMA has aborted the borderline of Jean Sermet but has now its own diplomatic version somewhere in between the (supposed) Sermet-line and the Treaty-line. But it still violates the Treaty! In this case: justice needs to be done yet.

To finish: the map which Michel Molia received from the IGN when he asked for information with some explanation by some IGN-official.

The explanation (added in black on the map) says that the Treaty was inprecise about where the source of the Ruisseau du Terme was. As said that is not true: in my opinion the text of the Treaty leaves no doubt about the course of the borderline.