My blog is a bit long, so probably off-putting.
It attempts to "prove" that people were walking from Scotland to Orkney in the early part of the #Neolithic period.
In extensive and detailed research I have found a series of observations derived from other peoples work that, put together, may be enough to prove that there was walkable land from Doggerland north to the Shetlands, and also from #Orkney to Caithness.
In brief , there is evidence of a passage of land leading from #Dogger Bank to a location in the north of the North Sea where a flint artefact was found half way between Shetland and Norway.
There is also evidence that that land collapsed towards the Norwegian Coast in 3000BC.
On Orkney, Barnhouse and many other small settlements across mainland Orkney are all shallow sites that are clearly not designed to be occupied in an Orkney winter. These settlements were all abandoned before 3000BC.
My only assumption is that when land in the North of the North Sea was lost so also was a bridge between South Ronaldsay on Orkney, and Caithness, north Scotland.
The Stones of #Stenness and Ring of #Brodgar were abandoned, unfinished, probably at 3000BC.
The Westray islands are abandoned at 3000BC, and not colonised again until the second half of the 3rd millennium BC.
#Skara #Brae, and the #Ness of #Brodgar, both have dated deposits from before 3000BC indicating there was some kind of occupation until then, but not till after 3000BC are the revolutionary solid structures with stone lined drains and other necessary amenities for winter weather designed and constructed.
The structures at the Ness of Brodgar were made of wood, largely, so they would not have lasted long, a couple of generations perhaps.
The dates of the human bones found in the cairns are largely assessed to before 3000BC, and the dates of the animal bones, also in the cairns, which were arguably being eaten by people, are largely after 3000BC.
This suggests that when a few groups of people isolated from mainland Britain lost the structural secuity of their solidly built structures, they may have sought desperate refuge in the cairns.
Temporary visitors returned, by newly developed boats, in the second half of the 3rd millennium BC.
Detailed, if longwinded, analysis is in the blog:-
http://orkneyriddler.blogspot.com/2025/04/the-orkney-riddle.html