The Egtved Girl, one of the famous mummified Danish bog bodies, was apparently born outside Denmark, probably in southern Germany:
http://www.bbc.co.uk/news/world-europe-32835804
http://www.nature.com/srep/2015/150521/srep10431/full/srep10431.html
Interesting sidelight on individual mobility in "barbarian" Europe.
Have they explored the alternative possibility that in the (presumably winter) months before her death she was cut off and snowbound, living on what she could find and drinking melted snow (non-local in origin)? It might have been immobility rather than mobility that marked the final few months of her life.
This stuff post dates my archaeological training but my understanding is that the underlying geology is what gives the unique chemical signature to the water and hence the human. Melted snow or collected rain, having no geology, would have a distinctive effect of its own, which I presume they would recognise.
Judging by the full article (Duncan's second link), the analysis seems to hang entirely on the ratio of strontium 87 to strontium 86 with nothing else considered. Each water source, or at least locality, is held to have a unique ratio - which may be true, and seems to be so for samples thus far taken.
There is however a weak link in any such single-element analysis: precipitation. Water evaporates from a multiplicity of sources, with oceans and rivers making the main, and forests a secondary, major contribution. When precipitated, a number of sources are likely to be mixed, and I suspect there would be no unique signature for precipitation as such. Hence, if a rainwater cistern, or water runoff, or even melted snow, provided seasonal drinking water, it could give the impression of completely nonexistent travel. It might be the case that all is as the study concludes, but because of the possible precipitation factor I would be wary about drawing migration-related conclusions without some form of independent supporting evidence.
Strontium is a great element for archeologists.
- Being of similar chemistry to calcium it is absorbed into the bones, which means it hangs around for millennia when all less permanent remains have washed away or mixed with their surroundings.
- As it is the build up in the bones that is examined, it gives a good idea of where someone might have been for the greater part of their life rather than any short term (ie, less than years) residence.
- Proportions of strontium-86 to strontium-87 vary from 0.7 to 4.0 and depend upon the rocks that have been dissolved into the local water. Strontium carbonate's solubility in water saturated with carbon dioxide (ie, rainwater) is 1 part per 1,000. Thus measuring the ratio can give a unique clue as to geographic origins.
Therefore, based on strontium analysis, the archeologists can definitely determine her normal place of residence rather than where she happened to be discovered.