Weststarbooks,
1. I ran the calculations for the example provided and they matched your results. You're right...simple math.
2. Google AI confirmed the location was/is the site of Fred Nolan's 20ton granite boulder he found buried in 6ft deep.
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Google AI added the 20ton boulder sat in a man-made cradle of smaller rocks.
3. I googled the Amundsen stone. Google indicated that stone was small, flat, red granite buried 5cm deep and was hand excavated. No mention it being placed by man.
Conclusion:
Clearly the fred nolan stone was intentionally placed for some purpose, maybe a marker of some kind.
However, the Admundsen stone does NOT appear to be intentionally placed and as such appears, at least to me, to be unrelated because of its small size and subject to movement over time.
Had the Admundsen stone been substantially larger and had signs of man's involvement, i would agree with your theory.
That's all i have to say on this subject.