Well, PM77, you beat me to it! Nice job as well - love the placemarks.
I was inspired by NormB's post on the Scott/Amundsen expeditions to do the same for Shackleton's Trans-Antarctic Expedition, and have been working on it for the last week or so.

I've done a fair bit of coding in the placemarks, (most of which duplicate yours, and probably for the same reason - the book gives a good lat/long at these locations ) so that when you click on a placemark it gives an appropriate blockquote from "South", an image or two in the balloon, and a link to the same eBook to which you refer.
Your overlay of Elephant Island is better than mine - I saw that same satellite image, but rejected it in favour of a rather scruffy map. However, I think my overlay of S Georgia may be better in some respects, since it also shows the difficult overland route from Peggotty Camp to Stromeness, Shackleton's last great obstacle. It isn't so nicely "tailored" as yours, though.
Another respect in which your post scores is in the nice red line joining the placemarks. I've been researching that aspect. Did you use EarthPaint or something similar?
Rather than see my work going to waste, I'd be happy to email you the coding that I've used in the placemarks, if you'd like to have it. All the images I've used are remote images, so it would be a simple cut-and-paste into each placemark. I think it would help make an excellent post into an outstanding "multimedia" one, if that doesn't sound too conceited

Again, thanks for a great post, and certainly worth five stars. Best I go and find a new project! But first, a couple of consolation beers...

Best Regards
Frank