This is really great, Dave. Thank you greatly for giving these details, it really makes the terrain come alive for me.
I'd often wondered how much his imagination deliberately grew his memories in his writing, but you've confirmed a strong basis of reality. I remember reading somewhere that in his later years he preferred not to visit the home territory. I'd thought that this might be linked to wishing to keep his memories as they were in his head.
I find it very easy to believe the rumours of mountain lions. Even in the UK there are regular stories of big cats that have escaped from somewhere and are living successfully on the fringes. Then there are the wallabies that have formed a colony somewhere (I assume they're still there, they haven't been in my news for a while).
Moving seamlessly from lions to mastodons....
Did Cliff ever mention the Boaz mastodons?
Boaz mastodon - Wikipedia
These bones were discovered by local farm boys in 1897 not far from the Simak farm, and I've assumed that the excitement of this was still about for the young Simak. I've wondered if this influenced his partiality to mastodons.
And moving seamlessly on, since you've been good enough to answer my questions so far...
How about Thunder Butte in "A Heritage of Stars"?
I've assumed that this refers to the Thunder Butte in South Dakota...
Thunder Butte
and that Cliff knew this from his travels working on various newspapers before he settled in Minneapolis. It looks as if it was a massive outcrop on the horizon for many miles.
Once I realised how much of his writing is linked to his landscape, it's always tempting in reading his work to link it to the map.