Is a tropical valley in glaciated mountains possible?

Question

Based on the circa 1900 pioneer theory that in arctic areas there are dormant volcanoes that produce hot springs, hot springs feed valleys that create a pocket of warm atmosphere. The valley then holds extra-large native plants like the Alaskan rose, native animals like bear, but also tropical jungle foliage and birds. Is it feasible?

Answer 1

Geographically it wouldn't be tropical since it wouldn't likely occur in the tropics (an exact band between 23.5 N and S latitude). But there could be areas of native lushness like there is near rivers and geothermal vents.  It most likely wouldn't be the same species you'd find in the tropics due to geographic isolation - the seeds would have to get there somehow.

Answer 2

This is like the question that Frank Sinatra sang about: What happens when an irresible force (like you) meets an (old) implacable object (like me)? The answer is that "something has go to give".

You can go on piling hotter and hotter earth vents on greater and greater glacial streams and not reach any serious result. However there is no known instance of this situation occurring. The glaciers are supreme.  

Answer 3

Warm air rises.

What do you think would keep it in a valley?