(urth) Inhumi in the Whorl

[Lee Berman]

>Andrew Mason: This doesn't sound as if they are just now abandoning it. They did so
>a while ago, and are now coming back to hand the keys over. It may be
>that they left just twenty years ago, as the humans started to arrive.
>But it may be that they left much earlier.
 
I think the evidence in at the crater Horn finds. It is ringed with a circle of blue
glass and the plant growth in circle is newer growth shrubbery compared to the surrounding 
mature trees. I think that's where the ship took off. So how long does it take a barren, 
burnt blast crater to grow shrubbery? I guess 20 years might work though perhaps somewhat
fewer in Blue years?