What causes lighter woods to yellow?  

Illustrated test of wood darkening from UV
A cabinet company has actually done tests of this sort of thing with a few species and finished vs unfinished. Interesting:
http://www.merillat.com/our-products/product-types/cabinetry/about-wood-...

Of course I'm kidding. I...
Of course I'm kidding. I might set it on the deck for a few days once the weather gets nice though to get it to the point that I don't have to worry about it shifting because I left a book on it for a few months. My maple floors have permanent rug spots and I'd like to avoid that.

I assume your rug spots
are lighter than the exposed areas of the floor ?

You are correct.
You are correct.

.

Mark,
I think I'm turning blush.

Mark -
One of these days you're going to post and unwillingly enter yourself into a style-off. I'll leave you begging for mercy.

I dont know
about that. Our man Mark has got it going on AND the cahones to throw down here on a regular basis.

.

I hate to be the bearer of bad news, Mark...
... but Betty's dead.
(I was one of the photographers for her funeral.)

How many possums
here think they hear a cry for help ? Little online intervention, anybody ? Head for the East Coast and bash Aunt Mark with a wet pillow (Gucci or better) ?

.