What to use to set marble ledge to wood window frame?

What would be the right stuff to set a marble ledge onto the 2 x 4 at the bottom of a window frame? The old stuff was something white that looked like mastic. Should that do the job or is there something better?
Thanks for all input
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construction glue (liquid nails) or silicone. the wood is going to move with changing humidity, and anything stiff will soon break.
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wrote:

It's been a while since I removed it but now that you mention it, I believe I discovered it had actually come loose and was being held in place by gravity and the bead of caulk. Doesn't experience any load bearing so I hadn't noticed it before removing it.
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I've used silicone caulk as have most of the installers I've seen, but you could also use construction adhesive as long as you don't over do it. Keep in mind you do want to be able to remove the ledge under some circumstances without damaging the frame or the ledge.
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