Looks like it broke off at a water bar.
Since when do they server water at bars?
Back to the slide, I've noticed from personal (uneducated) experience that snow often doesn't adhere to the base surface (frozen or wet.) Given that the snow was recent and hadn't settled, I guess that is not too surprising. I've found those slides to occur at steeper slope angles than what is in the picture.
Still, this is a useful reminder to always expect the unexpected.