Wash your hands and then go on about your day. You didn't defile a corpse, you disturbed a "final" resting place. The next rain would have done it anyways, nothing to worry about.

You didn’t defile anything, if anything you fulfilled why they would have wanted their ashes scattered in that vicinity. They likely enjoyed that spot for the same reasons you did and would probably be glad that you found it too

Wait......wait......wait

You brushed the dust BEFORE you ate your lunch? And since you're hiking I'm guessing you didn't wash your hands after you brushed away the dust?

Dude......I think you might have eaten some of someone's dead relative.

The corpse doesn't care.

All that's really significant are the people who care for it.

Crematorium ? then there's no corpse, there must have been ashes instead. Given it's a mountaintop, they've probably been scattered, if not by the relatives, at least by wind and rain. I understand your distress, but I think it's actually positive that this person still impacts the world, in a way, after they're gone. It impacted you, and then it impacted me. And who knows whom I'll tell this story next. You made that dead guy live on ! cheers

i accidentally defiled a corpse

For a second I was sure I was going to read a post about a dude having sex with a corpse. By "accident" of course... 😉

What did you have for lunch?

Like others have said, you didn't do anything wrong. Maybe say a prayer or light a candle for the person and their family if you're the praying type, but otherwise, don't worry about it too much.