This is a topic near to my heart, K Ann. I'm glad you've written about it.
I've hiked from Yosemite to Crete, Greece. And the amount of graffiti and discarded garbage his gotten worse every year. And it reaches below ground as well. I've explored caves in the middle east and found graffiti far below ground.
It's sad that people feel it necessary to "mark their territory" and destroy the pristine beauty of nature. 2 minutes of spray painting a rock wall can take hours to clean. And sometimes the cleaning is damaging as well.
I love reading your stories. And thank you for mentioning me in this one. :-)