The David Cross Memorial Sign is on Snowmass.  Many thanks to Bob Mattice for telling me about it and for contributing the photos.

He died on January 26, 2021 in the West Willow area off of the Snowmass Ski area.  For more information, see this January 28, 2021 Aspen Times article ("Missing Carbondale man found dead in backcountry near Snowmass; David Cross, 32, died in 'very hazardous terrain' in the West Willow area."):  https://www.aspentimes.com/news/police-skico-continue-search-at-snowmass-resort-for-missing-carbondale-man/

See this page for the David Cross obituary:  https://www.legacy.com/obituaries/capitalgazette/obituary.aspx?n=david-cross&pid=197717587

Photos of the sign are below; click on images to enlarge.