What is the history of the word gnarly?

The Word "gnarly" originated in the 1960s as a slang term used by surfers to describe difficult or challenging waves. It is derived from "gnarled," which refers to something twisted or rugged, often used to describe tree branches. Over time, "gnarly" evolved in popular culture, particularly within Skateboarding and extreme sports communities, to describe anything impressive, cool, or intense. Today, it is commonly used in a broader context to express excitement or enthusiasm.