Leon spent many summers in the mountains, camping, hiking, and painting.
He once spoke of his passion for nature: "I am aware that I am an incurable romantic. The things that count the most are light, space, air, running water, the sound of crickets, and coyotes at night - all things close to nature. Even in contemplating an abstract or semi-abstract composition, these are the motivating elements."
In 1944, with WWII still on, men were needed to fill forest ranger positions. Leon was hired to be a ranger that summer at the Big Springs Ranger Station a few miles north of Lassen National Park. It was here that he started experimenting with an approach that harkened back to his interest in Cezanne and John Marin, which resulted in a departure from the influence of Millard Sheets and the Southern California School of Regionalism.
After his retirement he spent much of his time at a second home in the Sierra Foothills near Georgetown. Scenes from that area became a major subject from this period.