Complex sentence: Holmes illustrated the atlas for Dutton's "Tertiary History of the Grand Canyon District" (1882); his triptych panorama of the Grand Canyon from Point Sublime is a masterpiece of American scientific illustration.
Split into simpler sentences: Holmes illustrated the atlas for Dutton's "Tertiary History of the Grand Canyon District" (1882). Holmes's triptych panorama of the Grand Canyon from Point Sublime is a masterpiece of American scientific illustration.