The pants in this photo are bell bottoms. Bell bottom's are tight until the knee then they bell out at the bottom. The leg opening of bell bottoms are wide, but they are not as wide as many people presume.
Christmas 1969 -- Isn't this kinda the look that Fred sports in the old Scooby Doo cartoons ? It is called Fashion Happenings. I think they look groovy. I love brown polyester stretchy pants with a gold shirt and scarf!