Had the exact same question and though the same thing as you ("I can't believe the author didn't think this was an important thing to make clear in the first pa

Had the exact same question and though the same thing as you ("I can't believe the author didn't think this was an important thing to make clear in the first paragraph") Didn't need much research because the picture later in the article made it clear: https://en.wikipedia.org/wiki/Qanat#/media/File:Qanat_cross_section.svg https://en.wikipedia.org/wiki/Qanat#/media/File:Qanat_cross_... Actually this has been my usual experience with wikipedia, the first paragraphs never make the subject clear to me, I always end up with a lot of questions.