Given a scientific passage and an answer, generate a question for the given answer.

Passage: In some soils, the organic portion is entirely missing. This is true of desert sand. At the other extreme, a soil may be completely organic. Peat, found in a bog or swamp, is totally organic soil. Organic materials are necessary for a soil to be fertile. The organic portion provides the nutrients needed for strong plant growth. Answer: no
Will contour lines ever cross?