Given a scientific passage and an answer, generate a question for the given answer.
One example: Passage: A frameshift mutation is a deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in RNA:. Answer: nucleotides.
Solution is here: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Explanation: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.

Now, solve this: Passage: Weathering changes solid rock into pieces. These pieces are called sediments. Sediments are described in the chapter Earth's Materials and Crust . Sediments are different sizes of rock particles. Boulders are sediments; so is gravel. At the other end, silt and clay are also sediments. Weathering may also cause the minerals at the Earth’s surface to change form. The new minerals that form are stable at the Earth’s surface. There are two types of weathering, mechanical and chemical. These are discussed in the next two concepts. Answer: weathering
Solution:
Over time, what changes solid rock into pieces?