Q. Consider the following statements regarding sedimentary rocks:

1. Sedimentary rocks are formed at Earth's surface by the hydrological system
2. The formation of sedimentary rocks involves the weathering of pre-existing rocks
3. Sedimentary rocks contain fossils
4. Sedimentary rocks typically occur in layers

Which of the above statements is / are correct? (UPSC Prelims 2001)
Answer: All are correct statements
Notes: All the provided statements about sedimentary rocks are correct. These rocks form at the Earth's surface mainly through hydrological processes, following the weathering of pre-existing rocks. They frequently contain fossils owing to their formation from biological remains, and are commonly found deposited in distinct layers or strata.