Consider the following statements made about the sedimentary rocks : I. Sedimentary rocks are formed at Earth’s surface by the hydrological system. II. The formation of sedimentary rocks involves the weathering of pre-existing rocks. III. Sedimentary rocks contain fossils. IV. Sedimentary rocks typically occur in layers. Which of these statements are correct ?

All four statements are correct. Sedimentary rocks originate from sediments produced largely by denudation (weathering and erosion) of pre‑existing rocks; these sediments are compacted and cemented (lithified) to form layered or stratified rocks such as sandstone and shale [1]. Many sedimentary rocks form at or near Earth’s surface through the hydrologic system (transport, deposition, and subsequent lithification of material by water and related agents) [2]. Because deposition commonly buries biological material, sedimentary rocks frequently preserve fossils and thus record past life and environments [3]. The characteristic bedding or strata of sedimentary rocks reflects their mode of deposition and varying depositional conditions over time [2].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > 13.2. Sedimentary Rocks or Detrital Rocks > p. 171
2. [2] https://www.craftonhills.edu/~/media/Files/SBCCD/CHC/Faculty%20and%20Staff/Personal%20Pages/rihughes/Geology-100-101/Ch14-Sedimentary%20Rocks.pdf
3. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > SEDIMENTARY ROCKS > p. 18