MCQ Detailed View

Sedimentary rocks are rocks that form from the accumulation and compaction of sediments over time. The natural process responsible for their formation is called lithification, which involves compaction and cementation of particles such as sand, silt, clay, and organic material. Lithification transforms loose sediments into solid rock, creating layers called strata.

The process of sedimentary rock formation begins with weathering and erosion of pre-existing rocks. These sediments are transported by agents like rivers, wind, glaciers, or ocean currents and deposited in layers in basins, lakes, oceans, or riverbeds. Over long periods, the weight of overlying sediments compresses the lower layers, squeezing out water and air. Minerals like calcium carbonate, silica, or iron oxides act as natural cement, binding the particles together during cementation.

Sedimentary rocks are classified based on their origin:

1. 
   

   Clastic sedimentary rocks – formed from fragments of other rocks (e.g., sandstone, shale).

   
   


2. 
   

   Chemical sedimentary rocks – formed from minerals precipitating out of solution (e.g., limestone, rock salt).

   
   


3. 
   

   Organic sedimentary rocks – formed from accumulated remains of plants or animals (e.g., coal, some limestones).

   
   

Lithification is a key concept in geology, earth science, and environmental science, as it explains the rock cycle and the continuous evolution of the Earth’s crust. Unlike processes such as hydration (chemical reaction with water), rejuvenation (river erosion process), or peroxidation (chemical oxidation), lithification specifically refers to the transformation of loose sediments into solid sedimentary rock.

Understanding lithification helps explain natural phenomena like fossil preservation, sedimentary basin formation, and resource deposits, making it a fundamental topic in the study of Earth’s surface and geological processes.