Final answer:
Sedimentary rocks fall into three categories: clastic, formed from weathered rock fragments; chemical, from evaporated mineral precipitates; and organic/biochemical, from accumulated organic material or organism shells.
Step-by-step explanation:
Sedimentary rocks are classified into three main categories: clastic, chemical, and organic. Each category has its unique process of formation that defines its characteristics.
Clastic sedimentary rocks are formed from the mechanical weathering and erosion of pre-existing rocks, which then undergo transport through wind, water, or ice. Once the sediments are deposited, they accumulate in layers and are then compacted and cemented together over time to form rocks like sandstone and shale.
Chemical sedimentary rocks form through the evaporation of water, which leaves behind minerals that crystallize and precipitate. This type of rock is typically found in areas with high rates of evaporation like salt flats, resulting in rocks such as halite.
Organic sedimentary rocks arise from the accumulation and lithification of organic debris, such as plants and animals, which can lead to the formation of coal and oil shale. Biochemical sedimentary rocks result from organisms such as foraminifera that precipitate minerals to form shells. When these creatures die, their calcium carbonate shells accumulate to form rocks such as limestone.