1. 3.2 – Sedimentary Rocks

2. Formation of Sedimentary Rocks
sedimentary rock: rock made up of combinations of different types of sediment sediment: loose fragments of rock, minerals, and organic materials two main processes convert loose sediment into sedimentary rock - compaction and cementation

3. compaction: process where sediment is packed together tighter by the weight of overlying sediments cementation: process where minerals precipitate into pore spaces between sediment grains & glue the sediments together

4. Classes of Sedimentary Rocks
classify sedimentary rocks by the processes that form the rocks and by the composition of the rocks three main classes of sedimentary rocks - chemical, organic, and clastic

5. Chemical Sedimentary Rocks
chemical sedimentary rock: forms when minerals precipitate (separate) from a water solution
when water evaporates or boils off, the minerals that were dissolved in the water are left behind

6. gypsum, rock salt (halite), and chemical limestone (oolitic
gypsum, rock salt (halite), and chemical limestone (oolitic!) are common chemical sedimentary rocks

7. geodes are common chemical sedimentary rocks, too!

8. Organic Sedimentary Rocks
organic sedimentary rock: forms from the remains of plants or animals coal and organic limestones are examples of organic sedimentary rocks

10. Clastic Sedimentary Rocks
clastic sedimentary rock: sedimentary rock that forms when fragments of sediment are compacted or cemented together
clastic sedimentary rocks are classified by the size of the sediments they contain

11. conglomerate: contains large, rounded pieces
sandstone: contains sand-sized grains

12. shale: contains clay-sized particles

13. Features of Sedimentary Rocks
unique features in sedimentary rocks can give clues to their origin
sediments are moved by four main agents: water, ice, wind, and the effects of gravity
as sediment is transported from its source to where it is deposited, the particles collide with each other &with other objects in their path

14. these collisions cause the particles to change size and shape
in general, the farther sediment travels from its source, the finer and smoother the particles of sediment become

15. in well-sorted sediments, all of the grains are roughly the same size and shape in poorly sorted sediments, grains are many different sizes

16. look for mud cracks, ripple marks, and fossils as clues – oldest materials on the bottom!