SEDIMENTARY ROCKS IN DEPTH

Lesson 7:  Sedimentary Rocks

Sedimentary Rocks in Depth

Formed from bits and pieces of other rock, compacted and cemented together.  Can also form out of solution.

Sedimentary Rock Terms

1. Sediments - bits and pieces of rock of all shapes and sizes

2. Weathering - when weather elements like wind, rain, sleet, snow, hail, cause sediments to chip off of the original rock.

3. Erosion - the movement of sediment through natural means of transportation like wind or bodies of water. 

4. Depositing - when sediment settles somewhere after being eroded from place to place.  Sediment usually deposits when wind dies down, or when bodies of water slow down/change direction.  

5. Compaction - when sediment squeezes together due to pressure from rocks or layers above it.

6. Cementation - when minerals in the pores/holes of rock cause the sediment grains to stick together.  When you tile a floor, build a brick wall, or glue things together, the water inside evaporates out, leaving a hard adhesive behind.

7. Lithification - imagine pores/holes filled with water inside of a pile of sediment.  Squeeze the water out by crushing the pores with pressure.  Like squeezing a sponge.  But sediment isn't a sponge.  It stays where you squeeze it and it hardens.  

8. Strata - layers in sedimentary rock.

9. Clastic - sedimentary rocks that form from bits and pieces of other rock.  Clastic rocks include fossils!

10. Porosity - the fraction of holes vs. material in sedimentary rock.

11. Evaporites - sedimentary crystals that form when water evaporates away.  These can be big crystals, but they are usually not as strong as crystals formed from magma cooling.