Rocks, Rocks and More Rocks! Sedimentary
Sedimentary Rock • What are sediments? • Notes: Small solid pieces of material that come from rocks or other living things like shells, bones, leaves, stems, etc.
Sediment What part does sediment play in forming sedimentary rock? When it rains, soil and debris from the surrounding land are eroded and washed into streams. From there, sediment particles from as small as clay to as large as boulders flow along with the water. Fast-moving water can pick up, suspend, and move larger particles more easily than slow-moving waters. This is why rivers are more muddy-looking during storms -- they are carrying a LOT more sediment than they carry during a low-flow period.
How does sediment become Sedimentary rock? • The process of sedimentation • Step 1 - Erosion Notes: Forces of running water, wind or ice that loosen & carry away fragments of rock
Processes Step 2 - Deposition • Notes: Sediments settle out of the water or wind carrying them & sink to the bottom of a lake or ocean`
Processes – Step 3 - Compaction • Notes: Process that presses sediments together. Thick layers of sediment build up over time & weigh down the layers compacting the sediment.
Processes – Step 4 - Cementation • Notes: Dissolved minerals seep into spaces between particles (sediments) & then crystallize as they harden.
Clastic Sedimentary Rock • Notes: Made from rock fragments that are squeezed together. Shale – forms from tiny particles of clay
Organic Sedimentary Rock • Forms where the remains of plants & animals are deposited in thick layers. COAL – forms from swamp plants buried in water for millions of years.
Limestone – forms in the ocean from hard shells with calcite from seashells, coral, clams & oysters or skeletons that pile up on the ocean floor for millions of years slowly changing the sediment to limestone
Chemical Sedimentary Rock • Forms when minerals that are dissolved in a solution crystallize • Example: Limestone – forms from calcite in dissolved seas, lakes & underground caves.
Chemical Sedimentary Rock(continued) • Rock Salt –forms from halite by evaporation
Uses of Sedimentary Rock • Flint – used for arrowheads
Uses of Sedimentary Rock • Sandstone – used on the White House
Uses of Sedimentary Rock • Limestone – used as blocks & slabs for buildings, making cement & steel
FOSSILS ALWAYS FOUND IN SEDIMENTARY ROCK Fossils!!