Post on 16-Dec-2015
Sedimentary Rocks
Sedimentary rocks are classified by the types of sediments that make up the rock
What are sediments?• Definition:–Small, solid pieces of material that
come from rocks or living things like bones, leaves, stems, etc
Sizes of Sediments
Sediments will layer up over time, forming layered rocks
There are 4 main processes needed to form sedimentary rock:
Step 1: EROSION (wash away)Forces of running water, wind, or ice that loosen & carry away fragments of rockCan you see the sediment moving in the water?
Have you ever seen sediments being moved during a hard rain?
There are 4 main processes needed to form sedimentary rock:
Step 2: DEPOSITION (drop down)Sediments settle out of the water or wind carrying them & settle to the bottom of a lake or ocean. Sediments move
down the sloped land & settle at the bottom.Over time these sediments layer up.
There are 4 main processes needed to form sedimentary rock:
Step 3:COMPACTION (smashed together)Process that presses sediments together. Thick layers of sediment build up over time & weigh down the layers compacting them.
Those smashed sediments can form into layers like the ones shown above.
There are 4 main processes needed to form sedimentary rock:
Step 4:CEMENTATION(glued together)Dissolved minerals seep into spaces between particles (sediments) & then crystallize as they harden.
3 Types of Sedimentary Rocks1. Clastic Sedimentary RockMade from fragments that are squeezed together
Comparing 2 Clastic Sedimentary Rocks:
ShaleForms from mud - tiny clay particles, quartz & calcite;
SandstoneForms from sand on beaches, ocean floor, river beds, etc
Comparing 2 more…
ConglomerateFrom rounded sediments
BrecciaFrom larger, sharp fragments
3 Types of Sedimentary Rocks2. Organic Sedimentary RockForms where the remains of plants & animals are deposited in thick layers
Comparing 2 Organic Sedimentary Rocks
CoalFrom swamp plants buried in water for millions of years (plants peat coal)
LimestoneForms from hard shells w/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
Use for coal & a location of limestone…
Coal Limestone***
Limestone in England where there was once H2O covering the land.
Plant Bowen is a power plant that uses coal. Has anyone seen this before? It’s not too far away!
3 Types of Sedimentary Rock
3. Chemical Sedimentary RockForms when minerals that have been dissolved in a solution with water, crystallize
Examples of Chemical Sedimentary Rock
Limestone ***Another form of limestone forms from calcite in seas, lakes & underground caves – forms caverns & sinkholes in the ground when it is eroded by ground water
Rock SaltForms from halite when evaporation leaves salt behind
Comparing 2 Chemical Sedimentary Rocks
Limestone ***
Rock Salt
600 million year old rock salt being mined in the Himalayan Crystal Rock Mine.Ruby Falls cave is made of limestone!
How did the cave form?
Uses: What things have been made from Sedimentary Rock?• Flint: Arrowheads
• Sandstone: THE WHITE HOUSE
• Limestone: Blocks & slabs for building, making cement & steel, flooring
Possibly the coolest thing about Sedimentary Rock…
FOSSILS are always found in Sedimentary Rock ONLY!
Why??? (this might be a good test question…)