1. Sedimentary Rocks Sedimentary rock is formed by erosion
Sediments are moved from one place to another
Sediments are deposited in layers, with the older ones
on the bottom
The layers become compacted and cemented together

2. Sedimentary Rock
Sedimentary Rocks are formed at or near the Earth’s surface
No heat and pressure involved
Strata – layers of rock
Stratification – the process in which sedimentary rocks are arranged in layers

3. Sediments
-pieces of material left by:
*wind *ice *chemical precipitation
*water *gravity
Step 1: WEATHERING
Chemical- minerals are chemically broken down

4. * Physical – minerals remain chemically unchanged

5. Step 2: EROSION
* transporting weathered materials to another location
* Wind, water, gravity and glaciers transport

6. Step 3: DEPOSITION
* sediments are deposited and sorted

7. * deposited into depressions called “sedimentary basins”
Step 4: BURIAL
* deposited into depressions called “sedimentary basins”
* the deeper it gets, the more pressure on it til……
2 ROCK BURIAL

8. Step 5 : LITHIFICATION (FYI – lithos: Greek for stone)
* physical and chemical process that changes it to sedimentary rock
1st Compaction
2nd Cementation & Solidification
new minerals precipitate more of the same type
around existing ones crystallize around
existing ones

9. FEATURES OF SEDIMENTARY ROCKS
BEDDING –
*horizontal layers
*if sorted,
graded bedding
CROSS-BEDDING -
*inclined layers
move forward like
sand dunes ))

10. RIPPLE MARKS
* when sediment is moved into small ridges by wind or wave action
* back & forth waves yield symmetrical waves
* currents, (like in rivers) asymmetrical waves
Sand dune – ripple marks from wind

11. Asymmetrical ripple marks

12. FOSSILS
*animals die, buried, lithified
* some plants replaced by other minerals
* shells, bones, etc. could leave impressions

13. CONCRETIONS
* lumps of fine grained silica
* called chert
*also called nodules
CHERT

14. MUD CRACKS
*wet clay dries and contracts
* cracks later fill with sediment

15. TYPES OF SEDIMENTARY ROCKS
CLASTIC formed by lithifications
Coarse Medium Fine
gravel sand silt & mud
some rocks sandstone siltstone
conlglomerates mudstone
POROSITY
* percent of open space between grains of sand
*good reservoirs for oil, natural gas, and H2O
* permeable if water can pass through

16. Porous Rock

17. a. rocks formed by evaporation
2. CHEMICAL
a. rocks formed by evaporation
- called evaporites ex: calcite, halite & gypsum S
DEAD SEA SALT
CALCITE

18. b. organic sedimentary rock -formed from the remains of living things
- most abundant is limestone (mostly calcite)
CaCO3 from shells
if shells are high in silica, they form siliceous ooze
- Coal – from remains of plant material…almost entirely carbon
Siliceous ooze
CALCAREOUS OOZE