Exam 3 Flashcards
Sedimentary Rocks, Metamorphic Rocks, Weathering (56 cards)
Types of Weathering
Mechanical
Chemical
What is Mechanical Weathering
When big pieces become little pieces
Ex. Roots, Water/Ice, Percussion, Abrasion, Rounding
What is Chemical Weathering and Give Examples
Weathering due to chemical process
Ex.
Oxidation: Mineral + Oxygen = New Mineral
Carbonate Dissolution: Carbonate + Weak acid = CO2
CO2 + atoms in water = Caves + Speleothems
Silicate Hydrolysis: Silicate + Weak Acid =
Clay Minerals, Silica in Water, Other Elements
*Ferromagnesian Silicates dissolve faster
Weathering Effects
Differential Weathering - Does not weather uniformly
Spheroidal Weathering - Makes rock more round and circular
Products of Weathering
Sediment
Chemicals Dissolved in Water
Clay Minerals
Karst Topography
Caves
Sink Holes
Sinking Streams
Types of Sedimentary Rocks
Clastic/Detrital
Chemical
Organic
Clastic/Detrital Sedimentary
Unconsolidated
- Sediment, Detritus
- Grain, Fragments
Lithification
- Compaction (squeezed next to each other)
- Cementation (calcite, quartz, hematite)
What is Pore Space
Space in-between grains
- can be filled with water, oil, natural gas
Wentworth Size Scale
Measurement Sediment Rock
> 256mm ————–Boulder ———–(gravel)
Conglomerate (round)
56-256mm ———–Cobble ———–(gravel)
Brecia (sharp)
4-64mm —————Pebble ———–(gravel)
2-4mm —————–Granule ———–(gravel)
1/16-2mm ————–Sand —————Sandstone
1/256-1/16mm ———Silt —————–Siltstone
<1/256mm ————-Clay —————-Claystone
Shale (compacted)
What does Fossiliferous Mean
Fossils are present in the rock
Chemical Sedimentary
Elements in water
Crystalized
Mineral Composition
Calcite (Sedimentary) —->
Limestone
a. finely crystalline = Micritic
b. coarsely crystalline = Travertine
Evaporite Minerals
Sea Water Evaporation
- Calcite = Micrite
- Gypsum = Rock Gypsum
- Halite = Rock Salt
Dolomite —->
Dolostone
Quartz —->
Chert/Flint
Organic Sedimentary
elements dissolved in water
crystallization by plants/animals
Calcite (Organic) —->
Limestone
c. Fossils = Fossiliferous Limestone
d. Chalky = Chalk
Organic/Plants
Plant Peat Lignite (Brown Coal) Bituminous Coal (Soft Coal) Anthracite Coal (Hard Coal)
Sedimentary Rock Classification
Features
Bedding Mud Crack Ripple Mark Cross Bedding Fossils
Bedding
Sedimentary Layering
Mud Crack
Paleoenvironment
fine grained
tops indicator
Ripple Marks
a. symmetrical, oscillation ripple, wave like
b. asymmetrical, current ripple, long build up, sudden drop off
Cross Bedding
erosion and deposition of current ripple
shows direction of current
