SEDIMENTARY ROCKSSire Kassama
2014
Intro to Info Sedimentary: fragments of sediment
cemented together 75% land area composed of sedimentary
rock Lithification: conversion of sediment to
sedimentary rock Sediment deposited in horizontal layers
called strata or beds Examples are: sandstone, shale, limestone;
Intro to Info Stalactites: limestone is left behind when
water evaporates and hang down from the roof; take thousands of years to form
Stalagmites: limestone is left behind when water evaporates and forming upward from the floor
Most sedimentary rocks are clastic or made from pieces of other rocks
Types of Sedimentary Rock Clastic: weathering of pre-existing rocks
transported to basin; texture consists of clasts (large pieces such as sand or gravel), matrix (mud or fine grained sediment), cement (calcite, iron oxide, or silica)
Organic Chemical: Also biochemical sedimentary rock;
evaporites, carbonates, and siliceous rocjs; firm within depositional basin from chemicals dissolved in seawater; chemicals may be removed and made into rocks with assistance from shell growth or biological processes
Clastic Sedimentary Rocks Clastic sedimentary rocks are classified
according to texture (grain size): 1. Gravel: Grain size greater than 2 mm
If rounded clasts = conglomerate If angular clasts = breccia
2. Sand: Grain size 1/16 to 2 mm. Sandstone (various types)
3. Clay: Grain size less than 1/256 mm Shale (if fissile)
Identifying Sedimentary Rocks
Rock Grain Color Hardness
Sandstone Medium Red or brown Hard
Mudstone Fine Black gray red or green
Hard
Clay Fine Red or brown Soft
Conglomerate Mixed Red or brown ,edium
Shelly limestone Medium with shells
Brown or gray Medium
Chalk Fine White soft
What would be the four stages in order of making a sedimentary rock?
weathering, transportation, deposition, compaction/cementation
Which sedimentary rock is most likely to be changed to slate during regional metamorphism?
1. breccia 2. conglomerate 3. dolostone 4. shale
Need To Know on Rocks ROCK NAME TYPE ( Igneous, Sedimentary, metamorphic) FORMATION Igneous (Extrusive, Intrusive) (volcanic, plutonic) (felsic or mafic) Sedimentary ( Clastic, chemical, biochemical, organic) Metamorphic (Regional, Contact Metamorphism) (low grade-high grade) ENVIRONMENT TEXTURE Igneous (phaneritic, aphanitic, porphyritic) Sedimentary (grain size) Metamorphic Foliated or non-foliated HARDNESS RANGE MINERALS PHYSICAL DESCRIPTION (Color) USES OTHER PROPERTIES
Sedimentary Rocks for The Soul
Limestone Is composed of calcite Fossils are likely to be found within limestone; carbonate
sedimentary rock Hardness: 4 Made from shells and fossils Shelly limestone full of small shells Another type of limestone is called coquina that is mostly
made from shells of sea animals including snails Oolitic limestone: delicately rolled spheres of calcite White, gray, or black Found in Belgium, China, England, Egypt, US Used Egyptian pyramids
Shale Not a clastic rock, but rather an organic
sedimentary rock splintery rock made from weathering of other
clastic rocks Most common sedimentary rock Minerals: kaolinite, smectite, and illite Used for roof tile, bricks, and pottery when
ground up Hardness: 3 Fossil rock
Bauxite Main source of aluminum Contains more than one mineral so is not
considered mineral Forms because of the weathering
process of soils mostly in tropical regions Not easily identifiable by streak and
hardness tests
Travertine Evaporite Forms in caves around hot springs
Chalk Major mineral within is calcite A type of limestone made from tiny
pieces of the mineral calcite
Coal Organic sedimentary rock With increased pressure, coal becomes
blacker, harder and better for burning Most coal formed in the swampy
Carboniferous period Mineral: carbon Hardness: 2 Used to generate electricity
Anthracite Black, shiny Found in Australia, China, US Type of coal Densest type of coal
Sandstone A clastic sedimentary rock Made from grains of sand stuck together Rough texture like sand paper Grains are rounded Made mainly of mineral quartz Found in Brazil, China, India, US Used in the making of buildings Minerals: quartz and feldspar
Gritstone Similar to sandstone but has larger
particles and is not rounded and feels rougher
Clay Clastic sedimentary rock Made of small particles of rock that are
too small to see even with a microscope Becomes sift and easy to break when wet Used in facial masks Minerals found within are kaolinite,
smecite and illite 2-3 on hardness scale
Mudstone Made of small particles too small to see
without microscope Black, gray, red, or green Very brittle
Conglomerate Made of a mixture of different sized
rounded rock such as pebbles, boulders, and sand
Coarse grained clastic rock Found in high
energy environments
Evaporite Chemical sedimentary rock Minerals: qypsum and halite In dry regions, where limited fresh water
flows, evaporites begin to dry out, as the water evaporates, minerals dissolved in water begin to harden and crystallize
Used in chemical industry for hydrochloric acid, plastics, and plaster of Paris
Chert Sedimentary rock with microcrystalline
and quartz
Dolostone Hard to distinguish from limestone Carbonate sedimentary rock Minerals composition includes calcite,
dolomite, and aragonite
Other Resources The following questions and answers are
from the New York State Regents Website: http://www.regentsprep.org/Regents/core/questions/topics.cfm?Course=ESCI
Geology.com
Carbonate: fossiliferous limestone composed of fossils in limestone matrix; oolitic limestone is dossil hash cemented together; chalk made of planktonic organism such as coccolithophores
Siliceous rocks: dominated by silica; form from silica-secreting organisms such as diatoms, radiolarims, or sponges; chert is formed through chemical reaction of silica in solution replacing limestone
Diatomite: siliceous rock; made of diatoms Coal: electricity: chemicals derived are used in
plastics, tar, synthetic fibers, medicine, and fertilizer
Organic Sedimentary Rocks (Coal)
Plant fragment rocks accumulate in swamps or marshes
Lack minerals which must be organic Peat: porous mass of brownish plant
resembling moss Lignite: crumbly and black Bituminous coal: dull to shiny, black sooty
with visible layers Anthracite coal: very shiny, slightly golden,
low density, no soot