structure of the earth and the rock cycle. lithosphere composed of minerals definition of...
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LithosphereLithosphere composed of composed of mineralsminerals
Definition of “Definition of “Mineral” ?Mineral” ?
A A rockrock is a natural solid substance is a natural solid substance made up of mineralsmade up of minerals
rocks classified by rocks classified by origin : 3 typesorigin : 3 types
Types of RocksTypes of Rocks
1. IGNEOUS1. IGNEOUS molten rock that has cooled and solidifiedmolten rock that has cooled and solidified
molten rock is molten rock is magmamagma or or lavalava
a) INTRUSIVEa) INTRUSIVE cools below surface; big crystals; coarsecools below surface; big crystals; coarse
b) EXTRUSIVEb) EXTRUSIVE cools at surface; finecools at surface; fine
Mafic and felsic igneous Mafic and felsic igneous rockrock
FelsicFelsic: mostly felsic minerals : mostly felsic minerals High in feldspar and silicate mineralsHigh in feldspar and silicate minerals LighterLighter Less denseLess dense
MaficMafic: mostly mafic minerals : mostly mafic minerals High in magnesium and iron High in magnesium and iron DarkerDarker DenserDenser
UltramaficUltramafic: all mafic minerals: all mafic minerals
2. SEDIMENTARY2. SEDIMENTARY
made up of sediments that have been made up of sediments that have been compacted and cemented.compacted and cemented.
sedimentssediments: all solid particles transported : all solid particles transported by water, ice, wind, gravityby water, ice, wind, gravity
mud, sand, shells, debris, dust, rock fragmentsmud, sand, shells, debris, dust, rock fragments
mudstone, sandstone, limestone, mudstone, sandstone, limestone, conglomerate, shaleconglomerate, shale
accumulate in accumulate in stratastrata (layers) (layers)
3. METAMORPHIC3. METAMORPHIC
altered from original rock by heat, altered from original rock by heat, pressure or chemical activitypressure or chemical activity
began as igneous, sedimentary, or began as igneous, sedimentary, or metamorphic rockmetamorphic rock
shale --> slateshale --> slate slate --> schistslate --> schist granite --> gneissgranite --> gneiss limestone --> marblelimestone --> marble
CoreCore InnerInner
5150 – 6370 km (below surface)5150 – 6370 km (below surface) Solid ironSolid iron 5400 – 9000 degrees F5400 – 9000 degrees F
OuterOuter 2900 – 5150 km2900 – 5150 km Molten ironMolten iron
Lower mantleLower mantle very dense; iron very dense; iron
and magnesiumand magnesium 670 – 2900 km670 – 2900 km
Upper mantleUpper mantle rigid at lower endrigid at lower end ““plastic” toward plastic” toward
crust: crust: asthenosphereasthenosphere
250 -670 km250 -670 km
Uppermost mantleUppermost mantle RigidRigid ““Moho” to 70 kmMoho” to 70 km
““Moho”Moho” Mohorovičić discontinuityMohorovičić discontinuity Boundary between crust and mantleBoundary between crust and mantle Change in seismic waves hereChange in seismic waves here
CrustCrust continentalcontinental : 25 miles thick : 25 miles thick
Lower mafic; upper felsic (granite)Lower mafic; upper felsic (granite) Less denseLess dense
oceanicoceanic: 5-6 miles thick: 5-6 miles thick Mafic (basalt)Mafic (basalt) More denseMore dense
LithosphereLithosphere = uppermost mantle and = uppermost mantle and crustcrust RigidRigid ultramaficultramafic
Lithosphere is divided into large Lithosphere is divided into large platesplates
rigidrigid plates “float” on the plates “float” on the plastic plastic asthenosphere, just deep enough to asthenosphere, just deep enough to support their own weight:support their own weight:
IsostasyIsostasy
Isostatic adjustmentIsostatic adjustment of crust: of crust:
add weight (sediment, glacial ice): crust add weight (sediment, glacial ice): crust will sinkwill sink
remove weight (erosion, glacial ice remove weight (erosion, glacial ice melts): crust will reboundmelts): crust will rebound