Unconformities,GeologicTimeScale,andUniformitarianism

Ms.PScience2016

DoNow– duetomorrow!

1. Compareandcontrastrelativedatingtoabsolutedating.

2. TheLawofSuperpositionstatesthat“youngerrockslieaboveolderrocksinanundisturbedsequence.”Whatdoesthewordundisturbedmean?

3. Howdoyouthinkrocklayersbecome“disturbed”?

TheLawofSuperposition–Oldestrocksareatthebottom,newestrocksareatthetop!

• Inhorizontallayers(originalhorizontality) ofsedimentaryrock,eachlayerisolderthanthelayeraboveit andyounger thanthelayerbelowit.

Gapsintherecord…

• Sometimesrocklayersaremissingalltogethercreatingagapinthegeologicrecord.

Unconformities:themissingevidence

• Missingrocklayerscreatebreaksintherocklayersequencecalledunconformities.

• Anotherwayofthinkingaboutanunconformity isthatitisasurfacethatrepresentsamissingpartofthegeologiccolumn.

CausesofUnconformities

• Non-deposition- whenthereisNOsedimentdepositedbecausethesupplyofsedimenthasbeencutoff.

• Erosion– movementofsedimentsfromoneplacetoanother.

C.F.U.

1. Whatissuperposition?

2. Explainwhatanunconformityis.

3. Whatcausesunconformities?

4. Howdounconformitiesaffectsuperposition?

• Paleontology: Thescientificstudyofearth’spast,particularlyfossils.

• Paleontologistsarescientistwhostudytheearth’sfossils.

• Whatisitcalledwhenananimalspeciesiswipedoutfromtheearth’ssurface.

Whatispaleontology?

GeologicColumn

• Notallrocksequenceshavebeenundisturbed.Somerockforcesaredisturbed(moved)byforceswithintheearth.Thismakesithardforgeologisttodeterminetherelativeageofarock.

• Todeterminetherelativeageofarockscientistuseageologiccolumn

• Ageologiccolumn isanarrangementofallthedifferentrocklayersfromaroundtheworldinwhichtheoldestrocksareatthebottom.

• Uniformitarianism—– Thesameprocess thathavechangedtheearthinthepastcontinuetochangetheearthtoday overalongperiodoftime.

– Basically,thethingsthatchangedtheearthinthepastarechangingtheearthtoday.

Howwastheearthformed?GeologicHistory

• Uniformitarianism– Weathering,erosion,anddeposition haveshapedtheearth’ssurfaceinthepastandarecontinuallyshapingtheearth’ssurfacetoday

– Rocksthatwereformedinthepastlooksimilartorockstoday

Evidencesupportinguniformitarianism

GeologicTimeScale

• ThegeologiccolumnrepresentsthethousandsofyearsthathavepassedsincethefirstrocksformedonEarth.

• Altogether,geologiststudyyears,andyears,andYEARSofEarth’shistory.

• Tomakethingseasier,scientistshavedevelopedthegeologictimescalewhichisascalethatdividestheearth’shistoryintodistincttimeintervals.

CFU

1. WhatdoesUniformitarianismmean?Howwouldweapplythistermtotheearthtoday?

2. Whatisthegeologictimescale?3. Accordingtothegeologictimescale

organismsstartedout_________andbecamemore_________overtime.

4. Howdidorganismsreallystartoutthough?

DoNow- day2– QUIZtomorrow!

1. Whatisanunconformity?2. Whatarethecausesofunconformities?3. WhatdoesUniformitarianismmean?How

wouldweapplythistermtotheearthtoday?4. Whatisthegeologictimescale?5. Accordingtothegeologictimescaleorganisms

startedout_________andbecamemore_________overtime.

6. Howdidorganismsreallystartoutthough???

SimpleComplex

PaleontologyQuiztomorrow!

• Packetsyouneedtostudy—– Fossils– LawofSuperposition–Unconformities,theGeologictimescale,andUniformitarianism

GeologicColumnActivity

• ReadthedirectionsonyoulabsheetsilentlyasIreadthemaloud.

• DoNOTwriteonyourdirectionssheet.

• Oneyouarefinishedcoloring,pleaseraiseyouhandtoaskforscissors.Gluesticksareinyourbasket

GeologicColumnActivity

• Shapes=fossils• Background=sediment• Wavylines=depositionwasnotcontinuous(maybeanunconformity!)

• Straightlines=depositionwascontinuous• Coloreachlayeradifferentcolor.Layersthatarethesameshouldbethesamecolor.

• Matchupthedifferentoutcropsaccordingtothefossils(shapes)andsediment(background)

Catalyst

1. Accordingtothegeologictimescaleorganismsstartedout_________andbecamemore_________overtime.

2. WhatisthelawofSuperposition?3. Whatisthegeologicscale?4. Whatisanindexfossil?5. HowcanfossilstellusaboutEarth’spast?