Geologic Time Test Study Guide

1. Whatisthedifferencebetweenuniformitarianismandcatastrophism?

2. Whatisrelativedating?

3. Whatisthelawofsuperposition?

Uniformitarianism: thesamegeologicprocessesshapingtheEarthtodayhavebeenatworkthroughoutEarth’shistory

Chapter 12 Section 1The Earth’s Story and Those Who First Listened

Catastrophism:aprinciplethatstatesthatgeologicchangeoccurssuddenly

Determiningwhetheranobjectoreventisolderoryoungerthanotherobjectsorevents

Theprinciplethatstatesthatyoungerrockslieaboveolderrocksinundisturbedsequences

4. Whatistheprincipleoforiginalhorizontality?

5.Whatisanunconformity?Whatcausesunconformities?

Chapter 12 Section 1Relative Dating

Anunconformityisabreakinthegeologicrecordcreatedwhenrocklayersare erodedorwhensedimentisnotdepositedforalongperiodoftime

Sedimentisgenerallydepositedinflat,horizontallayers.Ifitistiltedandbent,thenitoccurredaftertherocklayersformedinflat,horizontallayers

Unconformity

What is an unconformity?

Layer(s) of missing rock, due to erosion or nondeposition.

6.Whatisafossil?

7. Inwhattypeofrockaremostfossilsfound?

8.Whatisatracefossil?

9.Whatisanindexfossil?

Tracesorimprintsoflivingthingsthatarepreservedinrock

Anynaturallypreservedevidenceofanimalactivity(coprolite)

Chapter 12 Section 2Evidence of the Past

SedimentaryRock

Fossilsoforganismsthatlivedduringarelativelyshort,well-definedgeologictimespan(trilobites)

10.Whatarethe2conditionsthatfavorpreservationofanorganismasafossil?

11.Howcanfossilshelpbuilddetailedpicturesofpastenvironments?

Chapter 12 Section 2Evidence of the Past

1. RapidBurial– protectsanorganismfrombeingeatenordecomposing

2. PossessionofHardParts– theyaremorelikelytoremainintactlongenoughtobecomefossilized

1. Fossilizedclamshells:theremusthavebeenanoceanthere

2. Fossilizedcoral:theremusthavebeenashallowtropicalseathere

3. Coal:Theremusthavebeenaswampwithtropicalplants

12. Whatisradioactivedecay?

13. Whatisabsolutedating?

14.Whatisthemostcommonmethodofabsolutedating?

15.Whatishalf-life?

16.Whatisanisotope?

Anymethodofmeasuringtheageofaneventorobjectinyears

Radiometricdating

Chapter 12 Section 3Absolute Dating: A Measure of Time

Thetimeneededforhalfofasampleofaradioactivesubstancetobecomestable

Anatomthathasthesamenumberofprotonsasotheratomsofthatelementbutadifferentnumberofneutrons(andthereforeadifferentatomicmass)

Theprocessofunstablenucleibecomingstablebyspontaneouslybreakingapartandreleasingenergy

17.Whatisradiometricdating?

18.Whycan’tradiometricdatingbeusedtodatesedimentaryrock?Howdogeologistsgettheageofitthen?

Chapter 12 Section 3Absolute Dating: A Measure of Time

Amethodofdeterminingtheageofanobjectbyestimatingtherelativepercentagesofaradioactive(parent)isotopeandastable(daughter)isotope

SedimentinrocksareweatheredfromsomanydifferentrocksofdifferentagesTheymustrelatethesedimentaryrocktodatablemassesofigneousrock

19. Howoldistheearth?

20. WhatdogeologistscalltheperiodoftimebeforetheCambrianperiod?

21. Beabletoplacetheerasinthecorrectorderfromoldesttomostrecent.

22.Howlongagodidthedinosaursbecomeextinct?

Chapter 12 Section 4Eras of the Geologic Time Scale

PaleozoicàMesozoicà Cenozoic

4.6Billion-ish yearsold

Pre-Cambriantime

65millionyearsago

23.Whicherameans“Ancientlife”becausegeologiststhoughtthiswastheoldestrockthatexisted?Listsomebasicfactsfromthisera.

24.Whicherawasthe“AgeoftheReptiles”?Listsomebasicfactsfromthisera.

25.Whicherawasthe“AgeoftheMammals”?Listsomebasicfactsfromthisera.

CenozoicEra

Chapter 12 Section 4Eras of the Geologic Time Scale

MesozoicEra

PaleozoicEra -- dominatedbyfish,Amphibians,EarlyReptiles,Landplantsemerge

-- Earlybirdsappear,firstflowingplants,dinosaursdominant

-- Mammals,primates,andhumans