ASBOG General Questions & Answers Updated 2026

ASBOG General Questions &
Answers Updated 2026
WhatAisAaAfoldAlineAandAhowAisAitAused?A-
AAnswerATheAfoldAlineAisAaAhingeAlineAalongAwhichAaAverticalAcrossAsectionA
mayAbeAconstructedAandAthenAflattenedAoutAtoAaAhorizontalAorAmapAview.AItAi
sAusedAtoArepresentAtheAsubsurfaceAalongAanyAgivenAlineAinAaAmapAview.AItA
needAnotAbeAperpendicularAtoAstrike.


WhatAisAtheAangleAandAsideArelationshipsAforAtheAsinAequation?A-
AAnswerAsinαA=AoppositeAside/hypotenuse


WhatAisAtheAangleAandAsideArelationshipsAforAtheAtangetAequation?A-
AAnswerAtanαA=AoppositeAside/adjacentAside


IfAanAattitudeAisAgivenAasA35,AS25E,AwhatAdoesAthatAmean?A-
AAnswerATheAattitudeA35,AS25E,AifAgivenAasAaAplane,ArepresentsAaAdipAofA35
AinAtheAS25EAdirection.AThisAwouldAtranslateAtoAaAstrikeAofAN65EA(orA90Aawa
y),AandAdipAofA35S.ATheABoardAwantsAtoAseeAAnswersAinAtermsAofAstrikeAand
AdipAwithArespectAtoAtheAtwoAnorthAquadrants.ATheAattitudeA35,AS25E,AifAgive
nAasAanAapparentAdipAvaueAorAtheAbearingAandAplungeAofAaAline,Arepresents
AaAlineAplungingA35AinAtheAdirectionAS25E.AApparentAdipAisAivenAinAtheseAter
msAtoArepresentAtheAapparentAdipAangleAinAaAgivenAdirection.


WhatAisAtheAgeneralAformAofAtheAthicknessAequationAandAwhyAwouldn'tAyouA
wantAtoAuseAit?A-
AAnswerAThicknessA(t)A=AoutcropAwidteAperpendicularAstrikeA(w)AsinA[dipA(δ),A
slopeA(σ)].AGenerallyAitAisAeasierAtoAsolveAaAthicknessAproblemAgraphicallyAbe
causeAyouAneedAtoAdrawAaAdiagramAtoAscaleAanywayAtoAgetAtheAslopeAangle
A(σ)AandAtheAperpendicularAoutcropAwidthA(w).


IfAyouAhaveAaAflatAsurfaceAandAanAoutcropAwidthAthatAisAnotAperpendicularAto
Astrike,AwhatAequationAwouldAyouAuseAtoAcalculateAtheAthicknessAofAtheAunit?
A-
AAnswerAtA=AlAsinAβAsinAδ;AlA=AtraverseAdistanceAacrossAtheAoutcrop;AβA=A
angleAbetweenAstrikeAandAapparentAdipAdirection;AδA=Adip

,WhatAisAtheAgeneralAequationAforAcalculatingAtheAapparentAdipAofAaAbedAand
AwhenAcan'tAthisAequationAbeAused?AWhatAotherAmethodsAcanAbeAusedAanAalt
ernative?A-
AAnswerAtanαA=AtanδAsinβ;AαA=AapparentAdip;AδA=Adip;AβA=A(angleAbetwe
enAstrikeAandAapparentAdipAdirection);AThisAequationAcan'tAbeAusedAforAsolvin
gAtrueAstrikeAandAdipAfromAtwoAapparentAdips.AInAorderAtoAsolveAaAproblem
AinvolvingAtwoAapparentAdipsAyouAmustAeitherAsolveAgraphicallyAorAusingAthe
Astereonet.ATheAstereonetAsolutionAisAmuchAsimplerAandAlessAtimeAconsuming.


WhatAdefinesAanAIndexAFossil?A-
AAnswerAAnAindexAfossilAidentifiesAandAdatesAtheAstrataAinAwhichAitAisAfound.
AItAcombinesAaAwideAgeographicArangeAwithAaAnarrowAstratigraphicAoccurrence
.


WhatAisAnetAslipAandAwhereAisAitAmeasured?A-
AAnswerANetAslipAisAtheAdistanceAbetweenAtwoAformerlyAadjacentApointsAonAei
therAsideAofAaAfault,AmeasuredAonAtheAfaultAsurfaceA(inAtheAplaneAofAtheAfaul
t).


WhatAisAanAunconformity?A-
AAnswerAAnAunconformityAisAaAgapAinAtheAgeologicArecord;AanAinterruptionAin
AtheAdepositionalAsequenceAthatAimpliesAupliftAandAerosionAhaveAremovedApart
AofAtheAgeologicalArecordAorAnon-depositionAhasAoccurred.


WhatAisAtheA"RuleAofAV's"?A-
AAnswerATheAoutcropAofAaAformationAasAitAcrossesAaAvalleyAformsAaAVAshape
A(asAviewedAonAaAmap).ATheAVApointsAinAtheAdirectionAthatAtheAformationAun
derliesAtheAvalley.


WhatAisAaAtypeAlocality?A-
AAnswerAAAtypeAlocalityAisAtheAplaceAwhereAaAgeologicAfeatureA(suchAasAaAfo
ssilAspeciesAorAgeologicAformationAorAmember)AwasAfirstArecognizedAandAdescr
ibed.AItAcontainsAtheAtypeAsection.

, DefineAtypeAsection.A-
AAnswerATypeAsectionAisAtheAoriginallyAdescribedAstratigraphicAunitAtoAwhichA
otherApartsAofAthAunitAinAotherAlocationsAmayAbeAcompared.AItAisApreferableA
toAdescribeAtheAlocationAwhereAtheAunitAattainsAitsAmaximumAthicknessAandAw
hereAthAtopAandAbottomAofAtheAunitAareAexposed.


HowAdoesAaAreverseAfaultAdifferAfromAaAnormalAfault?AHowAisAitAtheAsame?A
-AAnswerAAAnormalAfaultAisAaAdip-
slipAfaultAinAwhichAtheAhangingAwallAhasAmovedAdownArelativeAtoAtheAfootAw
all.AAAreverseAfaultAisAaAdip-
slipAfaultAinAwhichAtheAhangingAwallAhasAmovedAupArelativeAtoAtheAfootAwall
.ABothAnormalAandAreverseAfaultsAhaveAaAdipAbetweenA45AandA90.


WhatAisAtheALawAofAInitialAHorizontality?A-
AAnswerATheALawAofAInitialAHorizontalityAassumesAthatAtheAsequenceAofAlayer
sAwasAdepositedAhorizontallyAorAnearlyAso.ATheAoldestAlayerAisAthereforeAonAt
heAbottomAandAtheAyoungestAlayerAisAonAtop.AInAdissectedAtopography,AtheAy
oungestAlayersAwillAformAhillAtops.


WhatAisAtheALawAofASuperposition?A-
AAnswerATheALawAofASuperpositionAstatesAthatAtheAoldestAlayerAisAonAtheAbot
tomAandAtheAyoungestAlayerAisAonAtheAtop.AThisAassumesAthatAtheAlayersAhav
eAnotAbeenAoverturnedAduringAdeformation.AIfAtheAbedsAareAoverturnedAorAver
tical,AtheAstratigraphicAsuccessionAcan'tAbeAdeterminedAunlessAtheAabsoluteAag
esAofAtheAunitsAareAknown.AThisAlawAappliesAtoAanyAlayeredArockAsequenceAs
uchAasAsedimentaryAunitsAorAextrusiveAigneousArocks.


HowAareAcross-cuttingArelationshipsAusedAtoAdetermineArelativeAages?A-
AAnswerAIfAcross-
cuttingArelationshipsAexist,AtheAfeatureAthatAisAcutAisAolderAthanAtheAfeatureAt
hatAcutsAacrossAit.ARocksAmayAbeAcutAbyAintrusion,Afaulting,Aunconformities,Ao
rAreplacementAminerals.


WhatAtypeAofAVAwillAaAverticalAbedAdisplayAonAaAmap?A-
AAnswerAAAverticalAbedAwillAhaveAnoAV.AAAverticalAbedAcrossesAallAvariations
AofAtopographyAwithAaAstraightAline.AThisAisAalsoAtrueAofAanyAverticalAstructu
ralAfeatureAsuchAasAaAfault.