Jointing in sandstones, Arches National Park, Utah - by James R. DyerAbstractTable of contentsList of tablesList of figuresChapter one: Geology of Arches National ParkAbstractIntroductionPrevious investigationsField methodsStratigraphyPennsylvanian RocksHermosa formation

Pennsylvanian and Permian rocksCutler formation

Triassic rocksMoenkopi formationChinle formation

Triassic and Jurassic rocksGlen Canyon groupWingate sandstoneKayanta formationNavajo sandstone

Jurassic rocksSan Rafael groupEntrada sandstoneDewey Bridge memberSlick Rock memberMoab member

Summerville formation

Morrison formationSalt Wash memberBrushy Basin member

Cretaceous rocksCedar Mountain formationDakota sandstoneMancos shale

Tertiary (?) rocksFormation of Salt Valley

Quaternary (?) depositsMass wasting debris

Holocene deposits

Structural geologyRegional settingStructural geology of Arches National ParkFoldsFaultsSub-salt faultsSurface faults

Collapse structureJoints and fractures

Age of deformation

Chapter Two: Superpositon of zoned jointsAbstractIntroductionPrevious workSystematic joints and zoned jointsZoned joints in Arches National ParkOrigin of joins: Shear or extensionJoint domainsData collection and presentationDomain AObservationsDiscussion

Domain BObservationsDiscussion

Dihedral angle between joint setsDomain CObservationsDiscussion

Three-dimensional geometry of jointsObservationsDiscussion

Summary of observationsConclusions

Chapter Three: Origin of zoned jointsAbstractIntroductionGrowth of extension fracturesSresses on an elliptical crackStresses around a flat crack

Origin of joint zonesDeformation at the crack tipConclusions

Chapter Four: The influence of lithology on jointingAbstractIntroductionLithologic comparisonsMoab memberSlick rock member

Velocity measurementsDiscussions

The role of anisotropyConclusions

Chapter Five: the stress field about a joint zoneAbstractIntroductionJoints as paleostress indicatorsStress field about a joint zoneResolved stresses on the crackSolving for the stress field

Boundary conditions1. Open crack2. Closed crack

Examplesi. Closed crackia. Locked jointib. Frictional slidingic. Frictionless jointP ropagation of a younger joint

ii. Open crackia. is compressiveiib. are tensile

Conclusions

Appendix AAppendix BReferences cited