Presentation on theme: "Warm Up 12/3 The type of deformation in which the object permanently changes size and shape without fracturing is called ____. a. stress deformation c."— Presentation transcript:
1Warm Up 12/3The type of deformation in which the object permanently changes size and shape without fracturing is called ____.a. stress deformation c. brittle deformationb. elastic deformation d. ductile deformationFolding is usually the result of ____.a. tensional stresses c. shear stressesb. compressional stresses d. faultingWhich of the following combinations should favor folding rather than faulting?a. high temperature and high confining pressureb. high confining pressure and low temperaturec. low confining pressure and low temperatured. high temperature and low confining pressureAnswers: 1) d. 2) b. 3) a.
6Folded MountainsMountains that have formed primarily by folding are called folded mountainsCompressional stresses are the major force that forms folded mountainsThrust faulting is also a major component in folded mountains, which are often called fold-and-thrust beltsExamples: the Appalachians, the northern Rocky Mountains, and the Alps
8Fault-Block Mountains Large-scale normal faults are associated with structures called fault-block mountainsThe mountains form as large blocks of crust are uplifted and tilted along normal faultsAs the crust is stretched, a block called a graben, which is bounded by normal faults, drops downGrabens produce an elongated valley bordered by relatively uplifted structures called horstsExamples: Teton Range (Wyoming), Sierra Nevada, and the Basin and Range Province
13Concept Check What is a horst? A horst is an uplifted block bounded by normal faults.
14Domes and BasinsBroad upwarping in basement rock may deform the overlying cover of sedimentary strataWhen upwarping produces a circular or elongated structure, the feature is called a domeThe oldest rocks of a dome form the core of the mountainsDownwarped structures having a circular shape are called basinsLarge basins usually contain sedimentary beds sloping at low angles, the basins are usually identified by the age of the rocks composing them (youngest form the center)