1 / 31

Mountain Building

Mountain Building. Earth Science Ch. 11. 11.1 Forces in Earth’s Crust. Deformation: permanent change in the size or shape of rock Occur along plate margins and in the Earth’s crust. Stress: force applied to a rock Strain: change in the shape of rock

arawn
Download Presentation

Mountain Building

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Mountain Building Earth Science Ch. 11

  2. 11.1 Forces in Earth’s Crust • Deformation: permanent change in the size or shape of rock • Occur along plate margins and in the Earth’s crust. • Stress: force applied to a rock • Strain: change in the shape of rock • Folding: bending due to gradual stress on rock • Fracturing: breaking of rock.

  3. Brittle Deformation • At the surface, temperatures and pressures are low • Rocks behave like brittle solids and fracture once their strength is exceeded. • Ductile Deformation • At depth, temperatures and pressures are high and rocks become ductile. • Deep inside the Earth, a solid state flow occurs • Material under high temperatures and pressures are more likely to change shape and do not fracture.

  4. Rock type can also affect deformation • Igneous rock is more likely to fracture than sedimentary or metamorphic rock. • Sedimentary and metamorphic are more likely to fold before they will fracture.

  5. Types of stress • Compression: squeezing (convergent) • Tension: pulling apart in opposite directions (divergent) • Shearing: stress in opposite directions (transform)

  6. Isostasy • The crust floats on the denser mantle • The gravitational balance of the crust is called isostasy • Isostatic adjustments occur when changes occur in the crust. • When weight is added to the crust it responds by subsiding or sinking • When weight is removed from the crust it responds by rebounding or moving upward

  7. 11.2 Folds, Faults, and Mountains • Folds • Occur during mountain building • Form due to compression • Most occur in sedimentary rock • Bending of rocks • 3 main types: anticlines, synclines, and monoclines

  8. Anticlines • Arching of rock layers • Form ridges • Synclines • Downfolds in rock layers • Sometimes called troughs • Form valleys • Anticlines and synclines are normally associated with each other.

  9. Monoclines • Very broad folds • Large steplike folds • Found in areas that have faults

  10. Faults • Movement along a fracture • The rock surface that is above the fault is called the hanging wall • The rock surface below the fault is called the footwall. • The area where movement is occurring is called the fault plane • Faults are classified according to the type of movement • There are 4 major types of faults: normal, reverse, thrust, and strike-slip

  11. Normal • Occur due to tension • Hanging wall moves down relative to the footwall • Causes extension of the crust • Reverse and thrust • Occur due to compression • Hanging wall moves up relative to the footwall • Causes shortening of the crust • Strike slip • Occur due to shearing • Movement is horizontal

  12. Types of Mountains • Folding and faulting produce many of Earth’s mountains • Mountains are classified by the processes that formed them. • Orogenesis: processes involved in mountain building • Groups of mountains • Range: group of similar mountains • System: a group of mountain ranges • Belts: large groups of mountain systems, most are found along the edges of continents

  13. Folded Mountains • Form by folding due to compression • The Appalachians, Rockies, and Alps are examples • Sedimentary rocks are common • Volcanic Mountains • Form along plate boundaries and at hot spots • Contain igneous rocks • Aleutian Islands, Hawaii, Mid Ocean Ridge, Cascades

  14. Fault Block Mountains • Form due to movement along normal faults • Formed by tension at a normal fault • The valleys formed are called grabens. • The uplifted areas are called horsts. • Sierra Nevada Mountains

  15. Plateaus form when an area of the crust is uplifted vertically. Commonly contain sedimentary rock. • Domes are caused by bending upward of sedimentary layers. Commonly contain igneous and metamorphic rock.

  16. 11.3 Mountains and Plates • Convergent Boundary Mountains • Most mountains form at convergent plate boundaries • Colliding plates produce compression • When subduction occurs, volcanic mountains commonly form on the overlying plate

  17. Oceanic – Oceanic Convergence • Produce volcanic island arcs • Subduction zones and trenches form at the boundary • The more dense oceanic crust is subducted • Aleutian Islands • Oceanic – Continental Convergence • Produce continental volcanic arcs and folded mountains • Subduction zones and trenches form at the boundary • Oceanic crust is always subducted • Cascades, Rockies, and Andes

  18. Continental – Continental Convergence • Folded mountains form • Both crusts will build up because continental crust is not dense enough to be subducted. • Himalayas and Appalachian

  19. Divergent Boundary Mountains • Usually formed on the ocean floor • Forms the mid ocean ridge. • Divergent boundaries form fault block mountains • Volcanoes formed at a divergent boundary are called fissure or rift volcanoes • Non-Boundary Mountains • Hot spot volcanoes that form over a mantle plume • Hawaii

  20. Continental Accretion • Accretion: occurs when material is scraped off of a subducted plate and combines with the land. • Enlarges continental land masses • Any crust that has become embedded into a continent is called a terrane. • Terranes have a geology that is different from the continent that it is attached to.

More Related