Large scale topography Tectonics and Structure

1. Large scale topographyTectonics and Structure www.montana.edu/kmw/

2. Response of the mantle and crust to loading: Lake Bonneville • http://geology.utah.gov/utahgeo/gsl/flash/lb_flash.htm • http://geology.utah.gov/utahgeo/gsl/flash/lb_flash.htm

6. Say an icesheet is 4000 m thick, (the Antarctican icesheet is roughly this thick at its maximum thickness.) • How far does the lithosphere deflect beneath the icesheet? • Step 1. Calculate pressure due to ice + crust • Step 2. Calculate pressure due to mantle + crust • Step 3. Pressures are equal due to hydrostatic equilibrium • Given, • ice has a density of 917 kg/m3 • crust has a density of 2700 kg/m3 • upper mantle (that gooshes out of the way to allow this deflection of the surface) has a density of 3300 kg/m3 • thickness of the crust beneath the center of the icesheet and the region outside of it is the same.

7. Brook manual, p. 2-4 • Q 2-3 • Magnetic declination: the difference between geographic north and magnetic north • Magnetic declination of Philipp quad= • 7.5 deg E • Verbal scale in in/mi • Philipp: 1” = 62,500” = .98mi • Kingston: 1” = 24,000” = .38mi • Verbal scale in cm/km • Philipp: 1 cm = .625km • Kingston: 1cm = .24 km

8. Brook manual, p. 2-10 • Q 2.6 • Horiz scale is • 1:25,000 or 1” on map = 25,000” on ground • Vert scale is • 1” = 100’ or 1”=1200” • VE=Horiz scale/Vert scale = • 25,000/1200=20.8 • Q 2.7 • Average gradient (or slope) = rise/run, in words • 500 ft/(520 yds x 3 ft/yd)=500 ft/1560 ft = 1 ft/3.12 • for every vert. ft of elev gain, the dist moved in 3.12ft

9. Rock Cycle Weathering, transport, deposition • Repeated creation and destruction of crustal material (rocks and minerals) • Volcanoes, folding faulting, uplift • bring rock, water, gas to the Earth surface • Rocks disintegrates • weathers by exposure to water and air • Transport by gravity, water, wind • weathering products go back to the ocean • Deposition and burial • formation of sedimentary rocks • Deep burial • metamorphic rocks • Uplift, intrusion, or extrusion • rocks exposed, process begins again

10. Landform creation by:Weathering, transport, deposition • Weathering agents move into soil and rock along a weathering front • brings fresh rock up • Weathered material (regolith; soil) on surface + material brought in by wind, water, ice, animals = weathered mantle • Mantle remains in place or moves downslope by gravity • water can also carry it downslope • wind can remove it

11. large scale features of the Earth are the product of tectonic process tekton, Gr. for mason or builder processes in the core and mantle => processes and structure in the lithosphere http://www.geosociety.org/gsatoday/archive/15/7/pdf/i1052-5173-15-7-4.pdf

12. Plate Tectonics: the quick and dirty

13. Oceanic plate tectonics • Mid-ocean ridges: • the seams of a baseball • Volcanic eruptions produce new oceanic lithosphere • Cools, thickens, sinks http://www.pmel.noaa.gov/vents/nemo/education/images/plates_sm.jpg

14. Ocean landforms: Continental Shelf • The edges of the continents slope down from the shore into the ocean. • The part of the continent located under the water is known as the continental shelf. • In some places the continental shelf is fairly shallow and in other place it becomes very deep, but it is not the deepest part of the ocean.

15. Ocean Landforms: Continental Slope • The steep slope where the continental shelf drops to the bottom of the ocean floor is called the continental slope. • The depth of the ocean water increases greatly here.

16. Ocean Landforms: Mid-ocean ridge and Abyssal plain • On the bottom of the ocean, there is a central ridge, or mountain range, that divides the ocean floor into two parts. • These underwater volcanic mountains are known as the mid-ocean ridge.

17. Ocean Landforms: Trenches • There are many steep-sided canyons and deep, narrow valleys in the bottom of the ocean. • Ocean trenches are the deepest part of the ocean basin and are deeper than any valley found on land.

18. Ocean landforms: Guyots and Seamounts seamount http://www.utdallas.edu/~pujana/oceans/guyot.html

19. http://www.sanctuarysimon.org/monterey/sections/seamounts/project_info.php?projectID=100114&sec=smhttp://www.sanctuarysimon.org/monterey/sections/seamounts/project_info.php?projectID=100114&sec=sm

20. Brook, p 4-4 and 4-5 • Q 4.1(b) • Cones are associated with major river systems carrying high sediment loads • often formed at low stand (glacial times) • cones were then river deltas • Q 4.1 (c) • St Helena Island (15S, 5W); Easter Island (27S, 109W); Amsterdam Island (37S, 77E) • Islands, guyots, and seamounts were all formed at ocean ridges • The further it is from the ridge, the older it is • Q 4.2 (a) • Red Sea is the result of divergent plates under the continent • Arabian plate moving away from African plate • divergent plate boundary