Question

28. In dune fields the dunes are usually separated by relatively flat lying deposits that can deposited from either wind or water depending upon local circumstances. How does the porosity and permeability of these interdune deposits typically compare to those of the dunes (a) interdune deposits have higher porosity but lower permeability (b) interdune deposits have higher permeability but lower porosity (c) interdune deposits have lower permeability and porosity (d) interdune deposits have higher permeability and porosity (e) interdune deposits have similar permeabilities and porosity be 29. The dips of beds in an acolian reservoir unit vs. those of interbedded fluvial units are ypically.. ? (a) steeper and have less consistent angles (b) shallower and have more consistent angles (c) shallower and have less consistent angles (d) steeper and have more consistent angles (e) none of the above 30. The sand in aeolian deposits often has attractive reservoir properties being well-sorted and quartz rich. However the numerous thin layers that form on the slip faces of the dunes can mean (a) anisotropic (b) isotropic (c) vedotropic (d) endotropic (e) catatropic 31. As the gradient flattens from steep to shallow the flow style in a stream changes from.....? (a) delta to braided river to alluvial fan (b) delta to meandering river to braided river (c) alluvial fan to meandering river to braided river (d) braided river to alluvial fan to meandering river (e) alluvial fan to braided river to meandering river

Answer 1

28) c. Interdune deposits have lower porosity and permeability because permeabilty and porosity largely depends on grain size,shape and sorting and interdune sediments have poor packing which affects their water retention capabilities.

29) d. The dips of bed in aeolian reservoir unit are more steeper and have more consistent angle than interbedded fluvial units.

30)The numerous thin layers on the slip faces of the dunes means that the reservoirs permeability is Anisotropic or lateral permeability.

40) e. Alluvial fan to braided river to meandering river.

Meandering river is characterised by low gradient and therefore flow slows down. When Braided river is formed steep gradient is still present.