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b-carbonate shelves :
because continents are drained by large river systems , a large supply
of terrigenous debris is deposited onto continental shelves.Therefore ,
most shelves are covered by sand and mud composed of quartz and
feldspar the two principal minerals that comprise the granitic rock of
the continents.
Where the supply of river sediment is low and the waters of the shelf
are warm , there can be a buildup of calcium carbonate (ca co 3
)material composed of the shells of organisms .these shallow areas
are called carbonate shelves or platforms.
b- Deep –sea sedimentation :
There are two main sources of sediment for deep-ocean floor : (1)
terrigenous mud and sand that bypass the shallow continental shelf
and ,(2) the hard parts of surface –water microorganisms that settle to
the deep-sea bottom.
(source : invitaion to oceanography .2006. p :96,97,101,112)
Exercise : read the following questions and choose the right
answer :
1-sediment is : a- the sand that covers the beach.
b-sand, stones,mud….etc carried by water or wind and left on the
bottom of the ocean.
c-the water that is held in aquifers.
2- sediment found on the bottom of the ocean : a-come from land only.
b-come from the land and the sea.
c-come from the sea only.