Characteristics and interactions for stack and dunes

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Information about Characteristics and interactions for stack and dunes

Published on March 13, 2014

Author: mrsmithtgs



Characteristics of features and interactions of processses at Muriwai

The Stack

Characteristics • Manukau Breccia • Pohutukawa on top • 35m tall • West of otakamiro headland between maori bay and muriwai beach • Evidence of erosion eg notch

How processes interact. • Tectonic activity creates the manukau breccia. • Faulting lifts up the headland along the muriwai helensville fault. • Now wave erosion can occur • Wave erosion occurs on the headland to form a cave. • Wave erosion provides sediment for corraision to occur in the cave • Corraision makes the cave erode through to create a sea arch. • The Vegetation growth weakens the cave roof and makes it fall in . • Vegetation growth and wave erosion combine to create the stack.

The Sand Dunes

Characteristics • Southern end dunes are 15 – 20m high • Dunes by okiritoto stream are 8 – 10m high • Made up of quartz, feldspar at top titanomagnetite at bottom • Covered in Marram, Pingao and Spinifex

Interaction of Processes • LSD brings in the sediment • Insolation dries out the sediment or it would not be able to be moved • Onshore winds pick up the sediment and move it to the back of the beach • Dune vegetation catches the sediment moved by the wind as it stops the aeolian action by stopping the wind.

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