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THE OBLIQUE ASDIC AND ITS USE IN AN INVESTIGATION OF A MARINE HIGH‐ENERGY ENVIRONMENT 1
Author(s) -
DOBSON MAX
Publication year - 1969
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1969.tb01123.x
Subject(s) - geology , sediment , littoral zone , coring , oceanography , sampling (signal processing) , geomorphology , drilling , computer science , engineering , computer vision , mechanical engineering , filter (signal processing)
SUMMARY Methods whereby an Asdic may be used empirically to examine the sea bed are discussed. They indicate that on flat sea bottoms the effects of impedance and attenuation combine to produce a record usually distinctive enough to broadly classify the sediment over which the vessel is passing. These methods were used to interpret an area of unconsolidated sand, gravel and mud in the region of Arklow off the east Irish Coast. Echo‐sounder traverses and sea bed sampling were also employed to assist with the interpretations. The sea bed is composed of dissected residual gravels covered in places with mobile sand displaying a great variety of high‐energy bed forms. Mechanisms of sub‐littoral sediment circulation, based largely on the bed forms recognized in the Asdic records, are also discussed.