Magnetic and Sidescan Sonar Survey of the Firth of Thames

The survey was undertaken to refine existing data on the surficial sediments within the Firth of Thames shown on maps produced by Carter and Eade (1982), Naish (1990) and van Leeuwe (1991). From thesis: The sidescan sonar survey was carried in 1990 by the Marine Geosciences Group at the University of Waikato (D. Allen) to refine existing data on the surficial sediments within the Firth of Thames shown on maps produced by Carter and Eade (1982) Naish (1990) and van Leeuwe (1991). In this study, interpretation of the sonographic patterns identified showed: i) a large central love of relatively fine gravel, interpreted as being calc-gravel, due to the presence of cal-gravels in the central of the Firth of Thames being shown on the three previously produced maps; ii) coarse delta fan gravels off the eastern and western coasts of the Firth; iii) an area of bedrock through a mud veneer on the eastern side of the Firth of Thames, and a small area of what may be mussel or oyster beds on the western side of the Firth; iv) an area of mainly sandy bottom sediments off the western coast of the Firth between the landward gravels and the seaward muds; v) extensive areas of muds especially towards the south of the survey area. There were a number of differences noted between the facies map prepared for this study on the basis of sonographic interpretation and the maps produced by the previous studies, and these could be due in part to different sampling techniques and sampling densities, and also the last of detailed testing of the sidescan patterns identified.

Sidescan and magnetometer survey and interpretation in Firth of Thames.

Mid Firth of Thames - a band of data collection the full width of the Firth in area north of Kaiaua to approximately Tapu in the North.

Sidescan sonar survey November 1990. Magnetic survey November-December 1994.

Frequency of collection: One-off data collection.

Normal limitations associated with magnetic and sidescan surveying techniques, detailed in thesis. Attribute accuracy: Details in thesis

Investigation of sea bed sediments in the Firth of Thames.

Thesis available in University of Waikato library. Sensitivity/Confidentiality: No confidentiality.

Study completed

Related information: Earlier work undertaken by Carter and Eade (1982), Naish (1990) and van Leeuwe (1991).