The marine geology of Walker Bay, off Hermanus, SW Cape, South Africa

• Main Author: Lenhoff, Louis
• Other Authors: Rogers, John
• Format: Master Thesis
• Language: English
• Published: University of Cape Town 1995
• Subjects: Geology; Marine Geology; Walker Bay
• Online Access: http://hdl.handle.net/11427/22397; https://open.uct.ac.za/bitstream/11427/22397/1/thesis_sci_1995_lenhoff_louis.pdf

Bibliography: pages 55-58. The seafloor geology of Walker Bay on the southern Cape coastline is described by making use of geophysical information obtained over a period of 4 years, between 1986 and 1990. The data include side-scan sonar images, seismic profiles, seabed samples and observations by a Remotely Operated underwater Vehicle (ROV). Four sonograph facies were identified, based on their distinctly different reflectivity patterns. Using the seabed samples and R.O.V. observations, the physical characteristics of these facies are determined and presented in map format. Facies 1 consists of Bokkeveld Group rock outcrops with relatively high relief, occupying approximately 45 percent of the study area. Facies 2 represents similar outcrops but with low relief and partially covered by a thin veneer of unconsolidated sediment, including localized occurrences of loose cobbles and boulders. Facies 3 and 4 relate to sediment-covered areas displaying different bedform types. Facies 3 is dominated by well-defined patches of megarippled gravelly sand, whereas Facies 4 consists of small-scale rippled sand. The characteristics of the Facies 3 megarippled patches are discussed in detail and their relationships with the local wave pattern and nearby Facies 1 and 2 rock outcrops are investigated.