Geological structure and acoustic properties of sediments in Effingham Inlet

Abstract

[author abstract] Effingham Inlet is a unique fjord landscape located in Barkley Sound of Vancouver, Canada that was uncovered by glaciers around 15 ka. In this study, multibeam echosounder bathymetric and backscatter intensity values were recorded aboard the R/V Thompson on the University of Washington Oceanography Senior Cruise to Barkley Sound. The goal of this research study is to describe the acoustic properties of sediments seen along the Effingham Inlet fjord section and to relate patterns in acoustic properties to past and present geomorphological processes affecting the fjord. Little difference in the backscatter intensity values of similar seabed features at different locations in the fjord suggest that short-term processes of sedimentation and enduring glacial remnants have a larger effect on the backscatter intensity compared to long term geological processes and small differences in geological position. This cascade of effects makes it difficult to quantify the effects of geological processes over geomorphological processes affecting a fjord.