Surficial Geology: The Third Dimension in Habitat Mapping
| Book title | Marine Habitat Mapping Technology for Alaska |
|---|---|
| Year | 2008 |
| Article DOI | 10.4027/mhmta.2008.06 (about DOIs) |
| Pages | 91–97 |
| PDF link* | View full text in PDF format [324 KB] |
*This low-resolution PDF is optimized for viewing on screen. High-resolution chapters are available on CD only.
Abstract
Surficial geological maps provide an understanding of the morphology, sediment type, physical properties, and origin of the sediment making up the seafloor. An understanding of the Quaternary history is critical for the understanding of the geomorphic features present, such as drowned beaches and berms, glacial deposits, and sedimentary bedforms. The life history of critical habitats, like sponge or coral reefs, can be better understood once the Quaternary chronological development is known. Marine surficial geology is primarily determined from sub-bottom acoustic surveys and sediment coring. Four broad categories of marine seismic sources for high-resolution studies are in common use today: (1) high-powered echo sounders (controlled waveform), (2) accelerating water mass (boomers), (3) implosive (air guns), and (4) explosive (sparker). For habitat mapping, the first two are the most common acoustic sources used for providing this third dimension, usually concurrent with multibeam bathymetric surveys. Sediment cores are usually obtained using free-falling piston cores or seafloor operating vibrocore technology. In addition, large bucket grabs and dredges are used to examine surficial sediments and benthic ecology.
Habitat maps are derived from the morphology, sediment distribution, and benthic ecology. However, to fully understand the 3-dimensional architecture of the habitat, knowledge of the surficial geology is also required. By bringing together all these data sets in a GIS environment it is then possible to analyze the geospatial information interactively allowing for iterative interpretations. For example, the spatial distribution of different groundfish species and particular surficial geological units in Hecate Strait, on the Pacific northwest coast of Canada, show a strong correlation. It is from these associations that a better understanding of the total ecosystem can be made and ultimately managed.
