This week's Seafloor Sunday image is from an area near and dear to me -- it's within the study area for a component of my PhD research. It is a submarine canyon called Hueneme Canyon offshore of Ventura, California (see the map at the bottom for regional context). The image above is a perspective image looking from the head of the canyon at the shoreline towards the offshore. The canyon is about 300 m (1000 ft) deep and nearly 2 km (1.2 miles) wide at the far end of the image.
The next image (above) is a map view with the coastline of the Oxnard Plain at the top. The canyon was formed by turbidity currents (vigorous avalanches of mud and sand, essentially) starting around 15,000 years ago. The canyon is still active today, receiving huge volumes of sand from the northwest-to-southeast longshore transport of beach sand.
Research I did for my PhD investigated deposits far offshore in deeper water that originated from currents in the canyon. With a radiocarbon-dated sediment borehole we were able to show that large turbidity current events have been occurring regularly throughout the past 15,000 years. The amount of material delivered to the deep-sea increased over the past few thousand years, which we attribute to changing climate (El Niño-Southern Oscillation to be specific). I keep meaning to write a proper post about all that -- until then, here's the paper.
Images: (1) and (2) Hueneme Canyon images from the USGS Pacific Coastal & Marine Science Center; (3) Basemap created with free GeoMapApp.org tool.
