Sea-Floor Sunday #40: Puyallup Delta, Puget Sound

I apologize for the lack of posts lately … I have been incredibly busy the last month or so. On top of my day job and trying to finish manuscripts, I’m also heading back down to Patagonia in a few weeks to co-convene and lead a research conference. We are really excited about the mix of researchers that are coming to the conference. I will certainly post about the conference and share photographs when I return.

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Anyway … here’s a real quick Sea-Floor Sunday image. The USGS Seafloor Mapping program is a great source for sea-floor topographic (bathymetric) images and data. The image below is from the Puyallup river delta in Puget Sound, Washington (click on the images or here to go to the page on USGS’ site).

Color shaded-relief bathymetry of Puyallup Delta, offshore Tacoma Washington (credit: USGS)

As a sedimentary geologist, what I find most interesting are the features coming right off the delta and down onto the delta front in deeper water. This perspective image below is about a kilometer across and shows a couple interesting features.

Perspective view of Puyallup delta front, Puget Sound (credit: USGS)

The area marked with the ‘A’ is a channel feature coming directly from the river mouth (note the bedforms) and ‘B’ is showing some failure scarps on an oversteepened part of the delta slope.

If you go to the USGS site they also show a comparison of this newer, higher-resolution data with the legacy data of the ’70s/’80s — the difference is amazing.

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To learn even more about the sedimentary features and processes of the Puyallup delta, check out this paper:

Mitchell, N., 2005, Channelized erosion through a marine dump site of dredge spoils at the mouth of the Puyallup River, Washington State, USA: Marine Geology, v. 220, p. 131-151.

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