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Sea-Floor Sunday #25: West African continental margin

July 13, 2008

I apologize for the drop in frequency and quality of my blogging lately … I have a bunch of paper revisions that are all converging at once that I need to get done (in addition to my day job).

Today’s Sea-Floor Sunday image is neither a bathymetry (sea-floor topography) image nor a photograph. Today’s example is a fantastic line drawing from a 1964 paper about the Congo submarine canyon by Heezen et al. One degree of latitude is approximately 110 km, so this image spans over 2,400 km (1,400 mi) in the north-south direction. This image is near the beginning of the paper and provides context for the rest of the paper.

AAPG)

The Niger Delta is in the upper left of the image and the offshore/onshore volcanic chain immediately to the south is known as the ‘Cameroon line’. The subject of this particular paper is the Congo submarine canyon, which is the prominent submarine drainage system at ~6 degrees S. The Congo system is interesting because, unlike the Niger to the north, there is no large delta being constructed. The Congo river is directly connected to the head of the submarine canyon. For those interested in the transfer of terrigenous sediment (i.e., derived from continent) to the deep sea, this situation has some interesting implications regarding transport mechanisms. I’ll put together a more detailed post sometime soon.

You don’t see line drawings like this as much these days (this one by line artist Marie Tharp). While I certainly love the resolution that modern multibeam bathymetry technology can produce, there’s something to be said about an image that combines science (i.e., constrained by observations/data) with aesthetics. The monographs of Ernst Haeckel are a superb example of this.

Heezen, B.C., Menzies, R.J., Schneider, E.D., Ewing, W.M., and Granelli, N.C.L., 1964, Congo submarine canyon: AAPG Bulletin, v. 48, no. 7, p. 1126-1149.

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3 Comments leave one →
  1. July 13, 2008 10:58 am

    The line artist was Marie Tharp. I would put her in the three surnames that all geologists (Americans, at least) should recognize as artist-geologists, the other two being Atwater and Raisz.

  2. July 13, 2008 11:24 am

    Andrew … thanks, I’ve added that info to the post.

  3. July 14, 2008 4:26 pm

    This is an interesting diagram — I like the vocano islands that are depicted in the area — slightly to the South. Also, down towards the bottom of the diagram is the coast of Namibia (South-West Africa) where methane gas plumes from the slope offshore have been reported and photographed from a space satellite.

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