Ocean Bottom 'Grid' Off
Africa Result Of Sonar Itself

By Chris P.


Thank you for asking my opinion about the symmetrical, rectangular seafloor artifacts off the northwestern coast of Africa as seen via a popular online map viewer. This is the second time I know of that this particular piece of imagery has generated the exact same buzz online.

I have spent countless hours over the last 15 years acquiring, processing, integrating (with other data sets) and presenting (in nautical chart format) sidescan and multibeam data as makes up the interesting bits of the imagery in question. The lines you see conform to the grid pattern we most often use when characterizing a patch of seabed for whatever the reason (fisheries habitat, platform anchorages, navigational charting, geological investigations, fibre-optic cable routes, pipeline routes, shallow (relative to seabed) hazards surveys, ... the list tends to get tedious from here ...)

We lovingly refer to this sort of grid acquisition of data as "mowing the lawn" ... it is a very apt analogy ... just as boring, but you have to pay attention unless you miss a spot. The line spacing on these grid surveys is usually established to provide overlap between one "swath" and the next. My cursory measurements of the water depth and line spacing in the area of question seem to correspond to a sonar survey grid.

The artifacts in question are, in my professional opinion, most certainly artifacts of a prior, high-resolution survey being merged with the Satellite Surface derived data seafloor imagery background.

The majority of the seabed imagery displayed via the online map viewer in question is derived from satellite observations of gravity. Ocean waters actually do bulge and dip slightly according to the sub-sea "topography" immediately below. (Think of the wonderful time-lapse imagery of clouds flowing over mountaintops as seen in the film Koyannisqatsi. The clouds in that imagery cannot possibly reflect the detail of the mountain peak it is flowing over, but you definitely know that a peak exists below it.) Gravity data of this sort is very, very coarse. That is why the higher-resolution data stands out so much against it.

I have personal experience directly relevant to this very fact. I was lucky enough to have participated in an expedition last year to map a very large group of seamounts north of the Galapagos Islands. When we started acquiring our survey data, we found that the gravimetric satellite imagery was incorrect ... instead of a grouping of 5 seamounts, we found a solitary, large-plateaued feature not at all suggested by the more coarse satellite data.

Our most accessible final planetary frontier, for me, is still a constant source of amazement and awe ... as well as crushing boredom at times. I keep a skeptical eye open for anomalies such as the one seen off the northwest coast of Africa and do what I can to approach those anomalies with a healthy skepticism. The imagery in question in the Canary Basin has all the hallmarks of being a data artifact and not an ancient "artefact" of a lost civilization. The most convincing evidence, of course, would be finding the data set which was used to create this imagery. That data set would be very difficult to forge ... at least, any forgeries would likely be spotted by my much more talented brethren in the offshore survey realm.

Safe journeys,
Chris P.


Here is the NOAA debunk of the story





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