Ancient Coastlines Examined

In a recent blog entry (see “Looking for MegaAmerica”) I suggested that evidence of the maritime civilization(s) which once inhabited the Caribbean and Gulf basins would most likely be found along the now-ancient coastlines. I included a Google Earth screen grab to better demonstrate where this coastline might be but this estimate is based solely on obvious sub-surface features that appear on Google Earth and other maps. To refine my theory, I needed to obtain detailed depth readings for specific areas and, thanks to Angie Micol, of Satellite Discoveries (, I now have this data. It turns out that the National Geophysical Data Center (NGDC), a division of the National Oceanic and Atmospheric Administration (NOAA), maintains a number of databases containing information about America’s coastlines and the surrounding area. See for more information of the data and services available from NGDC.

One of the first areas I wanted to examine was the large underwater “canyon” that lies about 80 miles SE of the point where the Mississippi/Alabama border touches the Gulf of Mexico. Please see the photo below for a map of the area I call Study #1. If you’d rather examine it yourself on Google Earth, the area is roughly defined by longitudes -87.6 on the left and -87.3 on the right and by latitudes 29.8 on the top and 28.1 on the bottom.

This rectangular area is approximately 76 miles wide by 117 miles high (8,892 square miles), which makes it a huge canyon indeed! The NGDC Web site provided me with more than a half-million data points for the area and each data point includes the longitude and latitude to six decimal places and the depth to the nearest 1/10th foot (1.2 inches).

The canyon area (aka Study #1) ranges in depth from 14.3 feet to 2,748.7 feet (after I threw out one anomalous point of 3,458.3 feet) which certainly puts portions of it above the surface 8,000 to 10,000 years ago! Could the “point” of the inverted “V” canyon be the site of an ancient port?

There are several other specific areas I want to examine in detail using the NGDC data and then I hope to begin a project of reconstructing the coastlines of the southern United States and the Florida Peninsula at various points in time, beginning 8,000 years ago and working backwards to the last glacial maximum, about 22, 000 years ago, when sea levels were at their lowest.

Please feel free to post any relevant data on this site or email it to rja (at) Your input will be greatly appreciated and acknowledged!

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