Eastern Garbage Patch, aka Gilligan's Island

Steven Colbert reported Tuesday October 30, 2007 on the "Great Pacific Garbage Patch"

"It's heap of debris floating in the Pacific that's twice the size of Texas.  To give you a sense of scale, Texas is a heap of debris one time the size of Texas."

Turns out the garbage is real and there is a nice Wikipedia entry on it, including links to both popular press articles as well as genuine science publications:

http://en.wikipedia.org/wiki/North_Pacific_Gyre

Once known as the "horse latitudes", the North Pacific Gyre is a region where the circulating ocean currents are slow and tend to cause floating debris to collect.  Since plastic degrades only very slowly, it collects and persists for decades in this area about half way between San Francisco and Hawaii.

There is only about 5 kg per square kilometer, so it isn't like a solid layer you can walk on.  But it is in the form of millions of small bits, all of it indigestible.

Just as today we ponder the 'iridium layer' above which there are no dinosaur fossils,  archaeologists 100 million years from now may wonder at the origin of the 'plastic layer' above which there are no human fossils.