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Undersea River Found

The DSIR Water Sciences Division is tracking a massive underwater canyon and river system running along the sea-floor from Kaikoura to East Cape.

"The Hikurangi Trough acts as a dispersal unit for all the sediment pouring into the sea, funnelled down steep submarine canyons, " says researcher Philip Barnes. The sediment ranges from trickling grains to thousands of tons of material shifted by seismic activity. The trough borders a channel, a "deep-sea Mississippi" which runs for over 500 kilometers and is up to 5 kilometers wide in some places.

Researchers have been puzzled recently by the discovery that the channel takes a sharp right angle turn off Mahia and heads eastwards out into the Pacific. It may have changed course because of a very large submarine landslide, Barnes suggests. He hopes that a planned cruise might clear up some of the questions surrounding this major sediment transportation system.