Procesos estuarinos en el Canal Beagle...

ISLA F; BUJALESKY, GG; CORONATO

RAGA

AGA

Año: 1999 vol. 54 p. 307 - 318

0004-4822

The Beagle Channel is a tectonic valley that was completely covered by ice during the Last Glaciation, and was flooded by the sea a t approximately 8,000 years BP, re- aching a maximum sea level between 6,000 and 5,000 years BP. Earthquakes and ash falls were recorded in the deeper and exposed sediments. The estuarine (fjord) dynamics are controlled by significant and seasonal pluvial sources, and by tidal flow from both the east (Atlantic) and the west (Pacific). During the summer of 1998, a t 12 m depth two layers in the water column were locally identified either by salinity or temperature. The persistent and episodically strong winds from the south-west result in the development of high-energy beaches and very steep cliffs. The narrowing (sill) of Archipiklago Gable not only conditions morphologically the fjord dynamics, but it also limits the relative effects of the eastern- and wes- tern-flowing tidal currents, and the gravity waves which originate from the west. Deep-water sedimentation is controlled by gravity flows, either triggered by earthquakes, or related to seasonal river plumes. Within the fine and anoxic sedi- ments, ash layers were recorded. Shallow-water sedimentation is controlled by tidal interactions (Bancos Gable and He-