Origin of Fjords

Hudson Estuary

The Hudson estuary in New York has been described as a fjord, and as a drowned river. Beneath the river bed there is a deep bedrock canyon filled with drift and sediments containing organic material. This canyon continues under the sea, cut into the continental shelf, where it becomes a great submarine canyon. The origin of the buried bedrock canyon of the Hudson river is clearly related to the cause of the canyon in the continental shelf, which extends to great depths. Obviously the submarine canyon cannot have been carved by ice.

In my interpretation the canyon of the Hudson River was formed by a mechanism of in situ disintegration along joints or faults, and some of the disintegration product was washed out by fast currents, as the land was raised above the sea. In the steep section of the continental shelf, drift formerly present in the channel was mostly eroded away by currents. Organic sediments accumulated in the estuary since these catastrophic events. Similar mechanisms can account for features of other fjords, that otherwise seem enigmatic.

For the conventional geologic history of the area, see: Overview of New York Geology.