Topography

Iceland is located in the northern North Atlantic, just south of the Arctic Circle. It is the largest part of the Mid Atlantic Ridge that rises above sea level.

Except for the south coast, the coastline is indented by many bays and fjords of various shapes and sizes. A typical cross section in Icelandic fjords is with steep sides and a flat bottom filled with sediments. The fjords gradually deepen when approaching the open shelf where the depths are generally 100-200 metres. Only very few Icelandic fjords have shallow thresholds. This is different from many fjords in other high latitude regions, where it is common to see shallow thresholds close to the mouth of the fjords. The south shore of Iceland is characterised by sandy beaches, without good harbours.

The shelf is narrowest off the south coast, or down to 20 km wide. It is broadest off the west and north coast, where it extends over 100 km offshore. The shelf is indented by deeper channels that are often prolongations of the fjords. At the shelf break, the depth generally increases rapidly down to about 1000-1500 m where the slope towards the abyss becomes gentler.

Iceland lies at the junction between two submarine ridges, the Mid Atlantic Ridge and the Greenland-Scotland Ridge. Of particular importance is the exchange of water across the Greenland-Iceland Ridge, through the Denmark Strait, and over the Iceland-Faroe Ridge. Both ridges prevent direct connection of waters below their threshold depth of 620 m and 550 m respectively. Only a relatively narrow channel with depths exceeding about 300 m separates the Icelandic shelf and the broad shelf off Greenland. In contrast the Iceland-Faroe Ridge has a more even depth of 400-550 m over its whole length.

To the southwest of Iceland, the Mid-Atlantic Ridge is called the Reykjanes Ridge which gradually increases in depth as it extends southwards. To the north of Iceland the Kolbeinsey Ridge is a continuation of the Mid-Atlantic Ridge. It stretches to the Jan Mayen Fracture Zone that lies between Jan Mayen and Greenland. South from Jan Mayen, the Iceland-Jan Mayen Ridge extends to the Iceland-Faroe Ridge and separates the Iceland Sea from the Norwegian Sea to the east.

The Jan Mayen Fracture Zone marks the northern limit of the Iceland Sea, separating it from the Greenland Sea. To the south, the Greenland-Iceland Ridge provides a natural boundary of the Iceland Sea. The Iceland Sea is split in two by the Kolbeinsey Ridge, with the deeper part in the east, i.e. the Iceland Plateau reaching about 2200 m. West of the ridge there is a channel reaching the Denmark Strait, bordered in the west by the East Greenland shelf. South of Iceland and east of the Reykjanes Ridge is the Iceland Basin. West of the Reykjanes Ridge between Iceland and Greenland lies the Irminger Sea.

References and further information

References: (Malmberg 2004)

For full citation and further information on the ecosystem in general see this page

Steingrímur Jónsson, The Marine Research Insitute/University of Akureyri