Hovedøya or Hovedøen is one of several small islands off the coast of Oslo

Oslo

Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

, Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 in the Oslofjord

Oslofjord

The Oslofjord is a bay in the south-east of Norway, stretching from an imaginary line between the Torbjørnskjær and Færder lighthouses and down to Langesund in the south to Oslo in the north....

. The island is quite small, no more than 800 metres across in any direction, the total area is 0,4 square kilometre. It is well known for its lush and green nature, with a wide variety of trees, bushes and flowers

The name

The name is from Norse

Norsemen

Norsemen is used to refer to the group of people as a whole who spoke what is now called the Old Norse language belonging to the North Germanic branch of Indo-European languages, especially Norwegian, Icelandic, Faroese, Swedish and Danish in their earlier forms.The meaning of Norseman was "people...

 times (Hofudøy). The first element is hofud n 'head' (here in the sense 'hill' or 'height'), the last element is øy (ø) 'island'. The name is a reference to the top of the hill on the island. At 47 metres it is the tallest point of the inner Oslofjord islands by a good margin. The name comes in various spellings. While øy for island would be Norwegian, it was later changed for ø under Danish

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 influence, later changed to the finite form øen. Today it is variously given as Hovedøya (common) or sometimes Hovedø(y)en (conservative).

History

The Cistercian monastery

Monastery

Monastery denotes the building, or complex of buildings, that houses a room reserved for prayer as well as the domestic quarters and workplace of monastics, whether monks or nuns, and whether living in community or alone .Monasteries may vary greatly in size – a small dwelling accommodating only...

, Hovedøya Abbey

Hovedøya Abbey

Hovedøya Abbey was a Cistercian monastery on the island of Hovedøya in Oslo Fjord, founded in 1147 and dissolved in 1532 just before the Reformation.-History:...

, was built on the island, and opened on 18 May 1147. During the Medieval period, the monastery was a leading economical force in the Oslo region. It was however closed down before the Reformation

Protestant Reformation

The Protestant Reformation was a 16th-century split within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. The efforts of the self-described "reformers", who objected to the doctrines, rituals and ecclesiastical structure of the Roman Catholic Church, led...

 after the abbot came into conflict with King Christian II. The military official at Akershus Fortress

Akershus Fortress

Akershus Fortress or Akershus Castle is a medieval castle that was built to protect Oslo, the capital of Norway. It has also been used as a prison.- Construction :...

 had the abbot imprisoned and the monastery looted and burned down in 1532. Parts of the ruins of the monastery remain on the island, but much of the stonework was used in the expansion of Akerhus Fortress in the 17th century.

The island has also been used for military installations, and former military buildings and artillery remain on the island. When Denmark-Norway became involved in the Napoleonic war, two cannon batteries were built to defend Oslo

Oslo

Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

 and Akershus Fortress

Akershus Fortress

Akershus Fortress or Akershus Castle is a medieval castle that was built to protect Oslo, the capital of Norway. It has also been used as a prison.- Construction :...

 in 1808 (again using the monastery ruins as a quarry). Four depots for gunpowder were built in 1826 on the high points of the island to ward off intruders, and a fifth was built in 1867. On the eastern half of the island is a Victorian house, popularly known as the "Laboratory". It was used by Director of Armory Ole Herman Johannes Krag

Ole Herman Johannes Krag

Ole Herman Johannes Krag was a Norwegian officer and firearms designer.-Biography:Ole H. J. Krag was born in Vågå, in Oppland county, Norway. Krag grew up in various locations where his father, Hans Peter Schnitler Krag , served as pastor, including Vågå, Fredrikshald and Christiania...

, co-inventor of the Krag-Jørgensen

Krag-Jørgensen

The Krag-Jørgensen is a repeating bolt action rifle designed by the Norwegians Ole Herman Johannes Krag and Erik Jørgensen in the late 19th century. It was adopted as a standard arm by Denmark, the United States of America and Norway...

 rifle in the late 19th century.

Today the island is a popular destination for tourists and bathers, who can enjoy the island's natural beauty, scenic pastures, historic buildings as well as fairly benign (for Norway) bathing temperatures.

Natural history

The island has an interesting geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, being composed mainly of Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 and some Silurian

Silurian

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...

 mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

 and limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

. The transition between the two periods is beautifully exposed on the south-eastern tip of the island, illustrating very well the sudden marine transgression

Transgression (geology)

A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the land sinking or the ocean basins filling with water...

 that marks the shift between two very important parts of Earths history.

Criss-crossing the island is ores of diabas from a major rift event

Rift

In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....

 in the Oslo area in the Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

. The diabas has been heavily quarried for building material, and the island can boast about 20 quarries from Medieval to 19th century age. The island has rock dating back to late Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 and the eastern parts is littered with erratic boulders

Glacial erratic

A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the Latin word errare, and are carried by glacial ice, often over distances of hundreds of kilometres...

 deposited during the last Ice Age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

, thus the island illustrate well the local geological events spanning half a billion years.

The mostly sedimentary geology has given the island a very fertile soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

, giving it Norways highest biodiversity

Biodiversity

Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

found in such a small place. A few plant species found on the island do not occur anywhere else in Norway.

Due to the geology and natural diversity, the island has been declared a natural preserve. While no part of the island is off limit to the public, collecting plants and taking rock-samples is banned.

Visiting Hovedøen

The island is connected to Oslo by means of two boat routes (lines 92 and 93) which dock on the North side of the island. Service is year-round although very limited during the winter season. In summer time a small cafeteria right by the monastery ruins is open to the general public.

External links

• Katolsk.no Catholic webpage about the monastery
• OsloSurf.no entry on Hovedøya