Gardnos crater

{{short description|Meteorite impact crater in Norway}}

{{infobox terrestrial impact site

| age = 500 ± 10 Ma

| confidence = Confirmed

| country = Norway

| diameter = {{convert|5|km|mi|0}}

| district = Buskerud

| drilled = No

| exposed = Yes

| map = Norway

| municipality = Nesbyen municipality

| name = Gardnos crater

| photo = Gardnos.jpg

| photo_caption = Gardnos Crater

}}

Gardnos crater (Gardnos krateret) is a meteorite impact crater in Nesbyen municipality in Buskerud, Norway. It is located inside Meteorite Park (Meteorittparken) at Gardnos {{convert|10|km}} north of the town of Nesbyen.

{{cite web|url= https://snl.no/Gardnos_meteorittkrater |title= Gardnos meteorittkrater|publisher= Store norske leksikon|author=Rune S. Selbekk, University of Oslo |accessdate= October 1, 2017}}

Gardnos crater is {{convert|5|km|mi|0}} in diameter, and was created when a meteorite with an estimated diameter of {{convert|200|to|300|m|ft}} struck 500 million years ago. At first this site was believed to be a volcanic crater, but in 1990 two geologists, Johan Naterstad and Johannes A. Dons, confirmed that it was in fact formed by meteorite impact.{{Cite Earth Impact DB | name = Gardnos | accessdate = 2008-12-30 }}{{cite web

|url= http://tordalbygdeutvikling.origo.no/-/bulletin/show/587070_geolog-johan-naterstad-besoeker-toerdal?ref=checkpoint

|title= Geolog Johan Naterstad

|publisher= Tørdal Bygdeutvikling

|accessdate= October 1, 2017

|archive-date= October 11, 2017

|archive-url= https://web.archive.org/web/20171011233241/http://tordalbygdeutvikling.origo.no/-/bulletin/show/587070_geolog-johan-naterstad-besoeker-toerdal?ref=checkpoint

|url-status= dead

}}

{{cite web|url= http://www.nhm.uio.no/om/aktuelle-saker/arkiv/2009/dons.html|title= Johannes A. Dons|publisher= University of Oslo Naturhistorisk museum|accessdate= October 1, 2017}}

The original bedrock in the area was fractured and a powder of crushed rocks was forced into all the fractures (an impact breccia). This is the origin of the peculiar rock in this area. It is possible to drive into the centre of the crater, which makes the Gardnos crater one of the world's most accessible meteorite craters. There are two trails through the surrounding natural region, with information signs describing the unique geology of the area.{{cite web|url=https://www.duo.uio.no/handle/10852/33234 |title= The Gardnos structure : the impactites, sedimentary deposits and post-impact history|publisher= University of Oslo|author= Kalleson, Elin|accessdate= October 1, 2017}}