The Saksunarvatn Ash, first found in the Faroe Islands, is a tephra produced by the Grímsvötn volcanic system in Iceland. Since its discovery in the Faroe Islands, dark tephra with a similar stratigraphic position has been described at numerous locations around the North-Atlantic region; including 46 sites in Iceland (soil and lake sediments), 37 marine sediment cores from the North-Atlantic, 23 terrestrial locations in northern Europe (Faroe Islands, Scotland, Orkney, Shetland, Norway and Germany), and 4 sites from the Greenland Ice Sheet. The chemical composition of the tephra found around the North-Atlantic is, in most cases, within the published chemical range of the Saksunarvatn Ash originally found in the Faroe Islands, i.e. tholeiitic basalt with MgO and K₂O wt% that places it in the more evolved part of the Grímsvötn chemical field. Published ages of the inferred Saksunarvatn Ash range significantly, dating from 10,625 ± 53 to 9586 ± 315 cal yr BP, although the widespread usage of the ice-core age of ~10,300 yr BP has given the tephra high chronological importance. Based on the reported sites, the tephra covers an area of about 2 million km². However, in the last decade new studies have shown that the Grímsvötn volcanic system produced several widely distributed tephra layers of very similar chemical composition in the time period from 10,400–9900 yr BP. Hence, the Saksunarvatn Ash appears to be one of multiple early Holocene Grímsvötn tephra layers distributed around the North-Atlantic area. Where such tephras are identified, they therefore reflect a time interval rather than a precise marker as previously anticipated. Although still chemically indistinguishable, these Grímsvötn tephra layers represent a marker horizon around the North-Atlantic region spanning approximately 500 years, and are referred to as the G10ka series tephra. The exact number of eruptions that form the tephra marker horizon remains unknown, but up to seven have been proposed.

Saksunarvatn灰首先在法罗群岛发现，是由冰岛的Grímsvötn火山系统生产的特非拉火山。自从在法罗群岛发现以来，北大西洋地区周围的许多地方都描述了地层位置相似的暗色特非拉；包括冰岛的46个地点（土壤和湖泊沉积物），北大西洋的37个海洋沉积物核心，北欧的23个陆地地点（法罗群岛，苏格兰，奥克尼，设得兰群岛，挪威和德国）以及格陵兰冰上的4个地点片。在大多数情况下，在北大西洋周围发现的特非拉的化学成分在已发布的法拉群岛最早发现的Saksunarvatn灰的化学范围内，即，含MgO和K ₂的胆汁玄武岩O wt％将其放置在Grímsvötn化学领域的更发达的部分。推断的Saksunarvatn Ash的公布年龄范围很广，从10,625±53到9586±315 cal BP，尽管冰芯年龄约10,300 BP的广泛使用已赋予特非拉高度的时间顺序重要性。根据报告的地点，特非拉覆盖约200万平方公里²。然而，在最近的十年中，新的研究表明，在10400-9900 BP的时间段内，Grímsvötn火山系统产生了数个分布广泛，化学成分非常相似的特非拉火山层。因此，Saksunarvatn灰似乎是分布在北大西洋地区周围的多个全新世早新世特非拉层之一。因此，在鉴定出此类提弗拉之后，它们反映的是时间间隔，而不是先前预期的精确标记。尽管在化学上仍然无法区分，但这些Grímsvötn特菲拉层代表了横跨北大西洋地区大约500年的标志性地平线，被称为G10ka系列特菲拉。形成特非拉标记层的确切喷发次数尚不清楚，但已提出多达七次。