Saksunarvatn tephra
Encyclopedia
In the science of tephrochronology
, the Saksunarvatn tephra is volcanic ejecta that formed an ash layer that is useful in dating Northern European sediment layers that were laid down during the Boreal
period, the warm climate phase that followed the cold snap of the Younger Dryas
as the earth made the transition from the last Pleistocene
glaciation to the current interglacial
, or Holocene
. This was a period of rapid climatic transitions around the North Atlantic, some of which took place during a matter of decades. Similar effects are evident in independent palaeoclimatic reconstructions obtained from pollen zone
s, marine and ice-core
records, but these sequences cannot be reliably calibrated with one another. The ash layer from a specific volcanic event, deposited simultaneously over wide areas, provides a common reference point or time marker called a horizon, which establishes simultaneity in the sequences wherever that layer is found: this set of techniques is called tephrochronology
.
Radiocarbon dating
establishes a date for the Saksunarvatn tephra of ca 10.200 years BP calibrated, during the late Pre-Boreal climatic phase of rapid warming. The volcanic event happened on Iceland. The name commemorates the site where the ash layer was initially recognized, Lake Saksunarvatn on the island of Streymoy in the Faroe Islands
, described by Waagstein and Johansen, 1968.
Tephrochronology
250px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at the height of the [[volcanologists]] hands is [[rhyolitic]] [[tephra]] from [[Hekla]]....
, the Saksunarvatn tephra is volcanic ejecta that formed an ash layer that is useful in dating Northern European sediment layers that were laid down during the Boreal
Boreal (period)
In paleoclimatology of the Holocene, the Boreal was the first of the Blytt-Sernander sequence of north European climatic phases that were originally based on the study of Danish peat bogs, named for Axel Blytt and Rutger Sernander, who first established the sequence. In peat bog sediments, the...
period, the warm climate phase that followed the cold snap of the Younger Dryas
Younger Dryas
The Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought between approximately 12.8 and 11.5 ka BP, or 12,800 and 11,500 years before present...
as the earth made the transition from the last Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
glaciation to the current interglacial
Interglacial
An Interglacial period is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age...
, or Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
. This was a period of rapid climatic transitions around the North Atlantic, some of which took place during a matter of decades. Similar effects are evident in independent palaeoclimatic reconstructions obtained from pollen zone
Pollen zone
Pollen zones are a system of subdividing the last glacial period and Holocene paleoclimate using the data from pollen cores. The sequence provides a global chronological structure to a wide variety of scientists, such as geologists, climatologisists, geographists and archaeologists, who study the...
s, marine and ice-core
Ice core
An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental build up of annual layers of snow, lower layers are older than upper, and an ice...
records, but these sequences cannot be reliably calibrated with one another. The ash layer from a specific volcanic event, deposited simultaneously over wide areas, provides a common reference point or time marker called a horizon, which establishes simultaneity in the sequences wherever that layer is found: this set of techniques is called tephrochronology
Tephrochronology
250px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at the height of the [[volcanologists]] hands is [[rhyolitic]] [[tephra]] from [[Hekla]]....
.
Radiocarbon dating
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...
establishes a date for the Saksunarvatn tephra of ca 10.200 years BP calibrated, during the late Pre-Boreal climatic phase of rapid warming. The volcanic event happened on Iceland. The name commemorates the site where the ash layer was initially recognized, Lake Saksunarvatn on the island of Streymoy in the Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
, described by Waagstein and Johansen, 1968.