Pollen analysis

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Analysis of the distribution of pollen grains of various species contained in surface layer deposits, especially peat bogs and lake sediments, from which a record of past climate may be inferred. Because the lake sediments accumulate over time, a core of the mud will show that the mud at the bottom will be the oldest and the mud at the top will be the newest. By separating the samples of the core, we can get a record of how the vegetation around that site has changed. This has shown us that the area around the Great Lakes was tundra 11,000 years ago. For more details, please see the Palynology entry.

[edit] History

Modern pollen analysis dates back to Lennart von Post when he presented a paper on fossil pollen grains in Swedish bogs to the 1916 Scandinavian Scientist Conference in Oslo^[1]. The paper was repeated in the same year in Stockholm but was not fully published until 1918. Antecedents of this work can be traced in the writings of scientists such as Früh (1885)^[2], who enumerated most of the common tree pollen types, together with a considerable number of spores and herb pollen grains. In a study of bottom samples from Swedish lakes by Trybom (1888)^[3], Pinus (Pine) and Picea (Spruce) pollen was found in such profusion that he considered them to be serviceable as "index fossils". Lagerheim (in Witte 1905) and C.A.Weber (in H.A.Weber 1918) appear to be among the first to undertake percentage frequency calculations.

Pollen analysis was refined and developed by Johs. Iversen and Knut Fægri in their now classical textbook on the subject ^[4].

Pollen analysis enjoyed a popular period during the latter half of the 20th Century as the dominant method for investigations into the development of vegetation and climate during the Quarternary period. It was perfected into a refined instrument of research, highly versatile and giving surprisingly intimate insights into conditions of the recent past.

[edit] References