Abstract
Fossil diatoms found in three samples, upper, middle, and lower stratum from Ohkui diatomite, Komoro city, Nagano Prefecture were investigated. In three samples,73 taxa belonging to the 23 genera and 8 families including unidentified 6 taxa were found.
Species of the Genus Fragilaria ( middle part,5%; upper part,64% ), Genus Melosira ( lower part,62%; middle part,56%; upper part,4%) and Genus Stephanodiscus ( lower part,13%; middle part,24%; upper part,18% ) appeared to be dominant.
The accumulation environment of this diatomite was assumed to be a lake or a marsh with stagnant water, based on the species component and dominant species of each part.
