Microfaunal Associations

The most abundant microfossils found in Champlain Sea glacial and post-glacial deposits are various species of ostracodes and calcareous benthic foraminifera, and the sclerite, Myriotrochus vitreous (Sars).  In one study, as reported by Cyril Rodrigues, 210,000 fomraminiferal tests and 10,000 ostracode valves were collected from 148 sample of Champlain Sea sediment.  The dominant ostracode and foraminiferal species were classified, respectively, into nine and fifteen assemblages.  The following table (Rodrigues) shows the dominant species of these assemblages.  The specific classification of the species in assemblages will be shown later on.

Dominant Foraminiferal and Ostracode Species

Foraminiferal Species

Ostracode Species

Astronion gallowayi Loeblich and Tappan

Cytheromorpha macchesneyi (Brady and Crosskey)

Cassidulina reniforme (Norvang)

Cytheropteron arcuatum Brady, Crosskey and Robertson

Elphidium clavatum (Cushman)

Cytheropteron inflaum Brady, Crosskey and Robertson

Elphidium incertum/asklundi (Williamson)/Brotzen

Cytheropteron latissimum (Norman)

Elphidium sp.

Cytheropteron nodosum Brady

Eoeponidella pulchella (Parker)

Cytheropteron paralatissimum Swain

Hayesina orbicularis (Brady)

Cytheropteron pseudomontrosiense Whatley and Masson

Islandiella helenae Feyling-Hanssen and Buzas

Heterocyprideis sorbyana (Jones)

Islandiella norcrossi (Cushman)

Palmenella limicola (Norman)

Pateoris hauerinoides (Rhumbler)

Sarsicytheridea punctillata (Brady)

Two important factors can be determined from the microfaunal species. 

All of the species listed above resided in marine environments.  There is, however, one freshwater microfossil species that is found in the non-marine sediments underlying the Champlain Sea sediments: the ostracode Condona subtriangulata.  This supports the theory that there was an initial freshwater episode, characterized by proglacial lakes, which was later inundated by high salinity bottom waters.

Since species such as the foraminifera Cassidulina reniforme are important cold water indicators in Quaternary sediments, this foraminiferal assemblage also supports theory that the marine environment was indeed a cold one.

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