Published online by Cambridge University Press: 01 May 2009
The complete sequence of Fenland deposits at St. Germans consists of five clays interbedded with four peats; the whole is apparently of post-Glacial age, and the later beds at least were laid down in historic times. Fourteen specimens were collected from the clays, and all yielded foraminifera. Forty-one species of these are indigenous, five are derived from the Chalk, and twelve from the Kimmeridge Clay. Of the indigenous species nearly all are forms tolerant of brackish-water, while species intolerant of this are almost lacking. From this fact and from the presence of many fragments of peat in the clays it is concluded that these are of brackish-water origin. From the presence of a proportion of micaceous silt in many of the clays, accompanied by and correlated with foraminiferal species less tolerant of brackish water, occasional ingress of estuarine water is presumed.