Date of this Version
This is an extension of a series of studies by one of the authors and his associates (1) on fossil pollen in peats of the North Central States. The purpose of such studies has been to secure information concerning the general trend of climate in postglacial time, as an aid in interpreting present vegetation.
These previous studies have indicated that postglacial climate has been largely of continental type, cool at first and later warm. Separating the cool dry from the warm dry period there appears to have been a definite although brief period of greater humidity, relative if not absolute. A similar increase of humidity is believed to have occurred recently.
In the present study diatom remains, as well as pollen, have been considered. This was necessitated by the destruction of all carbonaceous matter in the upper layers by the fire which led to the discovery of the deposit.
The recent character of the deposit permits a study of the latter portion only of postglacial climate, but the results so far as they go, are consistent with those obtained elsewhere. We estimate the record to extend back at least 1800 years— basing this figure on the age of cypress stumps and a conventional figure of three centuries per foot of peat. This estimate seems quite conservative.