MICHIGAN ACADEMY OF SCIENCE. 
107 
PEAT DEPOSITS AS GEOLOGICAL RECORDS. 
Charles A. Davis. 
In the United States, peat has been but spasmodically and rather super- 
ficially studied, until recently, and practically not at all to determine its 
value as' a record of conditions which may have existed during the time in 
which it was in the process of formation. The great area of the country, and 
its richness in unexplored fields for research, each attractive and important 
in varying degree, have kept busy those who might have turned to the study 
of peat from its geological aspects; and but few botanists have considered 
it within their realm of research, except as a paradoxical substratum, in 
which plants, having nearly all the forms of protection against the loss of 
moisture from their tissues possessed by desert types, were yet growing 
where the soil was always apparently wet. 
A few writers, in a casual way, have published sufficiently elaborate papers 
to show how little they really had worked below the surface, on the subject, 
and others have frankly copied these and thus perpetuated incomplete work 
and erroneous ideas. 
In Canada, somewhat careful and extended work has been done on the 
so-called “fossil” peat beds, marking an interglacial period. European 
writers have gone much farther than any others and have published some 
important studies of peat deposits in various parts of the British Isles, Scan- 
dinavia and Germany, which have thrown light on some of the possibilities 
of this interesting type of recent fossil beds. 
The basis for intelligent and profitable study of the geological history 
which is to be found in these deposits seems to lie in that fascinating field 
of botany which involves the relationships of plants to their environment, 
combined with the equally delightful study of physiography. In other 
words, before peat deposits, as such, can be profitably investigated, the 
way in which peat is now being formed must be thoroughly examined into, 
not alone from the viewpoint of the physiographer but as well from that of 
the plant ecologist. The deposits must be considered from the aspect of the 
origin and form of the surface on which they have been laid down, in 
order to know what to expect as to types of vegetation which may be 
found. 
Previous to such a study, however, it is essential to become familiar with 
the conditions under which peat may be formed, and the habits and ecological 
relations of the important groups of plants which are concerned in peat 
formation, as well as the ways in which these may be modified by various 
physiographic and climatic conditions. 
The following underlying principles must be kept in mind in making in- 
terpretations : 
(1) Peat is always found where the ground water level is sufficiently high 
to prevent ordinary decay; this implies complete saturation of the material 
for the greater part of the time. The more complete the seclusion of air, 
the less the vegetable matter shows true decay. 
