i9i 7] FORSAITH—ALLOCTHOXOUS PEAT 203 



this thin autocthonous deposit, all the microscopical sections showed 



a 



muck" formed by sedimentation similar in composition to that 



already described for the bog in Cambridge and in more south- 

 ern regions. Material from several lakes in eastern Canada was 



- 



minutely examined, and structural evidences of allocthonous peat 

 were found to correspond so closely to those in the United States 

 that any further discussion of them is unnecessary. 



Since the shallow or intermittent lakes are not favorable to an 

 accumulation of any appreciable amount of peat, owing to periods of 

 drought and constant agitation by waves, they will receive but 

 brief consideration. Many of this type were observed around 

 Zellwood and Lake Tohopikaliga in Florida, and several small 

 ponds in New Hampshire. In all there was little peat, especially 

 in the south, where there are distinct wet and dry seasons favoring 

 the destruction of whatever material may have gathered during 

 periods of inundation. 



There now remains only one distinct kind of fresh water peat to / 



nam 



:ly, that found in river estuaries. One example 

 at Pablo Creek near Jacksonville, Florida, will be discussed. 

 Topography indicates that the space between two elevations was 

 once occupied bv a river a mile in breadth. This broad stream 



6 



filled its bed with 

 r accumulated so t 



by an allocthonous layer of peat, excepting the channel of a mean- 

 dering river. Tests showed a uniform deposit about 12 ft. in depth. 



Fig. ii shows 



g. n snows tne microsco 



)ical character of the material, and 

 studies of the entire vertical series indicate a general uniformity. 

 It will be observed that coniferous woody fragments are very 

 abundant, as indicated by a uniseriate ray in tangential section 

 and an absence of vessels. There are also present the more evident 

 lacustrine derivatives, such as a broken sponge spicule, pollen, 

 amorphous material, and a group of spores. These structure> 

 indicate that the deposit, like those found in the now open and 

 filled lakes, has arisen by similar processes of deposition in open 



water. 



The peat illustrated in fig. 11 is especially favorable for com- 

 parison with thin sections of the more lignitoid coals (bituminous) 





