232 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



grow best in the bogs. So abundant, as a rule, are the sphagnums in 

 this particular type of swamp that many bogs are popularly referred 

 to as moss bogs. 



Bogs do not always originate from ponds. In the Pacific North- 

 west, in northern New England and eastern Canada, and to some 

 degree in less humid regions, they may develop in flat, poorly drained 

 situations of almost any description, wherever the ground is wet 

 enough to favor the growth of the sphagnums ; and in this connec- 

 t ion there is one remarkable type of bog that is of particular interest, 

 namely, the so-called raised bog (pi. 2). These are met with only 

 in regions where the climate is exceptionally congenial to the sphag- 

 nums, for they owe their formation almost wholly to the activity of 

 these plants. The raised bog of North America corresponds to the 

 " Hochmoor " of northern Europe. Sometimes they are referred to 

 as hanging bogs or climbing bogs. 



A raised bog may originate on any flat, sphagnum-covered surface 

 where the slope is not too steep. Ordinarily, it starts as a bog of the 

 usual type. The mass of sphagnum, absorbing the water that falls in 

 the form of rain or snow, slowly grows upward, and eventually the 

 mossy surface of the bog, underlain by a spongelike mass of peat, 

 may come to lie 10, 15, and even 20 feet above the original flat sub- 

 stratum. Raised bogs are so termed from the fact that commonly 

 they are much higher near their centers than at their margins, their 

 surface contour, in typical cases, resembling an inverted saucer. 



Because of their dependence on atmospheric moisture, raised bogs 

 are confined to regions of copious precipitation and high atmospheric 

 humidity. Their presence in any region is significant, in the present 

 connection, because it indicates climatic conditions suitable to the 

 growth of surgical sphagnum. In Nova Scotia and coastal New 

 Brunswick, where sphagnum of surgical quality is widely distrib- 

 uted, for example, raised bogs are a frequent type. The same is 

 true of eastern Maine. South and west of these regions (in the 

 east) , however, raised bogs are practically absent and sphagnum of 

 surgical quality is of very local occurrence. 1 But it should be added, 

 in this connection, that the absence of raised bogs from a region does 

 not necessarily indicate an absence of surgical sphagnum ; singularly 

 enough raised bogs are not developed to any extent in the Pacific 

 Northwest, 2 a fact which I am not prepared to definitely explain. It 

 is further important to note that, while their presence in a region 

 indicates that climatic conditions are congenial to sphagnum de- 

 velopment, the raised bogs themselves, except locally in wet depres- 

 sions, do not afford edaphic conditions suitable to the development 



1 In this connection, see Nichols, G. E., Raised bogs in eastern Maine, Geog. Rev. 

 7 : 1.VI-167. f. 1-.2. 1010. 



- See Rigg, G. B., Early stages in bog succession. Puget Sound Biol. Sta. Bull. 2 : 195- 

 210. pi. X9, 30. 1919. 



