Raised bogs in eastern North America: transitions in landforms and gross stratigraphy

Abstract

A regional survey of 60 raised bogs was made in eastern North America to determine the geographic patterns of bog landforms and gross peat stratigraphy. Three major types of bogs were identified: (i) midcontinental forested bogs with a longitudinal crest, radiating lines of forest growth, and an actively growing surface of loose Sphagnum hummocks, (ii) non-forested northern or maritime bogs with a convex or plateau shape, various networks of pools, hollows, and firm compact hummocks, and a more slowly growing surface that produces deeply humified bands or recurrence surfaces throughout the peat profile, and (iii) semiforested continental bogs with a forested crest, networks of linear hummocks and flat hollows on the lower flanks, and shallow expanding pools on the hollows. The peat stratigraphy on these semiforested bogs is also intermediate, with recurrence bands in the compact upper portions of the profile, becoming looser and more irregular toward the bottom. The geographic changes in landform patterns and gross peat stratigraphy indicate that forested bogs with a linear crest represent an early stage of bog development and are replaced in time by a nonforested plain with pools as changes in the slope and the hydrologic properties of the surficial layers of peat restrict runoff and infiltration, producing a rise in the water table. Thus on a regional scale autogenic bog processes may be as important as climate in controlling bog patterns and peat stratigraphy.