1.4 ORIGINS AND MIGRATION OF CEDAR 

 FORESTS 



1.4.1 Glacial Effficts 



The advance and wasting of glaciers strong- 

 ly influenced thie topograpfiy of the land both under 

 the glaciers and over the entire continent's coastal 

 area, due to direct glacial action, isostatic crustal 

 movement, and major variations in sea level. During 

 earlier interglacial periods, the northeast coast of the 

 United States has been as far as 72 km further inland 

 than today's shore; during the Wisconsin glaciation, 

 sea level was as much as 60 to 80 m lower than its 

 current height (Bloom 1983). The extent and timing 



of sea level rise and fall remains controversial (Bloom 

 1983). 



Glacial melting from 17,000 to 10,000 years 

 before the present (B. R) led to the formation of glacial 

 lakes and outwash beds of various sizes. Glacial 

 lakebeds, kettleholes of the glacial moraine, and out- 

 wash plain streambeds are landscape features that 

 now support cedar communities in the Northeast 

 (Figure 5). Further south, glacial meltwaters filled 

 rivers and streams, the remnants of which now form 

 the stream bank and backswamp wetlands (Figure 6) 

 in the New Jersey Pine Barrens, the Delmarva penin- 

 sula, Florida, and elsewhere. Such environments 

 provide habitats for cedar growth. Conditions 

 peculiar to the mid-Atlantic region are discussed in 

 the Dare County case study (Chapter 7). 



Figure 4. Cumloden Swamp, Falmouth, Massachusetts. Permanent high water, the result of damming by a 

 roadway, is causing the slow death of mature cedars. This picture was taken five years after the road was 

 built, and one year before the death of the last cedars. 



