bottom and there cannot have been any great vertical change in 

 its position since its formation. Since the peat is soft and of 

 high water content I think it likely that the sample from ZOO 

 inches has moved downward by compaction from the weight of 

 the peat which developed above it, and consequently it gives an 

 erroneous estimate of the rate of rise of sea level. A second 

 difficulty arises from the fact that Spartina alter niflora may 

 form peat at some depth below mean high water. Such peat 

 would give an exaggerated estimate of the change in sea level. 



These difficulties w^ould be overcome if a series of samples were 

 secured from immediately above the substratum at a place where 

 the rising sea level had permitted the high marsh to grow inward 

 and upward over the slope of the upland. 1 hope to do this in the 

 area from which the aforementioned cores were obtained. 



Barghoorn: Well, I wouldn't object to the top 200 inches. I think that the 



compression factor would support those dates rather than upset 

 them. 



Redfield: My point is that one sample of peat has sagged, but the other 



sample has not. The rate of rise of sea level, and we would 

 like to know the rate of rise, whether it is continual, gradual, 

 reversive, or what, could be estimated by making a series of 

 measurements of this type. 



Oppenheimer: Is there any evidence of animal fossil remains at the same 

 depth as you used? 



Barghoorn: Which depth did you mean? 



Oppenheimer: In the peat. 



Barghoorn: There was an extensive study made of the animal remains of 



the Boylston Street site. 



Rubin: I would like to comment on the first portion of your talk where 



you show the cellulose decreasing tremendously with chemical 

 decomposition. The lignins, however, stayed the same. In 

 radiocarbon dating we are interested in migration of the carbon 

 and so this is quite important. For the last few years, since, 

 in fact, you showed me one of these slides back at Andover, we 

 have been using the cellulose fraction, extracting the lignins and 

 throwing them down the sink, with sodium hydroxide. Now, even 

 though the cellulose decreases from, as you showed, 60 down to 

 3, it is still the cellulose that grew in the plant at that time. You 

 are sure because of the cell wall remaining attached. The lignin, 

 which stays in the same proportion can, with the rise in pH, 

 move with the ground water, even though you say that it is 



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