Redfield: It runs down to about 4. 5 meters - 15 feet. 



Odum: How deep do the roots on the marsh plants go? 



Redfield: Oh, the live ones go down 6 inches to a foot. 



Odum: So there is no possibility that your plants are drawing water 



from a fresher source ? 



Redfield: I wouldn't think so. You have a very firm crust of living roots 



and then it is extremely mushy and fragmented. 



Chapman: Indications are that the roots of salt marsh plants are in pretty 



saline water generally. 



Odum: On the coast of Texas as you come around from Houston or 



somewhere about halfway down, the marsh drops out. There 

 are several possible explanations. Two of the most probable 

 ones are that the tide is low along the whole coast and the inlets 

 get less and the evaporation goes up. It is conceivable that 

 where you do not have much marsh it is more sandy. You may 

 go from a place where there is an underlaying with a fresh 

 water table to one which is underlain with a more salty table. 



Chapman: I have been thinking more about this and I take it that this is a 



peat or peaty kind of soil all the way down. Is it? 



Redfield: All the way down. Yes. 



Chapman: Well, peat has the capacity to retain water. It acts as a sponge. 



One of the difficulties which I encountered when I was working 

 on the Boston marsh was the difficulty of using ordinary record- 

 ers of the type I had used in England because the spongy nature 

 of the peat retained the water. It remained saturated so that I 

 would think that this kind of technique would only operate really 

 effectively as long as there is uniform material down through 

 your marsh, and if the marsh geologically is composed of sev- 

 eral distinct strata which differ in coarseness or fineness of 

 material, one would undoubtedly get irregularities in the 

 curve which woxild be related to the marsh structure. For ex- 

 ample, in the marsh I worked on in New Zealand, particularly 

 where there is this layer of fresh water peat about a foot beneath 

 the surface, we found that the movement of the water was almost 

 entirely restricted to the peat zone and that there was no move- 

 ment if your recorders were in the mud. As soon as you got 

 quite a short distance through the peat, there was no movement 

 in the water at all in the mud zone, but if your recorder went 

 into the peat zone then there was miovement of the water. If the 

 soil is entirely a peat and there is a source of water underneath. 



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