then I think one can see, because of the spongy nature of the peat, 

 that the water would remain relatively stagnant, and that such 

 movements as occur would only probably be reasonably adjacent 

 to the creeks. 



Chamberlain: I have two questions. Will you say a little more about the phys- 

 ical nature of the substratum below your 15 foot marsh deposit? 



Redfield: It seems to be glacial till. I have worked in an area; each time 



1 go I move 5 feet in sort of a grid pattern so as not to be dis- 

 turbed by the previous bore hole. I have really sounded out now 

 a considerable area. There are variations in depth, and every 

 once in a while I hit a large stone. Every once in a while I can 

 feel gravel. Sometimes the probe just stops abruptly as though 

 I have gotten into something pretty hard not obviously too gritty. 

 I think it is what you might call boulder clay, would you not. Dr. 

 Bradley? 



Chamberlain: The other point. Would you describe the instrument you used to 

 measure your temperature variations? 



Redfield: Yes. The instrument is a thermistor. I use a 1/2 inch steel 



rod. At the end 1 have put a little plastic point. I wrap this 

 with tape pretty well. Then I fasten the thermistor on with tape 

 so that I leave about an inch of its casing exposed. Then a flex- 

 ible tube runs up to a micro -ammeter which enables me to read 

 the thing. The thermistor actually is encased in a strip of 1/2 

 inch copper tubing such as you use for gas lines and the ends 

 are pinched down. It is embedded in wax so as to avoid disturb- 

 ances which might come from mechanical effects. 



Chamberlain: Did you have any difficulty getting a thermistor which was appro- 

 priate for this kind of work? 



Redfield: No, I did not. I cannot tell you the properties of it because I 



was not interested in finding out, but I could get those from the 

 man who designed the instrument. The particular recording 

 system we have used is not a very good one, and I hope to get 

 one which is better. You see, these determinations depend on 

 the precise calculation of the mean temperature. I am quite 

 sure that if I played with my data I could bring them into adjust- 

 ment. It may be that I am off 0. 2 degree in my estimate of the 

 mean temperature. 



Bradley: Is that decrease in the chlorinity due to underground fresh water 



flowing in the till ? 



Redfield: 



That is my thought. 



85 



