CONTENTS (Continued) 



Pajge 



CHAPTER 5. HUMAN IMPACT ON THE HIGH MARSH 47 



Salt Marsh Hay 47 



Changes in the Amount of High Marsh 50 



Mosquito Ditches 52 



Pollution 54 



Petroleum Hydrocarbons 55 



Heavy Metals 55 



REFERENCES 61 



FIGURES 



Number Page 



1 Sea level relative to the present level on the Atlantic 

 continental shelf during the past 36,000 years 2 



2 Variation in apparent sea level at New York City as shown 

 by a smoothed tide gauge record and the elevation of a 

 Spartina patens marsh in New Haven, Connecticut, calculated 



from the distribution of Pb^-^'^ in the sediment 5 



3 Age and depth of salt marsh peat in different areas 6 



4 Characteristics used by Johnson (1925) to distinguish 

 between salt marsh peat deposits containing low marsh 

 plants (1) Spartina alterniflora , and high marsh plants 



(2) Spartina patens and (3) Distichlis spicata 7 



5 Redfields' model for salt-marsh development over accumu- 

 lating sediment on a sandflat and over the upland under 



the influence of rising sea level 8 



6 Departure from the annual mean of average monthly sea 

 level, water density, temperature, and salinity at three 



primary tide stations 11 



7 Annual variation in mean sea level at Boston, Massachusetts, 

 compared with mean annual water density, temperature, and 

 salinity, plus annual discharge of the Charles River 



including urban waste water 12 



V 



