352 TRANSACTIONS OF THE 



entire substance of the plants, and the inorganics form but a small per- 

 centage ; while the vegetable portion, or the carbon, constitutes nearly the 

 entire mass. Marl, on the other hand, resembles the ashes of plants, and 

 most nearly that of seaweed. The ashes of wood give from ^ to 2 per 

 cent of the weight of the wood. Grasses give from 6 to 9^ per cent of 

 ash. Seaweed, as in the table, gives 16.46, and mean of 5 other kinds 

 mentioned by Johnston, 16.60 per cent. Supposing the marl to be the 

 inorganics of plants, then the lowest bed would result from a mass of 

 vegetable in the form of coal. 



If of wood, at least, 25x50, or 1,250 feet thick. 

 do grasses, do 25xl0|, 262 do 



do seaweed, do 25x6 150 do 



It is also stated that it requires about 24 tons of seaweed to make one 

 ton of kelp. 



1st. These marl beds might, possibly, be beds of marine manure, depo- 

 sited by animals feeding on seaweed. But their extent makes it improba- 

 ble. 



2d. They may be the remains of immense beds of weed thi'own upon the 

 shore by the gulf stream, when the lower part of Jersey and large sections 

 of similar land in the southern states were under water, and the coast line 

 was in the neighborhood of Staten Island and Philadelphia. The immense 

 amount of seaweed collected in the midst of the Atlantic, within the tro- 

 pics, would, probably, be sufficient to produce these results. 



3d. There are facts stated in the report that show, conclusively, that in 

 the southern portion of this State, at a " comparatively recent period, the 

 ground has been several feet lower than it now is ; that it has been ele- 

 vated to a hight several feet above that at which it is now ; and that it is 

 now, and has been for a long time past, sinking slowly." (p. 84). 



This alternate rising and falling ef the lower part of Jersey appears to 

 me the most natural way in which this weed could have been collected 

 with so little mixture of sand, at the time that this portion of the State 

 formed the delta of the Delaware and Hudson rivers. Suppose the exist- 

 ence of bays similar in character, but greater in extent than those that 

 skirt the Atlantic coast from the eastern end of Long Island to the straits 

 of Florida, the barrier keeping off the waves of the Atlantic, would 

 allow the weed to accumulate and rot on the bottom.* The first bed hav- 

 ing been thus collected, rotted down, and the vegetable portion carried off, 

 a settlement of the coast barrier would let in the sea, with its waves to 

 cover up the first bed of marl, with the sea sand 110 feet deep. This 

 repeated, would account for all the facts. 



If the hypothesis that I have stated be the true origin of this marl, then 

 the same cause may have produced the same effect on any part of the 

 similarly situated coast of the United States, This marl is known to cross 

 the Delaware river into the State of Delaware, at St. Georges. May it 



*At Islip, on Long Island, they rent out the strand at the rate of §1.75 per rod per year, 

 for the privilege of collecting the seaweed as manure. 



