376 



addressed to the department of the Coast Survey at Washington 

 by the American Academy of Arts and Sciences, requesting 

 that such marks might be set up and observations made; and 

 that in compliance with this request orders had been given to 

 this effect. 



Mr. Desor made some remarks on the Swamps bordering 

 the western rivers. 



The banks of the western rivers, particularly those emptying 

 into Green Bay, are bordered by a belt of trees, seldom more 

 than two miles in width, beyond which are generally extensive 

 swamps. The trees in this region are mostly White and Yellow 

 Pines, which are probably enabled to grow in this situation, 

 from the drainage of the river banks. On the Ministick, a shal- 

 low river flowing into Lake Michigan on the northern shore,, 

 above a point fifty miles from its mouth, the banks are of sand, 

 covered with a pine forest. This drift deposit is in one place 

 forty feet thick, with a bed of clay beneath, ten feet thick. The 

 river bank descends towards the land by a slope of 15°, to a 

 swamp which is within one hundred rods of the river, and at a 

 higher level. It is difficult to understand how the water is 

 retained in this position in opposition to the common law of 

 percolation. Mr. Whittlesey has suggested that a thick bed of 

 leaves in the swamp may have some effect in preventing the 

 drainage of its waters. 



Mr. Alger called the attention of the Society to the 

 recent discovery in New Jersey of a valuable and extensive 

 deposit of massive phosphorite. 



It occurs in the town of Hurdsville, Morris County, New Jer- 

 sey, a few miles from the Morris Canal. It is associated whb 

 magnetic iron pyrites, and rarely with copper pyrites, altogether 

 forming a vein of about eight feet in width, traversing a gneiss 

 or hornblendish rock. These metallic sulphurets occupy the 

 lowest part of the vein, but are often penetrated by the outer 

 crystallization of the phosphorite, which is sometimes met with 

 in very regular prisms of the usual hexahedral form and several 

 inches in length, entirely surrounded by the metallic gangue. 

 The superincumbent portion of the vein, of about five. feet 



