GEOLOGY. 355 



Gulf of Mexico. So many accounts have been given by different observers, 

 that for the present purpose it is not necessary to specify them. Attention 

 is called to them now as indications of a period of subsidence, and then one 

 of elevation preceding the present. 



The fossils, it will be perceived, are in circumstances which require that 

 the ground should have occupied a much more relative level than the pres- 

 ent, and the covering which is over them is upland soil, portions of that in 

 New Jersey are in cultivation, and are among the most valuable and pro- 

 ductive soils in the state. While, on the contrary, the remains of trees, etc., 

 which arc specially referred to in this paper are all as low as the present 

 level of high tide, and are covered only by water, or by marsh mud, and 

 roots. They are also of a much more recent date, some of them having 

 been growing trees within the memory of persons now living, and the sub- 

 sidence which has produced them is one that is still in progress, as I wish now 

 to show. 



All along the Delaware Bay there is a salt marsh, from a mile to five 

 miles back, and back of it the land is low and almost level. At a point near 

 Salem, a portion of what is now salt marsh was, within the memory of man, 

 a maple grove on this upland, and an island in the middle of it is still so. 

 In another place, land which has been cultivated is now salt marsh. In an- 

 other place, land is salt marsh which is mapped in the earlier maps as tim- 

 ber ; an owner of an extensive tract there, told me he had lost at least 1,000 

 acres of timber land by the advance of the tide upon it. This advance is 

 marked every year by its cutting off a small fringe of the timber which dies, 

 and the process seems to go on more and more rapidly and the timber 

 which is killed is never replaced by timber, but by salt marsh. I found old 

 men who had seen timber growing where now it was marsh, and in some 

 places I found long rows of the red cedar standing in the marsh, a foot deep 

 or more in the mud of the marsh. 



The lower part of New Jersey is exceedingly favorable for observations of 

 this character, from its being so flat that on a railroad line, running through 

 Cape May County, the highest point was not more than twenty-eight feet 

 above high water, and the average but eleven feet. On such shores it will 

 readily be perceived that a very slight depression of the surface must bring 

 a broad strip of land under water, and that marks of such depression will 

 be found in much greater abundance than in localities where the shores 

 are bolder. 



The people along the shore of such places are very sensible of this change 

 of level between land and water, and arc perfectly well satisfied that the re- 

 mains of the timber found are in the places where they grew, and that they 

 have not gone down by the ground washing away, or becoming more corn- 

 pact. When it was objected to them that the white cedar trees have no tap 

 roots, but grow directly upon the muck, and, of course, that they might have 

 settled ; it was readily admitted that one might think so, but for the fact 

 that when the cedar grows so that its roots can reach hard ground as they 

 can when the swamp is shallow, that then the timber is worthless on account 

 of the fibres interlocking so that it cannot be split into shingles, and that in 



