248 GEOLOGICAL SURVEY OF NEW JERSEY. 



when the soil is not too dry.* In this way moist swamps become 

 meadows. This land, if left to itself and protected from fires, 

 soon recovers, but there is another kind of grassy land, namely 

 " Savanna," which is of little worth in New Jersey at present, 

 and destined to remain unchanged for many years to come. 



The formation of snch grass land in New Jersey is usually dne 

 to a hard-pan which is often only a few inches below the surface. 

 Hard-pan is the name applied to a dense, almost impenetrable 

 stratum of compacted material. It is generally soil in the pro- 

 cess of becoming rock. In these savanna lands f it is bog-ore 

 and organic materials cementing the particles of sand. It is 

 covered by several inches of humus, which is saturated with 

 water and is sour in consequence. Here and there on knolls in 

 these sloughs, a pitch-pine grows, but topples over in the course 

 of time, owing to the slight hold which it has upon the soil- 

 The hard-pan is similar to the u ortstein " of Northern Europe and 

 the u alios" of the French Landes. This stratum exists in all 

 degrees of hardness, and often in sufficient quantities to prevent 

 the growth of trees on considerable areas of land, but in a region 

 where even good wood-land has little value, the comparatively 

 small area of savanna is not worthy of much consideration, be- 

 cause the cost of drainage and preparation would amount to more 

 than the land is likely to be worth for some time to come. 



Stretching along the coast of Southern New Jersey and along 

 the Delaware river, fringing the mainland and bays, and extend- 

 ing along the rivers far inland, are many miles of salt marshes. 

 They are of course treeless. J In former times these lands were 

 banked and cultivated much more extensively than at present. 

 Owing to the difficulty of keeping the banks in order, they have 

 in large part been abandoned. The marshes, endless to the eye, 



* Constant burning causes deterioration of pasturage in the course of time. The weaker grasses are 

 gradually killed. On salt marshes and wild meadows where the soil is very moist, so that the roots are 

 not injured by fire, regular burning is a benefit. 



t The term savanna is a relic of the Spanish in America and in general merely means a tract of level 

 land covered with low vegetation, usually grass. It is used throughout the world in this sense. In old 

 Spanish the word means a " sheet," and was originally applied to a flat snow-covered region. 



J In places hardy shrubs and trees are gradually intruding on the marshes as they become by deposit 

 higher and sweeter. In other places groups of trees may be seen which have been killed by too large a 

 dose of salt water. 



