248 GEOLOGICAL SURVEY OF NEW JERSEY. 
when the soil is not toodry.* 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 such grass land in New Jersey is usually due 
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 ft 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 ‘‘ortstein” of Northern Europe and 
the “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.{ 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. 
+ 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. 
{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. 
