SUPRA-LITTORAL BELT 99 
in many places along the east and west sides, the shore between these levels 
shows little or no evidence of its proximity to the salt water. On the Spit, 
however, the environmental conditions within this storm beach belt, and like- 
wise the character of its plant covering, are much simpler and more constant, 
along the same level from end to end of the beach. We may therefore consider 
the plant covering here as more typical of the usual shore conditions between 
these levels, and we will discuss it first. 
1. StoRM BEACH OF THE Spit (FROM 8 TO 12 FEET). 
The character of the soil of the south shore of the Spit up to high-water 
level has already been briefly described. Above this level and on upward to the 
top of the Spit, which, from 500 east to 800 west, is on the average 11.5 feet 
above mean low water, the soil is either of fine gravel or, above 8.5 feet, chiefly 
of fine sand. There is, however, a small area of firm soil on the top of the Spit 
at 900 to 1,000 west. Here rubbish from gardens has been dumped, and a 
heavier soil has been formed, bearing a more varied vegetation. This area, 
because of its highly artificial and rapidly changing character, will be left out 
of our further discussion. We must, however, recognize its importance as the 
source from which many upland plants may have reached the less-disturbed 
portions of the Spit. Along the western end of the Spit, between 600 and 1,000 
west, and between the 8 and 8.5 foot levels, the sand has a considerable admix- 
ture of humus. A few patches of similar soil are found between these levels on 
the eastern half of the Spit near 600 east. On the top of the Spit also, where a 
denser permanent vegetation is present, e. g., near 600 west and from 0 to 200 
east, a considerable amount of more or less decayed plant remains has collected 
in the sand. Elsewhere the soil is a sand, the dry, superficial layer of which is 
readily shifted about by wind and water, though the deeper layers are held more 
firmly by the rhizomes and roots of Ammophila and, less frequently, by those of 
other plants. The slope of the beach, above the 8-foot level, varies from a rise of 
1 foot in 40 feet in certain places (e. g., 400 and 600 east, and 900 west), to a 
steepness of 1-foot rise in 8, 10, or 12 feet along the middle portion of the Spit. 
The plant covering of this belt differs from that of the lower belts we have 
discussed in its sparser character and in its less distinct zonation (plates Vv, XIII, 
and xiv). The dominant plant over most of this belt is Ammophila arenaria, 
which spreads from the 8.5 or 9 foot level on the south side, up over the top of the 
Spit at 11.5 or 12 feet and down not quite so far on the north side. All other 
species are scattered generally and sparsely over the Spit, or occur in a few local 
groups. While only 6 or 7 of the 40 species found here have a lower limit of 
distribution at all closely approaching the 8-foot level, they do range with the 
Ammophila up to the top of the Spit and down the north side. The remaining 
thirty-odd species are chiefly upland plants, not at all characteristic of sea 
beaches, and are distributed over the higher parts of the Spit in a manner 
giving no evidence of clear zonation. The most clearly distinguishable con- 
tinuous horizontal boundary along the beach, above the Spartina glabra, is the 
sparsely covered, or usually nearly bare, strip of gravelly beach between 7.5 
and 8.5 feet. This is the region where the beach is washed by the waves of 
the Inner Harbor during ordinary high tides of summer. The gravel at this 
level is more disturbed than at lower levels, the particles being moved about 
almost daily. In summer it is only when the water has risen to near the high- 
