266 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
NC On CRE IURE л ыш. Whar fos eie oleas d Ra p 22.20 
odd а uM AU A AE Аад ТУАР еліте ақтарады .26 
ЖЕРАР АН es ae DOs re а ANN eG rece 108.22 
This has a higher percentage of organic matter than any other 
soil thus analyzed in the same report,* but this may mean merely 
that most of the other samples were taken from cultivated land, 
where the humus was long ago exhausted, for the virgin forests in 
the northwestern part of the island certainly have plenty of 
humus. Curiously enough, of all the mechanical analyses pub- 
lished for Long Island soils in the work mentioned, the one that 
matches this most closely is that of the “Galveston clay” (salt 
marsh) from two miles northeast of Far Rockaway. In fact the 
two analyses do not differ any more than two different ones of 
the same type of soil might be expected to. Whether or not this 
indicates that our prairie was once a salt marsh it is impossible to 
say; but, if it was, the surface must have undergone considerable 
tilting since, to give the Plains a southerly slope of one in 350; 
and it would not be very easy to explain why the prairie is sepa- 
rated from the present salt marshes by several miles of forest. 
It is possible also that some if not most of the soil has accumulated 
as dust in the course of centuries; but if that.were the case it 
would be difficult to account for the absence of a dust layer in 
the surrounding forests, whose topography is very similar, and in 
many other level regions. Although the origin of the soil is not 
a botanical problem, this particular type of soil is so closely 
correlated with the prairie vegetation that one cannot help puzzling 
over it. No satisfactory explanation is available at the present 
writing, however. 
A partial chemical analysis was reported in the first paper 
cited herein, and no additional information on that point has been 
obtained since. The amount of potash, one of the most important 
constituents, is entirely unknown. As elsewhere in the western 
half of Long Island, the soil fertility seems to increase a little 
toward the west, if the vegetation is a safe guide. 
The small areas of bare ground between the tufts of herbage 
* Dr. Hilgard found only т per cent of humus in a sample carefully selected by 
the writer about a mile southeast of Hicksville. 
