70 
[AsSrtMBLT 
attributed by the farmers to the unsuitableness of the manure for 
their soils; but the soils in New-Jersey, on which it succeeds 
when used in small quantities, are similar to those of Long-Island. 
Silt, or harbor mud, might be used with great advantage as a 
manure on sandy, and even On loamy soils. It contains an abundance 
of animal and vegetable matter, more or less perfectly decompo- 
sed, and thus fitted to fertilize the land. 
ALLUVIAL DEPOSITES. 
The phenomena of the alluvial deposites of the district are of 
much practical importance to the State, as they increase or lesson 
the value of particular situations. The phenomena of land slides, 
sand dunes, or hills of drifting sands; the formation of peat, shell- 
marl, and bog iron-ore; the washing away of the land so as to form 
banks, bars and shoals in our rivers, and bays, and along our' 
coast, — are the most important. 
Alluvial deposites open one of the most interesting and impor- 
tant fields of geological research. In them w^e study present 
causes, and are enabled to investigate all those natural changes 
which are now m progress, and which serve to modify the present 
surface of the earth. -^"s^^: 
Peat. 
Peat abounds in many parts of the district; in fact there are few 
marshes that do not contain it. The best peat lies at the depth of 
three or four feet below the surface, as that above, often contains 
vegetable fibres of partially decayed plants, and is inferior in quali- 
ty to the compact, black or brown tremulous mud that lies below. 
Ligneous peat, or that derived from decayed wood, is as common 
as the other, but is inferior in quality. It is found in almost all 
low grounds, and frequently contains the trunks and branches of 
cedar and other kinds of wood of great durability, wh^ich have 
undergone little change. 
It is a circumstance of no small practical importance, and one 
that serves to show the adaptation of means to ends, that peat is 
rarely seen in warm climates, while it abounds in cold and wet re- 
gions. The reason is obvious; in warm climates the organic allu- 
vions are too nearly decomposed to form peat, and the organic 
matter is removed, either by insects or by putrefaction. Peat is so 
common in every part of the first geological district, that it is su- 
