94 
[Assembly 
Page. 
Salts, alkalies, and pulverized rock, good manures on 
some soils. Reasons why, 67 
Iron in some states of combination beneficial, 68 
Marls, 68 
Organic contents of soils important, 68 
Manures. Rotations of manures, 68 
Double rotations of crops, 68 
Manures of Long-Island, , . . . 69 
Reason of the utility of ashes, ........... 69 
Suggested improvement in their use. 69 
Harbor mud, 70 
Alluvial deposites, 70 
Peat — varieties and general remarks, 70 
Situations in which it is found, 70 
Value not yet appreciated, 71 
Used for fuel, burning bricks and lime, and for ma- 
nure, 71 
Shdl Marl Mode of accumulation, 71 
Situations in which it is found, 71 
How it may be recognized, 72 
Often covered by peat, 72 
Uses of this marl for manure, lime, and for whiting,. 72 
Value not yet appreciated, 72 
Bog Ore. Mode of formation, 72 
Localities and uses, » 73 
HI. Local Details of the Economical Geology of Suffolk County. 
Jllluvial action. 
Encroachments of the sea. Remarks, 74 
Degradation of the S. E. and N. E. sides of I^ong-Island, 74 
" Gardner's, Plum, and Gull Islands, 74 
" " Oyster-Pond Point, 75 
Marine alluvial detritus. Beaches, shoals, spits, 76 
General causes and effects, 76 
Local details, 77 
Long-Island was formerly composed of several islarnds, . 77 
Alluyial beaches, bars, spits, &c. formed and now form- 
ing, 77, 78 
Effects of these deposites rendering some harbors safe 
and spoiling others, 78, 82 
Land slides. Causes, ...» * 82 
Local details in Suffolk county, ... i ... . 82 
Slide at Troy, - 82 
Sand dunes. Causes and local details, \ 83 
Mode of arresting their progress, 84 
Economical uses of sands, 85 
Salt marshes. Mode of formation. Marine peat, 85 
Alluvial sandstone and conglomerates. Mode of formation, 86 
Pyrites, brown iron ore, hematite. Geodes, 86 
