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[ASSEMB LY 
and a marsh connects the largest island, or peninsula, with the main 
land, so that the water stagnates. These flats, of which there are some 
hundred acres, will eventually be valuable land, but several generations 
may pass away before that time, unless they be diked out. The islands 
are on a line with the rocky shore above Upper Red Hook Landings 
and are the outcropping edges of the same strata. 
An island of alluvial ooze is forming about two and a half miles be- 
low Rhinebeck Landing, and extensive flats under water are also in 
process of formation. Between Emmet's and Thompson's Landings, 
clay hills bound the bay on the east, in which these depositions are 
taking place. Three small creeks also empty into it, and by their de- 
posits assist in the accumulation. 
At the mouth of Caspar creek a small delta is forming. 
At the mouth of Wappinger's creek a small alluvial deposition com- 
mences, which extends, with little interruption, until it joins that of 
Fishkill Creek, and continues thence to the Highlands. There are few 
places where it shows itself above water, even at ebb tide, but it is 
an alluvial bank from 60 to 600 yards broad, and nearly 10 miles in 
length. 
There are many small alluvial marshes and flats, which are too small 
to notice, and they can be of comparatively little value, even prospec- 
tively, except for manure. The river ooze is every where well adapted 
for fertilizing the soil. 
The main object in introducing these alluvions into the annual report 
is their prospective value as land, capable of tillage, by diking them 
out, where the value of land and the small expense of diking will jus- 
tify the change. Some of these alluvions, if reclaimed and tilled, 
w^ould benefit the health of the adjacent country. Where the water 
stagnates on them, bilious, intermittent and remittent fevers are pro- 
duced. 
Lacustrine and Marsh Mluvims. 
These are formed by the combined effects of the growth and decay 
of organic matter, and the deposits of the waters from the adjacent 
country flowing through them. The nature of the material forming 
these alluvions varies much, according to local causes. If the water 
flowing into lakes or marshes, with a gentle current, be loaded with 
