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1891.J 
origin, and as such offer the best means of defining the height of 
the water surface in which the delta was formed ; for on fol- 
lowing up the axis of a lobe along its gentle ascent to the plain 
in which all the lobes unite, the height at which the ascent of 
the lobe changes to the flat of the plain can be determined within 
five or ten feet at the most; and this height is manifestly that of 
the standing water in which the delta was built. The agreement 
of this with the height of what has been taken to be the front of 
the Catskill delta, north of South Cairo, is satisfactory ; the 
Potuck delta front being about 280 feet, and that of the Catskill, 
270 feet. 
The upper surface of the Potuck delta is gravelly, with well- 
worn pebbles up to three or four inches, but commonly smaller. 
On asking a farmer about these gravel-fields elsewhere in the 
valley, he pointed to a remnant of the Potuck valley-filling half a 
mile farther north, saying the pebbles were coarser there ; he added 
that the pebbles extended only about a foot and a half below 
the surface, and beneath that there is a great depth of sand ; his 
well was sunk fifty feet in pure sand without meeting rock ; and 
from this he argued that the gravel field (the Potuck delta on 
which we stood) was “made land”, meaning thereby that it was 
loose material carried to its present position ; but he had gained 
no clear idea of the process and conditions under which it was 
carried . 
A fine view is gained from the lobes of the delta eastward over 
the next broad stretch of flood-plain meadows bordering the Cats- 
kill ; and crossing these for nearly a mile to the southeast, one 
may pass the stream by a foot-bridge in the rear of the old Salis- 
bury Manor, a large stone house built a hundred and fifty years 
ago. Here some of the harder gray layers of the Hamilton 
sandstone cross the stream ; they may be traced southward, ris- 
ing obliquely eastward up the valley-side until they form one of 
the stronger ledges in the front of the Hamilton bluffs, there 
known as Yedder’s Hill. Some thirty feet of these sandstones 
may be seen in the bank of the stream ; their strike is close to the 
meridian, with a dip of ten degrees to the west; the bedding is 
uneven, with conchoidal fracture ; two of the beds, four or five 
feet thick, are extremely irregular, like tumultuous flows of 
muddy sands ; the upper of these is overlain by three or four 
inches of conglomerate, w r ith flinty pebbles of oval form, up to 
