THE PALISADES PORPHYRY. 147 
general parallelism to the bedding of the formation, being subordinately 
twisted and contorted into all sorts of shapes, so that on a cliff-side their 
inclination often changes from a nearly horizontal one to one of 20° or 
even 40° within a few feet. Where the lines are developed the crystals of 
quartz and orthoclase are noticed to bear no relation to them at all, com- 
monly cutting across them, and at all angles, the larger orthoclases even 
extending across two or three of the lines. Very much of the rock is 
observed to be without any sign of this lining. 
Under the microscope, as shown in the previous chapter, the Palisade 
rock presents the common characters of a quartz-porphyry, and there is no 
trace of a clastic nature. The quartzes are all in doubly terminated crys- 
tals, and streams of black particles run around them as if pushed aside 
when the rock was in a viscous condition. The whole rock presents a ver- 
tically columnar structure, not developed so completely as in some of the 
diabases, but still very noticeable. The structure lies at right angles to the 
dip, which is some 10° to 20°, east-south-east, varying between those figures. 
In the main cliff, since it trends with the strike, the columns appear at first 
sight much more nearly vertical. 
As already said, both in the Palisade Creek and in the bay at the 
south end of the Palisades, the underlying rocks are in sight. At the lat- 
ter place a single cliff-side shows the great porphyry overlying a thickness 
of 100 feet of diabase and diabase-amygdaloid. These are disposed in two 
great flows 44 and 56 feet thick, respectively, while the top of a third is seen 
rising just above the sand. Lach of these diabases has most perfectly de- 
veloped crowning and basal amygdaloids. We have thus a most unequivo- 
cal case of the superposition of true quartziferous porphyry upon the typical 
diabases and amygdaloids of the series. 
The same layer that forms the Palisades—or another one closely like 
it—appears again in a bold point of bare rock 150 feet high, on the north- 
east side of Baptism River Bay, a mile and a half below the Palisades. 
Here the underlying diabases and amygdaloids are again seen in position. 
The top of the point slopes off lakeward with the dip (about 8°). The 
more minute peculiarities of the rock, and its rude columnar structure at 
1See Figs. 1 and 2 of Plate XII; also pp. 99 and 109 of this Memoir. 
