388 
GEOLOGY OF THE FIR.ST DISTRICT. 
The rocks, consisting of grits, slaty grits, gritty slates, and slates, dip to the east-southeast 
from fifty to ninety degrees. An example of contortion, represented on Plate 24, fig. 1, may 
be seen on this island about forty or forty-five rods south of the north end of the rocky portion. 
Contorted rocks are seen in place a little below Oak hill and Catskill ferry. They contain 
basanite, and rocks continue in place to Croft’s point^(Vide Plate 29, fig. 1).* 
At the point one and a half miles below Croft’s point, the rocks are much contorted, as 
represented on Plate 9, figs. 1 and 2; and a short distance below the wharf, a fault may be 
seen, as represented PI. 9, fig. 12. A short distance below this point in Clermont, the strata 
are vertical, composed of alternating strata of grit or greywacke and slate. The divisional 
planes of the slate mahe an angle with the strata, as represented on PI. 10, fig. 7. The 
dotted strata are the grit rocks, from a few inches to three or four feet thick, and the shaded 
strata have their lamina of cleavage in the position ,pf the lines of shading. This locality is 
on a small point; and in the next bend bf the shore' below, is an example of zigzag contortion, 
as represented on PI. 9, fig. 3. At the point below, where the north line of Germantown in¬ 
tersects the shore, veins of calcareous;.spar intersecfethe strata of grit and slate. The dip is 
here very variable. Another example of zigzagjihontortion,'’as represented on PL 9, fig. 4, 
may be seen about opposite to the north end of the Ooze island, where contortion is indicated 
on PI. 29, fig. 1. 
Nearly opposite the light-house below Bristol, on the eastetn shore, two examples of contor¬ 
tion may be observed, as represented'on PI. 9, figs. 6, 7. The rocks are alternations of grits 
and slates, as represented on those figures. The localities are-about a quarter of a mile from 
each other, and equidistant from a point oppos^ to the light-house, and are represented on 
PI. 29, fig. 1, at a? and y. 
Below Barrytown or Upper Redhook landing, areAwo lon^ narrow rocky islands called 
Magdalen islands'!. The strata on them are well^expos.edvt'^, view, dipping as usual to the 
east-southeast, or more nearly east, at high angles... These islands are on a line with the 
shore above Barrytown, and are probably a continuation of’^tKe same line of elevation, and 
are composed of the same kinds of rock. 
About one mile below Rhinebeck landing,- thick layers of grit are interstratified with slate, 
and bent nearly as represented on PI. 10, fig'. 9.t A few rods farther south on the shore, the 
slate has its ;cZeauag*e nearly vertical; 'while the dip of the^fata, both of the grit and slate, 
is about sixty degrees to the east (Vide PI. 10, fig. 8)! ,At a distance of thirty or forty rods 
still farther south, the rocks are bent in opposite directions, as represented PI. 9, fig. 8, and 
PI. 10, fig. 9. 
The arched, bent and contorted strata of grits, slaty grits and slates, may be seen to great 
advantage from one to three miles below Rhinebeck landing, by going near the shore in a 
small boat. 
* The -word tertiary, after clay hills, should read quaternary. Figures 1 and 2 illustrate also the alluvial flats, both the marshes 
and those covered by the tide. 
t The lines of shading on the slate do not represent the true directions of the lamination. A fe-w rods above this locality, no¬ 
dules of argillaceous iron ore were observed imbedded in the slate. 
