222 Messrs. Jackson ond Alger on the 
able height; but its character was clearly indicated by the long 
causeway, known as the “ Bar,” that runs out into the sea for more 
than a mile, and over which the billows were heard to roll in with 
great violence. From the information we obtained, we are led to 
believe that the substrata of sandstone are there seen to crop out 
from beneath the trap, thus making the western terminus of 
the North mountains similar to the Eastern. 
At the northeast point of Long Island, the amygdaloid, on 
which the irregular columnar rock rests, is accessible, and its 
cavities are found filled with nodules of chlorite, to the exclu- 
sion of the zeolites, which, as we shall have occasion to show, 
more generally occur in other places. These nodules, when 
broken, present laminz, of a beautiful leek-green color, radiating 
from the centre, and rarely crystallized in low tabular crystals, 
often intersecting each other. The chlorite has often been 
removed by external causes, thus imparting to the rock a vesicu- 
lar appearance ; but in some few cases, the cavities were natu- 
rally left void, constituting real vesicular amygdaloid. 
The veins of jasper, as they traverse the amygdaloid, become 
singularly altered in their character, being converted into a sub- 
stance, resembling in appearance ‘imperfectly burned bricks of 
potters’ clay. The specimens from the interior of the vein, 
where it had not been acted upon by exposure, presented the 
same appearance; some parts. were in fact perfect clay-stone. 
As the veins entered the superincumbent trap, they became 
altered in appearance, and in the course of a few yards, were 
converted into a very perfect red jasper. Three or four veins 
were observed, presenting similar appearances. 
In crossing Petit Passage, a deep and precipitous channel, 
through which the flood tides rush with great violence into the 
