LONG-ISLAND DIVISION. 
249 
or of the quaternary or alluvial deposits. It is supposed to underlie the whole of Long island, 
except that part near Hurlgate, at the west-northwest extremity of the island, where the drift 
is superimposed directly on the primary rocks. 
Mineral Composition and Texture. 
The general character of the composition and texture has already been alluded to ; the local 
characters will be made known in discussing the different localities that have been examined, 
and the sections obtained from various sources. 
The great storm and gale of the eleventh and twelfth of October, 1836, in consequence of 
the encroachments of the sea on the land, exposed beautiful sections of the strata on the 
coast, and gave an opportunity, not often presented, of examining fresh sections along an 
extensive line of coast.* The remainder of the autumn of that year was devoted to mean¬ 
dering the coast, and ascertaining the order of superposition of the different masses on Long 
island. 
At Oysterpond point, the storm caused a breach across the point about forty rods from its 
eastern extremity, washed off the drift deposits (that form some of the surface in that vicinity) 
except some large blocks, and exposed the underlying red clay. This could only be seen at 
ebb tide, and was in a few days covered by sand and gravel washed over it by the surf. 
Between Brown’s point and Petty’s bight, about three to three and a half miles w'est of 
Oysterpond point, the sections figured on Plate 4, figs. 4, 5, 6, 7, 8, were observed. 
Figures 4 and 5 of Plate 4 represent the brown and reddish slaty clays (which are left 
blank on the figures) penetrating upwards, and deranging the position of the superincumbent 
sand; while the clay and pebble beds above, and which also belong to the same geological 
epoch, rest unconformably upon them. The lines are not drawn to illustrate the contortions 
of the brown and red clays, for it would require an artist to give all the beautiful and com¬ 
plicated curves that a fresh section exposed to view. The contortions of these two sections 
were probably produced by the lateral thrust of slides, though no traces of slides were there 
observed except these contorted strata; and there is no other cause to which I can ascribe the 
effect, where the underlying strata are undisturbed as was the case in fig. 5. 
Fig. 7 of Plate 4, shows alternations of arched strata of sand and clay, covered unconfor¬ 
mably by a stratum of clay, which rests horizontally on the denuded edges of the arched 
strata. Four distinct periods are here indicated: 
1. The deposition of the alternatmg strata. 
2. Their elevation and denudation. 
3. The deposition of the clay bed unconformably. 
4. The deposition of coarse materials and boulders. 
* In a short time after such sections are made, the sand and gravel beds crumble down so as to conceal the strata, or the clay 
beds slide ; so that the observer is so very liable to wrong conclusions from so many sources of error, that it is almost impos¬ 
sible to avoid them all. 
Geol. 1st Dist. 
32 
