630 
GEOLOGY OF THE FIRST DISTRICT. 
dykes, and are interlaminated with, all the rocks in the geological series until after the 
formation of the red sandstone of New-Jersey; and no traces of the intrusion of this rock 
are found in any of the strata of a later period. It is hence inferred that the trappean injec¬ 
tions took place between the periods of the red sandstone of Rockland county and New-Jersey, 
and the Long-island division. The trappean injections seem to have produced great and 
marked changes in the rocks in Westchester, Rockland, Orange and Putnam counties, and 
more particularly in the limestones. These changes cannot, in all the localities, be referred 
to the trap alone, as augitic, granitic and sienitic rocks of a preceding era are also associated 
in many places, and in these latter cases the metamorphic changes and development of crys¬ 
tallized minerals are much more marked. 
2. The next older series of injections among the rocks, that seems to have produced meta¬ 
morphic changes, is that of the quartz veins. These traverse the gneiss, granite, and all the 
rocks up to the period of the newer strata of the Ontario division, but have not been observed 
traversing any of the rocks of a more recent date. This period seems to have been that in 
which most of the metamorphic changes were made in the rocks of the Champlain and Ontario 
divisions in the Hudson valley, but which had been broken up before the deposition of the 
limestones of the Helderberg division. 
3. Another and perhaps more than one period of metamorphic action, preceded the last, 
and seems to have been produced by the protrusion and injection of granite and sienitic and 
augitic rocks. These rocks are not ascertained to have been more recent than the deposition 
of the limestones of the Champlain division, but appear to belong to the epoch immediately 
preceding the slates and grits of the Champlain division, since they have altered the pre¬ 
existing rocks where they came in contact up to that time; but we find no traces of such 
changes in any of the more recent rocks. This period seems to be that at which the white 
and red limestones of Orange, Putnam, Rockland and Washington counties, in New-York, 
and of Sussex county in New-Jersey, were brought to a metamorphic form, perhaps height¬ 
ened by subsequent jyeriods. 
4. Another period of the protrusion and intrusion of granite, seems to have been that of the 
transverse upheaves in a west-northwest and south-southeast direction ; as beds and veins, and 
inteitruded masses of these rocks, are far more numerous along and near the lines of these 
transverse axes of disturbance than elsewhere, and the rocks along these lines are more 
altered, and loaded with interesting minerals. 
The period of this elevation is not ascertained. It is inferred to have preceded the red 
. sandstone of Rockland and New-Jersey, as these strata rest nearly undisturbed on rocks of 
this era near Stony point; and to have been more recent than the newest rocks of the Cham¬ 
plain division, as they are all deranged by it. It is also thought probable that it is more 
recent than the rocks of the Catskill division, as they appear to have been fractured and 
slightly deranged by the transverse upheave, but it is not demonstrated. It is thought not 
improbable that the transverse upheave was contemporaneous with that succeeding the coal 
formation, which affected the rocks so much along the great axes, or series of parallel axes, 
