AXES OF ELEVATION. 
605 
CHAPTER X. 
DIP AND STRIKE OF ROCKS, AND GENERAL INFERENCES FROM THE 
FACTS IN THIS VOLUME. 
In the preceding chapters of this volume,, tlie rocks of the First geological district of the 
State of New-York have been described, as far as they have come under examination during 
the survey, and some observations made antecedent, by myself and others, have been intro¬ 
duced ; but I have not been able to collect all the published observations of others, in conse¬ 
quence of not having access to all the works in which their observations have been recorded. 
I have endeavored to give credit to all, where credit was due, but am sensible of some im¬ 
portant omissions ; among which may be mentioned some of those of Dr. S. L. Mitchill, Dr. 
Akerly {On the Geology of the Hudson); Prof. A. Eaton {Geology of the Northern States); 
various articles, by sundry persons, in Bruce's Mineralogical Journal, Annals Lyceum of 
Natural History of New- York, Journal of the Academy of Natural Sciences of Philadelphia, 
Memoirs of the Albany Institute, ^c. 
There remain for consideration, various facts connected with. 
1. Axes of elevation, ^ Longitudinal, ) 
i Iransverse. > 
2. Fractures of the strata, joints and veins. 
3. Ages of rocks, and periods of elevation and of metamorphic agency. 
4. Cause that has led to all these disturbances, and changes of character. 
1. Axes of elevation. Various isolated facts have been observed on this subject, some of 
which have been alluded to in various parts of this work ; enoygh to demonstrate two main 
directions of elevation, transverse and nearly perpendicular to each other. The contortions 
of rocks, the metalliferous and other veins, the altered and modified rocks, etc., are found 
almost constantly associated with the axes of elevation, one of which ranges between north 
and northeast; and the other about west-northwest, or along joints and fractures, nearly 
parallel to these directions. The other directions of joints and lines of fracture and distur¬ 
bance, although not uncommon, are less frequent. 
The following table shows the strike and dip of the strata, as observed in various places in 
the First geological district. Some of them were estimated by the eye in their strike, not 
having a compass at all times ; and the dip was always estimated by the eye, and both are 
considered as only approximations to the truth. 
Geol. 1st Dist. 77 
