No. 50.] 
247 
When the elevatory movement has been along the trafisverse frac- 
tures, the dip is sometimes to the north-northeast, but most frequently 
to the south-southwest ; and when the upheave has been along the Ion- 
giiudinal fractures, the dip is to the west-northwest or to the east-south- 
east. The upheaves have generally occurred along both these lines of 
fracture, giving echelon movements to the masses of strata, so their 
dip is commonly oblique to the direction of ranges of hills and 
mountains, and even to the usual line of the emergence of the strata 
on the surface. The southeast angles of the masses, between the in- 
tersecting fractures, are usually elevated, giving mural precipices on 
the eastern and southern faces of the hills, while the strata dip more 
or less gradually to the northwest. 
The same general principles hold true in the rocks lying lower in 
the series, as the Hudson slate group, (a part of which are metamor- 
phic,) and the rocks of the Highlands, except that the southwest an- 
gles of most of the masses of those strata have been highly elevated, 
giving a high easterly dip, and that they have been exposed to a great- 
er number of elevatory movements, producing a greater derangement 
of the stratification. 
Most of the streams follow the lines of these two systems of frac- 
ture, changing from one to the other to produce many of their changes 
of direction. I have been enabled to trace some of these lines of fault 
across mountains and valleys, for many miles. 
Metallic veins occur in several places along both these systems of 
fracture, and it is mostly in consequence of the echelon movements 
that have occurred in the strata since their first breaking up,* that it is 
a matter of much practical difficulty to trace out the continuation of 
metalliferous veins and beds, so as to open them in the most favorable 
locations. 
General and local sections will illustrate these and numerous other 
interesting and important facts in the final report of the geological sur- 
vey. 
* There are distinct evidences of at least three elevatory movements, viz : one (at 
least) before the deposition of the Shawangunk grit strata j another after the deposi. 
tion of the Shawangunk, Helderberg and Catskill mountain series, and before the ter- 
tiary epoch, and another since that period. 
