28 TACONIC PHYSIOGRAPHY. 
The joints of this region may be grouped as follows, the groups 
being named approximately in the order of their prevalence: 
Strike joints striking N. 20° W.-N. 30° E. 
Dip joints striking N. 05° W.-N. 90° W. 
Dip joints striking N. 60° E.-N. 80° E. 
Diagonal joints striking N. 35° W.-N. 55° W. 
GENERAL RELATION OF STRUCTURE AND MATERIAL TO 
FORM. 
The general relation of structure and material to form can now be 
examined. In the Green Mountain area a gently undulating surface 
replaces, at least on Hoosac Mountain (PL V, A), the overturned 
anticlinal structure. In the Dome, in Pownal, on the same range, th 
structure of which was carefullv worked out by the writer in 1897, th 
overturn is still sharper, yet the form is that of a rather symmetric! 
oblong dome of gentle slopes and the material is quartzite and gneisi 
In neither case has form been determined by structure. The dolomi 
area on this range east-southeast of Brandon appears to consist of 
central anticline with a syncline on either side, but its roundish sum] 
mits rising above the adjacent but underlying quartzite and schist 
reflect neither its structure nor the greater solubility of its material) 
On the other hand, as will be shown beyond, there is the most intimate 
relation between structure, material, and form in the 5-mile strip o: 
dolomite east of Lake Dunmore. 
In the Rensselaer Plateau a typical " peneplain " replaces a corn 
gated trough-like synclinorium. 
In the schist area there is a general parallelism between the cres 
of the ridges and the axes of the synclines. This is more noticeabl 
in the southern part of the range and its spurs and outliers, but the 
course of the ridge near the southwest corner of Vermont seems t( 
have been determined bv the erosion of the Hoosic River, whicl 
crosses the strike. (See map, PL I.). Farther north this parallelism 
is less perceptible. The forms of Mount Anthony and Grass, Bear. 
Woodlawn, and Dorset mountains give no clue to their structure.' 
The schist appears to have behaved practically like material oi 
homogeneous structure and composition. 
The longitudinal valleys are anticlinal, synclinal, or both, and lie 
in calcareous rock. Both structure and material have had to dc 
with their formation. The transverse and diagonal ones are hide-' 
pendent of material and bedding. In PaAvlet, Arlington, Iloosick. 
and Pownal they cross limestone. The diagonal system of joint? 
may have had something to do in determining their course. On the 
western side of the Taconic Range in Berlin and Stephentown a 
very narrow anticline of limestone 5 miles long is crossed by four 
