16 Wisconsin Academy of Sciences, Arts, and Letters. 
portions of the British Isles, and also by Kjerulf 1 for Norway. 
Haughton, and more recently Brogger, 2 have conclusively proven 
. that in the districts which they studied the normal faults con¬ 
form in direction to the general system of joints; but the import¬ 
ance of this result, though reinforced and emphasized by 
Daubree, 3 lias never been fully appreciated. 
For the region of the eastern United States it was developed 
in the author’s paper referred to, that the joints and normal 
faults of greatest prominence follow in any particular part of 
the province one or more of three or four general directions. 
These directions approximate to the meridian and the equator, 
and to diagonal intermediate bearings. There seems good rea¬ 
son to believe that as regards the first two of the directions men¬ 
tioned the approximations to meridian and equator are fairly 
close—generally within 5 degrees. As regards the intermediate 
directions this is far from being the case, and there are in general 
not two but several intermediate directions; yet their general 
tendency to occupy rather distinctly intermediate positions be¬ 
tween the meridian and the equator is sufficiently manifest. 
Wherever close observations have been made it has been found 
that not four but a considerably larger number of directions may 
be made out, as will be clearly indicated in the following tables. 
These observations receive, moreover, strong support from the 
studies of Green, Prinz, and others dealing with the orientation 
of the broader earth features upon the entire planet. 
North Carolina .—Since the author’s paper 4 wms published it 
was learned that a careful measurement of joint and dike direc¬ 
tions had been made by Mr. F. B. Laney within the Newark area 
of North Carolina, and as a result of his studies Mr. Laney 
stated that joints and dikes alike were oriented mainly north and 
south, east and west, northwest and southeast, and northeast and 
southwest. Mr. Laney has kindly turned over to the author his 
i Kjerulf, Theodor. Die Geologie des siidlichen und mittleren Nor- 
wegen. Authorized German edition by Gurlt. Bonn, 1880, pp. 1-350. 
2Brogger, W. C. Spaltenverwerfungen in the Gegend Langesund- 
skien, Nyt Magazin for Naturvidenskaberne. Yol. 28, 1884, pp. 253- 
419, with map. 
s Daubree, Geologie experimentale. Vol. I, pp. 289-385. 
4}. c. 
