Hobbs—The Correlation of Fracture Systems. 
29 
States should so clearly correspond with the orientation of the 
grander features of the planet as they have been worked out in 
the studies of Prinz 1 and others. Prinz has found that the 
major features of the earth are arranged in two nearly recti¬ 
linear series running northwest and southeast, and northeast and 
southwest, with an intermediate series directed nearly along the 
meridian. It is evident that the present study merely blazes the 
way for a more thorough and careful correlation to be made 
when the available data are more nearly adequate for the solu¬ 
tion of the problem. It is therefore hoped that geologists will 
co-operate to the extent of measuring and recording the direc¬ 
tion of joint and fault planes within the districts which they 
individually have opportunity to examine. 
University of Wisconsin, 
Madison, Wisconsin, 
May 20, 1905. 
i Prinz, W. Sur les similitudes que presentent les cartes terrestre 
et planetaires (Torsion apparent des planetes.) Ann. de robservatoire 
royale de Bruxelles, 58th year, 1891, pp. 304-337. 
