474 WILLIAM HERBERT HOBBS 



area, since in this case also the tendency would be for blocks to 

 rupture along the diagonals. 



The oriented drainage of the Pomperaiig Valley .—^'\\\\ this brief 

 summary of the geological structure within the Pomperaug Val- 

 ley area we may consider its drainage. It was found in study- 

 ing the area that the streams, large and small, for considerable 

 distances adhere with great fidelity to the directions of some of 

 the prevailing faults, and that in many cases after being diverted 

 from them, it was noted that they had returned persistently to 

 the old direction. This correspondence of drainage lines to 

 geological structure planes is far too close to be accidental. 

 The four prevailing fault series diverge from their nearest neigh- 

 bors at angles of about 39°, 20°, 29°, and 92°. A difference in 

 angle between a fault direction and the general direction of a 

 stream course equivalent to 7°, or about one third the small- 

 est difference of angle between neighboring fault directions, 

 would represent a divergence of one in eight, which would hardly 

 be accepted by the eye as an indication of parallelism. It is 

 not to be expected that the actual course of a stream will now 

 be coincident with or even absolutely parallel to any fault direc- 

 tion, for there have unquestionably been many local conditions 

 which have produced larger or smaller migrations of the river 

 channels. Their general direction has, however, it would seem, 

 been maintained despite the minor accidents which have marked 

 their life-histories, and even under so revolutionary a change as 

 complete reversal of drainage. 



It was further shown in the investigation under review, that 

 in the walls of crystalline rocks surrounding the Newark beds in 

 the Pomperaug basin, the same adhesion of the water courses to 

 the direction of the observed faults (extended) could be deter- 

 mined. It was hardly to be expected that these peculiarities 

 would cease to be observable so soon as the immediate vicinity 

 ol the Newark basin was left behind, if it be indeed true that the 

 dislocation of the area is due to a compression of the general 

 region in which this area of Newark rocks and the much larger 

 one of the Connecticut valley are included. Owing, however, 



