THE HOUSATONIC VALLEY. 801 



as well as in an east and west direction. The compression from 

 the north and south has produced no dislocation, as no transverse 

 faults have been discovered. 



III. The rocks of this area have been very sharply folded. 

 The types of folds are the unsymmetrical, with short and steep 

 western and longer eastern limbs, and the overturned and sharply 

 compressed fold with an easterly dipping axis. Reduced and 

 ruptured underthrown limbs are not uncommon, but the evidence 

 is that the extent and the throw of these minor faults is very 

 slight. On the southeast flank of Tom's Hill this has produced 

 the structure which Suess has called Schuppenstvuktur. I would 

 suggest, as an English equivalent of this term, weather-board 

 structure. 



IV. An important reversed fault, which has been termed the 

 Housatonic Fault, has a northerly course along the eastern 

 border of the area of schist ridges. Its course very nearly coin- 

 cides with that of the Housatonic River for a considerable dis- 

 tance. The fault is traced from near Sheffield village to beyond 

 South Canaan, a distance of about twelve miles. North of the 

 Maltby Quarry it has the characters of an overthrust which 

 increases in throw in going north, owing to the northerly pitch 

 of the beds to the west. This has carried the Canaan Dolomite 

 of the eastern or normal limb over the newer Egremont Lime- 

 stone and Everett Schist of the western reversed limb. South 

 of the Maltby Quarry the western limb has been upthrown, 

 bringing Cambrian Quartzite and Gneiss against the dolomite. 

 The dolomite has been extensively crushed and metamorphosed 

 along the fault plane. Tremolite and white pyroxene have been 

 extensively developed in the vicinity of the fault plane, and 

 vein quartz has cemented the dolomite fragments together, pro- 

 ducing a fault breccia. 



It is very probable that the rapid alternations of pitch which 

 characterize this area are not altogether unusual. It is only 

 rarely, however, that the areal relations shed so much light upon 

 the form of the crest lines and trough lines of folds. What 

 has been set forth will, I think, show that evidences of general 



