EXAMPLE OP A EAULT SYSTEM 



169 



ing metamorphosed the underlying conglomerate it is also in relief, can be 

 easily identified and its outcrops followed. Conditions for study could 

 hardly be more ideal. The 

 complex mosaic produced 

 by the faults is well 

 brought out by the out- 

 crops of both basalt layers 

 (see figures 39 and 40). 

 Blocks which are repre- 

 sented on a small scale in 

 figure 40 are, however, 

 each subdivided into many 

 blocks of lower order. 

 Thus the cliff represented 

 at a a (figure 40) when 

 studied in detail reveals 

 the complex system of 

 faults which is represented 

 in figure 41, and much the 

 same could be said of each ^^^gurv: 39. 

 section of the district. A 



The arrangement of these fragments of a thin flow 

 particularly ragged group of basalt having a flat easterly dip was caused by an 

 of fault blocks outlined in elaborate system of faults. South Britain, Connec- 

 - T, , n ,1 ,1 ticut (U. S. Geological Survey). 



baaalt toward the north 



end of the basin has acquired the appropriate name of "Eagland." The 

 appearance here and in the near-by Orenaug Hills the writer has likened 

 to a jam of floating ice-cakes. Along the course of a graben-like canyon, 

 between the last mentioned hills, the fault blocks are well displayed and 

 have been described in the following words (see figure 42) : 



"In crossing the west twin of Orenaug Hill in a direction from west to east, 

 one encounters cliffs nearly at right angles to the course which are too steep 

 to be sealed. From the top of these cliffs the rock surface, with its thin layer 

 of mold, inclines gently to the eastward to the foot of a similar cliff, to which 

 succeeds a gently sloping summit and a new cliff", as before. Approaching the 

 eastern margin, cliffs appear upon the east, and these soon become the most 

 important ones. If next a start be made at the northernmost point of the 

 basalt in the same hill, where it terminates in a sharp prow between steep 

 cliffs on both the east and west, . . . and a course be taken southward 

 through the intermontane valley, the nearly vertical eastern cliff face, which 

 trends south ± 5 degrees east, can be followed on the right over a quarter of a 

 mile for a portion of the distance in a narrow canyon. After emerging from the 

 canyon the cliff recedes on the right, but its direction is continued in a cliff on 



-Effect of Faults in displacing a Basalt 

 Flow 



