34 GEOLOGICAL SURVEY OF ALABAMA. 



structure can be explained under the supposition of a 

 compressing force acting from the southeast, by assuming 

 that the trough of the synclinal lying to the east of 

 Murphree's Valley was lapped under the anticlinal of the 

 valley, and when faulting occurred, the underlapped beds 

 were thrust under those to the northwest of the fault plane. 

 Thus while the arch of the fold of Murphree's Valley 

 appears to have been thrust over towards the southeast, as 

 if by a force coming from the northwest, in reality, the 

 motion of the strata has been in the opposite direction, 

 impelled by a force acting as in the other cases from the 

 southeast, those beds whose lateral motion was greatest being 

 thrust under those which yielded less in that direction, thus 

 uplifting them into an arch with its steeper side, its fault and 

 its reversed or overturned strata towards the south-east. 



TRANSVERSE FOLDS. 



In addition to the plicating effects of lateral pressure 

 already considered, there has also been in this region a gen- 

 eral, though less prominent, transverse folding of the strata. 

 A flexing, faulting and wrinkling of all the formations at, or 

 nearly at, right angles with the axis of the valley, or approxi- 

 mately in a south-east and north-west direction. Whether 

 this system of flexures has resulted from pressure or other 

 cause, whether the cause operated from the south-west or 

 from the north-east, would be much easier asked than defi- 

 nitely answered. That it does exist as a widely extended 

 system, slightly affecting the geological structure, and very 

 distinctly modifying the topography, is a matter of daily 

 observation. 



These transverse flexures are more distinctly seen in the 

 ridges and high lands, where their outlines are freely exposed. 

 In some places they extend for miles, in others they can be 



