346 UNIVERSITY' OF VIRGINIA PUBLICATIONS 



age exist here, showing that the rocks have been affected at different times 

 by forces applied in different directions. At one point in the bed of this 

 stream the bedding strikes in an east-west direction, while the strike of 

 cleavage is north-south. The slates outcropping on the hill nearby, show 

 that they have been affected by the same movements; the slaty cleavage 

 shows snme folding. 



South of the river the bedding again assumes its normal northeast- 

 southwest strike, although changes from this direction are common, due 

 either to folding with pitching axes, or to faulting. Near the borders of 

 the pre-Cambrian igneous and sedimentary rocks the faults can be readily 

 recognized. At such places the sedimentaries are almost entirely removed 

 by erosion and comparatively small displacements are readily seen. Where 

 these rocks remain in considerable thickness faulted structure cannot be 

 determined, since the throw is relatively small and beds of sufficiently 

 different character have not been brought into contact. Where the out- 

 crops are favorable for observation they commonly show normal faulting 

 on a small scale. This seems to be especially true of exposures in the 

 vicinity of igneous dikes. 



The general structure of the sedimentary belt appears to be anticlinal 

 rather than synclinal, and the preponderance of field evidence gathered 

 by detailed mapping strongly indicates that the preservation of the Cam- 

 brian rocks in this area has been due chiefly to normal faulting, which 

 lowered the beds below the plane of erosion. 



Normal faults were observed in two different parts of the area. About 

 1 mile southeast of White Sulph,ur Springs along the road which cuts 

 across the slate belt, there is a series of fault blocks of small size occurring 

 in a cut by the roadside Figure 3 shows this section (line BB' of map, 

 fig. 1) drawn to scale. In a small stream on the north side of Rappahan- 

 nock River about 1.5 miles northwest of White Sulphur Springs, normal 

 faulting was again observed striking approximately in an east-west direction. 



The variations in dip and strike of the Cambrian beds of the area are 

 very great, and many of them are of such character that they can be ex- 

 plained only by normal faulting. When it is borne in mind that this dis- 

 trict is only a few miles west of the New York- Virginia Triassic belt, which 

 is known to be cut by normal faults in various directions, characteristic 

 of other Triassic areas in the eastern United States, these structures are 

 normally what would be expected to occur. Since the Cambrian lies on 

 a basement of the same general character as the Triassic, and occurs in 

 a nearby region, it is more than likely that the deformation which affected 

 the latter would likewise affect the former. 



