An interesting feature becomes apparent if we zoom in on the meanders of the North Fork of the Shenandoah River, just northwest of Massanutten Mountain. 


Note that these meanders have long, parallel limbs, and that those limbs are almost perfectly perpendicular to the trend of Massanutten Mountain's ridges. 


During Appalachian mountain-building, these rock layers were compressed from the southeast towards the northwest.


 The rocks responded to this compressive stress in two ways: 


(1) they folded, with the folds developing perpendicular (NE-SW) to the principal stress direction (SE-NW), 


and they extended laterally, opening up a series of fractures that were parallel (SE-NW) to the principal stress direction (SE-NW).


In other words, as Africa crashed in from the southeast, the rocks of the Shenandoah Valley got squished towards the northwest, and popped apart towards the southwest and the northeast.


Later, the North Fork of the Shenandoah River took advantage of these fractures, which were easier to erode into than the unfractured rock next to them.


The underlying rock structures help to determine the surface landforms.


Though we don't observe the fractures themselves, the long limbs of the North Fork's meanders mark their location in an uncannily precise pattern.