Both shear and compaction bands occur extensively within Entrada Sandstone cropping out in the San Rafael Desert, Utah, and Aztec Sandstone cropping out in Valley of Fire State Park, Nevada. Individual bands within the sets of bands commonly are spaced anywhere from centimeters to meters apart (Figures 1(a) and (b)). It is not uncommon, however, to observe neighboring bands with anastomosing or inosculating patterns with trends and dips varying by 25 degrees or more over the scale of centimeters to meters (Aydin, 1978; Aydin and Johnson, 1983).

Figure 1. Outcrop photo showing parallel pattern of deformation bands in Aztec sandstone. View is to the north, bedding is approximately horizontal. From Sternlof (2006).

When two distinct sets of either shear or compaction bands overprint, they form a crosshatch pattern (Figures 2(a) and (b)) with varying degrees of intersection angles (Aydin and Reches, 1982). Individual sets within crosshatch patterns have spacing ranging from a few centimeters to a few meters with both sets typically exhibiting comparable spacing. Here the nature of the intersections is intriguing. The younger bands generally cross-cut the older ones. This cross-cutting is obvious for shear bands but assigning age relationships to the intersecting compaction bands is not straight forward. There are also cases that one band near the intersection turns sharply and becomes parallel to the band belonging to the other set without intersecting it. Both types of geometries may occur at the same location as shown in Figure 3.

Figure 2. Outcrop photo showing a typical anastomosing pattern of deformation bands located along trend, but about 200 m south of the outcrop shown in Figure 1. View is to the north, bedding is very nearly coincident with the outcrop face in the foreground. From Sternlof (2006).

Figure 3. Outcrop photo showing a typical cross-hatch pattern of deformation bands in Aztec sandstone. Bands in the two sets are at high angle to each other and to bedding (approximately coincident with the outcrop face (main photo)). Looking down the axis of intersection of a cross-hatch set illustrates how planar bands can be, and how sharp their intersections (inset photo). From Sternlof (2006).