The photomicrograph in Figure 1 shows a volumetric deformation band, most likely a compaction band in Aztec Sandstone in Valley of Fire State Park, Nevada, illustrating its composite architecture as it crosses across several beds. The band has irregular boundaries amplified from layer to layer. It is possible to identify pockets of compact grains bounded by strings of large pores from the BSE image (Figure 2) showing details of a band architecture (Torabi et al., 2015). This kind of texture is likely related to the incremental growth process of bands through a heterogeneous granular medium.

Figure 1. A mosaic of images showing composite nature of a compaction band across layers of Aztec Sandstone at Valley of Fire State Park. The band has rough boundaries. However, there is not a clear offset across the layers. From Torabi et al. (2015).

Figure 2. Mosaic photomicrograph of a compaction band and a BSE image of a portion of it showing pockets of compact grains separated by strings of large pores. HR for host rock, CG for pockets of compact grains, P for some large pores. Extracted from Torabi et al. (2015).