Figure 1 shows a regular pressure solution set on a slab of limestone on the frontal wall of a building near Wall Street, NY. Because the building stones are cut and polished, they commonly provide excellent views of pressure solution structures. However, the surfaces of building stones are prone to physical and chemical weathering.

Figure 1. A set of pressure solution seams in limestone on a building stone near Wall Street, NY. The vertical dimension of the picture is about 80 cm.

Unlike the example in Figure 1, the geometry of PSSs is generally much more irregular than other structural elements as shown in the photograph in Figure 2. Therefore, it is usually difficult to distinguish between PSS sets and to measure their geometric attributes. The spacing of PSSs is generally much smaller so that adjacent sub-parallel pressure solution seams with curved geometry merge or overlap thereby further complicating the pattern of the set and the spacing therein.

Figure 2. A set of pressure solution seams in a carbonaceous building stone, Quai Du Louvre, Paris, FR. The darker features are mostly fossils, some of which are truncated by the pressure solution seams. The longer dimension of the yellow post-it pad is 7.5 cm.

Figure 3 illustrates a pervasive set of PSSs associated with two folds in clastic rocks in which the PSSs are parallel to the axial planes of the folds. This is reassuring in terms of the fact that both fold axes and pressure solutions are oriented perpendicular to the greatest compression at the time of their formation. Further discussion of this subject can be found in 'Interaction of Pressure Solution Seams,' 'Growth of Pressure Solution Seams,' and 'Pressure Solution Seam Spacing.'

Figure 3. A well-developed set of pressure solution seams along cross-beds in sandstone slabs used as wall cover at Milan's Malpanse International Airport departure terminal, Italy. Note that a majority of the seams are linked.