In lots of cliff and canyon photos I see this type of erosion where the rock has been eroded underneath each layer:
https://cdn.audleytravel.com/4024/2871/79/1017230-north-rim-grand-canyon.jpg
The strata and outcrops shader can get me close, but I can't seem to get that erosion between layers to where there are kind of lateral grooves or cracks under each layer in the canyon wall. Any tips?
After a compute terrain/normal you can displace laterally, so that can be done procedural by XZ stretched fractal for horizontal cracks. The difficulty is to get those horizontal lines broken up and shifted, so masking comes into play, and/or warping the horizontal lines. Masking by vertical columns, e.g. But the outcome would still be kind of regular.
Another method would be to use an image map projected laterally. So either on X or Z and mixed/added with a 90ยบ rotated version, or cylindrical (where X is then a small number and Y the height of the image).
Vector displacement is alo a way (even without compute normal/terrain), but that has the disadvantage that it's one way, so either +X or -X, e.g.