Cobbles and Setts can comprise of three main rocks that are-
- Sedimentary Rocks– Such as sandstone or siltstone, are relatively easier to cut and shape.
- Metamorphic Rock– Such as Gneiss, Quartzite or Marble, may retain some of the cleavage planes of its sedimentary ancestor, which is not always a desirable trait, and so this type is rarely used.
- Igneous Sett– Such as basalts and granites, are usually much harder and have few, if any, cleavage planes.
- Sizes of cobbles– (3 ½” x 3 ½” x 3 ½”) +/- & (8″ x 4″ x 2″) +/-