Stratus (St) Found at very low levels (less than 2000 meters, or 6500 feet), stratus clouds are thick, large, heavy-looking gray clouds that dominate the sky. Precipitation normally does not occur with this cloud, although drizzle or mist may be observed.
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles. Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism.
Phyllite. is a fined grained metamorphic rock.Shale is the parent rock. It is made up of clay minerals. Shale can metamorphose into slate, phyllite, schist or gneiss depending on the degree of heat and pressure. Phyllite has a greater degree of metamorphism than slate but less than schist.neiss is a medium to course grained metamorphic rock.Shale is the typical parent rock. It is made up of clay minerals. Shale can metamorphose into slate, phyllite, schist or gneiss depending on the degree of heat and pressure. Gneiss has the greatest degree of metamorphism in this group.