Sedimentary rocks are the most commonplace rock kinds which might be freely uncovered in the world’s floor. They are shaped from other rock substances for the reason that they may be made up from the buildup of weathered and eroded pre-present rocks.
Greywacke is variation of sandstone that saperate from other to hardness, dark color, and poorly sorted angular grains of quartz and feldspar. Generally found in Palezoic strata. Generally larger grain can be sand clast. Matrix material more than 15%.