Of the 3 main classes of rock, this one accounts for about 75% of all the exposed rocks on land
Most authors presently use the term "mudrock" to refer to all rocks 
composed ... Chemical sedimentary rock forms when mineral constituents in 
solution... [DOC] [TLE] Earth's crust - Simple English Wikipedia, the free encyclopedia [PAR] The crust is made up of different types of rocks: igneous, metamorphic, and ...