Metamorphic rock the foliation is called "gneissosity"), granoblastic (includes granulite, some marbles and quartzite), and hornfelsic (includes hornfels and skarn). Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by
Now That's What I Call Rock of "Now" features contemporary pop acts with rock roots and takes a "big-tent" approach to the genre. Cliff Chenfeld, co-owner of the Razor & Tie and a consultant for "Now That’s What I Call Rock", feels "most music listeners are pretty open" and this release "is a means of introducing some of those bands to that broader audience who I think would embrace it." The compilers of the set wanted to avoid defining what rock music is in 2016, but instead tried to give what people think it is, "as opposed to using a term for rock that might have