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
Slate (magazine) working on a long, ambitious project of some sort," Plotz said in an interview. "Slate" introduced a paywall-based business model in 1998 that attracted up 20,000 subscribers but was later abandoned. A similar subscription model was implemented in April 2001 by "Slate"s independently owned competitor, Salon.com. "Slate" started a daily feature ”Today's Pictures” on November 30, 2005, which featured 15-20 photographs from the archive at Magnum Photos that share a common theme. The column also features two flash animated ”Interactive Essays” a month. "Slate" was nominated for four digital National Magazine Awards in 2011 and won the NMA for General