1.
On the surface, weathering and erosion break down the igneous rock into pebbles, sand, and mud, creating sediment, which accumulates in basins on the Earth's surface. ... If it becomes buried deep enough within the crust to be subjected to increased temperature and pressure, it may change into metamorphic rock.
2.
Granite is an igneous rock that forms when magma cools relatively slowly underground. It is usually composed primarily of the minerals quartz, feldspar, and mica. When granite is subjected to intense heat and pressure, it changes into a metamorphic rock called gneiss.
