exposure to pressure is a kind of condition & exposure to heat is a kind of condition ->  exposure to heat and pressure are kinds of conditions  exposure to heat and pressure are kinds of conditions & if something is formed by certain conditions then that something will likely be formed in an area with those conditions ->  if something is formed by being exposed to heat and pressure then that something will likely be formed in an area with heat and pressure  great can mean high in value & extreme means very high in value ->  extreme can mean great  extreme can mean great & metamorphic rocks are formed by rocks being exposed to extreme heat and pressure ->  metamorphic rocks are formed by being exposed to great heat and pressure  if something is formed by being exposed to heat and pressure then that something will likely be formed in an area with heat and pressure & metamorphic rocks are formed by being exposed to great heat and pressure ->  metamorphic rock will likely be formed in an area with great heat and pressure  great can mean high in value0 & underground means buried deep below other rocks ->  as rocks are buried deeper underground, the pressure / heat on that rock will increase  as rocks are buried deeper underground, the pressure / heat on that rock will increase & deep means great in depth ->  if a rock is buried deep underground then the pressure / heat on that rock will be great  metamorphic rock will likely be formed in an area with great heat and pressure & if a rock is buried deep underground then the pressure / heat on that rock will be great ->  metamorphic rock is likely to be formed in an area deep underground  metamorphic rock is likely to be formed in an area deep underground & a site is a kind of area -> metamorphic rock is likely to be formed in a site deep underground