The way that this form of metamorphism works is that rocks are scraped against each other causing them to be ground into a powder. Then this powder is reformed due to the pressure in the zone and the heat caused by friction of the two rock surfaces.ocks are classified by the processes under which they were formed. The differences in formation account for variations in the appearance of the rocks and, with some practice, you can learn to recognize the different types by sight. Metamorphic Rocks are rocks that have changed form due to heat and pressure.
Growing 4 to 6 feet in height and width, both mophead and lacecap hydrangeas can be used as specimen plants, in mixed borders or in mass plantings. The mountain hydrangea (H. macrophylla subsp. serrata) is a subspecies of bigleaf hydrangea that has slightly smaller leaves and flowers (see image at right).
For instance, growing a hydrangea in soil with a pH level of about 6.0 - 6.2 will produce a plant with pink flowers, while lowering the pH level to about 5.2 - 5.5 will produce a plant with purple/blue flowers.