Answer: Heidi Doody. Heidi Doody was built by Margo Rose and had the voice of Norma MacMillan and Donna Miller. Heidi was introduced as a stranger who saved Buffalo Bob's life in Africa. Later, Heidi was adopted and became Howdy's sister.
The descending of rock layers at subduction zones causes metamorphism in two ways; the shearing effect of the plates sliding past each other causes the rocks coming in contact with the descending rocks to change. Some of the descending rock will melt because of this friction.
Thus, if we know the facies of metamorphic rocks in the region, we can determine what the geothermal gradient must have been like at the time the metamorphism occurred. This relationship between geothermal gradient and metamorphism will be the central theme of our discussion of metamorphism and plate tectonics.