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.
Rocks can be metamorphosed simply by being at great depths below the Earth's surface, subjected to high temperatures and the great pressure caused by the immense weight of the rock layers above. Much of the lower continental crust is metamorphic, except for recent igneous intrusions.