When granite and shale are subjected to intense heat and pressure, they can transform into a variety of metamorphic rocks. Here's a breakdown of how each rock changes:

Granite:

* Under moderate pressure and heat: Granite can transform into gneiss, a metamorphic rock characterized by its distinct banding of light and dark minerals.

* Under extreme pressure and heat: Granite can be further metamorphosed into migmatite, a rock that exhibits a mixture of igneous and metamorphic characteristics, with bands of melted granite and recrystallized minerals.

Shale:

* Under moderate pressure and heat: Shale transforms into slate, a fine-grained metamorphic rock that splits easily along flat planes.

* With increasing pressure and heat: Slate can transition into phyllite, a rock with a slightly coarser grain size and a sheen on its surface.

* Under even more intense conditions: Phyllite transforms into schist, a metamorphic rock with larger, easily recognizable mineral grains.

* At the highest pressure and heat levels: Schist can be further metamorphosed into gneiss, which is a common end-product for both granite and shale under extreme conditions.

Important Note: The specific metamorphic rock formed depends on the exact temperature, pressure, and composition of the original rock.

Here's a visual representation:

Granite:

Granite -> Gneiss -> Migmatite

Shale:

Shale -> Slate -> Phyllite -> Schist -> Gneiss

This transformation process is called metamorphism, and it plays a significant role in the Earth's geological cycle.