Shale exposed to great pressure and heat transforms into metamorphic rocks. The specific type of metamorphic rock depends on the intensity of the pressure and heat, as well as the original composition of the shale.

Here are some possibilities:

* Slate: This is formed when shale undergoes low-grade metamorphism. It has a fine-grained, layered texture and is often used for roofing and flooring.

* Phyllite: With increasing pressure and heat, slate transitions into phyllite. It has a slightly more pronounced layering and a sheen due to the presence of mica minerals.

* Schist: Under higher metamorphic conditions, phyllite transforms into schist. This rock is characterized by its distinct, coarse-grained layering with visible mica flakes.

* Gneiss: Gneiss represents the highest grade of metamorphism of shale. It has a banded appearance due to the separation of minerals into distinct layers.

So, while shale itself doesn't directly transform into a specific rock type, the intense pressure and heat cause it to metamorphose into various metamorphic rocks like slate, phyllite, schist, or gneiss.