Bull of Heaven

Gilgamesh and Enkidu fight the Bull of Heaven - what is the bull? scale, ability, figure, proportion, figurative or literal? It splits the earth several times so deeply people fall into the crevices. The heros fight it, kill it, quarter it and throw the tail at Inanna. How does the bull break the earth? How does it fly down from heave? How do Inanna and her father fly?