does anyone know why this happened to my sourdough loaf?
This type of sour dough is like a Ciabatta with a higher hydration value. When I make a Ciabatta, the 2nd rise is what is important. After the 2nd rise, I flip the dough upside down on a cookie sheet with parchment paper. I then dimple the dough with my fingers almost right through to the bottom. This disperses the gas for a more even rise. The gas pocket is a result of the hydration value.
forgot the salt looks like :)