In permaculture we look to nature as a teacher to show us how to biomimic it’s design to create life rich systems. There is a hierarchy of soil creation in nature. The richest regions of life on earth can be found in the shallow marines. These are brakish in characteristic meaning they have a mixture of both salty and fresh water. This makes for a very unique set of circumstances which is the edge of where fresh water from places such as rivers meet salty water from such places as gulfs or a seas. Shallow marines are often found at the mouths of river deltas where you can also find deposition systems such as mangroves, which are teaming with life, and tropical estuaries which are THE richest ecosystems on the planet.
When building an aquatic system (aquatic systems produce more life than land based systems) it is beneficial to look to shallow marines as a bench mark to what can be created in ponds, lakes, chinampas, fish tanks, or any aquatic system designed for food production.