The Black Shoals desperately honorsand protects. As a metaphor, the shoal cannot be reduced to the ocean, theshore, or an island. It always has the potential to be something else thatcannot be known in advance.
I think the author challenges Brathwaite's perception of the older black woman sweeping the sand outside of her home. The author incorporates the black shoal as a representation of the lady performing her morning routine. The sand travelling to her house was also once on shore, now reaching the Land including her house; this completes the black shoal.