Answer: Ultimately, a beach erodes because the supply of sand to the beach can not keep up with the loss of sand to the sea. Most sand is transported from inland via rivers and streams. The damming of most waterways in the US has thus prevented a major supply of sand from getting to our beaches.
It can't really be codominant since lowercase letters are recessive, and condomance needs 2 dominant alleles of a different types. So really it should be BB for blue, RR for red and BR for patchwork...
