You wrote: "Emulsified water and oil hardly seem to me to fit the definition of disorder. The molecules are still distinct and separate. (Believe me when I say I have no expertise in any of this.)
"Looks to me like following similar reasoning, the erosion of varied sizes of mountains, boulders, rocks and pebbles into a smooth beach of evenly sized particles of sand is the creation of order."
Reply: Oh, I do believe you--that you have no expertise in any of this! You obviously do not understand what emulsions are. Do the experiment in your kitchen, and then explain why the water and oil spontaneously separate. Use the 2nd law, and explain why we have order appearing FROM DISORDER.
You posed an interesting question--why do sandy beaches have a distribution of particle sizes within a narrow range. What do you think is the answer? Is "Intelligent design/ intervention" for each grain of sand an answer?