Where I walk weekly (Del Monte Beach in Monterey, California), I beachcomb for shells, glass, and particularly stones. Most of what gets cast up is rather dull and uninteresting - gray and black rocks of no particular noteworthiness.

However, there are always at least some gemlike little rocks of various hues: yellow, green, white, orange, caramel and chocolate brown, reddish-brown, pale blue, etc. These are often well-worn and oval.

Every foray differs from the previous (quantity and "quality" of what gets thrown onto the strand by the relentless waves), yet certain stretches tend to have a consistent concentration of these gemlike stones.

I reckon quantity is determined by the strength of the tide, so full moon and new moon can be expected to produce a good harvest.

Storms would be another factor, obviously.

I assume when certain deposits are washed up, it's because the waves are "digging deep" in certain locations on the ocean floor where these types of stones tend to be concentrated.

So I can predict in a small way what portion of the beach will produce which type of stone; is it possible to predict with a greater certainty which area of the bay is going to get scooped out based on lunar phases and weather patterns?

Basically I'm wondering why certain spots on the ocean floor are "reaped" on one occasion but not on another. Is it such a complicated interplay that it can't possibly be predicted?

1 Answer 1


The ocean floor is almost entirely undisturbed by waves - What you are finding comes from the coastal littoral.

You can gain some general estimates from direction and strength of storms, but the movement of the sea is chaotic overall. Oceanographers can make general statistical predictions, but there is just too much to track.

Read this article on the 28,000 ducks that were lost in the Pacific 24 years ago to gain some insight into just how variable movement of water is.


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