Pebbles with holes

[lillylemon]

I found a pebble last week on the beach which has a hole in it. The hole doesn't go right through the bebble, only about half way and is about the diameter of a pencil. What could have caused it?

[rsvp]

the action of the force of the sea against a stone

[Graham-W]

Could be piddocks that cause them. No, really!
See here: http://en.wikipedia.org/wiki/Pholadidae

[jomifl]

It depends on the type of mineral that the pebble is composed of. If it is limestone then most likely a piddock hole, If it is flint then it could be the remains of a fossil sponge that has been eroded by wave action. These in their whole state are usually a roughly spherical hollow flint with the inside encrusted with crystals.

[annieigma]

I was walking along under beachy head in sussex and found those little rocks that,when bashed open, look like diamonds. Further on by the light house there was an enormous chalk fossil of some sort of centipede type animal or perhaps a very large sea shell type thing. the rock, it looked like chalk, was about a metre long and the detail was perfect. there are always rock falls there so it may have come down the night before, as this was early morning ( we were winkling)
unfortunately the tide was on the turn and the only way back up to land was at burling gap, via a rope ladder, so we legged it. But, getting back to the question, there were also stones with holes or partial holes through them, some appeared to be flints that had been rolled by the sea action and were either round or circular flat shaped. Some had small crustacian remains embedded in the hole,you could spend hours on a beach with rocks and stones, so much natural history.

[heathfield]

Minerals can accumulate in small pockets within the rock as the rock is formed. Later, these small pockets may dissolve or erode more quickly than the surrounding stone, leaving a hole. Examples can be found in many different types of rock.