As an Amazon Associate, I earn from qualifying purchases with no additional costs for you. Holes in rocks can be formed in strikingly different ways. Sometimes holes are a result of water erosion — the simplest and the most obvious way of holes formation. But you will be surprised to know that holes can be formed at the very first stages of rock solidification. Moreover, some holes in hard and almost indestructible rocks can be produced by small mollusks. Get on board! Holes can be found in all three types of rocks.
Holes can be secondary and created by weathering. Additionally, holes in beach pebbles are created by boring mollusks. Primary holes are created simultaneously with the volcanic rock formation because of the gas bubbles trapped during lava solidification. Swiss cheese-resembling cliffs on the seaside, boring mollusks and burrowing creatures, champagne corks… Do you see any connection?
After reading the following article, you will see the connection and will be able to explain a lot of intriguing things around. If you are interested in checking out the best rockhounding tools I recommend and use you can find them by clicking here Amazon link. Holes in rocks are a sign of the next stage of the rock cycle. Holes in rocks are usually a sign of rock weaknesses. Softer minerals and rock strata can be destroyed much faster than the harder ones.
In most cases, holes are the result of weathering and erosion. Such volcanic rocks like pumice and scoria receive their holes during the solidification of lava.
Different processes are responsible for holes formation. Holes are mostly indicators of rock weaknesses. However, sometimes holes are formed at the same time as a rock. Such holes can be considered an essential part of the rock and form a specific vesicular texture , as in the case with basalt. Holes can be formed simultaneously with rock or millions of years later. Different types of rock undergo different mechanisms of holes formation. Weathering, which is represented by water and wind erosion, the abrasive activity of waves, and the boring and burrowing activity of living organisms, create holes in rocks.
Holes in rocks can be also created simultaneously with rock solidification, as in the case of basalt, pumice, and scoria rocks. Simultaneously formed holes are typical for igneous volcanic rocks like basalt, scoria, pumice, and sedimentary rocks like sandstone and limestone. The tiny holes between the individual grains sand in sandstone rock are called pores. The pores in a rock collectively make up its porosity , which is an important property to know in groundwater, geotechnical studies, and petroleum geology.
Holes can be created millions of years later after the rock formation. These secondary holes are mostly caused by exogenic processes , mainly weathering and erosion. Almost perfectly round holes in rocks at the beach puzzle all rock lovers. However, inventive nature has an answer. Holes in rocks at the beach can be created in two ways.
The most common one is when holes are caused by boring sponges, burrowing worms, or mollusks, such as piddocks. These creatures produce almost perfectly round holes. The second cause of holes is water erosion, which wears weaker parts of the rock away. Stones, with a naturally occurring hole running through them, are known as hag stones. Holes can be caused in nature by boring sponges, burrowing worms, or mollusks, such as piddocks.
Piddocks — are the marine bivalve mollusks of the family Pholadidae. These rock boring bivalves effectively drill into the rock, which breaks off and erodes into cylinder shape holes a few centimeters across.
Piddocks live their lives inside that shelter and stick their siphuncles out to filter the seawater. Sometimes shells of bivalvia can be observed inside the holes.
What a pleasure it was to learn the answers to questions ive asked myself for years. Thank you x. You are most welcome, and thank you for your comment! Fascinating, I have seen loads of these sometimes with the paddock inside, never knew what caused the holes or how the little fellow got in there, thank you for such an informative article, I am constantly amazed by what is all around us.
So interesting, than you. Most welcome, Mary! I love finding them myself, and luckily the beaches around Scotland have lots of piddock-holed stones. Really glad you found it useful, and I hope you find lots more! For the last 25 years in southwest florida Venice,and Engelwood Florida Gilf of Mexico in the winter I have picked stones with holes.
I read I do not remember the name of the book in a southwest Florida nature book that some kind of a snail sits on the stones and secretes a solution of sorts which the sea and sand eventually bores a hole right through.
I have found different sizes from one inch to three by four inches. They make beautiful sculptures as well as natural jewelry. Thanks for your information on all of these wonderful natural gifts on this earth. We thread a piece of string through the hole and hang it by the door of the house to keep Witches away.
Thank you for sharing this information. So interesting. I never wondered what made those holes, which seems surprising. Or to hold a piece of incense. So much fun to consider. That is a good idea! I love how everyone around the world seems to be drawn to these rocks. Thank you for sharing! If anyone has more definite info, they are welcome to leave a comment! Yes there are many piddocks in fresh water , I have found many in Lake Michigan north of Chicago , I always called them holey stones ,or church rocks , Wow glad to know how those holes got there.
Thanks for the information. Thank you for sharing that, Craig! I agree that minus 9 sounds way too chilly to be at the beach! Hi, I find these in Maine in the Penobscot and Allagash rivers, far from the ocean. You are welcome to email photos to jo at thehazeltree. I love the holey rocks! I never knew how the holes got there.. I love collecting shells, when I see the tourist on the beach searching for shells, I like to stop and talk about shells. We get a lot of piddocks here we call them angel wings.
Tiny ones and big ones. They are fragile like potato chips. The bigger they are the stronger they are. I love learning about shells. I live in Galveston Island Texas. There is definitely something special about them. Thanks so much for your comment. I love your name for them — I might use that myself! I never knew this! Where I live in the middle of Canada was once covered by an inland sea 80 million years ago.
I have picked up alot of rocks much like you have pictured and never considered it the handy work of a creature rather than erosion or quirk of formation. Let me know if you come to any conclusions! There are many of these holey stones on the East Coast of England. Thank you for the interesting information. Glad that this was of interest! Plenty here on the west coast too, and I still love finding them even though I have lots already!
Kim, the Omars, in Michigan, of which you speak, are not these. Omars are a greywacke stone, from the Belcher Islands, transported via glactial activity. Thanks for the great article! That sounds amazing, Denni!
There are some big piddock-holed rocks down on the shore here in Argyll — it seems, the more you find, the more keep popping up! It sounds as if you have got a real treasure there. I was very interested to read about the illustrious history of piddocks when I wrote this article!
Thanks so much for your lovely comment! Thanks so much for this post! I live on Vancouver Island west coast of Canada and have a growing collection of interesting rocks from beach walks.
Many have holes and look amazingly similar to the ones you have pictured. Now I know how they came to be and they are even more interesting. Glad to hear that this post has helped to solve the puzzle of the holes!
Email Address. A snack bar for piddocks. Peeping piddock. Like this: Like Loading Like Tweet Pin It Linkedin. By: Jo Woolf Tags: American piddock , angelwing , Atlantic , beachcombing , beaches , bivalves , boring molluscs , boring shellfish , clam , Common Piddock , Lismore , marine life , molluscs , natural history , nature , pebbles , pebbly beach , Pholas , Pholas dactylus , piddock holes , piddocks , rocks , Scotland , sea shells , sea shore , seashells , shellfish , shore life , wildlife.
Jo Woolf I live by the sea in Argyll, Scotland, and I write about the landscape, its wildlife and wonderful history. Jo Woolf August 21, at pm. Julio July 5, at pm. Jo Woolf July 6, at am. Kim July 6, at pm. Jo Woolf July 6, at pm. S Dymoke July 7, at pm. Jo Woolf July 8, at am. PigLove August 21, at pm Reply. PigLove August 21, at pm. Carmen Mandelc August 21, at pm Reply. August 21, at pm Reply. August 21, at pm. Jo Woolf August 22, at am. Scott Marshall August 21, at pm Reply.
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Jo Woolf May 16, at am. Ed May 16, at am Reply. Pam Sequeira May 16, at pm Reply. Jo Woolf May 16, at pm. Pam Sequeira May 16, at pm. Sharon King May 16, at pm Reply. Linda May 16, at pm Reply. Diane Bailey Beger May 21, at pm Reply.
Jo Woolf May 21, at pm. Jo Woolf June 26, at am. Hecataine June 25, at pm Reply. Fiona June 27, at pm Reply. Jo Woolf June 27, at pm. Jo Woolf August 18, at pm. Terry Gard November 16, at pm Reply. Jo Woolf November 16, at pm. William Grange March 20, at pm Reply. Jo Woolf March 21, at am. Walls between holes are more resistant to weathering because they tend to stay drier.
How clam borings come to be located many feet above sea level is a story for a future column. Don Garlick is a geology professor retired from HSU. He invites any questions relating to North Coast science, and if he cannot answer it he will find an expert who can.
E-mail dorsgarlick yahoo. Tags: Garlick's Notebook , science. More Garlick's Notebook ». Showing 1- 1 of 1. Add a comment. Switch to the mobile version of this page. North Coast Journal.
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